designing out waste a design team guide for civil engineering part 2 (interactive) 0

Part 2: tECHNICaL SOLUtIONS

Designing out Waste:a design team guide for

civil engineering

LESS WaStE, SHarPEr DESIGN

Halving Waste to Landfill

Halving Waste to Landfill

Demolition and site clearance 32

Fencing and safety barriers 36

Drainage 40

Earthworks including landscaping 49

Subbase and hydraulically bound materials (HBM) 66

Pavements and footways – bituminous 71

Pavements – concrete 86

railways – ballast, sleepers and track 93

Piling, retaining walls and tunnels 103

Structures – concrete 111

Structures – steel 117

ancillary structures 121

appendix C references and resources 125

Part 2: Technical SolutionsUsing this guide 4

Contents

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technical Solutions

This part of the guide describes how the Designing out Waste principles can be applied to specific elements and components of civil engineering projects by means of specific technical solutions. Quick reference look-up tables and summary sheets for the technical solutions are provided.

This document contains an extensive set of technical solutions that represent leading thinking in the profession; however it is a design guide not a manual of civil engineering. The final decision on which design options are selected for a specific project will depend on a number of factors, including cost, programme, buildability, engineering aspects, disruption to users, health and safety aspects and availability of materials and resources as well as waste.

Using this guide

Designing out Waste: a design team guide for civil engineering – is presented in two parts:

1. Design Guide provides the case for action, the principles of Designing out Waste, and a structured approach to implementing it in civil engineering projects.

2. technical Solutions provides technical information on an extensive series of design solutions and engineering techniques which can be used to improve materials resource efficiency in civil engineering projects.

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Designing out Waste - Part 2: Technical Solutions 76 Designing out Waste - Part 2: Technical Solutions

Look-up tables

The technical solutions and their applicability to different project types, new construction or maintenance/ refurbishment projects, are shown in the following look-up tables. A number of generic project types are used to illustrate how the technical solutions can be applied, and a brief description of the project types is given overleaf. Civil engineering covers a wide range of project types, so the list is not exhaustive and is intended as a guide only. Categories not shown are not excluded from the application of the Designing out Waste principles.

The following symbols are used in the look-up tables to indicate potential applicability:

✓ = the solution can be applied in this type of project; it is permitted in standards and specifications and there is experience of its use.

~ = the solution may be applicable, but may not be widely used or there may be restrictions on its use in specifications.

✗ = the solution is not applicable in this type of project.

technical solution summary sheets

Summary sheets for each of the technical solutions presented in the look-up tables are provided. The summary sheets are grouped under the following set of construction elements, but are not separated into new construction and maintenance/ refurbishment. Details of the applicability of each technical solution are given in the individual summary sheets.

Construction elements:

Demolition and site clearance; Fencing and safety barriers; Drainage; Earthworks including landscaping; Subbase and hydraulically bound materials (HBM);

Pavements and footways – bituminous; Pavements – concrete; Railways – ballast, sleepers and track; Piling, retaining walls and tunnels; Structures – concrete; Structures – steel; and

Ancillary structures.

Details of the applicability of each technical solution are given in the individual summary sheets. Each technical solution summary sheet includes:

What is it? A brief description of the technical solution and which Designing out Waste principle(s) applies;

Why should I use it? A summary of the main benefits in terms of reducing waste, reducing cost, effect on programme, reducing overall material use, increasing recycling content and reducing CO2 impact;

Where can I use it? Brief summary of suitable project types and applications including case studies with references/ links; and

How do I apply it? References to key documents which should be consulted if you wish to pursue the technical solution. A brief indication of potential problems and things to watch out for is also given.

A full list of key references for all the technical solutions is included in Appendix C.

Designing out Waste tool for Civil Engineering

The potential benefits that can be obtained from technical solutions selected can be explored in more detail by using the Designing out Waste Tool for Civil Engineering available at www.wrap.org.uk/designingoutwaste

The tool gives preliminary estimates of the quantitative benefits in terms of reduction in waste, cost saving and reduction in carbon footprint for each solution, enabling a comparison to be made between a range of potential solutions to identify the best options for a particular project.

Description of project types

Project type Description

Highways Earthworks, drainage, pavements and structures for all classes of road, from motorways to minor roads, footways and cycle tracks, surface works associated with tunnels.

airports Runways, taxiways, aprons, drainage and access roads. Buildings not included.

Utilities – streetworks Works associated with placing apparatus or inspecting, maintaining, adjusting, repairing, altering or renewing apparatus, changing the position of apparatus or removing it, or works required for or incidental to any such works (including, in particular, breaking up or opening the street, or any sewer, drain or tunnel under it, or tunnelling or boring under the street).

Utilities – infrastructure Capital works such as treatment works, pumping stations, outfalls, power stations, substations, wind turbines, access roads and surface works associated with tunnels.

tunnels Underground works only for tunnels large enough to require a tunnel boring machine or similar. All other aspects are dealt with under the relevant project types, e.g. utilities, highways.

railways Earthworks, ballast, tracks, drainage, signals, goods and engine yards, access roads, surface works associated with tunnels.

Ports and harbours Piers, wharves, jetties, crane systems, heavy duty pavements, railways, parking areas, access roads.

Bridges & structures Only covers the structural aspects, all other aspects are dealt with under the relevant project types.

Development site infrastructure

Roads, drainage, services and groundworks for greenfield and brownfield sites, including contaminated land.

Flood defence Embankments, sheet pile walls, retaining walls, drainage improvements and erosion prevention measures.

Coastal protection Revetments, rock armour and other erosion prevention measures.

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Using this guide

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http://www.wrap.org.uk/designingoutwaste


technical solution look-up table: new construction – page 1

technical solution

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Demolition and site clearance

Process demolition material for use on site ✗ ✗ ✓ ✓ ✗ ✗ ✓ ✓ ✓ ✗ ✗

Send demolition material off site for processing into recycled aggregate

✗ ✗ ✓ ✓ ✗ ✗ ✓ ✓ ✓ ✗ ✗

Send vegetation off site for PAS100 compost manufacture ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Fencing and safety barriers

Steel with high recycled content ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✗ ✗ ✗

Recycled aggregate in concrete barriers ~ ~ ✗ ✗ ✗ ✗ ~ ~ ✗ ✗ ✗

pfa and ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Drainage

Pipes with high recycled content ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Process street works arisings for pipe bedding and trench backfill

✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Manufacture Hydraulically Bound Materials (HBM) from excavation arisings

✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Foamed concrete with high recycled content for trench backfill ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✗ ✗

Trenchless technology to pipe installation ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✗ ✗

Tyre-derived rubber materials in combined surface and ground water filter drains

✓ ✓ ✗ ✗ ✗ ✗ ✓ ✗ ✓ ✓ ✗

SUDS and related techniques ✓ ✓ ✓ ✓ ✗ ~ ✓ ✗ ✓ ✓ ✗

Precast manholes, gullies, service ducts and cable troughing ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Key: ✓ Solution can be used in this application ~ It may be possible to use the solution in this application ✗ The solution is not suitable for this application See the technical solution summary sheets for details.

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technical solution

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Earthworks including landscaping

Balance cut/fill quantities ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓

Lime or cement to dry out wet fill ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓

Geosystems to enable steeper side slopes ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Treat unsuitable materials for landscaping and soils manufacture

✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Manufacture topsoil using PAS100 compost ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Remediation of contaminated soils ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✗ ✗

Stabilise or isolate contaminated soils ✓ ~ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✗ ✗

Geosystems to enable soft foundation soils to remain in-situ ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ~ ✓ ~

Ground improvement techniques to enable soft foundation soils to remain in-situ

✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ~

Tyre bales or other lightweight fill to enable soft foundation soils to remain in-situ

✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Recycled aggregates and/or HBM for working platforms ✓ ✓ ✗ ✓ ✗ ~ ✓ ~ ✓ ✓ ✓

Incorporate working platform into permanent works ~ ~ ✗ ✓ ✗ ~ ✓ ~ ✓ ✓ ~

Lime or cement to stabilise soils in-situ for use as capping ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Recycled aggregates for capping, structural backfill and slope repairs

✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Geosynthetic and lime/cement with original soil for slope repairs ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Tyre bales for slope repairs ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Vegetation to improve slope stability ✓ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✓ ✓ ~


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technical solution

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Subbase and hydraulically bound materials (HBM)

Treat existing soil to make HBM subbase/ballast ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Recycled/secondary aggregates to make HBM subbase ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Recycled/secondary aggregates as unbound subbase ✓ ✓ ✓ ✓ ✗ ~ ✓ ✗ ✓ ✓ ✓

Geogrids/geotextiles to reduce thickness of subbase ✓ ✓ ~ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Pavements & footways - bituminous

In-situ hot recycling of asphalt ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

In-situ cold recycling of asphalt ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

On site hot recycling of asphalt ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Ex-situ cold recycling of asphalt ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Reclaimed asphalt in base and binder course ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Reclaimed asphalt in surface course ✓ ~ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Secondary aggregates in base, binder and surface course ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Secondary aggregates in surface course ✓ ~ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Secondary aggregates in cold asphalt mixtures ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Reclaimed asphalt from other site in cold mixture ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Warm and semi-warm asphalt to reduce energy ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Collect and reuse chippings in surface dressing ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Retexturing asphalt pavement surfacing ✗ ✗ ✗ ✓ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Reclaimed asphalt in unbound subbase or capping off site ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Geogrids/geotextiles to reduce thickness of base ✓ ✓ ~ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

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14 Designing out Waste - Part 2: Technical Solutions Designing out Waste - Part 2: Technical Solutions 15


technical solution

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Pavements – concrete

Crack and seat with overlay for repairs ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Saw cut and seal with overlay for repairs ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Recycled aggregate in pavement concrete ✓ ✓ ~ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Secondary aggregates in pavement concrete ~ ~ ~ ~ ✗ ✗ ~ ✗ ~ ~ ~

pfa or ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Cold recycling of concrete and cement bound pavement layers (in-situ and ex-situ)

✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

railways – ballast, sleepers and track

Treat existing soil to make HBM subbase/ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Recycled and secondary aggregates to make HBM subbase/ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Recycled/secondary aggregates as unbound ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Geogrids/geotextiles to reduce thickness of ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

pfa or ggbs as cement replacement materials ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: containing recycled aggregate ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: containing secondary aggregate ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: recycled plastic ✗ ✗ ✗ ✗ ✗ ✓ ✗ ✗ ✗ ✗ ✗

Steel with high recycled content ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗


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Piling, retaining walls and tunnels

Precast concrete rather than cast in-situ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Precast tunnel lining segments on site ✗ ✗ ✗ ~ ✓ ✗ ✗ ✗ ✗ ~ ✗

Recycled/secondary aggregates in concrete ~ ~ ✗ ~ ~ ~ ~ ~ ~ ~ ~

Reuse of piled foundations ✓ ✗ ✗ ~ ✗ ✗ ✓ ✓ ✓ ~ ~

Plastic sheet piling ✓ ✗ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Steel with high recycled content ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

pfa or ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Recycled aggregates and/or HBM for working platforms ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Incorporate working platform into permanent works ~ ~ ✗ ✓ ✗ ~ ✓ ~ ✓ ✓ ✓


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Structures – concrete

Precast concrete rather than cast in-situ ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Assemble structures on site and move into place ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓ ✗ ~ ~

Recycled/secondary aggregates in concrete ~ ✗ ✗ ~ ✗ ~ ~ ~ ~ ~ ~

pfa or ggbs as cement replacement materials ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Gabions or other geosystems for soil retention and erosion protection

✓ ✓ ✗ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Structures – steel

Assemble structures on site and move into place ✓ ✓ ✗ ~ ✗ ✓ ✓ ✓ ~ ~ ✗

Steel with high recycled content ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Lightweight bridge decks ✓ ✓ ✗ ✓ ~ ✓ ✓ ✓ ~ ✓ ✓

ancillary structures

Precast concrete rather than cast in-situ ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

pfa or ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Reclaimed bricks or bricks with high recycled content ✓ ~ ~ ✓ ✗ ✓ ✓ ✓ ✓ ~ ~


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technical solution look-up table: maintenance/refurbishment – page 1

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Process demolition material for use on site ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗


✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Send vegetation off site for PAS100 compost manufacture ✓ ✓ ✗ ✗ ✗ ✓ ✓ ✗ ✓ ✓ ✓


Steel with high recycled content ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✗ ✓ ✓

Recycled aggregate in concrete barriers ~ ✗ ~ ~ ✗ ✗ ~ ~ ✗ ~ ~

pfa and ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓

Drainage

Pipes with high recycled content ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓


✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓


✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Foamed concrete with high recycled content for trench backfill ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Trenchless technology to pipe installation ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Tyre-derived rubber material in combined surface and ground water filter drains ~ ~ ✗ ✗ ✗ ✗ ✓ ✗ ✓ ✓ ~

SUDS and related techniques ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Precast manholes, gullies, service ducts and cable troughing ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓


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Balance cut/fill quantities ✓ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Lime or cement to dry out wet fill ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Geosystems to enable steeper side slopes ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓


✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Manufacture topsoil using PAS100 compost ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Remediation of contaminated soils ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Stabilise or isolate contaminated soils ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Geosystems to enable soft foundation soils to remain in-situ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗


✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗


✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Recycled aggregates and/or HBM for working platforms ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Incorporate working platform into permanent works ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Lime or cement to stabilise soils in-situ for use as capping ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗


✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Geosynthetic and lime/cement with original soil for slope repairs ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Tyre bales for slope repairs ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✓

Vegetation to improve slope stability ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗


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technical solution

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Treat existing soil to make HBM subbase/ballast ✓ ✓ ✗ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Recycled/secondary aggregates to make HBM subbase ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Recycled/secondary aggregates as unbound subbase ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Geogrids/geotextiles to reduce thickness of subbase ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✗ ✓ ✓ ✗

Pavements & footways - bituminous

In-situ hot recycling of asphalt ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

In-situ cold recycling of asphalt ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

On site hot recycling of asphalt ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Ex-situ cold recycling of asphalt ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Reclaimed asphalt in base and binder course ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Reclaimed asphalt in surface course ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Secondary aggregates in base, binder and surface course ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Secondary aggregates in surface course ✓ ~ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Secondary aggregates in cold asphalt mixtures ✓ ~ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Reclaimed asphalt from other site in cold mixture ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Warm and semi-warm asphalt to reduce energy ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Collect and reuse chippings in surface dressing ✓ ✗ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

Retexturing asphalt pavement surfacing ✓ ✗ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

Reclaimed asphalt in unbound subbase or capping off site ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✓

Geogrids/geotextiles to reduce thickness of base ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✓ ✗

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Crack and seat with overlay for repairs ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

Saw cut and seal with overlay for repairs ✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

Recycled aggregate in pavement concrete ✓ ✓ ~ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗

Secondary aggregates in pavement concrete ~ ~ ✗ ~ ✗ ✗ ✓ ✗ ✓ ✗ ✗

pfa or ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗


✓ ✓ ✗ ✓ ✗ ✗ ✓ ✗ ✓ ✗ ✗


Treat existing soil to make HBM subbase/ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Recycled and secondary aggregates to make HBM subbase/ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Recycled/secondary aggregates as unbound ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Geogrids/geotextiles to reduce thickness of ballast ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

pfa or ggbs as cement replacement materials ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: containing recycled aggregate ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: containing secondary aggregate ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗

Railway sleepers: recycled plastic ✗ ✗ ✗ ✗ ✗ ✓ ✗ ✗ ✗ ✗ ✗

Steel with high recycled content ✗ ✗ ✗ ✗ ✗ ✓ ✓ ✗ ✗ ✗ ✗


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Precast concrete rather than cast in-situ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Precast tunnel lining segments on site ✗ ✗ ✗ ~ ✓ ✗ ✗ ✗ ✗ ✗ ✗

Recycled/secondary aggregates in concrete ✗ ✗ ✗ ✗ ✗ ✗ ✗ ~ ✗ ✗ ✗

Reuse of piled foundations ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Plastic sheet piling ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✗


pfa or ggbs as cement replacement materials ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

Recycled aggregates and/or HBM for working platforms ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✓ ✗ ✗ ✗

Incorporate working platform into permanent works ✗ ✗ ✗ ✗ ✗ ✗ ✗ ✓ ✗ ✗ ✗

Gabions or other geosystems for soil retention and erosion protection ~ ✗ ✗ ~ ✗ ~ ~ ~ ~ ~ ~


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Assemble structures on site and move into place ✗ ✗ ✗ ~ ✗ ✗ ✗ ✗ ✗ ✗ ✗

Recycled/secondary aggregates in concrete ~ ~ ~ ~ ✗ ~ ~ ~ ~ ~ ~


Gabions or other geosystems for soil retention and erosion protection ~ ✗ ✗ ~ ✗ ~ ~ ~ ~ ~ ~

Structures – steel

Assemble structures on site and move into place ✗ ✗ ✗ ~ ✗ ✗ ✗ ✗ ✗ ✗ ✗


Lightweight bridge decks ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~




Reclaimed bricks or bricks with high recycled content ✓ ✓ ✓ ✓ ✗ ✓ ✓ ✓ ✓ ✓ ✓


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This section includes summary sheets for the following technical solutions:

Process demolition material for use on site;

Send demolition material off site for processing into recycled aggregate; and

Send vegetation off site for PAS100 compost manufacture.

TECHnICAL SOLUTIOn: Demolition and site clearance

Process demolition material for use on site

application: Development site infrastructure, capital utilities, bridges and structures, airports, highways, other project types where demolition of existing buildings or structures is required.

Designing out Waste Principle: Design for Reuse and Recovery.

What is it?Material from the demolition of existing structures can be processed on site to provide recycled aggregates that can be used in the new construction.

Where can I use it?Recycled aggregates can be used in unbound applications such as drainage, pipe bedding, general fill, capping, and subbase.

How do I apply it?Relevant environmental permits/licenses and exemptions and planning permission must be in place; producing recycled aggregates on site may increase the noise from the demolition activities, which may cause problems in built-up areas.

A pre-demolition audit should be carried out to ensure maximum value is obtained from the demolition materials. Soft materials should be stripped out before demolition to avoid contamination of the recycled aggregates with timber, plastic, plasterboard and other unsuitable materials.

Production of recycled aggregates should be carried out in accordance with the WraP Quality Protocol for the production of aggregates from inert waste (available at www.aggregain.org.uk) to ensure the recycled aggregates meet the relevant standards and are fully recovered from waste.

The ICE Demolition Protocol can be used to track the recovery of materials from the demolition phase and their incorporation into the new construction. The WRAP guidance document the efficient use of materials in regeneration projects, available at www.wrap.org.uk/construction gives guidance on linking demolition and new build, including links to the ICE Demolition Protocol and Site Waste Management Plans.

Why should I use it? Waste reduction: maximising reuse of demolition material will minimise the amount that has to be sent to landfill.

Cost reduction: it will generally be cheaper to produce recycled aggregates on site than to import aggregates.

recycled content: increases the recycled content of the scheme.

Programme: time has to be allowed in the programme for demolition to maximise recovery of materials. This may save time in the construction phase as a supply of aggregates will be available on site.

Carbon footprint: reduced carbon footprint compared to sending material off site and importing aggregate.

Other environmental benefits: reduced traffic to and from the site, with associated reduction in congestion. Reduced resource depletion.

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www.aggregain.org.uk

www.wrap.org.uk/construction


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application: Development site infrastructure, capital utilities, bridges and structures, airports, highways, other project types where demolition of existing buildings or structures is required.


What is it?Material from the demolition of existing structures is sent to a nearby aggregate recycling plant where it is processed to provide recycled aggregates that can be used in the new construction or on other sites.

Where can I use it?Recycled aggregates can be used in unbound applications such as drainage, pipe bedding, general fill, structural backfill, capping, and subbase. Material produced at a high quality recycling plant may also be suitable for use in asphalt or low strength concrete.

How do I apply it?If it is not possible to process the demolition material on site because of lack of space, time, planning restrictions or other reasons, the demolition material should be sent to a nearby recycling plant where it can be processed into recycled aggregates. It will generally be possible to produce higher quality materials and a wider range of products at a fixed recycling plant; an example is the urban quarry facility operated by Coleman and co in Birmingham (case study available at www.aggregain.org.uk/case_studies/coleman_and.html

A pre-demolition audit should be carried out to ensure maximum value is obtained from the demolition materials. Soft materials should be stripped out before demolition to avoid contamination of the recycled aggregates with timber, plastic, plasterboard and other unsuitable materials.

Production of recycled aggregates should be carried out in accordance with the WraP Quality Protocol for the production of aggregates from inert waste (available at www.aggregain.org.uk) to ensure the recycled aggregates meet the relevant standards and are fully recovered from waste.

The ICE Demolition Protocol can be used to track the recovery of materials from the demolition phase and their incorporation into the new construction. The WRAP guidance document the efficient use of materials in regeneration projects, available at www.wrap.org.uk/construction gives guidance on linking demolition and new build, including links to the ICE Demolition Protocol and Site Waste Management Plans.

Why should I use it? Waste reduction: maximising reuse of demolition material will minimise the amount that has to be sent to landfill.

Cost reduction: recycled aggregates will generally be cheaper than primary aggregates, especially in urban areas.


Programme: saves time during the demolition phase compared to processing the material on site.

Carbon footprint: reduced emissions compared to use of primary aggregates if recycling plant is close to the demolition site compared to source of primary aggregates.

Other environmental benefits: reduced noise and dust compared to processing material on site, but greater transport and associated congestion, noise and vibration. Reduced resource depletion.


Send vegetation off site for PaS100 compost manufacture

application: Landscaping of embankments and surrounds for buildings, highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Vegetation can be harvested on site either as part of a wider construction programme or during seasonal maintenance and sent off site for processing into a composted material. The compost can be used either at the same site or different locations. Use is normally by blending the compost with excavated soil to create a growing medium suitable for landscape establishment.

Compost provides the soil with basic levels of primary nutrients, such as nitrogen, potassium and phosphate, and a full range of minor nutrients.

Where can I use it?Vegetation can be obtained from site clearance or routine maintenance works. Ensure that invasive species such as hogweed and Japanese knotweed are not included.

Compost can be used in any application where it is required to establish the growth of various types of plant materials, including grasses, trees and shrubs.

How do I apply it?BSI PaS100 Publicly available Specification for composted materials (2005) ensures that compost produced is of the required standard. The Association for Organics Recycling (formerly the Composting Association) provides a certification scheme to ensure compliance with PAS100.

Extensive guidance is available on the WRAP website on the specification, the use of compost in brownfield regeneration, various case studies, and compost suppliers www.wrap.org.uk/compostingWhy should I use it?

Waste reduction: encourages the reuse of vegetation debris which would otherwise go to landfill.

Cost reduction: cost saving when compared with landfil disposal.

recycled content: 100% of vegetation debris is used.

Programme: no significant impact.

Carbon footprint: effective reuse and recycling of material has low carbon impact.

