05-series 5000 base, sub base and gravel wearing course new

5/28/2018 05-Series 5000 Base, Sub Base and Gravel Wearing Course New

Standard Technical Specification - 2002 Series 5000: Subbase Road Base And Gravel Wearing Course

Table of Content

Ethiopian Roads Authority Page 5000-1

SERIES 5000: SUBBASE ROAD BASE

AND GRAVEL WEARING COURSE

TABLE OFCONTENT

TABLES AND FIGURES................................................................................................................. 6

DIVISION 5100: SUB-BASES ....................................................................................................... 7

5101 Scope..................................................................................................................................7

5102 Materials.............................................................................................................................75103 Material Sources for Sub-Bases .........................................................................................7

5104 Material Requirements For Gravel Sub-Base ..................................................................7

(a) General......................................................................................................................7

(b) Grading Limits..........................................................................................................7

(c) Grading Modulus......................................................................................................8

(d) Plasticity Index .........................................................................................................8

(e) Californian Bearing Ratio (CBR).............................................................................8(f) Compaction requirements.........................................................................................8

(g) Los Angeles Abrasion ..............................................................................................9

5105 Material Requirements For Crushed Stone Sub-Base........................................................9

(a) General......................................................................................................................9

(b) Grading Limits..........................................................................................................9

(c) Grading Modulus....................................................................................................10

(d) Plasticity Index (PI) ................................................................................................10

(e) Compaction Requirements .....................................................................................10

(f) Los Angeles Abrasion ............................................................................................10

(g) Particle shape; Flakiness Index ..............................................................................10

5106 Construction Requirements For Sub-Bases Using Recycled Material ............................10

(a) General....................................................................................................................10

(b) Milling/Scarifying ..................................................................................................10

(c) Placing, Spreading and Compacting.......................................................................115107 Construction Requirements..............................................................................................11

(a) General....................................................................................................................11

(b) Stabilization............................................................................................................11

(c) Trial Areas ..............................................................................................................11

(d) Traffic on Sub-base ................................................................................................11

5108 Protection and Maintenance.............................................................................................12

5109 Sub-Base as a Filter or Separating Layer.........................................................................12

5110 Classification of Layers for Payment Purposes ...............................................................12

5111 Construction Tolerances ..................................................................................................12

(a) Levels .....................................................................................................................12

(b) Width ......................................................................................................................13(c) Thickness................................................................................................................13


Series 5000: Subbase Road Base And Gravel Wearing Course Standard Technical Specification -2002

Table of Content

Page5000-2 Ethiopian Roads Authority

(d) Cross Section.......................................................................................................... 13

5112 Testing ............................................................................................................................. 13

(a) Process Control ...................................................................................................... 13

(b) Routine Inspection and Testing.............................................................................. 13

5113 Measurement And Payment ............................................................................................ 14

Item 51.01 Sub-base layer constructed from gravel or Crushed stone:.......................... 14Item 51.02 Extra over Pay item 51.01 for excavation of material in: ............................ 15

Item 51.03 Sub-base layer constructed from gravel or crushed stone obtained from

existing pavement layers:....................................................................................... 15

Item 51.04 In situ reconstruction of existing Sub-base layer as:.................................... 16

Item 51.05 Sub-base layer constructed Extra over Pay item 51.03 (a),(b),(c)&(d) and

Pay item 51.04 (a),(b)&(c) from recovered pavement material mixed with existing

bituminous surfacing material................................................................................ 17

Item 51.06 Extra over Pay item 51.04 for adding extra material ................................... 17

Item 51.07 Extra over Pay item 51.04 for blading the material to windrow.................. 18

Item 51.08 Extra over Pay item 51.03 for excavating material in existing pavement

layers in restricted areas ......................................................................................... 18Item 51.09 Compacting the floors of pavement excavations ......................................... 18

Item 51.10 Watering the pavement excavation floor ..................................................... 19

Item 51.11 Variations in the number of roller passes applicable to pay item 51.09 ...... 19

Item 51.12 Extra over Pay item 51.09 for compacting pavement excavation floor in

restricted areas........................................................................................................ 19

DIVISION 5200: ROAD BASES ...................................................................................................20

5201 Scope ............................................................................................................................... 20

5202 Dimensions ...................................................................................................................... 205203 Materials .......................................................................................................................... 20

(a) Sources of Material ................................................................................................ 20

(b) Road Base Material Types ..................................................................................... 20

5204 Material Requirements For Crushed Rock Or Stone....................................................... 20

(a) General................................................................................................................... 20

(b) Grading................................................................................................................... 20

(c) Plasticity Index....................................................................................................... 21

