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Mixtures – How to Specify Them
Andy SimmsJacobs Laboratories
London Asphalt Specification ( Makes the following simpler!)
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Idealised Pavement Structure (Flexible or Flexible Composite)
Surf ace CourseBinder Course
Base
Sub Base
Capping Lay er
Sub grade
Fou
ndat
ion
Surf acing
Formation Lev el
Pav ement
Road Surf ace
Specification for Highway Works
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HAPAS Certificate
HAPAS - Highway Authorities Product Approval
Scheme• New Materials including Thin Surface Course Systems• Proprietary systems, e.g. Masterpave, Axoflex, Durapave• Specified through SHW Clause 942 • Approval through BBA
• Two year guarantee
Asphalt Standards and Specifications
BS asphalt standards that you use in all contracts were changed on 1 January
All the laying standards and BS test methods also changed on 1 January.
Specification for Highway Works has also been revised (IAN101 & IAN102).
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Why? - Principles of European Standards
Harmonisation of individual countries specifications and test methods
Elimination of barriers to tradeBS EN’s have greater authority/legal standing than current BS’s
The European Standard brings compliance and conformity in to the standard
Enforcement is a trading standards issue
Asphalt Product Standards
7 standards covering the products
1 standard covering Recycled Asphalt
2 standards covering Factory Production Control (QA)
(44 Standards covering test methods)
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The EN 13108 Family of Standards - Products
BS EN 13108-1 Asphalt ConcreteBS EN 13108-2 Asphalt Concrete for Very Thin LayersBS EN 13108-3 Soft Asphalt (Nordic countries)
BS EN 13108-4 Hot Rolled Asphalt
BS EN 13108-5 Stone Mastic AsphaltBS EN 13108-6 Mastic Asphalt
BS EN 13108-7 Porous Asphalt
The European Standards for Asphalt
Properties and other parameters− categories selected from tables− Includes recipe and performance related testing
Product IdentificationAttestation of Conformity −EN 13108-20 Initial Type Testing −EN 13108-21 Factory Production Control [FPC]
what we call QACE Marking
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On request
All the key informationrequired by law
EN Standards - Important Differences from BS
ENs relate to the product….“in the back of the lorry”, but some properties are installation dependent (BS 594987)Some description changes - mixtures prefixed by an abbreviation of their type: AC, HRA, SMA − e.g. 14 SMA surf 40/60
Some test method changes e.g. Wheel tracking instead of stabilityFormalised specification of reclaimed asphalt in BSEN13108-8Changes to compliance ‘Q’ values (Operating Compliance Level)
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UK Guidance Documents
PD 6691 – the EN 13108 family of asphalt mixtures applicable to the UK
PD 6692 - the EN 12697 family of 44 standards covering the testing of asphalt mixtures.
PRODUCT STAND ARD
PD 6691:2007
PD6691 has been drafted in a format which is similar to BS 4987-1 & BS594-1.
PD6691 contains detailed guidance on EN13108 Parts 1, 4, 5 (material specific requirements), 20 & 21 (Attestation of Conformity)
PD6691 Annexes contain stand-alone example specifications for all commonly used asphalt mixtures.
Requirements for Type testing (Protocols in BS594987)
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Requirements for Type Testing
Ac Properties(Design Void Content, deformation resistance)
Performance HRA properties (voids, resistance to permanent deformation)
SMA Binder Course properties (voids, resistance to permanent deformation)
PD 6691:2007
Example Mixture Specifications
Annexes
B - Asphalt Concrete
C - Hot Rolled Asphalt (incl. Coated Chippings)
D - Stone Mastic Asphalt (Not TSCS)
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PMB
Binder Grade
Course type
Size ‘D’ mm
Asphalt type
160/220100/15070/10040/6030/4510/20
BASEBINSURF
3260/32
2050/20,60/20
1450/14
1050/10
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HRASMAAC
How to build a description
One from each line is essential
PMB 100/15070/10040/6030/45Mix type
perfdesrec
Binder gradesurf
Course type
55/14F or C
35/14F or C
30/14F or C
55/10F or C
30/10F
15/10F
0/2F or C
Stone content/size ‘D’HRA
Material type
HRA Surface Course Descriptions
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Typical Descriptions; additional UK detail
All the information goes into the designation
−AC 32 HMB base 30/45 [30/45 = pen grade ]
PSV of the aggregate can be used in the UK mixture designation - not mandatory in the EN’s
−AC 10 close surf 100/150 PSV60
−SMA 10 surf 40/60 PSV65
−HRA 35/14 F surf PMB des [ des = design mix]
PD 6691:2007 - Nomenclature.