Other environmental benefits: aesthetic appearance of landscaped areas.

CONtENtS

www.aggregain.org.uk/case_studies/coleman_and.html

www.aggregain.org.uk/case_studies/coleman_and.html


www.wrap.org.uk/construction

www.wrap.org.uk/composting


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TECHnICAL SOLUTIOn: Fencing and safety barriers

Steel with high recycled content

application: Steel usage in the construction of highways, railways, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?In general there is a highly developed market for steel recycling and about 40% of the steel produced in the world is from recycling. This means that steel purchased for construction is likely to have a high recycled content and also that steel scrap arising on site will have a market value.

Steel can sometimes be reclaimed from site and put to direct use elsewhere without recycling.

Where can I use it?A high proportion of the steel used in the construction industry is already produced by recycling and there are generally no limitations on its use for any purposes.

All steel has a recycled content that varies between 10% and 100% and steel construction products are highly recycled. Recent research by the Steel Construction Institute has found that on average, 84% of UK’s construction steel is recycled and a further 10% reused.

The location of scrap merchants is readily researched on the internet and many websites are available to identify the nearest merchant to a particular UK postcode.

How do I apply it?The properties of the recycled steel are the same as those of the virgin material and the relevant British Standard specifications apply, e.g.

BS EN 10293:2005 Steel castings for general engineering uses.

BS EN 1559-1:1997 Founding. technical conditions of delivery. General.

BS EN 1559-2:2000 Founding. technical conditions of delivery. additional requirements for steel castings.

BS 4483:2005 Steel fabric for the reinforcement of concrete. Specification.

BS 4449:2005+a2:2009 Steel for the reinforcement of concrete. Weldable reinforcing steel. Bar, coil and decoiled product. Specification.

Why should I use it? Waste reduction: surplus or waste steel is normally sold to a scrap merchant for recycling.

Cost reduction: there is an associated cost recovery in the reclamation or recycling of steel.


Programme: no impact on programme.

Carbon footprint: the recycling process requires lower levels of resource than primary steel production.

Other environmental benefits: no waste generation. Reduced resource depletion.



Steel with high recycled content;

Recycled aggregate in concrete barriers; and

pfa and ggbs as cement replacement materials.

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recycled aggregate in concrete barriers

application: Construction of barriers for highways, railways, airports, utilities, harbours, docks and waterways, power generation and in development of brown- and greenfield sites.


What is it?At the moment the use of recycled concrete aggregate (RCA) is restricted to replacing coarse aggregate (>4mm) which precludes using most secondary aggregates. It is likely that suitable recycled concrete aggregate will be obtained from two main supply streams, either preconsumer waste from concrete production (precast or ready-mix concrete plants) or from demolition projects such as disused airfield structures, concrete framed or clad buildings. This ensures a relatively high quality material with < 5% brick and <1.0% impurities. Potential sources need to be able to provide sufficient quantity, consistent quality and usually be fairly close to the site where the concrete is to be used to ensure that the economics are viable.

Where can I use it?Safety, noise or security barriers are required in many applications. In some cases the barriers do not fulfil a structural purpose and the use of recycled concrete aggregates would not appear problematic although the overseeing engineer’s approval may still be required.

If the barrier is structural then reference should be made to the Technical Solution for the use of recycled aggregate/secondary aggregates in concrete. Recycled concrete aggregate is used as a partial replacement for primary aggregate and may be used in some applications up to 20% replacement level; however, it may be possible to use it up to the 60% replacement level with the overseeing engineer’s approval.

How do I apply it?Requirements for RCA for use in concrete in general are indicated in BS 8500-2:2006.

The SHW 1702.2 states that ‘Unless otherwise specified in Appendix 17/4, aggregates shall conform to the British Standards listed in 4.3 of BS 8500-2 except that recycled concrete aggregate (RCA) and recycled aggregate (RA) shall not be used’. However, this is dated May 2004 and conflicts with BA 92/07 dated May 2007.

Ba 92/07 is an Advice note in the Design Manual for roads and Bridges entitled the use of recycled concrete aggregate in structural concrete and provides information on the use of recycled concrete aggregate (RCA) as a replacement for coarse natural aggregates in structural grade concrete, www.standardsforhighways.co.uk/dmrb/vol2/section3/ba9207.pdf It encourages designers, contractors and concrete suppliers to consider the use of RCA.

The WRAP Research Report on Mix design specification for low strength concretes containing recycled and secondary aggregates provides guidance.

TRL PPr36 the use of recycled aggregate in structural concrete gives details of performance testing to determine engineering properties and durability.

Why should I use it? Waste reduction: the use of recycled aggregates reduces the quantity of waste sent to landfill.

Cost reduction: is often cheaper than using primary aggregates.


Programme: no significant impact on programme.

Carbon footprint: materials are usually available locally; therefore there is a saving on transport in lorry movements and fuel.

Other environmental benefits: reduced resource depletion.


pfa and ggbs as cement replacement materials

application: Construction of pavements, piles and retaining walls for highways, airports, utilities, harbours, docks and waterways, power generation and in development of brown- and greenfield sites, structural concrete for railways.


What is it?Concretes mixes where a proportion of the cement is replaced by pulverised fuel ash (pfa) or ground granulated blastfurnace slag (ggbs) result in reduced early-age thermal cracking in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pfa and ggbs have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pavement, pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.

Where can I use it?Pozzolans, like pfa and ggbs, have not gained popularity in fast track construction because of their slower strength gain at standard curing temperatures – however where time constraints do not exist they may produce a more durable and ultimately higher strength concrete. For example cement replacement is considered to enhance resistance to sulphate attack and to alkali-silica reaction. In addition there is some evidence that pfa or ggbs have the effect of reducing permeability to both gases and liquids so encouraging their usage in particular applications such as cut-off walls.

How do I apply it?The Concrete Society technical report 40 (1991) provided early guidance on the use of pfa and ggbs in concrete.

BS EN 197-1:2000 (Composition, specifications and conformity criteria for common cements) gives the allowable compositions of cements incorporating pfa or ggbs. The ICE specification for piling and embedded retaining walls permits the use of cement replacement materials provided they can be shown to have no deleterious effects.

Details of the recommended levels of replacement are given in the Specification for Highway Works, Clause 1001.3, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf and the associated notes for Guidance, Clause 1001.10, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf

network Rail - Model Clauses for Civil Engineering Works, Section 80, Structural Concrete, Clause 80.005 indicates the replacement levels allowed and applications for pfa, ggbs and microsilica.

Why should I use it? Waste reduction: the use of waste/by-product materials for cement replacement reduces the quantity of cement used.

Cost reduction: some reduction in the cost of procuring cement.

recycled content: replaces cement with alternative materials (e.g. up to 50% pfa and 65% ggbs in the SHW).


Carbon footprint: the use of waste/by-product materials saves in the embodied energy needed to manufacture cement.

Other environmental benefits: obviates need to dispose of waste materials by other means.

CONtENtS

http://www.standardsforhighways.co.uk/dmrb/vol2/section3/ba9207.pdf


http://www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf



http://www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf




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Drainage


Pipes with high recycled content;

Process street works arisings for pipe bedding and trench backfill;

Manufacture Hydraulically Bound Materials (HBM) from excavation arisings;

Foamed concrete with high recycled content for trench backfill;

Trenchless technology to pipe installation;

Tyre-derived rubber material in combined surface and ground water filter drains;

SUDS and related techniques; and

Precast manholes, gullies, service ducts and cable troughing.

TECHnICAL SOLUTIOn: Drainage

Pipes with high recycled content

application: Plastic pipes for drainage and buried services for highways, railways, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Most plastics can be recycled however the extent to which they are recycled depends upon both economic and logistic factors. As a valuable and finite resource, the optimum use for most plastic after its first use is to be recycled, preferably into a product that can be recycled again. The UK uses over 5 million tonnes of plastic each year of which an estimated 19% is currently being recovered or recycled.

Recycled plastic is widely used in mainstream construction products such as sewerage and drainage pipes, water pipes, and ducting.

Where can I use it?Pipes for sewerage, drainage, potable water and other buried services can be made from recycled PVC and polyethylene.

How do I apply it?The WRAP website gives information on recycling plastics for construction purposes www.wrap.org.uk/recycling_industry/information_by_material/plastics/index.html

Information on recycling is provides on the British Plastics Federation website www.bpf.co.uk/Sustainability/Plastics_recycling.aspx

The recycled plastic pipe must comply with the same British or European standard used for new pipe for the particular application being considered.

CE marking is used to indicate that the product conforms to the appropriate European Construction Products Directive.

Why should I use it? Waste reduction: less used plastic going to waste.

Cost reduction: it will generally be cheaper to recycle than using virgin material.


Programme: no impact on the construction schedule.

Carbon footprint: less oil used for plastic production and less energy consumed in production.

Other environmental benefits: good corrosion resistance to both fresh and salt water, and chemicals. Can be produced in aesthetically pleasing colours.

CONtENtS

http://www.wrap.org.uk/recycling_industry/information_by_material/plastics/index.html



http://www.bpf.co.uk/Sustainability/Plastics_Recycling.aspx

http://www.bpf.co.uk/Sustainability/Plastics_Recycling.aspx


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application: streetworks, capital utilities, airports, highways, ports and harbours, development site infrastructure in new construction and maintenance projects.


What is it?The processing of arisings from street works to be suitable for use as recycled aggregates for pipe bedding, surround, haunching and trench backfill on the same or other sites.

Where can I use it?Recycled coarse aggregate and recycled concrete aggregate complying with BS EN 13242 are permitted for pipe bedding in the Specification for Highway Works Series 500. Recycled aggregates are permitted for trench backfill (Class 8 Fill) in Series 600. The aggregates shall not contain more than 1% other materials (Class X). The Specification for Highway Works is available at www.standardsforhighways.co.uk/mchw/vol1/index.htm

Recycled aggregates are permitted for use under the Specification for the reinstatement of Highways provided they are meet the requirements of the Specification for Highway Works and any additional requirements imposed by the local Highway Authorities and Utilities Committee (HAUC). The Specification for the reinstatement of Openings in Highways is available at www.dft.gov.uk/pgr/roads/network/local/streetworks/cop/roo/prefacetoappendix29.pdf Links to the national and regional HAUCs are available at www.hauc-uk.org.uk/category/7/

How do I apply it?Production of recycled aggregates should be carried out in accordance with the WraP Quality Protocol for the production of aggregates from inert waste (available at www.aggregain.org.uk) to ensure the recycled aggregates meet the relevant standards and are fully recovered from waste.

Many utility companies are keen to increase the recycling of arisings from their street works and are working with their supply chain to ensure maximum recovery and reuse of the materials. A case study of Severn Trent’s closed loop system is available at www.aggregain.org.uk/case_studies/severn_trent.html

WRAP has produced a guidance document on recycled materials in trench reinstatement; this is available at www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html

Why should I use it? Waste reduction: material excavated to install new drainage or renew existing drainage can be processed and used on the same or other projects.

Cost reduction: processing arisings to make recycled aggregates will generally be cheaper than primary aggregates, especially in urban areas, as it eliminates the cost of disposal of the arisings.

recycled content: increases the recycled content of the project.

Programme: no effect; ‘closed loop’ systems ensure a constant supply of processed materials is available for backfill to new excavations.

Carbon footprint: reduced emissions compared to use of primary aggregates if recycling plant is close to the site compared to source of primary aggregates.




application: streetworks, capital utilities, airports, highways, ports and harbours, development site infrastructure in new construction and maintenance projects.


What is it?Binders and additives can be used to treat arisings from street works to render them suitable for use as backfill for excavations. These materials are categorised as Stabilised Materials for Fill (SMF) or non-flowable Structural Materials for Reinstatements (nFSMRs) under the Specification for the Reinstatement of Openings in Highways and can be used to treat a range of soil types to render them suitable for use as backfill. HBM can also be manufactured using recycled aggregates and binders.

Depending on their properties and the traffic level, SMFs and nFSMRs may be used for trench backfill, subbase and, for nFSMRs on lightly trafficked roads, for base and combined base and subbase.

Where can I use it?Stabilised Materials for Fills (SMFs) include materials derived from excavated spoil, virgin, secondary or recycled materials that have been improved by re-processing, regarding and/or by the inclusion of a cementitious, chemical or hydraulic binder. SMFs are generally non-flowable and require compaction. They may be prepared on site or at an off site facility and transported to site. Four classes of SMF may be produced, equivalent to different categories of backfill. SMFs are described in Appendix A9 of the Specification for the reinstatement of Openings in Highways, available at www.dft.gov.uk/pgr/roads/network/local/streetworks/cop/roo/prefacetoappendix29.pdf

HBMs are classed as non-flowable Structural Materials for Reinstatements (nFSMRs) in Appendix A9 of the Specification for the Reinstatement of Openings in Highways. HAUC advice Note 2009/01, available at www.hauc-uk.org.uk/publication/8, states that, “Hydraulic mixtures (HBMs) manufactured and used against the detailed requirements given in the Specification for Highway Works 800 series may be considered approved for national use without the need for trials with individual street and road authorities in accordance with Appendix A9 of the Specification.”

How do I apply it?The use of cementitious binders and additives enables a wide range of materials to be produced from trench arisings, including high strength/stiffness materials for use as base and subbase.

WRAP has produced a Quality Manual for Hydraulically Bound Mixtures and a guidance document on recycled materials in trench reinstatement; these are available at www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html

Why should I use it? Waste reduction: material excavated to install new drainage or renew existing drainage can be processed and used on other projects.

Cost reduction: reuse of the arisings eliminates the cost of disposal and replacing them with imported fill; this will generally exceed the cost of processing the materials for use as SMF.


Programme: no effect, as recycling operations are run on a ‘closed loop’ basis so material is always available to backfill new excavations.

Carbon footprint: reduced emissions compared to use of primary aggregates and disposal of the arisings to landfill.

Other environmental benefits: reduced transport compared to sending arisings to landfill and importing new aggregates; reduction in congestion in urban areas. Reduced resource depletion.

CONtENtS

www.standardsforhighways.co.uk/mchw/vol1/index.htm

www.standardsforhighways.co.uk/mchw/vol1/index.htm

http://www.dft.gov.uk/pgr/roads/network/local/streetworks/cop/roo/prefacetoappendix29.pdf



http://www.hauc-uk.org.uk/category/7/


www.aggregain.org.uk/case_studies/severn_trent.html

www.aggregain.org.uk/case_studies/severn_trent.html

www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html



www.dft.gov.uk/pgr/roads/network/local/streetworks/cop/roo/prefacetoappendix29.pdf



http://www.hauc-uk.org.uk/publication/8

http://www.hauc-uk.org.uk/publication/8

http://www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html




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Foamed concrete with high recycled content for trench backfill

application: Trench reinstatements in highways.


What is it?Foamed concrete is an Alternative Reinstatement Material (ARM), and is one of the materials allowed as a Structural Material for Reinstatements (SMR) for use in highway construction and maintenance. This is a cement bound material that is prepared off site, generally as a ‘prescribed mix’ at an approved mixing plant and under appropriate quality control procedures. It is a flowable material that does not require any compaction. Foamed concrete is an ARM but is approved for use without trials (HAUC 2002), and is consequently the most commonly used ARM. As such it is the only ARM detailed in the practical guide to reinstatements (HAUC 2006). Recycled and secondary aggregates can be used in foamed concrete.

Where can I use it?Foamed concrete can be used on highways as base on Road Type 1, 2, 3 or 4 (30msa or less), as subbase on all Road Types (up to 125msa) and other paving projects such as parking areas etc.

How do I apply it?Information on the use of foamed concrete for the reinstatement of highways is given in the HAUC Specification for the reinstatement of openings in highways, www.dft.gov.uk/pgr/roads/network/ local/streetworks/cop/roo/prefacetoappendix29.pdf This in turn makes reference to Clause 1043 of the SHW, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf However, there is a major difference in the age of the required strength range, 90 days in the HAUC spec and 7 days in the SHW.

Why should I use it? Waste reduction: reduces the amount of excavated material for disposal.

Cost reduction: it will generally be cheaper to reuse reclaimed material than use primary aggregate.


Programme: it will generally be significantly quicker to use excavated materials than to export them as waste and import suitable materials.

Carbon footprint: there will be a reduction in CO2 from less vehicle movements taking materials off site and importing suitable materials.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction in lorry movements. Reduced resource depletion.


trenchless technology for pipe installation

application: Installation, repair and renewal of services and drainage for buildings, highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.

Designing out Waste Principle: Design for Materials Optimisation.

What is it?Trenchless and minimum excavation technology covers a range of techniques for installing, replacing or renovating underground services (including cable/communications systems) while minimising or eliminating excavation from the surface. Techniques include pipe jacking/ microtunnelling, guided drilling/directional drilling, auger boring, impact moling/ rod pushing and pipe ramming. In-situ replacement techniques include pipe bursting or pipe eating, whilst renovation techniques include sliplining and other methods of lining.

Where can I use it?In congested urban environments where disturbance to the heavily trafficked infrastructure (roads, railways, pedestrian footways) is reduced and subsurface obstacles can be avoided. Trenchless techniques are frequently used through motorway and rail embankments to avoid disruption to users.

Selection of the trenchless technology method is site specific and particularly dependent on the ground conditions. For example auger boring is suitable for cohesive soils, whilst guided drilling and directional drilling is suitable for soft but diverse formations.

The suitability of repair and renovation techniques is dependent on the condition of the old pipe.

Instances of settlement or heave may be mitigated by good planning, design and installation techniques.

How do I apply it?The Highways Agency Advice note Ha 120/08 gives Guidance on the trenchless installation of services beneath motorways and trunk roads. The Manual of Contract Documents for Highway Works (MCHW 5.8) provides methods of implementation and specifying trenchless construction.

Guidance is given in CIRIA Reports SP147 (trenchless and minimum excavation techniques) and tN127 (trenchless construction for underground services).

Further advice is available from the Pipe Jacking Association who publishes a Guide to best practice for the installation of pipe jacks and microtunnels and an introduction to pipe jacking and microtunelling design.

Why should I use it? Waste reduction: avoids trenching and the disposal of trench spoil to landfill. Primary aggregates not required for trench backfilling.

Cost reduction: site specific. Savings can be substantial if allowance is made for environmental and social costs.

recycled content: trench excavation is avoided as in-situ material is reused.

Programme: Generally no significant impact on programme – although this is site specific.

Carbon footprint: saves in lorry movements to remove trench spoil and import suitable backfill.

Other environmental benefits: significant benefits in so far as road, rail and waterway traffic can proceed unimpeded. Landscape or protected areas remain unspoilt.

CONtENtS







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tyre-derived rubber material in combined surface and ground water filter drains

application: Drainage for rural highways and airfields.


What is it?The traditional material for combined surface and ground water filter drains adjacent to bound pavements is unbound aggregate. However, any overrunning vehicle can throw loose chippings onto the pavement, causing chipping damage to other vehicles or presenting a foreign object damage threat on airfields. The use of bituminous-bound shredded used tyres in the top 150 mm to 200 mm of the drain provides adequate weight to hold them in place during normal use whilst significantly reducing those threats. The binder is paving grade bitumen with mineral additives and synthetic polymers.

Where can I use it?Projects involving highways or airfields where the drainage is by a combined surface and ground water filter drain that runs close to the pavement. It has been estimated that a quarter of the primary network was edged with combined surface and ground water filter drain material in 1994. This situation mostly occurs on relatively busy rural roads without footpaths requiring other forms of drainage. It is particularly useful near lay-bys and entry or exit slip roads, where the potential for vehicles to wander onto the filter drain and disturb any loose aggregate is greatest.

Case studies of the use of Safedrain, a proprietary bituminous-bound shredded scrap tyre material developed and marketed by Roadtex Limited, on the A23 at Brighton and the A34 at Oxford in 1994 are described in TRL Report trL200.

How do I apply it?Details of the design of combined surface and ground water filter drains are given in Chapter 5 of Ha 39/98 www.standardsforhighways.co.uk/dmrb/vol4/section2/ha3998.pdf Details of the design of bituminous-bound shredded scrap tyres that can be used in place of the aggregate filter material are given in TRL Report trL200.

The tyre shred used for the drains should be produced in accordance with PaS107:2007 Specification for the manufacture and storage of size reduced tyre materials and the WraP/Environment agency Quality Protocol for tyre-derived rubber materials www.environment-agency.gov.uk/business/topics/waste/114455.aspx

This method can be used either in new build or when maintenance is being carried out on the filter drains. The use of bituminous bound filter drain material should reduce the need maintenance, but not cleaning, of the drain.

Why should I use it? Waste reduction: reduces the number of waste tyres having to be disposed of.

Cost reduction: it will generally be cheaper to use waste tyres than freshly won aggregate.


Programme: it should have no direct influence.

Carbon footprint: the carbon footprint of processing the tyres should be less than that to win the fresh aggregate it replaces.

Other environmental benefits: reduced storage of waste tyres.


SUDS and related techniques

application: Incorporated in the construction of buildings, highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Surface water drainage systems developed in line with the ideals of sustainable development are collectively referred to as Sustainable Drainage Systems (SUDS). At a particular site, these systems are designed both to manage the environmental risks resulting from urban runoff and to contribute wherever possible to environmental enhancement. SUDS objectives are, therefore, to minimise the impacts from the development on the quantity and quality of the runoff, and maximise amenity and biodiversity opportunities.

SUDS designs should aim to reduce runoff by integrating storm water controls throughout the site in small, discrete units. Through effective control of runoff at source, the need for large flow attenuation and flow control structures should be minimised.

Where can I use it?Typical SUDS components are filter strips, swales, infiltration basins, wet ponds, extended detention basins, constructed wetlands, filter drains and perforated pipes, infiltration devices, pervious surfaces, and green roofs. SUDS components can be used in a variety of infrastructure situations to intercept storm water flow, convey the water, store and filter as necessary to conform with SUDS objectives. The main uses are to:

reduce runoff rates and the risk of flooding;

encourage natural groundwater recharge;

reduce pollutant concentrations in storm water and protect water quality;

act as a buffer for accidental spills preventing discharge of contaminants into watercourses;

reduce the volume of surface water discharging to combined sewer systems and hence discharges of polluted water to watercourses; and

provide habitats for wildlife in urban areas and opportunities for biodiversity enhancement.

How do I apply it?CIRIA provide comprehensive advice on SUDS on their website www.ciria.org.uk/suds and have produced an interim code of practice. CIRIA Report C697 (the SUDS Manual) and C698 (Site handbook for the construction of SUDS) supersede CIRIA Reports C521, C522, C523 and C609 on the topic.

For highway situations much advice on controlling runoff and SUDS is given in the Design Manual for roads and Bridges, Volume 4 Section 2 Drainage www.standardsforhighways.co.uk/dmrb/vol4/section2.htm

Why should I use it? Waste reduction: recycling of water which would otherwise be wasted.