(d) Californian Bearing Ratio (CBR) .......................................................................... 21

(e) Aggregate Crushing Value (ACV)......................................................................... 21

(f) Mechanical Strength Requirements(TFVT)........................................................... 21

(g) Flakiness Index ...................................................................................................... 225205 Material Requirements for Naturally Occurring Granular Materials .............................. 22

(a) General................................................................................................................... 22

(b) Grading................................................................................................................... 22

(c) Plasticity Index....................................................................................................... 23

(d) Californian Bearing Ratio (CBR) .......................................................................... 23

(e) Aggregate Crushing Value (ACV)......................................................................... 23

(f) Abrasion................................................................................................................. 23

(g) Flakiness Index ...................................................................................................... 23

(h) Crushed Ratio......................................................................................................... 24

(i) Grading Modulus ................................................................................................... 24

5206 Material Requirements for Dense Bitumen Macadam .................................................... 24(a) Coarse Aggregates ................................................................................................. 24



Table of Content


(b) Fine Aggregate .......................................................................................................25

(c) Filler .......................................................................................................................25

(d) Binder .....................................................................................................................25

5207 Material Requirements For Mixed Bitumen Macadam ...................................................25

(a) Combined Aggregate Grading................................................................................25

(b) Mix Design Parameters for Dense Bitumen Macadam ..........................................265208 Construction Requirements For Crushed Rock And Crushed Boulder Road Bases........27

(a) Equipment...............................................................................................................27

(b) Placing and Compaction.........................................................................................27

(c) Stabilization............................................................................................................28

(d) Trial Sections..........................................................................................................28

(e) Traffic on Road base...............................................................................................28

5209 Construction Requirements For Crushed Gravel Road Base...........................................29

(a) Equipment...............................................................................................................29


(c) Stabilization............................................................................................................30

(d) Trial Sections..........................................................................................................30(e) Traffic on Road Base..............................................................................................30

5210 Construction Requirements For Dense Bitumen Macadam Road Base ..........................30

(a) Equipment...............................................................................................................30


(c) Trial Sections..........................................................................................................32

(d) Traffic on Road Base..............................................................................................32

(e) Weather Limitations ...............................................................................................33

5211 Construction Tolerances ..................................................................................................33

(a) Level and Grade......................................................................................................33

(b) Width ......................................................................................................................33

(c) Thickness................................................................................................................33

(d) Cross Section ..........................................................................................................34

5212 Measurement And Payment.............................................................................................34

Item 52.01 Base layer construction.................................................................................34

Item 52.02 Extra over Pay Item 52.1 for excavation of material....................................35

Item 52.03 Base layer constructed from from existing pavement layers........................35

Item 52.04 In situ reconstruction of existing base layer ................................................37

Item 52.05 Extra over Pay item 52.04 for adding extra material....................................38

Item 52.06 Extra over Pay item 52.04 for t blading the material to windrow ................39


layers in restricted areas: ........................................................................................39Item 52.08 Compacting the floors of pavement excavations..........................................39

Item 52.09 Watering the pavement excavation floor......................................................40

Item 52.10 Variations in the number of roller passes applicable to pay item 52.08.......40


restricted areas ........................................................................................................40

Item 52.12 Trial Sections..............................................................................................40

Note on additional Pay Items....................................................................................................41

DIVISION 5300: BREAKING UP EXISTING PAVEMENT LAYERS ............................................... 42

5301 Scope................................................................................................................................425302 Selecting The Material .....................................................................................................42



Table of Content


5303 Classifying The Material ................................................................................................. 42

(a) Existing bituminous material ................................................................................. 42

(b) Non-cemented material .......................................................................................... 42

(c) Cemented material ................................................................................................. 42

5304 Plant And Equipment ...................................................................................................... 42

(a) General................................................................................................................... 42(b) Milling equipment.................................................................................................. 43

5305 Construction .................................................................................................................... 43

(a) General................................................................................................................... 43

(b) Milling.................................................................................................................... 44

5306 Storing Recovered Pavement Material ............................................................................ 45

5307 Measurement And Payment ............................................................................................ 46

General ............................................................................................................................ 46

Item 53.01 Excavating and removing existing bituminous material.............................. 47

Item 53.02 Milling out existing bituminous material..................................................... 47

Item 53.03 Excavating and spoiling material from an existing pavement and/or the

underlying fill......................................................................................................... 48Item 53.04 Sawing or cutting asphalt or cemented pavement layers ............................. 48

Item 53.05 Removing the remaining asphalt from the underlying layer........................ 48

Item 53.06 Preparing stockpile sites............................................................................... 49