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Some standard AC designations and binder grades
A wide choice of binder is available
Mixture Summary – HRA
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Mixture Summary – SMA
• For full document see http://www.qpa.org/downloads/asphbulletin02.pdf
What about Laying?
BS 594987: 2007 Transport, Laying & Compaction
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BS 594987
Combination of BS594-2 & BS4987-2Covers all EN 13108 asphalt mixtures found in PD 6691Min and max compacted thicknessesAccuracy of finishImproved clarity on laying, formation of joints etc.Application of Coated Chippings and Rates of SpreadMeasurement of Texture DepthCompaction Sampling and testing for assessment of compacted asphaltMixture Approval / Type testing Protocols
Specification for Highway Works
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http://www.standardsforhighways.co.uk
SHW 900 Series
IAN101/07 (revision Feb 08)• New Asphalt Standards
• Good opportunity for a “Spring Clean”
• New requirements to improve durability
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Laying asphalt for greater durability
900 Series in summary
• Clause 901 Bituminous Pavement Mixtures
• Clause 903 Placing and Compaction of Bituminous Mixtures
• Clause 920 Bond Coats, Tack Coats and Other Bituminous Sprays
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Improved clarity for Clause 901 and 903
Clause 901: Requirements for− Aggregates− Bitumen− Aim to avoid undue repetition in individual material clauses
Clause 903: Clarify the requirements with respect to laying -particularly those affecting pavement durabilityRequirement for Method Statements
Already included in Sector Scheme 16 − Compaction procedure (paving speed, paving width, number of
passe s and number of rollers) − Joint formation
Faces of all cold upstanding edges to be painted Air v oids not more than 2% above those in the main matSealant applied to top surf ace of base and binder course joints :
Bond coats - BS 594987 Tables 3 - 4
New 0.15kg/m2
Planed 0.6kg/m2
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Clause 929 Dense Base and Binder Course Macadams (Design Mixtures)
Simplified:Volumetric requirements in PD6691Job mixture approval trial mix volumetrics - details given in BS 594987 Annex CJob mixture approval trial resistance to deformation –details given in BS594987 Annex DStiffness requirement− Smin 1500MPa
Deformation resistance − WTR to BS 598-110 until EN 13697:22 data available
Clause 937 (SMA), 943 (Perf. HRA) and 952 (Deformation Resistance)
• Clause 937 selects deformation requirements from PD 6691 Table D2
• Clause 943 selects deformation requirements from PD 6691 Table C3
• Clause 952 Deformation Resistance is no longer required (incorporated into relevant Clauses: 929, 930, 937 and 943)
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Clause 942 Thin Surface Course Systems
(11/06) Surfacing Integrity - Performance Guarantee14 The Contractor shall guarantee the integrity of the surfacing and the workmanship for a period of five yearsfrom the Contract completion date, or as otherwise specified in Appendix 7/1.NFG 24 (11/06) The guarantee periods should be clearly stated as relating only to the surface course. An appropriate Special Requirement should be included in the Conditions of Contract which draws particular attention to sub-Clauses 942.14. 942.15 and 942.16. At the end of the five-year guarantee period, the surfacing should be expected to be in at least a “Moderate/Acceptable” or a better condition after discounting any faults caused by the substrate, where the surface conditions are as defined in Appendix R of TRL Report 176.
SHW Clause 942 BBA HAPAS Classes for texture depth
Do not over-specify
High speed
Medium speed
Low speed <40mph
[1.3]
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SHW Clause 921 Surface Macrotexture of Bituminous Surface Courses
Clause 953 Durability of Bituminous Mixtures –Saturation Ageing Tensile Stiffness (SATS) Test
Required for all binder course and base mixesMixture conditioned under pressure in a wet atmosphere Mixture must have retained stiffness >80%Mixtures containing 2% hydrated lime will be deemed to comply
• Mainly a problem for all granite aggregate mixtures
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