Cost reduction: cost effective means of controlling storm water runoff.

recycled content: recycling water whilst maintaining quality.

Programme: impact on programme is site specific.

Carbon footprint: reuse of natural resource.

Other environmental benefits: provides habitats for wildlife and encourages biodiversity.

CONtENtS

www.standardsforhighways.co.uk/dmrb/vol4/section2/ha3998.pdf


www.ciria.org.uk/suds

www.ciria.org.uk/suds

www.standardsforhighways.co.uk/dmrb/vol4/section2.htm

www.standardsforhighways.co.uk/dmrb/vol4/section2.htm



Precast manholes, gullies, service ducts and cable troughing

application: Highways, railways, utilities, development site infrastructure.

Designing out Waste Principle: Design for Off Site Construction.

What is it?The benefits of off site factory manufacture, or controlled prefabrication on site or at a nearby location, are well documented. Many drainage items (such as manholes and gullies) and service ducts and cable troughing can now be purchased as prefabricated units and placed directly in position rather than having to be constructed on site with bricks and concrete. This greatly reduces waste compared to on site construction. Generally a better quality product can be produced by precast techniques and the need for temporary works is usually reduced.

Where can I use it?Standard drainage details for all highway applications, including new construction on development sites or replacement of old drainage systems.

How do I apply it?Further information is available in the WRAP document Current practices and future potential in modern methods of construction (2007). Case history studies are also reported by WRAP in Waste reduction potential of precast concrete manufactured offsite.

Design and performance requirements in highway applications are given in Volume 4 Section 2 Drainage of the Design Manual for Roads and Bridges; for railway applications the network Rail Model Clauses covering track Drainage and External Service Ducts and troughing are relevant; Building Regulations Part H Drainage and Waste Disposal should be consulted in buildings construction projects.

Why should I use it? Waste reduction: has the potential to significantly reduce waste produced on site.

Cost reduction: efficient precasting techniques may reduce costs.

recycled content: opportunities may exist for increasing the recycled content during prefabrication.

Programme: rapid installation enabled by prefabricated units reduces construction timescales.

Carbon footprint: minimises delay to road, rail and other users during construction works so improving fuel efficiency.

Other environmental benefits: Less disruption in terms of noise, dust, and vibration because of faster construction.

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Balance cut/fill quantities;

Lime or cement to dry out wet fill;

Geosystems to enable steeper side slopes;

Treat unsuitable materials for landscaping and soils manufacture;

Manufacture topsoil using PAS100 compost;

Remediation of contaminated soils;

Stabilise or isolate contaminated soils;

Geosystems to enable soft foundation soils to remain in-situ;

Ground improvement techniques to enable soft foundation soils to remain in-situ;

Tyre bales or other lightweight fill to enable soft foundation soils to remain in-situ;

Recycled aggregates and/or HBM for working platforms;

Incorporate working platform into permanent works;

Lime or cement to stabilise soils in-situ for use as capping;

Recycled aggregates for capping, structural backfill and slope repairs;

Geosynthetic and lime/cement with original soil for slope repairs;

Tyre bales for slope repairs; and

Vegetation to improve slope stability.

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TECHnICAL SOLUTIOn: Earthworks including landscaping

Balance cut/fill quantities

application: Earthworks, all project types.


What is it?For highways, railways and other linear transport infrastructure developments, vertical and horizontal alignments should be selected to enable the reuse of excavated material from areas of cut as bulk fill in areas of embankments. For development sites, foundation levels should be chosen to enable excavated material from one area to be used as bulk fill elsewhere to create a level site for the new development.

Designers should also aim to minimise the overall amount of earthworks.

Where can I use it?Any project type where earthworks are required.

How do I apply it?The choice of horizontal and vertical alignments for transport infrastructure is governed by the standards of the relevant infrastructure owner. It is also necessary to carry out a ground investigation to determine whether materials from areas of cut will be suitable for use as fill and whether excavation of weak foundation materials is required in areas of embankment. Allowance also has to be made for any necessary landscaping, noise bunds, etc. Development of alignments and the final cut/fill balance is thus an iterative process that continues until the design is finalised.

Redevelopment or regeneration projects may require the demolition of existing structures and the construction of new ones on adjacent sites. Coordination between the two phases is required to ensure that materials that have to be excavated during the demolition phase can be used in the new construction phase.

Ground investigations may reveal that materials from areas of cut are not suitable for use as fill in their current condition, or that foundation conditions are not suitable for the proposed development. In the following sheets, a number of technical solutions are presented that can improve the quality of the materials so that they can be retained on site and do not have to be disposed of as waste.

Why should I use it? Waste reduction: avoid sending large quantities of waste to landfill or having to import fill to make up levels.

Cost reduction: it will generally be cheaper to move material on site than to send it off site and/or import suitable material.


Programme: it will generally be significantly quicker to move materials on site than to export them as waste and/or import suitable materials.

Carbon footprint: reuse of excavated material will minimise the carbon footprint of the earthworks.


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Lime or cement to dry out wet fill



What is it?Many earthworks materials can be too wet to be suitable for use as fill in the permanent works, particularly at shallow depths and when earthworks are carried out in winter or periods of wet weather. The materials would have to be excavated and disposed off (to landfill or exempt sites) and suitable fill materials imported. However, many materials can be rendered suitable by the addition of small quantities of lime and/or cement, enabling the materials to be retained on site and avoiding the import of fill materials.

Where can I use it?Any project type where earthworks are involved: highways; railways; new utilities infrastructure; power generation; development sites (commercial, industrial,

housing, mixed). This method is particularly useful where the construction programme is tight and it is not possible to wait until the materials dry out naturally.

The method is suitable for weak rocks, sands, silts and clays, with cement being used for granular materials and lime for cohesive ones. Lime followed by cement can be used for wet cohesive soils if a higher strength of fill is required. The method can also be used to treat soils in-situ to be suitable as capping layers.

The method is not suitable for soils with high organic content, where it may not be effective, or soils containing sulfates or sulfides, where it can lead to expansive reactions after the materials have been placed. The method is suitable for natural soils and can be used for some contaminated soils with low levels of contamination. Extra testing is required to demonstrate that the contaminants cannot be leached out of the treated material.

The use of excavated chalk treated with cement for a variety of uses on an access road to a new school at north Popley, Basingstoke is described in a case study www.aggregain.org.uk/case_studies/north_popley.html In all, over 1,000 m3 of chalk that would otherwise have been disposed to landfill and replaced with imported aggregates was retained on site.

How do I apply it?Details of the design process are given in Ha74/07 treatment of fill and capping materials using either lime or cement or both www.standardsforhighways.co.uk/dmrb/vol4/section1/ha7407.pdf

If it is proposed to use this method, it is important to consider it from an early stage in the design process and ensure that adequate information is obtained during the ground investigation to assess whether the materials are suitable and to obtain parameters for the detailed design stage. If it is not considered until the construction stage it may be difficult to carry out the necessary testing and trial mixes in the time available. Proceeding without adequate testing risks the technique not working or being subject to expansive reactions at a later stage.

Why should I use it? Waste reduction: avoid sending large quantities of waste to landfill or exempt sites.

Cost reduction: it will generally be cheaper to treat material on site than to send it off site and import suitable material.


Programme: it will generally be significantly quicker to treat materials on site than to export them as waste and import suitable materials.

Carbon footprint: using lime or cement will increase the CO2 emissions, but this will be compensated by the reduction in vehicle movements taking materials off site and importing suitable materials.


CONtENtS

www.aggregain.org.uk/case_studies/north_popley.html

www.aggregain.org.uk/case_studies/north_popley.html





Geosystems to enable steeper side slopes

application: Construction of steeper slopes for highways, railways, waterways, and in the development of brown- and greenfield sites.

Designing out Waste Principle: Design for Reuse and Recovery; Design for Materials Optimisation.

What is it?Geosystems, often incorporating a geosynthetic material, are frequently used to improve the stability of slopes and to enable steeper slopes to be constructed.

Geosystems mobilise the soil strength by incorporating an engineered geo-component and, for reinforced soil slopes, this will generally use either polymeric or steel reinforcement. Other types of geosystems include gabions, crib walls, anchored earth, soil nailing, and tyre bale soil retention systems. These techniques are based on minimum disturbance to the existing slope, whereas other approaches might involve the import of better quality fill to reconstruct the slope or retaining wall construction.

Where can I use it?Geosystems can be used to improve slopes of marginal stability or to construct steeper side slopes at locations where there is limited land availability. The techniques are particularly appropriate to transport applications such as the steepening of slopes for highway widening purposes, and the remediation of unstable cutting and embankment slopes on the rail and underground networks.

Although these are the main applications, geosystems can be used in a wide range of situations where infrastructure is being developed with limited land availability.

How do I apply it?WRAP gives guidance on Sustainable Geosystems in Civil Engineering applications, available at www.aggregain.org.uk

Design information is given in the Design Manual for roads and Bridges, in Ha68/94 (Design methods for the reinforcement of highway slopes by reinforced soil and soil nailing techniques), BD68 (Crib retaining walls), BD70 (Strengthened/reinforced soils and other fills for retaining walls and bridge abutments), and in BS8006 (Code of practice for reinforced soils and other fills).

CIRIA Report C573 (a guide to ground treatment) and Report C572 (treated ground – engineering properties and performance) provide guidance for the design engineer. Various other reports give information on techniques, e.g. C637 Soil nailing – best practice guidance, C591 Infrastructure cuttings condition appraisal and remedial treatment, C592 Infrastructure embankments condition appraisal and remedial treatment, C516 Modular gravity retaining wall - design guidance.

Why should I use it? Waste reduction: strengthening of the existing ground minimises the disposing of excavated material to landfill.

Cost reduction: significant cost savings can normally be made.

recycled content: locally available soils are employed in the geosystem so that the import of primary aggregates is avoided.


Carbon footprint: reduction in the use of concrete and steel and reductions in lorry movements needed to remove unacceptable material and import suitable fill.

Other environmental benefits: lorry traffic on adjoining roads is reduced in many cases. Steeper side slopes are more aesthetically pleasing than retaining wall solutions.


treat unsuitable materials for landscaping and soils manufacture



What is it?Excavated material from shallow depth is often unsuitable for use as fill in embankments and backfill to structures, as it may be too wet or have significant organic matter. Provided the materials are not contaminated, however, they can be a useful resource for manufacturing topsoil for the site when mixed with compost complying with PAS100.

Where can I use it?Any application where topsoil is required to establish the growth of various types of plant materials, including grasses, trees and shrubs.

How do I apply it?BS3882: 2007 (Specification for topsoil and requirements for use) gives details of the required properties of topsoil for various purposes.

CIRIA Report C513 (1999) the reclaimed and recycled construction materials handbook gives advice on reclaiming and recycling soil for use as topsoil.

BSI PaS100 Publicly available specification for composted materials (2005) ensures that compost produced is of the required standard. The Association for Organics Recycling (formerly the Composting Association) provides a certification scheme to ensure compliance with PAS100.

Significant guidance is available on the WRAP website on the specification, the use of compost in brownfield regeneration, various case studies, and compost suppliers www.wrap.org.uk/composting

Why should I use it? Waste reduction: encourages the reuse of excavated soil which would otherwise need to go to landfill.

Cost reduction: when compared with the cost of transport and that of imported topsoil.



Carbon footprint: effective reuse and recycling of material saves in lorry movements in importing topsoil.

Other environmental benefits: aesthetic appearance of landscaped areas, reduced disruption from lorry movements.

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http://www.aggregain.org.uk




Manufacture topsoil using PaS100 compost



What is it?Excavated soil or reclaimed topsoil can be reused together with PAS100 compost to manufacture fertile topsoil for landscape establishment. The compost can be produced by processing harvesting vegetation on or off site either as part of a wider construction programme or during seasonal maintenance.

Where can I use it?Any application where it is required to establish the growth of various types of plant materials, including grasses, trees and shrubs. It is important to identify suitable materials on site to mix with the PAS 100 compost to manufacture topsoil.

How do I apply it?BS3882: 2007 (Specification for topsoil and requirements for use) gives details of the required properties of topsoil for various purposes.

BSI PaS100 Publicly available specification for composted materials (2005) ensures that compost produced is of the required standard. The Association for Organics Recycling (formerly the Composting Association) provides a certification scheme to ensure compliance with PAS100.

Significant guidance is available on the WRAP website on the specification, the use of compost in brownfield regeneration, various case studies, and compost suppliers www.wrap.org.uk/composting

Why should I use it? Waste reduction: encourages the reuse of soil and vegetation debris which would otherwise go to landfill.

Cost reduction: cost saving when compared with importing topsoil.

recycled content: reuse of excavated soil or reclaimed topsoil together with 100% use of vegetation debris.


Carbon footprint: effective reuse and recycling of material and less lorry movements in importing topsoil in some situations.

Other environmental benefits: aesthetic appearance of landscaped areas.


remediation of contaminated soils

application: Remediation of contaminated soil for use as foundations for earthworks and buildings for highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Land is considered to be contaminated if it contains elevated concentrations of potentially harmful substances. Many brownfield sites contain contaminated soils, which require treatment before the site can be developed. A range of remediation technologies are available, either on site or at adjacent ‘hub’ sites; these include; soil washing, biodegradation of organic contaminants, thermal desorption, soil vapour extraction for volatile organics and petroleum, chemical methods, or stabilisation with cementitious agents to form HBMs and prevent migration of contaminants. Treatment of groundwater may also be required. These treatments will generally be cheaper than disposal of large volumes of hazardous waste to landfill.

Where can I use it?Especially in the development of brownfield sites, many of which may be contaminated. Particular care has to be taken when dealing with contaminated land, and liaison with the regulatory authorities should take place from as early a stage as possible in the project life cycle.

It will be important for the designer to understand clearly what the regulatory requirements will be for the processing of the contaminated materials, including any emissions to air or water, testing and any long term monitoring and validation, and on how recovery of the materials from waste will be assessed and demonstrated.

How do I apply it?Guidance on the management of land affected by contamination, including model procedures and requirements for contaminated land reports, are available on the Environment Agency website www.environment-agency.gov.uk/research/planning/33710.aspx

Materials Management Plans, described in the CL:aIrE Code of Practice, can be a suitable way of demonstrating recovery from waste www.claire.co.uk/index.php?option=com_docman&task=cat_view&gid=932&Itemid=25

CIRIA Report C622 (2004) “Selection of remedial treatments for contaminated land: a guide to good practice” gives technical guidance on the viability of remediation, motives, and the treatment selection process.

ICE design and practice guides: Contaminated land - investigation, assessment and remediation, 2nd edition (2008) give guidance on investigation methods within a risk management concept and targets for remediation.

TRL Report 489 the processing of contaminated land in highway works (2001) gives specific guidance for highway projects.

Why should I use it? Waste reduction: encourages the reuse of the contaminated soil which would otherwise go to landfill.

Cost reduction: remediation is generally cheaper than disposal of large volumes of hazardous waste to landfill.


Programme: site specific impacts – in many instances “dig and dump” may not be viable. Remediation may be carried out as advance works to avoid impact on the main construction programme. Some techniques may require significant timescales, so it is important to consider this from an early stage.

Carbon footprint: saves on lorry movements in exporting contaminated material and importing suitable fill.

Other environmental benefits: reduced disruption in terms of traffic congestion, noise and vibration from lorry movements. Reduced resource depletion.

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http://www.environment-agency.gov.uk/research/planning/33710.aspx


http://www.claire.co.uk/index.php?option=com_docman&task=cat_view&gid=932&Itemid=25





Stabilise or isolate contaminated soils

application: Remediation of contaminated soil for use as foundations for buildings and earthworks for highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Land is considered to be contaminated if it contains elevated concentrations of potentially harmful substances. The contaminants may cause biological, chemical or physical harm (such as by radioactivity). Many brownfield sites contain contaminated soils, which require treatment before the site can be developed. Cement and lime stabilisation and solidification can be used to chemically stabilise and physically immobilise contaminants within a solid matrix that prevents leaching. This improves the engineering properties of the ground so that it can be used for redevelopment.

In extreme cases, such as radioactive contamination, cement-based slurry cut-off walls can be used to contain and isolate the area.

Where can I use it?Especially in the development of brownfield sites, many of which may be contaminated. Particular care has to be taken when dealing with contaminated land, and liaison with the regulatory authorities should take place from as early a stage as possible in the project life cycle.

It will be important for the designer to understand clearly what the regulatory requirements will be for the processing of the contaminated materials, including any emissions to air or water, testing and any long term monitoring and validation, and on how recovery of the materials from waste will be assessed and demonstrated.

How do I apply it?Guidance on the management of land affected by contamination, including model procedures and requirements for contaminated land reports, are available on the Environment Agency website www.environment-agency.gov.uk/research/planning/33710.aspx

Materials Management Plans, described in the CL:aIrE Code of Practice, can be a suitable way of demonstrating recovery from waste www.claire.co.uk/index.php?option=com_docman&task=cat_view&gid=932&Itemid=25

The British Cement Association and the British Lime Association have published the essential guide to stabilisation/solidification for the remediation of brownfield land using cement and lime which provides advice on site practices.

CIRIA Report C622 (2004) Selection of remedial treatments for contaminated land: a guide to good practice gives technical guidance on the viability of remediation, motives, and the treatment selection process.

ICE design and practice guides: Contaminated land - investigation, assessment and remediation, 2nd edition (2008) gives guidance on investigation methods within a risk management concept and targets for remediation.

Why should I use it? Waste reduction: encourages the reuse of the contaminated soil which would otherwise go landfill.

Cost reduction: generally cheaper than disposal of large volumes of hazardous waste to landfill.


Programme: site specific impacts – in many instances “dig and dump” may not be viable. Remediation may be carried out as advance works to avoid impact on the main construction programme. Some techniques may require significant timescales, so it is important to consider this from an early stage.

Carbon footprint: saves on lorry movements in exporting contaminated material and importing suitable fill.

Other environmental benefits: reduced disruption in terms of traffic congestion, noise and vibration from lorry movements. Reduced resource depletion.


Geosystems to enable soft foundation soils to remain in-situ

application: Construction of embankments or foundations for buildings, highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?In the construction of embankments or foundations on soft ground, the option of digging out the material and replacing it with better quality fill is often not only frequently very expensive but in many instances impractical.

Geosystems, usually incorporating a geosynthetic material, are frequently used in conjunction with other strengthening techniques (see technical solution on soft ground improvement) to stabilise the soft ground. Components of a geosystem may not necessarily be geosynthetic in nature; drainage components (such as band drains and horizontal drains) and strengthening components (such as stone columns, lime columns, vibro concrete columns, etc) may form part of the system.

Where can I use it?In the improvement of soft alluvial materials to facilitate the construction of embankments or foundations. Quite often appropriate in the reclamation of estuarine land for infrastructure development.

For example basal reinforcement, in the form of woven or knitted geosynthetics, is frequently used in conjunction with band drains and a basal drainage layer, to enable the more rapid construction of embankments for highways and railways.

These methods may not be appropriate for marginal material in the form of domestic landfill, industrial wastes and derelict sites of former industries.

How do I apply it?CIRIA Report C573 (a guide to ground treatment) and Report C572 (treated ground – engineering properties and performance) provide guidance for the design engineer.

WRAP gives guidance on Sustainable Geosystems in Civil Engineering applications, available at www.aggregain.org.uk

TRL Reports Cr341 (Highway embankments over soft compressible alluvial deposits: Guidelines for design and construction) and Pr71 (a guide to accommodating or avoiding soil-induced lateral loading of piled foundations for highway bridges) provide relevant advice.

Many of the ground improvement techniques have been researched by BRE and Report 424 (Building on fill: geotechnical aspects. 2nd Edition) provides a detailed account of research findings.

Why should I use it? Waste reduction: strengthening of the existing ground avoids disposing of the weak material to landfill.


recycled content: locally available soils are incorporated with geosynthetic materials into construction methods so that the import of primary aggregates is avoided.


Carbon footprint: saves in lorry movements to remove soft material and import suitable fill.

Other environmental benefits: lorry traffic on adjoining roads is reduced in many cases. Reduced resource depletion.

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application: Construction of embankments or foundations for buildings, highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?In the construction of embankments or foundations on soft ground, the option of digging out the material and replacing it with better quality fill is often not only frequently very expensive but in many instances impractical. Many methods are available to improve the ground and these include non-intrusive methods such as pre-loading, surcharging, and staged construction. Intrusive methods include direct excavation and treatment, soil displacement (by the weight of the embankment fill), vertical drains, dynamic compaction, stone columns, vibro concrete columns, jet grouting, lime/cement columns and deep soil mixing.

(Methods of soil reinforcement are not included in this Technical Solution)

Where can I use it?In the improvement of soft alluvial materials to facilitate the construction of embankments or foundations. Quite often appropriate in the reclamation of estuarine land for infrastructure development.

These methods may not be appropriate for marginal material in the form of domestic landfill, industrial wastes and derelict sites of former industries.


TRL Reports Cr341 (Highway embankments over soft compressible alluvial deposits: Guidelines for design and construction) and Pr71 (a guide to accommodating or avoiding soil-induced lateral loading of piled foundations for highway bridges) provide relevant advice.


Why should I use it? Waste reduction: strengthening of the existing ground avoids disposing of the weak material to landfill.


recycled content: the existing ground is improved and its replacement by primary aggregates is avoided.





tyre bales or other lightweight fill to enable soft foundation soils to remain in-situ

application: Construction of embankments or foundations for highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?In the construction of embankments or foundations on soft ground, the option of digging out the material and replacing it with better quality fill is often not only frequently very expensive but in many instances impractical.

The use of a lightweight embankment or abutment fill will improve the factor of safety against shear failure of the underlying soil. Lightweight fills require a lower bearing capacity and generate less ground movements than conventional materials, such as earth or rock fill. As well as reducing the load on the ground, lightweight fills require less internal strength to support their own weight.

Lightweight fills include tyre bales, pulverised fuel ash, expanded shale and clay, clinker, expanded or extruded polystyrene blocks. The use of fills which have a high recycled content is clearly advantageous both in cost and avoidance of waste.

Where can I use it?When constructing on soft ground, reducing the load by using lightweight fill for embankments or foundations may mean that the soft ground can remain in-situ without the need to dig out and replace or strengthen it. This approach is quite often appropriate in the reclamation of estuarine land for infrastructure development.

Tyre bales are light in weight and even when internal voids are in filled with sand to improve stiffness and stability they are considerably lighter than conventional fill and are therefore particularly suited to embankment construction on soft ground. Embankments constructed in this way tend to be free-draining.

Polystyrene embankments have also been used with success on the highway network although the cost of polystyrene fill can be high.


WRAP gives guidance on Sustainable Geosystems in Civil Engineering applications.