DIVISION 5400: GRAVEL WEARING COURSE AND GRAVEL SHOULDERS ................................50

5401 Scope ............................................................................................................................... 50

5402 Sources of Material.......................................................................................................... 50

5403 Material Requirements for Gravel Wearing Course........................................................ 50

(a) General................................................................................................................... 50(b) Grading................................................................................................................... 50

(c) Gravel Wearing Course Material Specification..................................................... 51

5404 Construction Requirements For Gravel Wearing Course................................................ 52

(a) Equipment .............................................................................................................. 52

(b) Crushing and Screening ......................................................................................... 52

(c) Transport, Placing and Spreading .......................................................................... 53

(d) Compaction ............................................................................................................ 53

(e) Trial Areas.............................................................................................................. 53

5405 Construction Tolerances.................................................................................................. 53

5406 Testing ............................................................................................................................. 54

5407 Measurement And Payment ............................................................................................ 55Item 54.01 Gravel Wearing course and Shoulder .......................................................... 55

Item 54.02 Extra over Pay item 54.01 for excavation of material in ............................. 55

Item 54.03 Gravel Wearing course and Shoulder constructed from gravel obtained from

existing pavement layers........................................................................................ 56

Item 54.04 In situ reconstruction of existing gravel wearing course and shoulder....... 57

Item 54.05 Extra over Pay item 54.04 for adding extra material .................................. 57

Item 54.06 Extra over Pay item 54.04 for blading the material to windrow.................. 58


layers in restricted areas ......................................................................................... 58

Item 54.08 Compacting the floors of pavement excavations ......................................... 58

Item 54.09 Watering the pavement excavation floor ..................................................... 59Item 54.10 Variations in the number of roller passes applicable to pay item 54.08 ...... 59



Table of Content



restricted areas ........................................................................................................59



List of Tables and Figures


LIST OF TABLES AND FIGURES

Table 5104/1 Grading Requirements for Sub-base Material: ................................................... 8

Table 5105/1 Grading Requirements for Crushed Stone Sub-base Material............................ 9

Table 5112/1 Testing Frequency............................................................................................. 13

Table 5112/2 Density requirements: ....................................................................................... 14

Table 5200/1 Grading Limits for Graded Crushed Stone Base Course Materials (GB1)....... 21

Table 5200/2 Mechanical Strength Requirements for the Aggregate Fraction of Crushed

Stone Base Course Materials (GB1) as Defined by the Ten Percent Fines Test 22

Table 5203/3 Recommended Particle Size Distributions for Mechanically Stable Natural

Gravels and Weathered Rocks for Use as Base Course Material (GB2, GB3) . 23

Table 5200/4 Combined Aggregate Grading Limits for Dense Bitumen Macadam .............. 26Table 5200/5 Mix Design Parameters for Dense Bitumen Macadam .................................... 26

Table 5403/1 Grading Requirements for Gravel Wearing Course and Gravel Shoulder ....... 51

Table 5404/1 Longitudinal grade tolerance ............................................................................ 54

Table 5405/2 Density requirements: ....................................................................................... 55



Division 5100: Sub-Bases


DIVISION5100: SUB-BASES

5101 SCOPE

This Division covers the specification of materials for, and the construction of, sub-base

pavement layers including the in-situ recycling of existing pavements.

5102 MATERIALS

Sub-base material shall be obtained from sources located by the Contractor and approved by

the Engineer or from existing pavement layers. The Contractor is required to obtain suitable

sources, which are closest to the area where subbase is being placed.

5103 MATERIAL SOURCES FOR SUB-BASES

The materials used for the construction of sub-base layers shall be either:

1. Natural Gravel;

2. Scoria (Cinder Gravel);

3. Weathered Rock;

4. Crushed Gravel;

5. Crushed Rock or crushed Boulders;

6. Recycled Pavement Material.

Any other granular material complying with the requirements of this clause.

5104 MATERIAL REQUIREMENTS FOR GRAVEL SUB-BASE

(a) General

Gravel material to be used for sub-base shall be obtained from approved sources in borrow

areas, cuts or existing pavement layers. The complete sub-base shall contain no material

having a maximum dimension exceeding two-thirds of the completed layer thickness.

Gravel Sub-base material shall, unless otherwise stated, conform to the following

requirements.

(b) Grading Limits

The sub-base material shall comply with one of the gradings shown in Table 5104/1 as

described in the Contract. The material shall have a smooth continuous grading within the

limits for grading A, B or C given below.





Table 5104/1 Grading Requirements for Sub-base Material:

Sieve Size (mm) Mass Percent Passing

A B C D

63.0 100 - -

50.0 90 - 100 100 100 -37.5 80-100

25.0 51 - 80 55 - 85 100

20 60-100

9.5 - 40 - 70 51 - 85

5 30-100

4.75 35 - 70 30 - 60 35 - 65

2.0 - 20 - 51 25 - 51

1.18 17-75

0.425 - 10 - 30 15 - 30

0.3 9-500.075 5 - 15 5 - 15 5-25 5 - 15

The complete sub-base shall contain no material having a maximum dimension exceeding

two-thirds of the compacted layer thickness.

Sub-base material shall, unless otherwise authorized, conform to the following requirements

when finally placed:

(c) Grading Modulus

The minimum Grading Modulus shall be 1.5 except where a material, having a lower Grading

Modulus but not less than 1.2, is approved for use by the Engineer.

(d) Plasticity Index

All sub-base materials shall have a maximum Plasticity Index of 6 or 12, as described in the

Contract, and when determined in accordance with AASHTO T-90. The plasticity product

(PP = PI x percentage passing the 0.075mm sieve) shall not be greater than 75.

(e) Californian Bearing Ratio (CBR)

The minimum soaked Californian Bearing Ratio (CBR) shall be 30% when determined in

accordance with the requirements of AASHTO T-193. The Californian Bearing Ratio (CBR)shall be determined at a density of 95% of the maximum dry density when determined in

accordance with the requirements of AASHTO T-180 method D.

(f) Compaction requirements

The minimum in- situ dry density of sub-base material shall be as specified hereinafter for the

layers in terms of a percentage of modified AASHTO density.

(i) 95% or 97% as required for material not chemically stabilized.

(ii) 95% or 96 % as required for chemically stabilized material.





(g) Los Angeles Abrasion

The Los Angeles abrasion value shall not exceed 51% when determined in accordance with

the requirements of AASHTO T-96.

5105 MATERIAL REQUIREMENTS FOR CRUSHED STONE SUB-BASE

(a) General

The aggregate used for crushed stone sub-base shall be derived from a parent rock that is

hard, sound, durable, and unweathered. It shall be obtained from sound rock from an

approved quarry or clean sound boulders. It shall contain no deleterious material such as

decomposed rock, clay, shale, or mica. The crushed aggregate shall comply with the following

requirements:

(b) Grading Limits

The grading of the crushed stone sub-base shall comply with one of the gradings shown in

Table 5105/1 as described in the Contract, or as approved or directed by the Engineer. The

grading shall follow a smooth curve without any marked gaps or excessive quantities at a

particular size, unless specified otherwise.

Table 5105/1 Grading Requirements for Crushed Stone Sub-base Material.

Sieve Size (mm) Percentage Passing by weight

A B C

Nominal size

37.5 mm

Nominal size

28 mm

Nominal size

20 mm50.0 100

37.5 95-100 100

28 100

20 60-80 70-85 90-100

10 40-60 50-65 60-75

5 25-40 35-55 40-60

2.36 15-30 25-40 30-45

0.425 7-19 12-24 13-27

0.075 5 - 12 5 - 12 5-12

Tests to determine whether the crushed stone material complies with the specified grading

requirements shall be conducted after the material has been mixed on the road and spread out.

The aggregate shall be produced entirely by the crushing of rock or boulders. Single stage

crushing will not be allowed and the crusher installation shall be capable of producing

material complying with the specified requirements. If, however, the nature of the parent rock

is such that despite every effort made the material remains deficient in the finer fractions, the

Engineer may allow the addition of approved soil fines, crusher fines or sand in controlled

quantities not exceeding 15% by mass of the aggregate. Fines shall be introduced at the

crushing plant.





(c) Grading Modulus

The minimum Grading Modulus shall be 1.5 except where a material, having a lower Grading

Modulus but not less than 1.2, is approved for use by the Engineer.

(d) Plasticity Index (PI)The Plasticity Index shall not exceed 6.

(e) Compaction Requirements

The minimum dry density to which the material shall be compacted shall be 95% unless

specified otherwise, shown on the drawings or ordered by the Engineer, of the maximum dry

density as determined by AASHTO T 180. Field dry densities shall be determined by the sand

replacement method as specified in AASHTO T 191 or nuclear method as specified in

AASHTO T 238.

(f) Los Angeles Abrasion

The Los Angeles abrasion value shall not exceed 45% when determined in accordance with


(g) Particle shape; Flakiness Index

The flakiness index, determined by testing in accordance with BS812, Part 105 or ASTM D

3398, shall not exceed 35.