BSI PaS 108:2007 Specification for the production of tyre bales for use in construction. TRL PPr080 tyre bales in construction gives design guidance and PPr045 provides case studies. TRL Reports Cr341 (Highway embankments over soft compressible alluvial deposits: Guidelines for design and construction) and Pr71 (a guide to accommodating or avoiding soil-induced lateral loading of piled foundations for highway bridges) provide relevant advice. TRL Report Cr356 (the use of polystyrene for embankment construction) gives guidance on specification, design, and construction.


Why should I use it? Waste reduction: reducing the loading on the existing ground avoids disposing of the weak material to landfill.

Cost reduction: significant cost savings can normally be made particularly if recycled material is used as fill.

recycled content: depending on the type of lightweight fill selected, for example recycling of waste tyres is beneficial.




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recycled aggregates and/or HBM for working platformsIncorporate working platforms into permanant works

application: Working platforms for piling rigs and cranes for the construction of highways, airports, utilities, tunnels, railways, harbours, docks and waterways, power generation and in development of brown- and greenfield sites.


What is it?A working platform provides a safe and durable working surface from which construction plant, such as piling rigs and cranes, can operate. Recycled aggregates can be used to form the platform. Alternatively hydraulically bound mixtures (HBM) made using lime, cement and other binders are a cost effective method of stabilising weak on site soils (or imported recycled aggregates).

Where can I use it?Clear economic and environmental benefits can be derived from the use of platforms, particularly:

where increased use can be made of either site-won or recycled materials;

when platforms can be used and reused for a variety of purposes throughout the construction process; and

when platforms can be reused for permanent works.

How do I apply it?WRAP (2006) produced a report on Guidance on the use of HBM in working platforms http://aggregain.wrap.org.uk/document.rm?id=3395 This also gives examples where working platforms can be utilised many times through a construction life-cycle.

General advice on the use of stabilised soils is given in the Specification for Highway Works 600 and 800 Series.

Further advice is given in TRL Contractor Report 151 (Stabilized capping layers using either lime, or cement, or lime and cement).

Why should I use it? Waste reduction: the use of site-won materials reduces the waste sent to landfill, particularly if the working platform can be incorporated into the permanent works.

Cost reduction: reduced costs compared with the option of importing primary aggregates for the platform.

recycled content: reuse of site-won materials and/or recycled aggregates.


Carbon footprint: use of site-won materials can lead to significant savings in lorry movements.

Other environmental benefits: obviates need to dispose of waste materials by other means. Reduced resource depletion.


Lime or cement to stabilise soils in-situ for use as capping



What is it?Soils at formation level may be too wet to support the subbase and pavement layers directly. The conventional solution is to place a capping layer of selected granular fill over the weak soils. If necessary, weak soils are excavated and replaced with a capping layer to maintain the finished road level. An alternative is to treat the soil in-situ with lime, cement, pulverised fuel ash or other binders to improve the strength to be equivalent to that of a capping layer of selected granular fill.

Where can I use it?Highways, airports, railways, ports and harbours and development sites. This method is particularly useful where the construction programme is tight as it is much quicker than excavating weak soils and placing imported fill.

The method is suitable for weak rocks, sands, silts and clays, with cement being used for granular materials and lime for cohesive ones. Lime followed by cement can be used for wet cohesive soils if a higher strength of fill is required.

The method is not suitable for soils with high organic content, where it may not be effective, or soils containing sulfates or sulfides, where it can lead to expansive reactions after the materials have been placed.

In-situ stabilisation of clay soils with lime and cement was used as an alternative to importing capping material on the A34 Chieveley/M4 Junction 13 improvement. The case study is available at www.wrap.org.uk/downloads/a34_M4.ab012a2f.1560.pdf

How do I apply it?Details of the design process are given in Ha74/07 treatment of fill and capping materials using either lime or cement or both www.standardsforhighways.co.uk/dmrb/vol4/section1/ha7407.pdf The technique is also covered in Series 600 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0600.pdf

If it is proposed to use this method, it is important to consider it from an early stage in the design process and ensure that adequate information is obtained during the ground investigation to assess whether the materials are suitable and to obtain parameters for the detailed design stage. If it is not considered until the construction stage it may be difficult to carry out the necessary testing and trial mixes in the time available. Proceeding without adequate testing risks the technique not working or being subject to expansive reactions at a later stage.

Why should I use it? Waste reduction: avoid sending large quantities of waste to landfill or exempt sites.

Cost reduction: it will generally be cheaper to treat material in-situ than to send it off site and import suitable material.



Carbon footprint: using lime or cement will increase the CO2 emissions, but this will be compensated by the reduction in vehicle movements taking materials off site and importing suitable materials.


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http://aggregain.wrap.org.uk/document.rm?id=3395


www.wrap.org.uk/downloads/A34_M4.ab012a2f.1560.pdf

www.wrap.org.uk/downloads/A34_M4.ab012a2f.1560.pdf







recycled aggregates for capping, structural backfill and slope repairs

application: Highways, railways, airports, capital utilities, bridges and structures and development sites.


What is it?Recycled aggregates can be used in a number of unbound applications on civil engineering sites.

Where can I use it?Recycled aggregates are permitted in a wide range of unbound applications in the 600 Series of the Specification for Highway Works, including general fill, capping and backfill to structures. Details are available at www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0600.pdf For structural backfill applications, when the Specification stipulates ‘recycled aggregate except recycled asphalt’ this means that the content of recycled asphalt in a recycled aggregate must not exceed 2%. For all applications, the content of ‘other materials’ in the recycled aggregate shall not exceed 1%.

Recycled aggregates can also be used to repair slope failures in cuttings and embankments. For this application, a grading similar to that for coarse grained capping (Class 6F5) is usually specified, to ensure a well-graded, high strength fill.

How do I apply it?numerous case studies of the use of recycled aggregates are available at www.aggregain.org.uk Use as capping, general fill, structural backfil and unbound subbase is illustrated by the M25 widening between J12 to 15 and Heathrow T5 spur www.aggregain.org.uk/case_studies/m25_j12_to_15.html The use of recycled aggregates in slope repairs is demonstrated by a case study of the A325 at Alice Holt in Hampshire www.aggregain.org.uk/case_studies/a325_major.html

The use of recycled and secondary aggregates in highway works is covered by HD35/04, which is available at www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf

Why should I use it?

Waste reduction: allows reuse of materials that might otherwise be disposed of to landfill or exempt sites.

Cost reduction: recycled aggregates are normally cheaper than primary aggregates, particularly in urban areas.

recycled content: increases the recycled content of the project

Programme: no effect on programme.

Carbon footprint: reduced compared to primary aggregates because of lower transport distances.

Other environmental benefits: reduction in resource depletion from quarrying.


Geosynthetics and lime/cement with original soil for slope repairs

application: Remediation of slopes for highways, railways, waterways, and in the development of brown- and greenfield sites.


What is it?Techniques to improve the structural properties of weak slopes, rather than removing the soil as unacceptable and importing more expensive alternative materials, include the addition of lime or cement to improve the soil and/or geosynthetic materials to provide reinforcement. In addition to more major remediation works, local soft spots can be readily repaired using these techniques.

Where can I use it?The techniques are particularly appropriate to the remediation of unstable cutting and embankment slopes on the road, rail, canal and underground networks. Widening of transport corridors can also be undertaken using the same techniques to steepen slopes.

How do I apply it?WRAP gives guidance on Sustainable Geosystems in Civil Engineering applications.

Design information is given in Ha68/94 (Design methods for the reinforcement of highway slopes by reinforced soil and soil nailing techniques) and Ha43/91 (Geotechnical considerations and techniques for widening highway earthworks).

CIRIA Report C573 (a guide to ground treatment) and Report C572 (treated ground – engineering properties and performance) provide guidance for the design engineer. CIRIA Reports C591 (Infrastructure cuttings condition appraisal and remedial treatment) and C592 (Infrastructure embankments condition appraisal and remedial treatment) give further information.

TRL Supplementary Report Sr751 gives advice on the use of fabric reinforcement for reinstating unstable slopes.

Why should I use it? Waste reduction: improvement/strengthening of the existing ground means that excavated soil does not have to be disposed of landfill.


recycled content: in-situ soil is reused so that the import of primary aggregates is avoided.


Carbon footprint: reduction in the use of concrete and steel if a retaining wall was used as an alternative. Reductions in lorry movements needed to remove unacceptable material and import suitable fill.


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www.aggregain.org.uk/case_studies/m25_j12_to_15.html


www.aggregain.org.uk/case_studies/a325_major.html

www.aggregain.org.uk/case_studies/a325_major.html

www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf




tyre bales for slope repairs

application: Slope remediation for highways, railways, waterways, and in the development of brown- and greenfield sites.


What is it?Recycled rubber tyres can be used in civil engineering works either as whole or part tyres, baled, shredded, chipped or crumbed tyres. Tyre bales are produced by compressing them in a bespoke baling machine and restraining them with tie-wire.

Bales and tyres can be used both for the construction of new slopes and the remediation of failed slopes and a variety of other civil engineering applications.

Where can I use it?Tyre bales are light in weight and even when internal voids are in filled with sand to improve stiffness and stability they are considerably lighter than conventional fill and are therefore particularly suited to embankment construction on soft ground. Embankments constructed in this way tend to be free-draining.

Tyre bales are fairly regular in size and shape and can be tied back to the soil behind them using a geotextile to produce a low height modular wall for retention of the toe of a slope, providing an alternative to stone-filled gabions.

Remediation of failed slopes can be carried using recycled tyres, for example a reinforced soil tyre wall tied with straps to buried anchor tyres has been used on a highway embankment in the UK.

How do I apply it?Advice is given in Design Manual for roads and Bridges, HD 35 Conservation and Use of Secondary and recycled Materials.

Tyre bales should be produced in accordance with BSI PaS 108:2007 Specification for the production of tyre bales for use in construction.

TRL Reports PPr80 (tyre bales in construction) gives design guidance and PPr045 (tyre bales in construction – case studies) gives examples of the use of tyre bales for slope repairs, flood defence and in the construction of low traffic roads across areas of soft ground. TRL rr30 (Maintenance and repair of highway embankments: Studies of seven methods of treatment) give guidance on tyres in the repair of a failed highway embankment of overconsolidated clay.

Why should I use it? Waste reduction: use of existing waste avoids the use of primary aggregates for new construction and remediation of slopes.

Cost reduction: tyre bales can be 20% cheaper than imported material.

recycled content: recycling of waste tyres.


Carbon footprint: uses waste materials which would otherwise need to be transported to landfill.

Other environmental benefits: avoids landfill and/or fly tipping of used tyres.


Vegetation to improve slope stability

application: Stabilisation of slopes for highways, railways, utilities, waterways, and in the development of brown- and greenfield sites.


What is it?Vegetation can be used to improve the stability of slopes which are either showing incipient signs of failure or are in need of steepening. Vegetation reduces pore water pressures particularly during the summer and strengthens a slope by root reinforcement. However moisture is required to promote and sustain plant growth and plant species need to be carefully selected.

The use of vegetation and bioengineering techniques is less intrusive than other remediation or stabilising techniques, which would often involve digging out and replacing the slope material, slope regrading or construction of more traditional forms of soil retention.

Where can I use it?

Vegetation can be used to stabilise slopes showing evidence of shallow slip failures, which is particularly likely in over-consolidated clays. The planting of live willow poles has proved particularly effective in this situation.

Bioengineering techniques can also be used to improve the stability of slopes which need to be steepened where land availability is limited. Steepening would otherwise need to employ retaining wall, soil nailing, or gabion construction. These techniques would involve the need to import materials and be more disruptive in terms of construction plant movements, etc.

Slopes prone to deep seated failures in the long term are unlikely to be effectively stabilised using bioengineering techniques.

How do I apply it?Guidance on the use of vegetation in civil engineering is given in CIRIA Report C708.

TRL Report 515 Vegetation for slope stability and Report 619 the use of live willow poles for stabilising highway slopes provide useful recommendations and case history studies.

Why should I use it? Waste reduction: avoids digging out the slope material and sending it to landfill.

Cost reduction: potential cost savings over more traditional engineering solutions.

recycled content: optimises the use of the existing slope material and avoids waste.

Programme: installation of vegetation is less intrusive and generally faster than other engineering solutions.

Carbon footprint: reduction in the use of construction plant and lorry movements to and from site.

Other environmental benefits: improves landscape and wildlife potential.

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Treat existing soil to make HBM subbase/ballast;

Recycled/secondary aggregates to make HBM subbase;

Recycled/secondary aggregates as unbound subbase; and

Geogrids/geotextiles to reduce thickness.Subb

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TECHnICAL SOLUTIOn: Subbase and hydraulically bound materials (HBM)

treat existing soil to make HBM subbase/ballast

application: Construction and maintenance of railway ballast and base and subbase for pavements for highways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Treating existing soil with binders/activators is known as ‘stabilisation’ of the soil to form a bound layer. It may be a one stage or two stage process. The two stage process uses lime to break down cohesive soils and then they are treated as in the single stage process, for non-cohesive soils, by adding a binder. The binder may be cement, ground granulated blastfurnace slag (ggbs) or pulverised fuel ash (pfa) or a combination of cement with either ggbs or pfa or lime. This process is usually undertaken in situ but may be done ex-situ. The production of HBM requires higher levels of binders/activators than the production of capping or the drying out of soils to be suitable as general fill.

Where can I use it?This process may be used as a subbase in any pavement construction or as a base in lightly trafficked pavements. Sulfates and sulfides in the soil can lead to expansive reactions with the binders and activators, so the soil should be checked thoroughly for these constituents.

Lime and cement were used to stabilise in-situ glacial till deposits to form a soil cement equivalent to Type 1 unbound subbase for one carriageway of a 24km scheme to upgrade the A120 in Essex between the M11 and the existing Braintree Bypass www.aggregain.org.uk/case_studies/use_of_ra_and.html

How do I apply it?The solution is covered by BS EN 14227 Parts 10-14.

The methodology for ‘stabilisation’ is given in the Specification for Highway Works, Clause 840, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf and the associated Notes for Guidance, Clause 840 discusses the testing procedures, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf

Guidance on the use of stabilised materials in earthworks is given in the Appendix to network Rail Model Clause 52 for Specifying Civil Engineering Works and generally takes the same approach to that in the Specification for Highway Works.

There are two useful Britpave documents; Britpave BP/08 technical data sheet – Stabilised soils as subbase or base for roads and other pavements and Britpave BP/15 Soil stabilisation- Guidelines for best practice.

Why should I use it? Waste reduction: the use of the existing soil reduces the quantity of material sent to tip.

Cost reduction: is cheaper to mix in-situ than off site, does not require primary aggregate.


Programme: no significant impacton programme.

Carbon footprint: the use of the existing soil gives a saving on lorry movements and fuel. Maximising the use of pfa and ggbs compared to cement and lime reduces the carbon footprint of the solution.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction in lorry movements, and valuable non-renewable aggregate sources are not wasted. Reduced resource depletion.

CONtENtS

http://www.aggregain.org.uk/case_studies/use_of_ra_and.html

http://www.aggregain.org.uk/case_studies/use_of_ra_and.html


www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf


www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf



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recycled/secondary aggregate to make HBM subbase

application: Construction and maintenance of subbase for pavements for highways, airports, utilities, railways, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Aggregate resulting from the processing of inorganic material previously used in construction, aggregate recovered from demolished concrete and aggregate from residues of industrial processes including mining. Typical materials include blastfurnace slag, burnt colliery spoil, china clay sand/stent, coal fly ash and pulverised fuel ash, foundry sand, furnace bottom ash, incinerator bottom ash aggregate, phosphoric slag, recycled aggregate, asphalt and concrete, recycled glass, slate aggregate, spent oil shale/blaise, steel slag and unburnt colliery spoil.

Where can I use it?Recycled/secondary aggregates may be used for hydraulic bound subbase beneath any pavements. A higher grade use of HBM is as base course for lightly trafficked pavements.

How do I apply it?Some of the secondary materials suitable for use in subbase and base are indicated in the Design Manual for roads and Bridges, HD 35/04, www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf Guidance on the use of HBM in road foundations is given in Interim Advice note 73/06 revision 1 (2009) Design Guidance for road Pavement Foundations (Draft HD25), available at www.standardsforhighways.co.uk/ians/pdfs/ian73rev1.pdf Use of HBM enables a foundation with higher stiffness to be produced, which can lead to reductions in the thickness of the subbase and overlying pavement layers if the design process in IAn73/06 is followed.

For the subbase in pavements construction the aggregate requirements are indicated in the Specification for Highway Works, Series 800, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf and the associated Notes for Guidance, Series 800, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf

There are two useful WRAP documents for HBMs; a WRAP Guidance document: Hydraulically bound mixtures incorporating recycled and secondary aggregates www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html and a WRAP Quality manual for hydraulically bound mixtures www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html

There is also a Britpave document which indicates the requirements in the European standards for HBMs, Britpave BP/13 technical data sheet – Cement and other hydraulic bound mixtures (The new European Standard BS En 14227, Parts 1-5).

Why should I use it? Waste reduction: the use of recycled or secondary aggregates in HBM reduces waste and can lead to thinner layers being required compared to unbound subbase.

Cost reduction: is cheaper than using primary aggregates.



Carbon footprint: the use of waste materials are usually available locally, therefore there is a saving on transport in lorry movements and fuel and use of primary aggregates. Maximising the use of pfa and ggbs compared to cement and lime reduces the carbon footprint of the solution.


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recycled/secondary aggregates as unbound subbase

application: Highways, railways, airports, capital utilities, bridges and structures and development sites.


What is it?The use of high quality recycled and secondary aggregates are permitted in unbound subbase applications under the Specification for Highway Works. The recycled/secondary aggregates give the same performance as primary aggregates for the same applications.

Where can I use it?The use of crushed slag, crushed concrete, recycled aggregates and well-burnt non-plastic shale is permitted in Type 1 and Type 2 unbound subbase. For recycled aggregates, the content of recycled asphalt must not exceed 50%, the content of glass must not exceed 25% and the content of other materials must not exceed 1%.

Crushed blast furnace slag and recycled concrete aggregate are permitted in Type 3 (open graded) unbound mixtures and Category B (close graded) unbound mixtures. For recycled concrete aggregate, the content of asphalt must not exceed 5% and the content of other materials must not exceed 1%.

Type 4 unbound mixture shall be made from recycled aggregates containing asphalt arisings, and may contain crushed rock, crushed slag, crushed concrete or well burnt non-plastic shale. It shall have a recycled asphalt content greater than 50% and not contain more than 25% glass and 1% other materials.

Full details are available in the 800 Series of the Specification for Highway Works, available at www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf

How do I apply it?numerous case studies of the use of recycled and secondary aggregates in unbound subbase are available at www.aggregain.org.uk Use as Type 1 and Type 4 unbound subbase is illustrated by the M25 widening between J12 to 15 and Heathrow T5 spur www.aggregain.org.uk/case_studies/m25_j12_to_15.html Spent railway ballast and blast furnace slag were used as Type 1 unbound subbase in the newport Southern Distributor Road www.aggregain.org.uk/case_studies/ 2720_performance.html

The use of recycled and secondary aggregates in highway works is covered by HD35/04, which is available at www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf

Why should I use it? Waste reduction: allows use of materials that might otherwise be used for lower value applications or disposed of to landfill or exempt sites.

Cost reduction: recycled aggregates are normally cheaper than primary aggregates, particularly in urban areas.

recycled content: increases the recycled content of the project


Carbon footprint: reduced compared to primary aggregates because of lower transport distances.


CONtENtS



http://www.standardsforhighways.co.uk/ians/pdfs/ian73rev1.pdf






www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html











http://www.aggregain.org.uk/case_studies/2720_performance.html

http://www.aggregain.org.uk/case_studies/2720_performance.html

http://www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf




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Geogrids/geotextiles to reduce thickness

application: Construction and maintenance of subbase/ballast for pavements/railtrack for highways, railways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Geogrids/geotextiles work by creating mechanical interlock of the aggregates and acting as a separator above the soil foundation; this allows a reduction in the thickness of the subbase/ballast layer in pavement or railtrack construction.

Mechanically stabilised foundation layers can sustain increased loadings, or provide the required performance with a reduced layer thickness.

Where can I use it?Geogrids/geotextiles can be used when constructing new pavements, carrying out major remediation of an existing pavement, strengthening the ballast for railway track construction.

Geotextile fabric acts as a good separator limiting deformation at the aggregate surface. Geogrids are particularly effective in reducing lateral movement because of granular interlock within the subbase as a result of stones being forced into the apertures of the grid.

The improved mechanical properties of the subbase/ballast may lead to an increased life.

How do I apply it?Design for traffic/railway loading is based on the stabilisation factor which will vary according to geogrid/geotextile type. The manufacturer’s performance data and design methodology should be taken into account.

Various TRL Reports, e.g. rr140 (Deformation of road foundations with geogrid reinforcement) and rr382 (Installation damage trials on geotextiles), give trial results.

WRAP document Sustainable Geosystems in Civil Engineering applications, www.aggregain.org.uk

Why should I use it? Waste reduction: improvement/strengthening of the subbase/ballast means that it may not need to be as thick.

Cost reduction: some cost savings may result because of the reduction in subbase/ballast thickness.

recycled content: the quantity of imported primary aggregates is reduced.

Programme: additional time required to place the geogrids, but balanced by reduced requirement for material; overall no significant impact.

Carbon footprint: Some reduction in lorry movements needed to import additional aggregate.

Other environmental benefits: lorry traffic on adjoining roads is reduced in many cases. A more durable product may require less maintenance.

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Pavements and footways – bituminous


In-situ hot recycling of asphalt;

In-situ cold recycling of asphalt;

On site hot recycling of asphalt;

Ex-situ cold recycling of asphalt;

Reclaimed asphalt in base and binder course;

Reclaimed asphalt in surface course;

Secondary aggregates in base, binder and surface course;

Secondary aggregates in surface course;

Secondary aggregates in cold asphalt mixtures;

Reclaimed asphalt from other site in cold mixture;

Warm and semi-warm asphalt to reduce energy;

Collect and reuse chippings in surface dressing;

Retexturing asphalt pavement surfacing;

Reclaimed asphalt in unbound subbase or capping off site; and

Geogrids/geotextiles to reduce thickness of base.

CONtENtS



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TECHnICAL SOLUTIOn: Pavements and footways – bituminous

In-situ hot recycling of asphalt

application: Highway and airfield pavements, principally surfacing layers.


What is it?There are two main types of hot in-situ recycling, Repave and Remix. With Repave, the existing road surface is heated to 150 ºC and scarified to a depth of 30 mm using a two-stage scarifier with spring loaded tines to avoid damage to street furniture. Then an oscillating, floating screed reprofiles and corrects levels for the required crown or crossfall. The process is completed by the immediate application of either a 25 mm asphalt surface course. Remix is an adaption of Repave where the machine is fitted with a small mixing unit, enabling the softened existing material to be mixed with specially designed new materials in order to restore the necessary properties of the surface course.

Where can I use it?Highway, airfield or other paving projects.

The method is suitable for sites that are large enough to warrant the necessary equipment where there are signs of deformation or surface fretting in the pavement but the component materials are sound and have the required properties.

The method is not suitable when tar is present in the asphalt being recycled, although this contamination is unlikely in surface course materials.

The Repave option is not suitable for surfaces showing signs of cracking, indicating that there is a potential deficiency in the material which could be worsened by the heating required for the process. Also, the process is only really suitable and economical on fairly long lengths of carriageway (several hundred metres) because of the size of the Repave machine.

This Repave process was used in HA Area 8 on the A421 near Bedford in early 2006 when snow, rain and temperatures down to -5 °C only extended the 15 night programme by one night www.colas.co.uk/colas-detail-page.asp?pageId=214 Slow lane rutting on the A1 between Stamford and Grantham was also rectified with Repave and a proprietary thin surface course during a recent summer www.colas.co.uk/upload-downloads/repave_Modern_asphalts_article.pdf The process has also been used on the A6119 dual carriageway on the outskirts of Blackburn to recycle 25 mm of existing material and apply 25 mm of new thin surface course, recycling 16,000 m2 of existing road surface which was in need of replacement www.colas.co.uk/colas-detail-page.asp?pageId=370

How do I apply it?Both options for the method are described in Chapter 5 of HD 31/94 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf with a standard specification for the Repave option in Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf

Why should I use it? Waste reduction: reduces the amount of planings used in lower grade uses or even disposed of.

Cost reduction: it will generally be cheaper to reuse reclaimed asphalt on site than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance.



Carbon footprint: there will be a reduction in CO2 from less vehicle movements taking materials off site and importing suitable materials; also the heat from the process welds the new materials removing the need for a tack coat. However, heating the existing surface to 150 ºC in situ will generate more CO2 than heating that material in the controlled environment of an asphalt plant.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction in lorry movements; also the heat penetrates deep into the road material allowing work to take place at virtually any time of year. Reduced resource depletion.

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In-situ cold recycling of asphalt

application: Highway and airfield pavements, principally on lower layers.


What is it?In-situ cold recycling techniques restore the structural integrity of a scarified road to a depth of up to 350 mm using cement or foamed bitumen (a patented means of expanding bitumen to about 15 times its original volume to facilitate efficient coating of the material to be processed). Retread is the most established process where the existing road surface is scarified, reshaped, new binder added (usually as an emulsion) and compacted.


The method is more suitable for lightly trafficked roads. It has the advantage over an overlay that the vertical geometry of the road is preserved, avoiding any ancillary work resulting from changes in finished road level that may occur and enabling the process to be used where access to side roads and adjacent premises must be maintained.

The method is not suitable for heavily trafficked roads, with a limit of 2 msa cumulative traffic having been set with foamed bitumen until trials on roads carrying higher traffic loads have demonstrated its suitability.

A series of trials with different options have produced successful results, as reported in TRL Report trL386. These sites include Lake Road Portsmouth, Kingston Road Teddington, Kingsway Bedford, A24 Epsom, Park Road Dartford, Valley Drive Gravesend and A1078 Kings Lynn.

How do I apply it?The methodology is described in Chapter 5 of HD 31/94 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf with the design method given in TRL Report trL611 (a development from TRL386). There is also a standard specification in Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf based on that methodology.


Cost reduction: it will generally be cheaper to reuse reclaimed asphalt on site than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance; the reduced energy requirement for cold asphalt should also provide a cost benefit.



Carbon footprint: there will be a reduction in CO2 from less vehicle movements taking materials off site and importing suitable materials, and from not heating the asphalt. This should more than offset CO2 emissions from producing the emulsion binder.


CONtENtS

www.colas.co.uk/colas-detail-page.asp?pageId=214


www.colas.co.uk/upload-downloads/Repave_Modern_Asphalts_Article.pdf

www.colas.co.uk/upload-downloads/Repave_Modern_Asphalts_Article.pdf



















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On site hot recycling of asphalt

application: Highway pavements and footways, principally on upper layers.


What is it?Reclaimed asphalt can be heated in a mobile mixing plant on site with the addition of small amounts of fresh bitumen and relaid in the excavation it came from. This technique is suitable for footways and minor repairs (potholes and patching) in local roads. The technique enables the material to be recycled back into the same application rather than being replaced with new asphalt. It is not suitable for heavily trafficked roads.

Where can I use it?Footways and minor repairs in local roads. The technique is only suitable for the surface layers and for small scale works, as the mobile mixing plant has a capacity of 5 tonnes.

How do I apply it?The application of this technique on footway repairs in Leicestershire is described in recycling in transport infrastructure by Reid and Chandler, 2001, TRL Publications.

Why should I use it? Waste reduction: reduces the amount of reclaimed asphalt used in lower grade uses or even disposed of.

Cost reduction: it will generally be cheaper to reuse reclaimed asphalt than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance.


Programme: reusing the material on site is often quicker than removing it from site and bringing in fresh material.

Carbon footprint: reduction in CO2 from almost eliminating the export and import of materials.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction in lorry movements. Reduces resource depletion.

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Ex-situ cold recycling of asphalt



What is it?Reclaimed asphalt planings can be processed in a pugmill with bitumen emulsion, fluxed bitumen, foamed bitumen and/or bitumen rejuvenators to form cold asphalt mixtures. This process can be carried in static plants remote from the site or mobile plant that is located near the works. Hydraulic binders, including cement, may also be included in the mixtures. As a result, there are a large range of cold-mix recycled materials involving a range of binders and binder blends.


The method can be used for all layers on lightly trafficked roads and runways. It can also be used for the structural layers of heavily trafficked roads and runways. However, the method is not suitable for surfacing when early trafficking is required.

A series of trials with different options have produced successful results, as reported in TRL Report trL611. These sites include Burntwood Bypass, Ramsgate Harbour Approach Road, A52 Froghall, A3088 Yeovil, A258 Beauchamp, A477 Llanteg and A40 Pwll Trap. These uses have been generally confined to relatively low volume applications, although it has been laid on the A38 Pear Tree as part of a major contract.

How do I apply it?The methodology is described in Chapter 5 of HD 31/94 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf with the design method given in TRL Report trL611. There is also a standard specification in Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf based on that methodology.


Cost reduction: it will generally be cheaper to reuse reclaimed asphalt than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance; the reduced energy requirement for cold asphalt should also provide a cost benefit.


Programme: it should have no direct influence using stockpiled reclaimed asphalt or stockpiled virgin aggregate.

Carbon footprint: there will be a reduction in CO2 from not heating the asphalt to balance the CO2 needed to produce the emulsion binder.


CONtENtS










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reclaimed asphalt in base and binder course

application: Highway and airfield pavements.


What is it?The aggregates in base and binder course asphalt mixtures are not significantly damaged in service. Therefore, the particles from planings are suitable for reuse in new asphalt mixtures provided they comply with the normal specification requirements. However, the binder adhering to the particles will have aged, requiring the properties of the additional fresh binder in the mixture to be adjusted to produce the standard binder properties after combination with the aged binder.


The method is suitable for any site provided there are adequate quantities of locally available reclaimed asphalt that has consistent properties.

The method is not suitable when tar is present in the asphalt being reclaimed.

Case studies: in the construction of the A34 Chieveley/M4 Junction 13 improvement, reclaimed asphalt from the M4 was used at a level of 10% in the new asphalt for the base and binder course. nearly 9,000 tonnes of reclaimed asphalt was used in the new base and binder course. The case study is available at www.aggregain.org.uk/case_studies/use_of_1.html

How do I apply it?Reclaimed asphalt is defined as a component material for fresh asphalt in BS EN 12697-8:2005. PD 6691:2007 recommends that limiting the amount of reclaimed asphalt to 50 % by mass of the mixture for base and binder course materials, but greater proportions can be used provided greater care is taken. The binder grade has to selected in accordance with Clause 902 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf where the use of reclaimed asphalt is specified; associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf are also available.

Why should I use it? Waste reduction: reduces the amount of planings used in lower grade uses or even disposed of by up to 100 % if those planings not used are stockpiled for future jobs.


recycled content: increases the recycled content of the scheme by 50% of these layers.


Carbon footprint: there will be a reduction in CO2 from less vehicle movements importing freshly won aggregate as well as winning that aggregate.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction n lorry movements bringing aggregates from the quarry. Reduced resource depletion.


reclaimed asphalt in surface course

application: Highway and airfield pavements, surface course.


What is it?

The aggregates in surface course asphalt mixtures are not significantly damaged in service except that the top face of the aggregate particles may be polished. Therefore, the particles from planings are suitable for re-use in new asphalt mixtures provided they comply with the normal specification requirements, which will be more restrictive than for lower layers, in particular with regard to polished stone value. However, the binder adhering to the particles will have aged, requiring the properties of the additional fresh binder in the mixture to be adjusted to produce the standard binder properties after combination with the aged binder unless the proportion of reclaimed is low. On large contracts when the reclaimed asphalt is to be reused on the same site in order to have a controlled source, the planings from one shift are generally used in the asphalt for the next shift.


The method is suitable for any site with a recommended routine addition of 10%. On large refurbishment sites where there is a consistent source of reclaimed asphalt, higher proportions can be used.

The method is not suitable when tar is present in the asphalt being reclaimed, although this contamination is unlikely in surface course materials.

Trials of up to 30% reclaimed have been monitored to demonstrate that it can produce satisfactory asphalt, as reported in TRL Report trL645. Subsequently, major contracts on the M4 at Cardiff and the M25 at Reigate have both involved resurfacing works with 25% reclaimed asphalt in the thin surface course mixture. The site at Reigate was monitored for carbon footprint and showed a saving of CO2 (TRL PPr304).

How do I apply it?Reclaimed asphalt is defined as a component material for fresh asphalt in BS EN 12697-8:2005. PD 6691:2007 recommends limiting the amount of reclaimed asphalt to 10% by mass of the mixture for surface course materials, but greater proportions can be used provided greater care is taken. The binder grade has to selected in accordance with Clause 902 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf where the use of reclaimed asphalt is specified; associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf are also available. However, specific advice on all aspects of recycling into thin surface course mixtures is given in TRL Road note 43 (in press).




Programme: it should have no direct influence using reclaimed asphalt, whether from the previous shift or stockpiled, or stockpiled virgin aggregate.

Carbon footprint: there will be a reduction in CO2 from less vehicle movements importing freshly won aggregate as well as winning that aggregate.

Other environmental benefits: reduction in congestion, noise, vibration and fumes resulting from the reduction in lorry movements bringing aggregates from the quarry. Reduced resource depletion.

CONtENtS

www.aggregain.org.uk/case_studies/use_of_1.html

www.aggregain.org.uk/case_studies/use_of_1.html












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Secondary aggregates in base, binder course and surface course

application: Highway and airfield pavements, lower layers.


What is it?Many categories of natural aggregates have been found to have suitable properties for use in asphalt. However, other secondary materials have been found to be suitable for some mixture types and can be used either instead of or in combination with natural aggregates. Secondary materials with coarse particle sizes are generally easier to incorporate because the fine aggregate and filler are produced automatically when crushing aggregate down to the coarse aggregate sizes. When used in a surface course mixture, the specification requirements are more restrictive, in particular with regard to polished stone value. Hence, while a wide range of secondary aggregates can be used in base and binder course, only a limited number (principally steel slag) are suitable for use in surface course.


The method is suitable for any road or airfield pavement. The method has been widely, but not systematically, used with some secondary materials becoming accepted. Blastfurnace slag it is suitable for use in base, binder course, surface course and chippings. Slate aggregate and china clay sand are widely used in the areas where these materials are abundant (north Wales and Cornwall respectively). Glass has been used as part of the coarse aggregate, usually up to 30%, in base and binder course asphalt mixture on sites including a new housing estate in Milton Keynes, an industrial estate in Stratford-upon-Avon, Pecks Hill Mansfield, M50 Twyning and M6 Knutsford, as reported in conference papers. The use in the surface course is not practicable because the glass would quickly polish. Incinerator bottom ash aggregate has been used successfully as coarse aggregate in base and binder course for hot and cold asphalt; several case studies are available at www.aggregain.org.uk

Basic oxygen steel (BOS) slag and Electric Arc Furnace (EAF) slag are widely used in surface course because they possess high skid resistance. Usage is predominantly in the areas where the materials are produced, principally Yorkshire, Humberside and north East England. BOS was investigated as a surface course aggregate with particular emphasis on its skid resistance, as reported in TRL Report trL566. Sites were monitored A46 nettleham Heath, A46 Welton Hill, A156 Drinsey nook, A1031, Cleethorpes, A15 Barnetby to Barton, A689 Wynyard, A16 Grimsby and A66 Middlesbrough.

Cement kiln dust has been used as replacement filler, as reported in TRL Report trL659.

How do I apply it?Asphalt is designed using secondary aggregates in the same way as for mixtures with natural aggregates except that the suitability of the secondary aggregates needs to be checked. A list of permitted secondary materials in highways is available in HD 35/04 www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf If a proposed material is not included because it has not been used previously, its physical durability and chemical reactivity will need to be checked in addition to the normal properties covered in BS EN 13043 and PD 6682 2:2003.

Why should I use it? Waste reduction: reduces the waste from the industry which the secondary material is derived from.

Cost reduction: depending on the source of the secondary aggregate, processing it should generally be cheaper than winning primary aggregate.

recycled content: depending on the source of the secondary aggregate, increases the recycled content of the scheme.


Carbon footprint: overall effect dependent on CO2 involved in processing the secondary aggregates to wining and transporting the freshly-won aggregate it replaces.

Other environmental benefits: potential to remove stockpiles of the secondary aggregates. Reduced resource depletion.


Secondary aggregates in cold asphalt mixtures

application: Highway and airfield pavements, generally for lower layers.


What is it?Many categories of natural aggregates have been found to have suitable properties for use in cold-mix asphalt. However, other secondary materials have been found to suitable for some mixture types and can be used either instead of or in combination with natural aggregates.


The method can be used for all layers on lightly trafficked roads and runways. It can also be used for the structural layers of heavily trafficked roads and runways. However, cold mixtures are not suitable for surfacing when early trafficking is required. The inclusion of secondary aggregates has been widely, but not systematically, used in these mixtures with some secondary materials becoming accepted.

The use of incinerator bottom ash as coarse aggregate with foamed bitumen binder in the base layer of an access road to a household waste recycling centre at bar End, Winchester is described in a case study at www.aggregain.org.uk/case_studies/recycled_and.html

How do I apply it?Cold asphalt mixtures are designed using secondary aggregates in the same way as for mixtures with natural aggregates except that the suitability of the secondary aggregates needs to be checked. A list of permitted secondary materials in highways is available in HD 35/04 www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf If a proposed material is not included because it has not been used previously, its physical durability and chemical reactivity will need to be checked in addition to the normal properties covered in BS EN 13043 and PD 6682 2:2003.

The methodology for designing cold mixtures is described in Chapter 5 of HD 31/94 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf with the design method given in TRL Report trL611. There is also a standard specification in Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf based on that methodology.

Why should I use it? Waste reduction: reduce the waste from the industry which the secondary material is derived from.

Cost reduction: depending on the source of the secondary aggregate, processing it should generally be cheaper than winning primary aggregate. The reduced energy requirement for cold asphalt should also provide a cost benefit.

recycled content: depending on the source of the secondary aggregate, increases the recycled content of the scheme.


Carbon footprint: overall effect dependent on CO2 involved in processing the secondary aggregates to wining and transporting the freshly won aggregate it replaces, and from not heating the asphalt. This should more than offset CO2 emissions from producing the emulsion binder.

Other environmental benefits: potential to remove stockpiles of the secondary aggregates. Reduced resource depletion.

CONtENtS




www.aggregain.org.uk/case_studies/recycled_and.html

www.aggregain.org.uk/case_studies/recycled_and.html











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reclaimed asphalt from other sites in cold mixture



What is it?This solution involves the same technique as ex-situ cold recycling of asphalt, except that the reclaimed asphalt (as planings and break-out from a number of small sites) is brought to a central processing facility where the cold mixture is produced. This can then be sent out to reinstate small scale streetworks or can be used in larger projects such as roads for new housing and industrial estates.

Reclaimed asphalt planings can be processed in a pugmill with bitumen emulsion, fluxed bitumen, foamed bitumen and/or bitumen rejuvenators to form cold asphalt mixtures. This process can be carried in static plants remote from the site or mobile plant that is located near the works. Hydraulic binders, including cement, may also be included in the mixtures. As a result, there are a large range of cold-mix recycled materials involving a range of binders and binder blends.


The method can be used for all layers on lightly trafficked roads, footways and runways. It can also be used for the structural layers of heavily trafficked roads and runways. However, the method is not suitable for surfacing when early trafficking is required.

Examples of the use of this technique in Hampshire are available in the case studies section of the AggRegain website www.aggregain.org.uk/case_studies

The base course of an access road for a new school at north Popley, Basingstoke was constructed using cold recycled bitumen bound material with a foamed bitumen binder using reclaimed asphalt from maintenance works elsewhere in the county. This method was so successful it was subsequently adopted by the developer for all the access roads in the estate. A similar material was used for footway repairs at Martyr Worthy near Winchester.

How do I apply it?The methodology is described in Chapter 5 of HD 31/94 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf with the design method given in TRL Report trL611. There is also a standard specification in Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf based on that methodology.

Why should I use it? Waste reduction: reduces the amount of planings used in lower grade uses or disposed of.

Cost reduction: it will generally be cheaper to reuse reclaimed asphalt than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance; the reduced energy requirement for cold asphalt should also provide a cost benefit.



Carbon footprint: the reduction in CO2 from not heating the asphalt should more that offset CO2 emissions from producing the emulsion binder.

Other environmental benefits: reduction in congestion, noise, vibration and fumes by reduction in lorry movements. Reduces resource depletion.

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Warm and semi-warm asphalt to reduce energy

application: Highway and airfield pavements.


What is it?Traditionally asphalt has been produced at relatively high temperatures that reduce the viscosity of the binder to a level at which the binder will coat the aggregate particles and mixing can take place without excessive mechanical effort, which means temperatures well over 100 °C. Warm asphalt mixtures incorporate a modifier or admixture, such as a wax, that will allow mixing at a lower temperature.


The method is suitable for all situations, but is particularly useful when there are strict time constraints on reopening or in adverse weather conditions.

How do I apply it?A synopsis of currently available modifiers and admixtures that can be used to produce warm and semi-warm mixtures is given in US Federal Highway Administration webpage www.fhwa.dot.gov/pavement/asphalt/wma.cfm The details include the constraints that need to be applied and differences needed to be employed in design from designing hot asphalt mixtures for each material.

Why should I use it? Waste reduction: it has no direct influence.

Cost reduction: The reduced energy requirement for warm asphalt should at least balance any extra cost for the modifier or admixture.

recycled content: it has no direct influence.

Programme: laying asphalt at a lower temperature will reduce the time needed to drop to a suitable temperature for trafficking, reducing the amount of lost time before reopening.

Carbon footprint: the reduced CO2 required to heat the asphalt will be balanced by that required to produce the modifier/admixture.

Other environmental benefits: reduced emissions from burning fuels, fumes and odours generated at the plant and the paving site.

CONtENtS

www.aggregain.org.uk/case_studies








http://www.fhwa.dot.gov/pavement/asphalt/wma.cfm


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Collect and reuse chippings in surface dressing

application: Highway pavements.


What is it?Surface dressing is procedure where chippings have to be broadcast over an already applied binder on the existing surface. An excess of particles have to be used in order to ensure that a sufficient and uniform layer comes into contact with the binder, with the excess being removed by sweeping. The removed particles are those that have not been in significant contact with the binder, so are relatively uncontaminated by it. If the recovered chippings are kept from being contaminated by other detritus, they can be used on another site.

Where can I use it?Highway projects.

The method is suitable for all pavements that are surfaced dressed and should be standard practice.

Details of a project for recycled surface dressing sweepings across Hampshire are given in TRL Report trL651. The case study is available at www.aggregain.org.uk/case_studies/reuse_of_surplus.html

How do I apply it?The design of road surfacing with recycled pre-coated chippings is as for other surfacing dressings with the method being given in TRL Road note 39 (6th edition). Guidance notes and codes of practice are obtainable from the RSTA at www.rsda-gb.co.uk/codes.htmWhy should I use it?

Waste reduction: reduce the amount of aggregate required in the longer term.

Cost reduction: the cost of the additional chipping that would otherwise have had to be purchased will be saved.



Carbon footprint: the reduction in CO2 from a reduced need to win and transport chippings.


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retexturing asphalt pavement surfacing

application: Highway and airfield pavement surfacing.

Designing out Waste Principle: Design for Material Optimisation.

What is it?Road surfacings with insufficient skid resistance are unsafe and need maintenance. If the lack of skid resistance is the result of extended trafficking and the component materials are appropriate, it may be possible to restore the skid resistance by retexturing rather than replacing that material. There are several different methods of retexturing including impact methods (bush hammering or shot blasting), cutting methods (grooving/grinding, longitudinal flailing or orthogonal flailing) and fluid action (hot compressed air or high-pressure water jetting). The different methods have different effects on the shape of the resulting surface texture.


The method is useful to extend the life of a surfacing that has polished after any extensive and satisfactory service life. It is particularly suitable for sound surfacings that have been heavily trafficked for a temporary period so that the surfacing has polished.

The method is not suitable for polished surfacings where the aggregates have polished prematurely without exceptional wear. If the aggregates do not have the appropriate long term microtexture, retexturing will not enhance its polished stone value.

When deciding whether it appropriate, the whole life costs need to be considered because the treatment will only defer the time before the condition requiring treatment reappears.

Case studies on the durability of these techniques are reported in TRL Report trL299.

How do I apply it?A study of processes, together with the early-life performance, of these techniques is given in TRL Report trL298. The process can be used as a guide to the design process.

Why should I use it? Waste reduction: defer the waste from the removal and replacement of the surface course.

Cost reduction: retexturing is cheaper than planing out and laying a new surface course, although such savings will have to be factored against the lower potential service life.

recycled content: it has no direct influence.

Programme: retexturing will be significantly quicker than removal and replacement, but the next maintenance intervention is likely to be brought forward.

Carbon footprint: the CO2 to retexture a surfacing should be considerably less than removal and replacement of the surfacing.

Other environmental benefits: operations have low dependency on weather conditions.

CONtENtS

www.aggregain.org.uk/case_studies/reuse_of_surplus.html

www.aggregain.org.uk/case_studies/reuse_of_surplus.html

http://www.rsda-gb.co.uk/codes.htm

http://www.rsda-gb.co.uk/codes.htm


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reclaimed asphalt in unbound subbase or capping off site

application: Foundations, all project types.


What is it?Excavated pavement materials (planings) are broken down by crushing and screening to be recycled as unbound subbase or capping material. The material has to comply with the normal specification requirements. A mobile crusher can be brought onto site for the purpose of providing this material from the existing pavement when the quantities are sufficient to justify this. Reclaimed asphalt can be difficult to process in a jaw type crusher because the material tends to clog the jaws, adversely affecting the grading of the recycled material, and the use of a granulator instead of a crusher can help overcome this problem and reduce the material to an acceptable and consistent grading.

Where can I use it?Any project type where pavement foundations are involved: highways; railways; new utilities infrastructure; power generation; development sites (commercial, industrial, housing, mixed).

The method is suitable for any planings that cannot be used at higher level. Whilst use in unbound applications is preferable to sending them to waste, greater value can be obtained by reusing the planings into asphalt mixtures for a similar layer or recycling them into lower bound layers.

The method has been used on a regular basis for some time, but it expected to reduce with a higher value being placed on reclaimed asphalt planings.

How do I apply it?The recycled asphalt can be treated as any other aggregate particles except for the possible need to avoid the conglomeration of particles. Specific categories have been set up for the use of recycled asphalt as capping (Class 6F3 in the 600 Series) and unbound subbase (Type 4 in the 800 Series). Requirements for these applications are given in the Specification for Highway Works www.standardsforhighways.co.uk

Why should I use it? Waste reduction: Reduce the planings not used for higher level uses that has to be disposed of.

Cost reduction: The savings in taking the planings to waste and supplying suitable freshly-won aggregate.



Carbon footprint: there should be a reduction in CO2 from not having to win and transport freshly won aggregate.



Geogrids/geotextiles to reduce thickness of base

application: Highway and airfield base layer of flexible pavements.


What is it?Geogrids are geosynthetic materials formed with a flat polymer structure as a system of mutually perpendicular longitudinal and cross drawn elements which are bonded by weaving, welding, gluing or binding at the points of intersection. Geotextiles are flat, permeable, polymer synthetic or natural textile materials which can be nonwoven, knitted or woven to produce an interlayer (usually at right angles) of two or more sets of yarn, fibres, tapes or other products.

Asphalt as a material works by resisting compression and shear but has limited strength in tension. Geogrids/geotextiles provide reinforcement to an asphalt layer that should increase the ability to resist tensile stresses. As such, the inclusion of geogrids/geotextiles reduces the layer thickness of the base that is theoretically required in order to avoid tensile strains that will initiate cracking.


The method is particularly useful when there are restrictions on the final level of the pavement, reducing the options for a standard design.

How do I apply it?There are no accepted design rules for the reduction in thickness that will result from the use of geogrids/geotextiles in the base. Geogrid/geotextile suppliers will generally have their own rules for calculating the appropriate thickness reduction. However, some clients and road authorities do not accept the claims for reducing the thickness, and discussions should be held before proceeding with this option.

WRAP document Sustainable Geosystems in Civil Engineering applications, www.aggregain.org.uk

Why should I use it? Waste reduction: strengthening of the base means that it may not need to be as thick.

Cost reduction: reduced thickness will reduce the cost of the asphalt, although it needs to be balanced against the cost of the geogrid/geotextile.

recycled content: the reduced need for component materials from the reduction thickness will need to be balanced against the materials required to manufacture the geogrid/geotextile.

Programme: the extra operation of applying the geogrid/geotextile is likely to extend the programme unless the reduced thickness allows less material to be excavated.

Carbon footprint: reduced thickness will reduce the carbon footprint of the asphalt, although it needs to be balanced against the carbon footprint of the geogrid/geotextile.

Other environmental benefits: reduced thickness can avoid additional excavation when the final level cannot be increased.

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http://www.standardsforhighways.co.uk



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Crack and seat with overlay for repairs;

Saw cut and seal with overlay for repairs;

Recycled aggregate in pavement concrete;

Secondary aggregates in pavement concrete;

pfa or ggbs as cement replacement materials; and

Cold recycling of concrete and cement bound pavement layers (in-situ and ex-situ).

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TECHnICAL SOLUTIOn: Pavements – concrete

Crack and seat with overlay for repairs

application: Maintenance of jointed concrete pavements or hydraulically bound mixture bases in highways, airfields, and access roads to harbour, docks, and other infrastructure facilities.


What is it?The crack and seat technique aims to induce fine cracks into jointed concrete slabs or hydraulically bound bases, before overlaying with a new asphalt surfacing. This then encourages the daily/seasonal thermal movement in the materials to occur at the induced cracks. These are at a closer spacing than the normal shrinkage cracks or joints, thus the thermal movements at individual cracks should be much smaller and the occurrence of transverse reflection cracks in the asphalt overlay should be minimised.

The crack, seat and overlay treatment has been shown to perform considerably better than control sections with the same overlay thickness, inhibiting reflection cracking above joints and pre-existing cracks in unreinforced concrete pavements and hydraulically bound bases. The closely related technique of saw cut, crack and seat is showing similar promise in providing a cost effective treatment option for reinforced concrete pavements.

The technique can provide a cost effective alternative to full depth reconstruction.

Where can I use it?If a jointed concrete or flexible composite pavement has deteriorated beyond the condition in which it may be cost effectively repaired, then the crack, seat and overlay technique may be appropriate. The technique is suitable for jointed concrete slabs or hydraulically bound bases or sub-bases. Saw cut, crack and seat can be used for the treatment of reinforced concrete pavements.

If the pavement is in good condition with minimal or no major defects, then saw cut and seal may be appropriate (see separate Technical Solution Summary Sheet). If the pavement is in very poor condition with long lengths of longitudinal cracking and/or poor foundation and drainage, full depth reconstruction may be necessary.

How do I apply it?

Details of the procedures are given in Clauses 715 to 719 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0700.pdf These clauses give the approach for crack and seat, saw cut crack and seat, and the various monitoring and back-analysis techniques.

TRL Road note 41 (Best practice guide for overlaying concrete) assists in the choice of treatment and gives advice on maximising durability.

TRL have completed a major research programme on the topic. TRL PPr441 (in press) reports on research and performance and includes many case history studies, whilst PPr442 (in press) provides a practical guide to design and construction based on the research findings.

Why should I use it? Waste reduction: reduction in the volume of materials taken to landfill.

Cost reduction: estimates indicate a material cost saving of about 40% when compared to traditional maintenance techniques.

recycled content: reuse (or recycling) of existing slabs/bases.

Programme: a reduced contract period minimises traffic delays and the cost to the travelling public.

Carbon footprint: energy consumption during construction is reduced compared to traditional full depth reconstruction or repair. Lorry movements to dispose of waste are reduced.

Other environmental benefits: use of primary aggregates is reduced. noise, vibration and dust caused by full depth construction are eliminated.

CONtENtS





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Saw cut and seal with overlay for repairs

application: Maintenance of jointed concrete pavements in highways, airfields, and access roads to harbour, docks, and other infrastructure facilities.


What is it?The principle behind saw cut and seal is to accommodate the stresses and strains associated with expansion and contraction of the underlying jointed concrete by introducing joints into the asphalt overlay directly above the joints in the concrete. These joints are then filled with an approved sealant, which because of its high flexibility stops the formation of reflection cracks at the surface, whilst controlling their development from a crack initiation slot below the surface.

Where can I use it?Saw cut and seal is an appropriate treatment for jointed concrete pavements in generally good condition. Performance with overlay thicknesses of less than 40mm has not been satisfactory and this is the minimum thickness for this technique to be applied, although it is preferable to have a thickness of at least 70mm.

Good quality control during the application of the saw cut and seal technique is an important factor in the performance.

How do I apply it?Details of the procedures are given in Clauses 713 and 714 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0700.pdf These clauses give the procedure for saw cut and seal of asphalt overlays on existing jointed concrete pavements together with the preparation of the pavement prior to laying the asphalt overlay and the saw cut and seal.

TRL Road note 41 (Best practice guide for overlaying concrete) assists in the choice of treatment and gives advice on maximising durability.

TRL Report 657 Improved design of overlay treatments to concrete pavements gives details on the monitoring of both trial and construction schemes.

Why should I use it? Waste reduction: reduction in the volume of materials taken to landfill compared with a full depth repair.

Cost reduction: low cost maintenance treatment for pavements in generally good condition.

recycled content: reuse (or recycling) of existing slabs/bases.

Programme: a reduced contract period minimises traffic delays and the cost to the travelling public.

Carbon footprint: energy consumption during construction is less than that required for a more far-reaching repair.

Other environmental benefits: noise, vibration and dust caused by a full depth repair are eliminated. Reduced resource depletion.

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recycled aggregate in pavement concrete

application: Construction and maintenance of pavements for highways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites, and in concrete for railway sleepers.


What is it?Use as coarse aggregate in pavement concrete of aggregate resulting from the processing of inorganic material previously used in construction and aggregate recovered from demolished concrete. There are often restrictions such that only crushed concrete resulting from reclamation or processing of concrete previously used in construction which originates from appropriately identified structures with a known history of use is permitted. This could include concrete from a single structure or materials such as railway sleepers and pavement concrete that have a high degree of uniformity. This gives confidence in the use of these aggregates in new concrete. A number of tests are undertaken to detect substances and chemicals potentially harmful to the durability of concrete.

Where can I use it?The Highways Agency allows the use of recycled aggregate (RA) and recycled concrete aggregate (RCA) for pavements subject to appropriate tests on the aggregate to ensure the durability of the concrete. RA and RCA may be used for concrete in many other applications.

How do I apply it?Requirements for RA and RCA for use in concrete in general are indicated in BS 8500-2:2006.

For pavements the aggregate requirements and requirements of the source of recycled aggregates are indicated in the Specification for Highway Works, Clauses 1001.6 – 1001.14, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf and the associated Notes for Guidance, Clauses 1001.14 -1001.26 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf

The testing required of the aggregates for determining the constituent materials are described in the Specification for Highway Works, Clause 710, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0700.pdf and the associated Notes for Guidance, Clause 710 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0700.pdf

Why should I use it? Waste reduction: the use of recycled aggregates reduces the quantity of waste disposed to landfill.

Cost reduction: may be cheaper than using primary aggregates.



Carbon footprint: the waste materials are usually available locally, therefore there is a saving on transport in lorry movements and fuel.


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Secondary aggregates in pavement concrete

application: Construction and maintenance of pavements for highways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites, and for structural concrete in railways.


What is it?Secondary materials may be reclaimed from residues of industrial processes including mining and industrial processes such as iron and steel production and power generation. Materials that may be used for pavements include blastfurnace slag, china clay sand/stent, pulverised fuel ash, used foundry sand, incinerator bottom ash aggregate, phosphoric slag, and slate aggregate. Other materials such as recycled glass and steel slag may be used when it can be shown that risks of ASR and volume instability, respectively, will be controlled.

Where can I use it?The Highways Agency allows the use of secondary materials for pavements subject to appropriate tests on the aggregate to ensure the durability of the concrete. network rail allow the use of blastfurnace slag in structural concrete.

How do I apply it?Some of the secondary materials suitable for use in concrete pavements are indicated in the Design Manual for roads and Bridges, HD 35/04, www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf

Details of the aggregate requirements are indicated in the Specification for Highway Works, Clauses 1001.6 – 1001.14, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf and the associated Notes for Guidance, Clauses 1001.14, -1001.26 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf

Why should I use it? Waste reduction: the use of secondary materials reduces the quantity of waste disposed to landfill.






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What is it?Concretes mixes where a proportion of the cement is replaced by pulverised fuel ash (pfa) or ground granulated blastfurnace slag (ggbs) result in reduced early-age thermal cracking in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pfa and ggbs have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pavement, pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.


How do I apply it?The Concrete Society Technical Report 40 (1991) provided early guidance on the use of pfa and ggbs in concrete.


Details of the recommended levels of replacement are given in the Specification for Highway Works, Clause 1001.3, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf and the associated Notes for Guidance, Clause 1001.10, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf





Carbon footprint: the use of waste/by-product materials reduces the embodied carbon associated with cement.

Other environmental benefits: obviates need to dispose of waste materials by other means. Reduces resource depletion.

CONtENtS



















What is it?Recycling techniques restore the structural integrity of the lower layers of a road using cement or other hydraulic binders. An existing road or building can be used as a ‘linear quarry’ with the concrete or hydraulic bound material being crushed, screened and sorted into aggregate sized particles. This can be undertaken on site with portable equipment or the material removed from site and processed at a nearby aggregate ‘factory’.

Where can I use it?These techniques can be used on highways, airfields or on other paving projects such as parking areas etc.

The method when used as base is more suitable for lightly trafficked roads with loadings of up to 30msa. When used in the subbase it will provide a high class bound foundation under any volume of traffic.

How do I apply it?TRL Report trL611 (a development from TRL386) is a guide to the use and specification of cold recycled materials.

The design for base layers can be found in the DMrB HD 26/06, www.standardsforhighways.co.uk/dmrb/vol7/section2/hd2606.pdf

The requirements for hydraulic bound materials for use as base or subbase can be found in the SHW Clauses 810 – 880, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf and the accompanying Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf

Why should I use it? Waste reduction: reduces the amount of material for disposal.

Cost reduction: it will generally be cheaper to reuse reclaimed concrete or hydraulic bound material on site than dispose of it and provide freshly won aggregate, particularly when it has to be transported some distance; the reduced energy requirement should also provide a cost benefit.



Carbon footprint: there will be a reduction in CO2 from less vehicle movements taking materials off site and not importing new concrete.


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Treat existing soil to make HBM subbase/ballast;

Recycled and secondary aggregates to make HBM subbase/ballast;

Recycled/secondary aggregates as unbound ballast;

Geogrids/geotextiles to reduce thickness of ballast;

pfa or ggbs as cement replacement materials;

Railway sleepers: containing recycled aggregate;

Railway sleepers: containing secondary aggregate;

Railway sleepers: recycled plastic; and

Steel with high recycled content.

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TECHnICAL SOLUTIOn: railways – ballast, sleepers and track

treat existing soil to make HBM subbase/ballast

application: Construction and maintenance of railway ballast and base and subbase for pavements for highways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Treating existing soil with binders/activators is known as ‘stabilisation’ of the soil to form a bound layer. It may be a one stage or two stage process. The two stage process uses lime to break down cohesive soils and then they are treated as in the single stage process, for non-cohesive soils, by adding a binder. The binder may be cement, ground granulated blastfurnace slag (ggbs) or pulverised fuel ash (pfa) or a combination of cement with either ggbs or pfa or lime. This process is usually undertaken in situ but may be done ex-situ. The production of HBM requires higher levels of binders/activators than the production of capping or the drying out of soils to be suitable as general fill.

Where can I use it?This process may be used as a subbase in any pavement construction or as a base in lightly trafficked pavements. Sulfates and sulfides in the soil can lead to expansive reactions with the binders and activators, so the soil should be checked thoroughly for these constituents.

Lime and cement were used to stabilise in-situ glacial till deposits to form a soil cement equivalent to Type 1 unbound subbase for one carriageway of a 24km scheme to upgrade the A120 in Essex between the M11 and the existing Braintree Bypass www.aggregain.org.uk/case_studies/use_of_ra_and.html

How do I apply it?The solution is covered by BS EN 14227 Parts 10-14.

The methodology for ‘stabilisation’ is given in the Specification for Highway Works, Clause 840, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf and the associated Notes for Guidance, Clause 840 discusses the testing procedures, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf

Guidance on the use of stabilised materials in earthworks is given in the Appendix to network Rail Model Clause 52 for Specifying Civil Engineering Works and generally takes the same approach to that in the Specification for Highway Works.

There are two useful Britpave documents: Britpave BP/08 technical data sheet – Stabilised soils as subbase or base for roads and other pavements and Britpave BP/15 Soil stabilisation- Guidelines for best practice.

Why should I use it? Waste reduction: the use of the existing soil reduces the quantity of material disposed to landfill.

Cost reduction: is cheaper to mix in situ than off site, does not require primary aggregate.



Carbon footprint: the use of the existing soil gives a saving on lorry movements and fuel. Maximising the use of pfa and ggbs compared to cement and lime reduces the carbon footprint of the solution.


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recycled/secondary aggregate to make HBM subbase/ballast

application: Construction and maintenance of railway ballast and subbase for pavements for highways, airports, utilities, railways, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Aggregate resulting from the processing of inorganic material previously used in construction, aggregate recovered from demolished concrete and aggregate from residues of industrial processes including mining. Typical materials include blastfurnace slag, burnt colliery spoil, china clay sand/stent, coal fly ash and pulverised fuel ash, foundry sand, furnace bottom ash, incinerator bottom ash aggregate, phosphoric slag, recycle aggregate, asphalt and concrete, recycled glass, slate aggregate, spent oil shale/blaise, steel slag and unburnt colliery spoil.

Where can I use it?Recycled/secondary aggregates may be used for hydraulic bound subbase beneath any pavements. A higher grade use of HBM is as base course for lightly trafficked pavements.

How do I apply it?Some of the secondary materials suitable for use in subbase and base are indicated in the Design Manual for Roads and Bridges, HD 35/04, www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf Guidance on the use of HBM in road foundations is given in Interim Advice note 73/06 Revision 1 (2009) Design Guidance for Road Pavement Foundations (Draft HD25), available at www.standardsforhighways.co.uk/ians/pdfs/ian73rev1.pdf Use of HBM enables a foundation with higher stiffness to be produced, which can lead to reductions in the thickness of the subbase and overlying pavement layers if the design process in IAn73/06 is followed.

For the subbase in pavements construction the aggregate requirements are indicated in the Specification for Highway Works, Series 800, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf and the associated notes for Guidance, Series 800, www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0800.pdf

There are two useful WRAP documents for HBMs; a WRAP Guidance document: Hydraulically bound materials incorporating recycled and secondary aggregates www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html; and a WraP Quality manual for hydraulically bound mixtures www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.html

There is also a Britpave document which indicates the requirements in the European standards for HBMs, Britpave BP/13 technical data sheet – Cement and other hydraulic bound mixtures (The new European Standard BS En 14227, Parts 1-5).

Why should I use it? Waste reduction: the use of recycled or secondary aggregates in HBM reduces waste and can lead to thinner layers being required compared to unbound subbase.

Cost reduction: is usually cheaper than using primary aggregates.



Carbon footprint: the use of waste materials are usually available locally, therefore there is a saving on transport in lorry movements and fuel and use of primary aggregates. Maximising the use of pfa and ggbs compared to cement and lime reduces the carbon footprint of the solution.


CONtENtS

www.aggregain.org.uk/case_studies/use_of_ra_and.html

www.aggregain.org.uk/case_studies/use_of_ra_and.html


















http://www.wrap.org.uk/construction/how_do_i_ reduce_waste/sectors/utilities/utilities_ guidance.html




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recycled and secondary aggregates as unbound ballast

application: Railways.


What is it?Recycled and secondary aggregates can be used in place of primary aggregates as unbound ballast for railways.

Where can I use it?Ballast for railways is required to be a free draining coarse aggregate with angular particles that will interlock to form a layer of good dimensional stability. The individual particles must be strong enough to resist surface attrition and degradation caused by the hammering action of rail traffic. Some recycled and secondary aggregates, such as blastfurnace slag and steel slag, possess the necessary properties for this application.

Ballast gradually becomes contaminated with fine particles due to the effects of rail traffic causing wear on the particles and dust blown in by the wind. It can also become contaminated with hydrocarbons, grease and other organic compounds from rail traffic, particularly in sidings and marshalling areas. The ballast can be recycled by washing to provide material suitable for reuse. network Rail and London Underground are looking at the issue of reusing spent ballast back into trackwork to increase the amount of recycling they undertake. Uncontaminated spent railway ballast is also considered suitable for use as recycled aggregate in road construction.

How do I apply it?Ballast must comply with the requirements of network Rail’s Standards and Specifications for track Engineering. Particularly relevant is the Specification for railway Ballast and Stoneblower aggregate (Nr/L2/trK/8100 which replaces RT/CE/S/006) which sets out the testing requirements for grading, particle shape, and particle strength as measured by the wet attrition value. Ballast is increasingly recycled by washing and the Specification for track Ballast returned by automatic Ballast Cleaners (rt/CE/S/009) provides the requirements. The use of recycled or secondary aggregates needs technical approval for rail applications, with the case often being based on information given in HA Standards.

Why should I use it? Waste reduction: allows reuse of materials that might otherwise be disposed of to landfill or exempt sites.

Cost reduction: recycled aggregates are normally cheaper than primary aggregates, particularly in urban areas. Secondary aggregates are available locally and may be cheaper than primary aggregates if transport distances are less.



Carbon footprint: usually reduced compared to primary aggregates because of lower transport distances.


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Geogrids/geotextiles to reduce thickness of ballast

application: Construction and maintenance of subbase/ballast for highways, railways, airports, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Geogrids/geotextiles work by creating mechanical interlock of the aggregates and acting as a separator above the soil foundation; this allows a reduction in the thickness of the subbase/ballast layer in pavement or railtrack construction.

Mechanically stabilised foundation layers can sustain increased loadings, or provide the required performance with a reduced layer thickness.

Where can I use it?Geogrids/geotextiles can be used when constructing new pavements, carrying out major remediation of an existing pavement, strengthening the ballast for railway track construction.

Geotextile fabric acts as a good separator limiting deformation at the aggregate surface. Geogrid is particularly effective in reducing lateral movement because of granular interlock within the subbase as a result of stones being forced into the apertures of the grid.

The improved mechanical properties of the subbase/ballast may lead to an increased life.

How do I apply it?Design for traffic/railway loading is based on the stabilisation factor which will vary according to geogrid/geotextile type. The manufacturer’s performance data and design methodology should be taken into account.

Various TRL Reports, e.g. rr140 (Deformation of road foundations with geogrid reinforcement) and rr382 (Installation damage trials on geotextiles), give trial results.

The use of geogrids/geotextile in railway earthworks is covered by network Rail Model Clause 52 for Specifying Civil Engineering Works and their product specification needs to comply with the requirements of Nr/SP/trK/010 (formerly RT/CE/S/010).

WRAP document Sustainable Geosystems in Civil Engineering application,www.aggregain.org.uk

Why should I use it? Waste reduction: improvement/strengthening of the subbase/ballast means that it may not need to be as thick.

Cost reduction: some cost savings may result because of the reduction in subbase/ballast thickness.

recycled content: the quantity of imported primary aggregates is reduced.

Programme: additional time required to place the geogrids, but balanced by reduced requirement for material; overall no significant impact.

Carbon footprint: some reduction in lorry movements needed to import additional aggregate.

Other environmental benefits: lorry traffic on adjoining roads is reduced in many cases. A more durable product may require less maintenance. Reduced resource depletion.

CONtENtS



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What is it?Concretes mixes where a proportion of the cement is replaced by pulverised fuel ash (pfa) or granulated blastfurnace slag (ggbs) result in reduced early age thermal cracking in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pfa and ggbs have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pavement, pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.




Details of the recommended levels of replacement are given in the Specification for Highway Works, Clause 1001.3 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf and the associated Notes for Guidance, Clause 1001.10 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_1000.pdf

network Rail - Model Clauses for Civil Engineering Works, Section 80, Structural Concrete, Clause 80.005 indicates the replacement levels allowed and applications for pfa, ggbs and microsilica. Sections 70-79, Piling and Embedded retaining Walls, implements the ICE specification which permits cement replacement.






Other environmental benefits: obviates need to dispose of waste materials by other means. Reduced recource depletion.


railway sleepers: containing recycled aggregate

application: Construction and maintenance of rail track for surface and underground rail networks.


What is it?Concrete railway sleepers can be precast using aggregate resulting from the processing of inorganic material previously used in construction and aggregate recovered from demolished concrete. There are often restrictions such that only crushed concrete resulting from reclamation or processing of concrete previously used in construction which originates from appropriately identified structures with a known history of use is used. These sources might include concrete from railway sleepers which are cracked and unserviceable. This gives confidence in the use of these aggregates as a number of tests are undertaken to detect substances and chemicals harmful to the durability of concrete.

Where can I use it?Railway sleepers precast using recycled concrete aggregate can be used in rail environments subject to appropriate tests on the aggregate to ensure the durability of the concrete and require the approval of the Engineer.


Current standards for structural concrete for rail (as for road structure) applications do not permit the use of recycled concrete aggregate and a departure from standard, subject to performance testing, is therefore required from the Engineer. It should be noted that recycled concrete aggregate is permitted in road pavement construction and compliance with these requirements (Specification for Highway Works, Clauses 1001.6 – 1001.14, www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf) may provide a route to product acceptance within the rail industry.



Why should I use it? Waste reduction: the use of recycled aggregates reduces the quantity of waste disposed to landfill.






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railway sleepers: containing secondary aggregate

application: Construction and maintenance of rail track for surface and underground rail networks.


What is it?Secondary materials may be reclaimed from residues of industrial processes including mining and industrial processes such as iron and steel production and power generation. Materials that are already used for pavements include blastfurnace slag, china clay sand/stent, pulverised fuel ash, used foundry sand, incinerator bottom ash aggregate, phosphoric slag, and slate aggregate. Other materials such as recycled glass and steel slag may be used when it can be shown that risks of ASR and volume instability, respectively, will be controlled. Similar usages are anticipated in the rail industry for manufacturing concrete railway sleepers and other ancillary concrete products.

Where can I use it?network Rail allow the use of blastfurnace slag in structural concrete, use of other secondary aggregates would be subject to appropriate testing to ensure the durability of the concrete and require the approval of the Engineer.

How do I apply it?network Rail Model Clauses for Civil Engineering Works, Section 80, Structural Concrete, Clause 80.006 comments on the use of air cooled blast furnace slag.

In gaining technical approval in the rail industry, the advice given on the use of secondary materials for concrete pavements in the Design Manual for Roads and Bridges HD 35/04, and the Specification for Highway Works Clauses 1001.6 – 1001.14, may provide a route to acceptance.

Why should I use it? Waste reduction: the use of secondary materials reduces the quantity of waste disposed to landfill.







railway sleepers: recycled plastic

application: Surface and underground railways.


What is it?Recycled plastic railway sleepers are being used to replace concrete sleepers and treated timber sleepers. Plastic sleepers have the advantage of low weight, good damping of noise and vibrations, and require no biocide treatment. Further research is needed in validating long term performance and durability (e.g. effects of uv radiation, ageing) in service.

Where can I use it?Recycled plastic railway sleepers can be used for surface and underground railway networks where rail traffic is of low speed. Concrete sleepers (or slabtrack) is currently preferred for new high speed installations.

Fire safety is a consideration and so fire retardants are incorporated in the recycled plastics.

How do I apply it?TRL PPr94 gives guidance on the feasibility of recycled plastic railway sleepers.

Further information is expected from the European ERA-nET Sustainable Enterprise (SUSPRISE) programme and the project “Railwaste” which is investigating the performance of railway sleepers from mixed plastic wastes.

Why should I use it? Waste reduction: avoids disposal of large quantities of PVC waste from other manufacturing processes.

Cost reduction: usually similar cost, or less, than concrete sleepers. Light weight can reduce delivery and handling costs.

recycled content: increases the recycled content of the scheme by using up to 100% recycled heavy duty plastic.

Programme: ease of handling and transportation can resulting in rapid installation.

Carbon footprint: use of recycled plastic reduces greenhouse gas emissions which would otherwise arise from the production of concrete sleepers. Reduction in lorry movements as more linear metres can be carried per delivery.

Other environmental benefits: provides an alternative to creosoted timber sleepers which are now prohibited from reuse for safety reasons. Reduces resource depletion.

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Precast concrete rather than cast in-situ;

Precast tunnel lining segments on site;

Recycled/secondary aggregates in concrete;

Reuse of piled foundations;

Plastic sheet piling;

Steel with high recycled content;

pfa or ggbs as cement replacement materials;

Recycled aggregates and/or HBM for working platform; and

Incorporate working platform into permanent works.








All steel has a recycled content that varies between 10% and 100% and steel construction products are highly recycled. Recent research by the Steel Construction Institute has found that on average, 84% of the UK’s construction steel is recycled and a further 10% reused.














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TECHnICAL SOLUTIOn: Piling, retaining walls and tunnels

Precast concrete rather than cast in-situPrecast tunnel lining segments on site

application: Various structural elements for highways, railways, utilities, harbours, docks and waterways, and power generation.


What is it?The benefits of off site factory production, or controlled prefabrication on site or at a nearby location, are well documented. Assembling the precast units on site and then moving them into place has the potential to significantly change operations on site, reducing the number of site activities and changing the construction process into one of a rapid assembly of parts that can provide many environmental, commercial and social benefits. Generally a better quality product can be produced by precast techniques and the need for temporary works may be reduced.

Assembling structures in this way is one of a group of approaches to more efficient construction sometimes called Modern Methods of Construction that also include prefabrication, improved supply chain management and other approaches. It should be noted that these techniques are already extensively applied in the building construction industry from which many lessons can be learned.

Where can I use it?Precast beams and bridge units are frequently used for constructing road, rail and foot bridges and box culverts are precast prior to jacking them beneath embankments. In replacement situations, the new structure is built alongside the existing one, which is then demolished and the new structure moved into place as a unit. The main driver for this method of construction is that it minimises closure or disruption of the road or railway, but it also allows more efficient construction of the new structure with reduced waste compared to constructing it in stages while keeping the road/railway functioning. In all cases, the methods of construction need to be considered at the preliminary design stage.

The use of precast units for rapidly constructing low height modular retaining walls, such as those needed for slope retention and silo installation, is already well established in the civil engineering industry. Precast pipes are also extensively used.

How do I apply it?WRAP (2007) Current practices and future potential in modern methods of construction. Case history studies are also reported by WRAP in Waste reduction potential of precast concrete manufactured off site.

For concrete structures, the Concrete Centre and the British Precast Concrete Federation are amongst those organisations providing advice on off site construction and precasting techniques.

CIRIA (2000) C516 Modular gravity retaining walls - design guidance gives guidance on design issues.




Programme: rapid on site assembly of the structure reduces construction timescales.

Carbon footprint: minimises delay to road, rail and other users so improving fuel efficiency.

Other environmental benefits: less disruption in terms of noise, dust, and vibration because of faster construction.


recycled/secondary aggregates in concrete

application: Construction and maintenance of piling, retaining walls and tunnels.


What is it?At the moment recycled aggregate is restricted to replacing coarse aggregate (>4mm) which precludes the use of most secondary aggregates. It is likely that suitable recycled aggregate will be obtained from two main supply streams, either preconsumer waste from concrete production (precast or ready-mix concrete plants) or from demolition projects such as disused airfield structures, concrete framed or clad buildings. This ensures a relatively high quality material with < 5% brick and <1.0% impurities. Potential sources need to be able to provide sufficient quantity, consistent quality and usually be fairly close to the site where the concrete is to be used to ensure that the economics are viable.

Where can I use it?The use of recycled aggregate in structural grade concrete is relatively new. Hence, the usage of Recycled Concrete Aggregate (RCA) is not advised for use in particularly sensitive or critical structural elements or structures until it has a longer track record. In some applications RCA is used as a partial replacement for primary aggregate and may be used up to the 20% replacement level; however, it may be possible to use it up to the 60% replacement level with the overseeing engineer’s approval.


The SHW 1702.2 states that ‘Unless otherwise specified in Appendix 17/4, aggregates shall conform to the British Standards listed in 4.3 of BS 8500-2 except that recycled concrete aggregate (RCA) and recycled aggregate (RA) shall not be used’. However, this is dated May 2004 and conflicts with Ba 92/07 dated May 2007. It is advised that a departure should be applied for use of RCA and RA in accordance with Chapter 7 of BA 92/07.

BA 92/07 is an Advice note in the Design Manual for Roads and Bridges entitled the use of recycled concrete aggregate in structural concrete and provides information on the use of RCA as a replacement for coarse natural aggregates in structural grade concrete, www.standardsforhighways.co.uk/dmrb/vol2/section3/ba9207.pdf It encourages designers, contractors and concrete suppliers to consider the use of RCA.



Why should I use it? Waste reduction: the use of recycled aggregates reduces the quantity of waste disposal to landfill.

Cost reduction: is usually cheaper than using primary aggregates.



Carbon footprint: the use of recycled materials are usually available locally, therefore there is a saving on transport in lorry movements and fuel.


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reuse of piled foundations

application: Construction of deep foundations for buildings, bridges and other structures in highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?The reuse of foundations for a new superstructure is technically feasible and is increasingly becoming part of standard practice. The concept of reusing foundations is being developed in response to increasing pressure on land availability for city re-development and to find more cost effective and sustainable methods of construction.

Where can I use it?Redevelopment of buildings in city centres frequently occurs and, in confined spaces such as these, there are often few options in terms of foundation location and reuse is particularly viable. In some cases, a mixed foundation solution may be adopted with new foundations used in conjunction with existing foundations. The main benefits are in the reuse of deep piled or diaphragm wall foundations, however the principles are applicable to shallow foundations although cost and environmental benefits are then small.

How do I apply it?The key to reuse of foundations is identifying the foundation locations, dimensions and load carrying capacity with a high degree of reliability. CIRIA Report C653 gives guidance on how foundations can be reused, the technical considerations, and advice on allowing new foundations to be reused in the future.

There are risks inherent in the reuse of foundations, but these can be controlled by risk assessment and careful design. Various guidance has been produced under the RuFUS project which was European Union partially funded research. This includes a best practice handbook on the reuse of foundations for urban sites (BRE EP75, 2006) which gives guidance on technical risks, decision models and the legal and financial issues. Case history studies where the reuse of foundations has been employed are given in the Proceedings of the International Conference (BRE EP73, 2006).

Why should I use it? Waste reduction: avoids the use of virgin materials for the construction of new piles.

Cost reduction: removing old piled foundations to make way for new foundations can cost significantly more than the construction of new piles.


Programme: transfer of load to existing piles reduces the extent of the new piling programme and hence speeds construction.

Carbon footprint: reduction in lorry movements in removing debris and importing new concrete and steel. The latter take significant energy to produce and reuse therefore improves “carbon accountancy” balance.

Other environmental benefits: significant benefits in reducing noise, dust and vibration both from heavy plant required to demolish the old foundations and also from more extensive new piling operations which would otherwise be required. Reduced resource depletion.


Plastic sheet piling

application: Soil retention, slope stabilisation, water retention or cut-off for highways, railways, utilities, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Plastic sheet piling manufactured from either polyvinyl chloride or fibre reinforced polymer has been extensively used for soil retention in north America and Europe particularly for waterway and marine applications. Recent innovations in the UK plastics industry have included the production of sheet piling from recycled polyvinyl chloride. This product is being increasingly used in the UK for highways and waterways related applications and offers a cost effective solution to the provision of low height soil retaining or water cut-off walls.

Where can I use it?Plastic sheet piling has been successfully employed and is expected to be increasingly used for permanent highway works and retention of the banks of waterways. The various products are mainly suited for structures with a low retained height because of the limitations in bending moment resistance, driveability and creep performance. For a cantilevered structure these issues become critical as the retained height approaches 2m and consideration then needs to be given to providing support at the top by anchoring or nailing the structure.

Other identified uses include temporary works (e.g. for deep trenching), stabilising slopes against shallow failures, noise barriers, construction of water channels, scour protection around bridge foundations, balancing pond and flood control walls to mitigate against the increasing number of flooding incidents caused by climate change, and cut-off walls to prevent the movement of groundwater/sea water.

How do I apply it?Guidance on the structural use of plastic sheet piling is given in TRL Report 533 and further information on performance and durability can be obtained from manufacturers. Plastic sheet piling produced from recycled material is more appropriate for use when designing out waste.

Monitoring of driveability trials for the particular application may be appropriate to convince the client of the suitability of the product. As specialised lightweight equipment has been developed for driving plastic piles, a specialist contractor should be engaged for the trial. There may be further merit in monitoring overall performance of the piling in the trial area to provide confidence in its serviceability.

Why should I use it? Waste reduction: avoid sending large quantities of PVC to waste from other manufacturing processes.

Cost reduction: it will generally be up to 50% cheaper than steel sheet piling.

recycled content: increases the recycled content of the scheme (100% of the pile material is recycled).

Programme: advantages include ease of handling and transportation of the lightweight piles which reduces costs of delivery and no craneage is required.

Carbon footprint: reduction in lorry movements as more linear metres can be carried per delivery.

Other environmental benefits: good corrosion resistance to both fresh and salt water, and chemicals. Can be produced in aesthetically pleasing colours.

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application: Construction of deep foundations for buildings, structures and tunnels for highways, railways, airports, harbours, docks and waterways, power generation and in the development of brown- and greenfield sites.


What is it?Composite cement concretes reduce early-age thermal cracks in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pulverised fuel ash (pfa) and ground granulated blastfurnace slag (ggbs) have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.

Where can I use it?Pozzolans, like pfa and ggbs, have not gained popularity in fast track construction because of their slower strength gain at standard curing temperatures – however for below ground construction this may not be an issue. Yet in some circumstances their properties may be advantageous. For example cement replacement is considered to enhance resistance to sulphate attack and to alkali-silica reaction. In addition there is some evidence that pfa or ggbs have the effect of reducing permeability to both gases and liquids so encouraging their usage for cut-off walls.









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recycled aggregates and/or HBM for working platformsIncorporate working platform into permanent works

application: Working platforms for piling rigs and cranes for the construction of highways, airports, utilities, tunnels, railways, harbours, docks and waterways, power generation and in development of brown- and greenfield sites.


What is it?A working platform provides a safe and durable working surface from which construction plant, such as piling rigs and cranes, can operate. Recycled aggregates can be used to form the platform. Alternatively hydraulically bound materials (HBM) made using lime, cement and other binders are a cost effective method of stabilising weak on site soils (or imported recycled aggregates).

Where can I use it? Clear economic and environmental benefits can be derived from the use of platforms, particularly where increased use can be made of either site won or recycled materials,

when platforms can be used and reused for a variety of purposes throughout the construction process,

when platforms can be reused for permanent works.

How do I apply it?WRAP (2006) produced a report on Guidance on the use of HBM in working platforms http://aggregain.wrap.org.uk/document.rm?id=3395 This also gives examples where working platforms can be utilised many times through a construction life-cycle.

General advice on the use of stabilised soils is given in the Specification for Highway Works 600 and 800 Series.

Further advice is given in TRL Contractor Report 151 (Stabilized capping layers using either lime, or cement, or lime and cement).

Why should I use it? Waste reduction: the use of site won materials reduces the waste sent to landfill, particularly if the working platform can be incorporated into the permanent works.

Cost reduction: reduced costs compared with the option of importing primary aggregates for the platform.

recycled content: reuse of site won materials and/or recycled aggregates.


Carbon footprint: use of site won materials can lead to significant savings in lorry movements.





Assemble structures on site and move into place;

Recycled/secondary aggregates in concrete;

pfa and ggbs as cement replacement materials; and

Gabions or other geosystems for soil retention and erosion protection.

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TECHnICAL SOLUTIOn: Structures – concrete

Precast concrete rather than cast in-situ








For concrete structures, the Concrete Centre and the British Precast Concrete Federation are amongst those organisations providing advice on modern methods of construction and precasting techniques.









assemble structures on site and move into place



What is it?The benefits of off site factory production, or controlled prefabrication on site at a nearby location, are well documented. Assembling these structures on site and then moving them into place has the potential to significantly change operations on site, reducing the number of site activities and changing the construction process into one of a rapid assembly of parts that can provide many environmental, commercial and social benefits.


Where can I use it?Assembly on site is now frequently used as a method of construction of road, rail and foot bridges and for installing box culverts beneath embankments. In replacement situations, the new structure is built alongside the existing one, which is then demolished and the new structure moved into place as a unit. The main driver for this method of construction is that it minimises closure or disruption of the road or railway, but it also allows more efficient construction of the new structure with reduced waste compared to constructing it in stages while keeping the road/railway functioning. The existing structure can then be demolished or dismantled more efficiently, allowing greater recovery and reuse of its materials for future projects.

The use of precast units for rapidly constructing low height modular retaining walls is already well established in the civil engineering industry.

In all cases, the methods of construction need to be considered at the preliminary design stage.

How do I apply it?WRAP (2007) Current practices and future potential in modern methods of construction.

For concrete structures, the Concrete Centre and the British Precast Concrete Federation are amongst those organisations providing advice on modern methods of construction.


Why should I use it? Waste reduction: has the potential to reduce waste produced on site.

Cost reduction: efficient prefabrication may reduce costs.

recycled content: opportunities may exist for recycling during prefabrication.

Programme: minimises disruption to transport networks by rapid on site assembly of the structure reducing construction timescales.



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recycled/secondary aggregates in concrete

application: Construction and maintenance of concrete structures.


What is it?At the moment recycled aggregate is restricted to replacing coarse aggregate (>4mm) which precludes the use of most secondary aggregates. It is likely that suitable recycled aggregate will be obtained from two main supply streams, either preconsumer waste from concrete production (precast or ready mix concrete plants) or from demolition projects such as disused airfield structures, concrete framed or clad buildings. This ensures a relatively high quality material with <5% brick and <1.0% impurities. Potential sources need to be able to provide sufficient quantity, consistent quality and usually be fairly close to the site where the concrete is to be used to ensure that the economics are viable.

Where can I use it?The use of recycled aggregate in structural grade concrete is relatively new. Hence, the usage of Recycled Concrete Aggregate (RCA) is not advised for use in particularly sensitive or critical structural elements or structures until it has a longer track record. In some applications RCA is used as a partial replacement for primary aggregate and may be used up to the 20% replacement level; however, it may be possible to use it up to the 60% replacement level with the overseeing engineer’s approval.


The SHW 1702.2 states that ‘Unless otherwise specified in Appendix 17/4, aggregates shall conform to the British Standards listed in 4.3 of BS 8500-2 except that recycled concrete aggregate (RCA) and recycled aggregate (RA) shall not be used’. However, this is dated May 2004 and conflicts with Ba 92/07 dated May 2007. It is advised that a departure should be applied for use of RCA and RA in accordance with Chapter 7 of BA 92/07.

BA 92/07 is an Advice note in the Design Manual for Roads and Bridges entitled the use of recycled concrete aggregate in structural concrete and provides information on the use of RCA as a replacement for coarse natural aggregates in structural grade concrete, www.standardsforhighways.co.uk/dmrb/vol2/section3/ba9207.pdf It encourages designers, contractors and concrete suppliers to consider the use of RCA.



Why should I use it? Waste reduction: the use of recycled aggregates reduces the quantity of waste disposal to landfill.

Cost reduction: is often cheaper than using primary aggregates.



Carbon footprint: the use of waste materials are usually available locally, therefore there is a saving on transport in lorry movements and fuel.






What is it?Concretes mixes where a proportion of the cement is replaced by pulverised fuel ash (pfa) or granulated blastfurnace slag (ggbs) result in reduced early-age thermal cracking in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pfa and ggbs have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pavement, pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.












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application: Various structural elements for highways, railways, development site infrastructure, utilities, harbours, docks and waterways, and power generation.


What is it?In some cases, it may be possible to replace concrete structures with solutions based on geosystems, such as gabions, crib walls, reinforced soil, anchored earth and soil nailing. Geosystems often enable the use of soils already present on site, possibly with the addition of a binder such as lime or cement, so reducing the waste produced by excavation and the need to import higher quality fill material. Geosystems are often hybrid structures comprising engineered geocomponents such as meshes, strips, boxes, tubes, facing units made of steel, concrete, timber, polymeric or geosynthetic materials.

Where conventional concrete or steel structures are replaced by geosystems, significant savings in the carbon footprint can be achieved.

Where can I use it?Geosystems are particularly suitable for low height modular retaining walls, although full height structures can be constructed depending on the geosystem being employed. In highway, railway and waterway situations they are frequently employed for soil retention and to improve slope stability. In coastal and marine environments, geosystems can perform the functions of both retaining soil and protecting against erosion.

Geosystems are frequently used for developing site infrastructure where earthworks are required to create a level platform for construction.

How do I apply it?Guidance on the use of geosystems, including applications, case studies and the waste and carbon savings that can be achieved is available in the geosystems module of AggRegain www.aggregain.org.uk/geosystems Technical guidance on the use of individual techniques is available in civil engineering textbooks and in the standards and specifications of the infrastructure owner.


Cost reduction: can often be a low cost solution.

recycled content: opportunities may exist for increasing the recycled content by reusing materials on site.

Programme: site specific, but is likely to be faster to install than using some conventional techniques.

Carbon footprint: geosystems can have a low contribution to embodied carbon compared to some conventional techniques.

Other environmental benefits: minimises the amount of materials that have to be brought on site. Utilising materials on site can reduce resource depletion.

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Structures - steel


Assemble structures on site and move into place;

Steel with high recycled content; and

Lightweight bridge decks.

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www.aggregain.org.uk/geosystems

www.aggregain.org.uk/geosystems


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TECHnICAL SOLUTIOn: Structures – steel

assemble structures on site and move into place



What is it?Off site manufacture of steel elements ensures better quality workmanship with minimal waste production and has been a feature of steel construction for many years. Assembling structures on site and then moving them into place has the potential to significantly change operations on site, reducing the number of site activities and changing the construction process into one of a rapid assembly of parts that can provide many environmental, commercial and social benefits.


Where can I use it?Assembly on site is now frequently used as a method of construction of road, rail and foot bridges. In replacement situations, the new structure is built alongside the existing one, which is then demolished and the new structure moved into place as a unit. The main driver for this method of construction is that it minimises closure or disruption of the road or railway, but it also allows more efficient construction of the new structure with reduced waste compared to constructing it in stages while keeping the road/railway functioning. The existing structure can then be demolished or dismantled more efficiently, allowing greater recovery and reuse of its materials for future projects.

In all cases, the methods of construction need to be considered at the preliminary design stage.

How do I apply it?WRAP (2007) Current practices and future potential in modern methods of construction.

SCI (2009) Benefits of off site steel construction in urban locations provides advice for the building sector which may be more generally relevant.

Why should I use it? Waste reduction: has the potential to reduce waste produced on site.

Cost reduction: efficient prefabrication may reduce costs.

recycled content: most steels have a high recycled content.

Programme: minimises disruption to transport networks by rapid on site assembly of the structure reducing construction timescales.



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How do I apply it?

The properties of the recycled steel are the same as those of the virgin material and the relevant British Standard specifications apply, e.g.












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Lightweight bridge decks

application: Rapid construction of bridges.


What is it?Fibre reinforced plastic (FRP) decks may provide an effective solution in cases where the advantages of light weight, rapid construction and corrosion resistance outweigh the additional material cost. FRP decks are likely to be used in combination with conventional materials in the design of new bridges and replacement of under-strength decks in existing bridges.

Where can I use it?Lightweight decks are ideal for the construction of footbridges or limited facility bridges (i.e. farm crossings, cycle routes, etc). The main structural members are normally designed using conventional materials, however where FRP main beams are used higher material factors are appropriate for ultimate and serviceability limit state designs.

FRP decks may be more costly than decks formed from conventional materials and, for this reason, their use is normally only considered where speed of construction significantly reduces costs and/or environmental impacts.

How do I apply it?The design of FRP bridges and highway structures is covered by the HA Departmental Standard BD90 www.standardsforhighways.co.uk/dmrb/vol1/section3/bd9005.pdf

Guidance is also given in CIRIA Report C564 on Fibre-reinforced polymer composites in construction.

Why should I use it? Waste reduction: factory production minimises waste.

Cost reduction: minimises installation and traffic delay costs, although material costs may increase.

recycled content: n/a

Programme: light weight decks can be rapidly assembled and lifted into place with a mobile crane.

Carbon footprint: reduction in lorry movements as more linear metres can be carried per delivery.

Other environmental benefits:less use of concrete and steel. Less disruption in terms of noise, dust, and vibration because of faster construction.

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pfa or ggbs as cement replacement materials; and

Reclaimed bricks or bricks with high recycled content.

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http://www.standardsforhighways.co.uk/dmrb/vol1/section3/bd9005.pdf




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TECHnICAL SOLUTIOn: ancillary structures









For concrete structures, the Concrete Centre and the British Precast Concrete Federation are amongst those organisations providing advice on modern methods of construction and precasting techniques.








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What is it?Concretes mixes where a proportion of the cement is replaced by pulverised fuel ash (pfa) or granulated blastfurnace slag (ggbs) result in reduced early-age thermal cracking in thick concrete sections because of the low heat evolution during hydration. Cements containing materials such as pfa and ggbs have been used for many years and both act to limit the temperature rise during hydration and hence thermal cracking. There is potential for their increasing usage in pavement, pile and retaining wall construction. Although the strength gain with time is slower than with conventional concrete, in the longer term higher strengths are attained.












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reclaimed bricks or bricks with high recycled content

application: Brick structures including buildings, walls, and arches.


What is it?On projects involving demolition, opportunities for on site reuse of building materials such as bricks should be considered. Reuse on site provides opportunities for cheap (or free) materials, and enables control of the supply of materials. If reclaimed materials are imported it is important that transport distances are minimised.

Bricks are one of the most common materials available both online and through reclamation outlets.

Use of reclaimed bricks, especially on site, is higher up the waste hierarchy than recycling them for use as recycled aggregate.

Where can I use it?Any building works depending on whether “character” bricks are required or whether it is a volume requirement.

How do I apply it?WRAP's reclaimed building products guide gives information on applications.

Advice on reclamation outlets is available on www.bremap.co.uk Specialist firms are available to assist, e.g. www.salvo.co.uk CIRIA www.ciria.org.uk/recycling have a construction recycling website which gives details of disposing of and buying materials such as bricks.

Storage of whole bricks prior to use in construction work and in containers prior to use in construction work are activities exempt from the requirements of the Waste Management Licensing Regulations www.aggregain.org.uk

Why should I use it? Waste reduction: the reuse or reclaim of materials is more efficient than a recycling solution.

Cost reduction: cost reduction if reclaimed on site and potential reductions if imported provided a nearby source is available.



Carbon footprint: the use of reclaimed bricks saves in the embodied energy needed to manufacture new.


Design solution reference

General references WRAP Guidence Designing out Waste: a design team guide for buildings (2009) www.wrap.org.uk/document.rm?id=7167 WRAP recycled content in construction products guide http://rcproducts.wrap.org.uk/ WRAP Materials Logistic Plan – good practice guidance www.wrap.org.uk/document.rm?id=4956 DfT Sustainable Highways: a Short Guide (2008), TSOTRL PPr 233 Sustainable choice of materials for highway works: a guide for local authority highway engineers (2008)TRL Road note 42 Best practice guide for durability of asphalt pavements (2008)WRAP recycled roads a step-by-step guide to local authority procurement www.wrap.org.uk/construction/tools_and_guidance/recycled_roads.html


Process demolition material for use on site

WRAP Guide the efficient use of materials in regeneration projects www.wrap.org.uk/construction/tools_and_guidance/regeneration.html ICE Demolition Protocol, revised 2008 www.ice.org.uk/knowledge/specialist_waste_board.asp WRAP Quality Protocol for the production of aggregates from inert waste www.aggregain.org.uk/quality/quality_protocols/index.html


WRAP Guide the efficient use of materials in regeneration projects www.wrap.org.uk/construction/tools_and_guidance/regeneration.html ICE Demolition Protocol, revised 2008 www.ice.org.uk/knowledge/specialist_waste_board.asp WRAP Quality Protocol for the production of aggregates from inert waste www.aggregain.org.uk/quality/quality_protocols/index.html

Send vegetation off site for PAS100 compost manufacture

BSI PaS100 Publicly available specification for composted materials, (2005)WRAP guides to compost specification and use:Compost specifications for the landscape industry www.wrap.org.uk/composting/compost_specifications/bsi_pas_100/ Case study, BaE Systems, Chorley www.wrap.org.uk/document.rm?id=6117 Case study, Housing Development www.wrap.org.uk/document.rm?id=5827 Compost in remediation and restoration of brownfield sites www.wrap.org.uk/document.rm?id=2841 report, soil manufacture at Cronton Colliery www.wrap.org.uk/document.rm?id=6209 Brownfield restoration – Lambton former coke works www.wrap.org.uk/document.rm?id=6774 Compost suppliers http://compostsuppliers.wrap.org.uk/ Introduction to PaS100 2005 www.wrap.org.uk/document.rm?id=2181

References and resources

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CONtENtS

www.bremap.co.uk

http://www.salvo.co.uk

www.ciria.org.uk/recycling


http://www.wrap.org.uk/document.rm?id=7167

http://rcproducts.wrap.org.uk/



http://www.wrap.org.uk/construction/tools_and_guidance/recycled_roads.html

http://www.wrap.org.uk/construction/tools_and_guidance/regeneration.html

http://www.ice.org.uk/knowledge/specialist_waste_board.asp


http://www.aggregain.org.uk/quality/quality_protocols/index.html

http://www.wrap.org.uk/construction/tools_and_guidance/regeneration.html



http://www.aggregain.org.uk/quality/quality_protocols/index.html

http://www.wrap.org.uk/composting/compost_specifications/bsi_pas_100/










http://compostsuppliers.wrap.org.uk/






WRAP Recycled Content in Construction Tool http://rcproducts.wrap.org.uk/

Recycled aggregate in concrete barriers

Ba92/07 the use of recycled concrete aggregate in structural concrete. DMrB Vol.2 Section 3 Part 9 www.standardsforhighways.co.uk/dmrb/vol2/section3.htm WRAP Report: Mix design specification for low strength concretes containing recycled and secondary aggregates http://aggregain.wrap.org.uk/document.rm?id=344 TRL PPr36 the use of recycled concrete aggregate in structural concreteTRL PPr037 the susceptibility of recycled concrete aggregate to alkali silica reaction


Drainage

Pipes with high recycled content

WRAP Recycled Content in Construction Tool http://rcproducts.wrap.org.uk/


Specification for Highway Works 500 Series. MCHW1 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0500.pdf Ha217/08 alternative filter media and surface stabilisation techniques for combined surface and sub-surface drains. DMrB Vol.4 Section 2 Part 4 www.standardsforhighways.co.uk/dmrb/vol4/section2/ha21708.pdf


WRAP Report recycled and stabilised materials in trench reinstatement (2007) www.wrap.org.uk/document.rm?id=3664 WRAP Report recycled materials in trench reinstatement, quality manual and template for hydraulically bound mixtures (2009) www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.htmlSpecification for the reinstatement of Openings in Highways, 2nd edition (2002) Highway Authorities and Utilities Committee (HAUC).HAUC Advice note 2009/01 the use of alternative reinstatement materials www.hauc-uk.org.uk/category/2/

Foamed concrete with high recycled content for trench backfill

Specification for the reinstatement of Openings in Highways, 2nd edition (2002) Highway Authorities and Utilities Committee (HAUC).Specification for Highway Works Clause 1043 Foamed concrete www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf Concrete Society - Good Concrete Guide 7 Foamed concrete: applications and specification

Trenchless technology to pipe installation

Ha120/08 Guidance on the trenchless installation of services beneath motorways and trunk roads www.standardsforhighways.co.uk/dmrb/vol4/section1/ha12008.pdf CIRIA Report SP127 trenchless and minimum excavation techniques: planning and selection (1998)

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Tyre-derived rubber material in combined surface and ground water filter drains

TRL Report 200 re-use of scrap tyres in highway drainagePaS107: 2007 Specification for the manufacture and storage of size reduced tyre materialsWRAP/Environment Agency Quality Protocol for tyre-derived rubber materials

SUDS and related techniques

CIRIA Report C697 the SUDS Manual (2007)

Precast manholes, gullies, service ducts and cable troughing


Balance cut/fill quantities

Lime or cement to dry out wet fill

Ha74/07 treatment of fill and capping materials using either lime or cement or both www.standardsforhighways.co.uk/dmrb/vol4/section1/ha7407.pdf

Geosystems to enable steeper side slopes

WRAP Report Sustainable geosystems in civil engineering applications


BSI PaS100 Publicly available specification for composted materials (2005)WRAP guides to compost specification and use:Compost specifications for the landscape industry www.wrap.org.uk/composting/compost_specifications/bsi_pas_100/ Case study, BaE Systems, Chorley www.wrap.org.uk/document.rm?id=6117 Case study, Housing Development www.wrap.org.uk/document.rm?id=5827 Compost in remediation and restoration of brownfield sites www.wrap.org.uk/document.rm?id=2841 report, soil manufacture at Cronton Colliery www.wrap.org.uk/document.rm?id=6209Brownfield restoration – Lambton former coke works www.wrap.org.uk/document.rm?id=6774 Compost suppliers http://compostsuppliers.wrap.org.uk/ Introduction to PaS100 2005 www.wrap.org.uk/document.rm?id=2181

Manufacture topsoil using PAS100 compost

BSI PaS100 Publicly available specification for composted materials (2005)WRAP guides to compost specification and use:Compost specifications for the landscape industry www.wrap.org.uk/composting/compost_specifications/bsi_pas_100/ Case study, BaE Systems, Chorley www.wrap.org.uk/document.rm?id=6117 Case study, Housing Development www.wrap.org.uk/document.rm?id=5827 Compost in remediation and restoration of brownfield sites www.wrap.org.uk/document.rm?id=2841 report, soil manufacture at Cronton Colliery www.wrap.org.uk/document.rm?id=6209Brownfield restoration – Lambton former coke works www.wrap.org.uk/document.rm?id=6774 Compost suppliers http://compostsuppliers.wrap.org.uk/ Introduction to PaS100 2005 www.wrap.org.uk/document.rm?id=2181

CONtENtS


http://www.standardsforhighways.co.uk/dmrb/vol2/section3.htm

http://www.standardsforhighways.co.uk/dmrb/vol2/section3.htm



http://www.aggregain.org.uk/document.rm?id=4577




http://www.standardsforhighways.co.uk/dmrb/vol4/section2/ha21708.pdf

www.wrap.org.uk/document.rm?id=3664




http://www.hauc-uk.org.uk/category/2/































Remediation of contaminated soils

CIRIA Report C622 Selection of remedial treatments for contaminated land. a guide to good practice (2004)ICE design and practice guides: Contaminated land - investigation, assessment and remediation, 2nd edition. Jo Strange & Nick Langdon. thomas telford (2007)the Definition of Waste: Industry Code of Practice. CL:aIrE (2008) www.claire.co.uk/index.php?option=com_docman&task=cat_view&gid=932&Itemid=25. TRL Report 489 the processing of contaminated land in highway works (2001)

Stabilise or isolate contaminated soils

CIRIA Report C622 Selection of remedial treatments for contaminated land. a guide to good practice (2004)ICE design and practice guides: Contaminated land - investigation, assessment and remediation, 2nd edition. Jo Strange & Nick Langdon. thomas telford (2007)the Definition of Waste: Industry Code of Practice. CL:aIrE 2008 www.claire.co.uk/index.php?option=com_docman&task=cat_view&gid=932&Itemid=25. TRL Report 489 the processing of contaminated land in highway works (2001)

Geosystems to enable soft foundation soils to remain in-situ

Standard geotechnics textbooksTRL PPr080 tyre bales in construction (2005)TRL PPr045 tyre bales in construction: case studies (2005)WRAP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk WRAP case study of use of tyre bales in a flood embankment on the river Witham www.aggregain.org.uk/case_studies/use_of_tyre.html


CIRIA Report C573 a guide to ground treatment (2002)CIRIA Report C572 treated ground – engineering properties and performance (2002)WRAP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk


TRL PPr080 tyre bales in construction (2005)TRL PPr045 tyre bales in construction: case studies (2005)

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Recycled aggregates and/or HBM for working platforms

WRAP Report Guidance on the use of HBM in working platforms (2006) http://aggregain.wrap.org.uk/document.rm?id=3395

Incorporate working platform into permanent works

WRAP Report Guidance on the use of HBM in working platforms (2006) http://aggregain.wrap.org.uk/document.rm?id=3395

Lime or cement to stabilise soils in-situ for use as capping

Ha74/07 treatment of fill and capping materials using either lime or cement or both www.standardsforhighways.co.uk/dmrb/vol4/section1/ha7407.pdf.


Specification for Highway Works 600 Series www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0600.pdf HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdfnumerous case studies on AggRegain including major projects such as M25 J12-15 widening www.aggregain.org.uk/case_studies/m25_j12_to_15.html Specification for Highway Works 600 Series www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0600.pdfHD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdfSeveral case studies on AggRegain including use as Class 6P on the M25 J12-15 widening www.aggregain.org.uk/case_studies/m25_j12_to_15.html HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdfCIRIA Report C592 Infrastructure embankmentsCIRIA Report C591 Infrastructure cuttings

Geosynthetic and lime/cement with original soil for slope repairs

CIRIA Report C592 Infrastructure embankmentsCIRIA Report C591 Infrastructure cuttingsWraP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk

Tyre bales for slope repairs

TRL PPr080 tyre bales in construction (2005)TRL PPr045 tyre bales in construction: case studies (2005)

Vegetation to improve slope stability

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http://www.aggregain.org.uk/case_studies/use_of_tyre.html







http://www.aggregain.org.uk/case_studies/m25_j12_to_15.html




http://www.aggregain.org.uk/case_studies/m25_j12_to_15.html






Treat existing soil to make HBM subbase/ballast

SHW 800 Series Clause 840 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf Britpave BP/08 technical data sheet – Stabilised soils as subbase or base for roads and other pavementsBritpave BP/15 Soil stabilisation - Guidelines for best practice

Recycled/secondary aggregates to make HBM subbase

WraP Guidance document: Hydraulically bound mixtures incorporating recycled and secondary aggregates www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html WRAP Quality manual for hydraulically bound materials www.wrap.org.uk/construction/how_do_i_reduce_waste/sectors/utilities/utilities_guidance.htmlBritpave BP/13 technical data sheet – Cement and other hydraulic bound mixtures (the new European Standard BS EN 14227, Parts 1-5)

Recycled/secondary aggregates as unbound subbase

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdfSHW 800 Series www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf HAUC – Specification for the reinstatement of openings in highways

Geogrids/geotextiles to reduce thickness

Various TRL Reports, e.g. rr140 (Deformation of road foundations with geogrid reinforcement) and rr382 (Installation damage trials on geotextiles), give trial resultsWRAP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk

Pavements and footways – bituminous

In-situ hot recycling of asphalt

Part 1 HD 31/94 Maintenance of bituminous roads, chapter 5 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdfSHW Clause 926 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf, and NG926 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf

In-situ cold recycling of asphalt

Part 1 HD 31/94 Maintenance of bituminous roads, chapter 5www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdfSHW Clause 947 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf, and NG947 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdfTRL 611 a guide to the use and specification of cold recycled materials for the maintenance of road pavements (2004)

On site hot recycling of asphalt

Part 1 HD 31/94 Maintenance of bituminous roads, chapter 5 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdf

Ex-situ cold recycling of asphalt

Part 1 HD 31/94, chapter 5 www.standardsforhighways.co.uk/dmrb/vol7/section4/hd3194.pdfSHW Clause 948 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf, and NG948 www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdfTRL 611 a guide to the use and specification of cold recycled materials for the maintenance of road pavements (2004)

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Reclaimed asphalt in base and binder course

BS En 12697-8:2005

Reclaimed asphalt in surface course

BS EN 12697-8:2005TRL 645 Feasibility of recycling thin surfacing back into thin surfacing (2005) and TRL Road note 43 (in press) PPr304 recycled asphalt in surfacing materials – a case of carbon dioxide emissions savings

Secondary aggregates in base, binder and surface course

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf TRL 659 Cement kiln dust (CKD) as filler in asphalt (2007)

Secondary aggregates in surface course

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf TRL 566 Basic oxygen steel slag as surface course aggregate: an investigation of skidding resistance (2003)TRL 659 Cement kiln dust (CKD) as filler in asphalt (2007)

Secondary aggregates in cold asphalt mixtures

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf for permitted secondary materials in highways

Reclaimed asphalt from other site in cold mixture

TRL 611Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf

Warm and semi-warm asphalt to reduce energy

US Federal Highway Administration webpage www.fhwa.dot.gov/pavement/asphalt/wma.cfm

Collect and reuse chippings in surface dressing

Case study in TRL 651 Maximising the use of recycled and secondary aggregates in Hampshire (2006)

Retexturing asphalt pavement surfacing

TRL 611 Clause 926 of the Specification for Highway Works www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0900.pdf and associated Notes for Guidance www.standardsforhighways.co.uk/mchw/vol2/pdfs/series_ng_0900.pdf

Reclaimed asphalt in unbound subbase or capping off site

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf SHW 800 Series Clause 807 for unbound subbase www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0800.pdf SHW 600 Series for capping www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0600.pdf

Geogrids/geotextiles to reduce thickness of base

WRAP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk

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http://www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html

http://www.aggregain.org.uk/opportunities/materials/hydraulically_bound/index.html














































Crack and seat with overlay for repairs

SHW700 Series www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0700.pdfCrack, seat and overlay for the maintenance of jointed concrete pavements and HBM basesVolume 1: research and performance. trL PPr441 (in press)Volume 2: a practical guide to design and construction. trL PPr 442 (in press)

Saw cut and seal with overlay for repairs

SHW 700 Series www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_0700.pdfTRL Report 657 Improved design of overlay treatments to concrete pavements. Final report on the monitoring of trials and schemes (2006)

Recycled aggregate in pavement concrete

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf Specification for Highway Works Clause 1001 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf

Secondary aggregates in pavement concrete

HD 35/04 Conservation and the use of secondary and recycled materials www.standardsforhighways.co.uk/dmrb/vol7/section1/hd3504.pdf Specification for Highway Works Clause 1001 www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1000.pdf

pfa or ggbs as cement replacement materials

ICE Specification for Piling and Embedded retaining Walls.Concrete Society technical report 40. the use of ggbs and pfa in concrete.


TRL 611 a guide to the use and specification of cold recycled materials for the maintenance of road pavements (2004)

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railway- ballast, sleepers and track

Treat existing soil to make HBM subbase/ballast

Recycled and secondary aggregates to make HBM subbase/ballast

Recycled/secondary aggregates as unbound ballast

Geogrids/geotextiles to reduce thickness of ballast

WRAP document Sustainable Geosystems in Civil Engineering applications www.aggregain.org.uk


Railway sleepers: containing recycled aggregate

Railway sleepers: containing secondary aggregate

Railway sleepers: recycled plastic


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Precast tunnel lining segments on site

Recycled/secondary aggregates in concrete

BS8500-2. Concrete - Complementary British Standard to BS En 206-1. Specification for constituent materials and concrete

Reuse of piled foundations

CIRIA Report C653 reuse of foundationsProc Int Conf reuse of Foundations for Urban Sites. BrE report EP75. BrE, Garston, (2006)

Plastic sheet piling TRL Report 533 Guidance on the structural use of plastic sheet piling in highway applications (2002)



ICE Specification for Piling and Embedded retaining Walls

Recycled aggregates and/or HBM for working platform

WRAP Guidance on the use of HBM in working platforms (2006) http://aggregain.wrap.org.uk/document.rm?id=3395

Incorporate working platform into permanent works

WRAP Guidance on the use of HBM in working platforms (2006) http://aggregain.wrap.org.uk/document.rm?id=3395

Structures - concrete


Assemble structures on site and move into place

Recycled/secondary aggregates in concrete

BS8500-2. Concrete - Complementary British Standard to BS EN 206-1 Specification for constituent materials and concreteSeries 1700 of the SHW (www.standardsforhighways.co.uk/mchw/vol1/pdfs/series_1700.pdf)Ba 92/07. the use of recycled concrete aggregate in structural concrete www.standardsforhighways.co.uk/dmrb/vol2/section3/ba9207.pdfTRL PPr036 the use of recycled aggregate in structural concrete


ICE Specification for Piling and Embedded retaining WallsConcrete Society Technical Report 40. the use of ggbs and pfa in concrete


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Structures - steel

Assemble structures on site and move into place


Lightweight bridge decks BD90/05. Design of FrP Bridges and Highway Structures www.standardsforhighways.co.uk/dmrb/vol1/section3/bd9005.pdf




ICE Specification for Piling and Embedded retaining WallsConcrete Society Technical Report 40. the use of ggbs and pfa in concrete

Reclaimed bricks or bricks with high recycled content

WRAP. Reclaimed building products guideBS EN ISO 14021:2001. Environmental labels and declarations — Self-declared environmental claims (Type II environmental labelling)

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