The crushed aggregate portion, which is retained on the 5 mm sieve, shall have at least 75

percent by weight of particles with at least two fractured faces and 100 percent with at least

one fractured face. The area of each face shall be equal to at least 75 percent of the smallestmidsection area of the piece. When two fractured faces are contiguous, the angle between the

planes of fractures shall be at least 30 degrees to count as two fractured faces.

5106 CONSTRUCTIONREQUIREMENTS FORSUB-BASESUSINGRECYCLED(IN-

SITU) PAVEMENT MATERIAL

(a) General

Construction of sub-bases using recycled (in-situ) existing pavement materials shall comply

with the requirements of Clause 5105 and with the requirements of this Clause.

(b) Milling/Scarifying

(i) Before scarification or milling is commenced, the surface of the existing pavement

shall be clean and free from soil and other deleterious matter.

(ii) The existing pavement shall be broken up to the depth described in the Contract

either by scarifying or by the use of an approved milling machine.





(c) Placing, Spreading and Compacting

Any material which is required to be added, to either supplement or modify the scarified

milled material, shall be evenly spread and thoroughly mixed into the scarified/milled

material to form a homogeneous material prior to compaction.

The material shall be placed, spread and compacted in accordance with the requirements ofClause 5105.

5107 CONSTRUCTION REQUIREMENTS

(a) General.

Sub-base material shall be spread on the approved sub-grade by mechanical means without

segregation. The material shall be loosely spread in layers to give a compacted thickness not

exceeding 200mm and not less than 100mm. The final compacted layer shall be free from

concentrations of coarse or fine materials.

1. The surface of each completed layer shall be moistened prior to the construction of

the succeeding layer. Determine the optimum moisture content according to AASHTO T 180

method D. Mix the aggregate and adjust the moisture content to obtain a uniform mixture

with moisture content within 2 percent of the optimum moisture content. Spread and shape

the mixture on the prepared surface in a uniform layer.

2. The material shall be compacted by the use of approved rollers progressing gradually

from the outside towards the centre of the layer, except on superelevated curves, where the

rolling shall begin at the low side and progress to the high side. Compact each layer full

width. Roll from the sides to the center, parallel to the centerline of the road. Along curbs,

headers, walls, and all places not accessible to the roller, compact the material with approved

tampers or compactors. Each succeeding pass shall overlap the previous pass by at least one

third of the roller width. Rolling shall continue until the entire thickness of each layer is

thoroughly and uniformly compacted to the specified density. Compact each layer to at least

95 percent of maximum density. Determine the in place density and moisture content

according to AASHTO T 238 and AASHTO T 239 or other approved test procedures.

(b) Stabilization

When specified in the contract or required by the engineer, sub-base layers shall be stabilized

as specified in Division 4600.

(c) Trial Areas

Prior to the commencement of normal working the Contractor shall construct a trial area of

not less than 1000 square metres using the materials and equipment proposed for the work to

demonstrate compliance with the requirements of this Clause.

(d) Traffic on Sub-base

The completed sub-base layer may be used by construction and public traffic subject to the

approval of the Engineer. Any such approval shall not relieve the Contractor of his

responsibility to maintain and repair any damage caused to the layer.





5108 PROTECTION AND MAINTENANCE

The Contractor shall protect and maintain the completed sub-base at his own expense.

Maintenance shall include immediate repairs of any damage or defects, which may occur and

shall be repeated as often as is necessary to keep the subbase continuously intact. Repairs

shall be made in a manner that will ensure restoration to an even and uniform surface.

5109 SUB-BASE AS A FILTER OR SEPARATING LAYER

This may be required to protect a drainage layer from blockage by a finer material or to

prevent migration of fines and the mixing of two layers. The two functions are similar except

that for use as a filter the material needs to be capable of allowing drainage to take place and

therefore the amount of material passing the 0.075 mm sieve must be restricted.

The following criteria should be used to evaluate a sub-base as a separating or filter layer:

a) The ratio D15(coarse layer) should be less than 5

D85(fine layer)where D15is the sieve size through which 15% by weight of the material passes and D85is the

sieve size through which 85% passes.

b) The ratio D50(coarse layer) should be less than 25

D50(fine layer)

For a filter to possess the required drainage characteristics a further requirement is:

c) The ratio D15(coarse layer) should lie between 5 and 40

D15(fine layer)

These criteria shall be applied to the materials at both the base course/sub-base and the sub-

base/subgrade interfaces.

5110 CLASSIFICATION OF LAYERS FOR PAYMENT PURPOSES

Payment for sub-base layers constructed from gravel material shall distinguish between layers

constructed with material from borrow pits, cuts or existing pavement layers, and in-situ

recompacted layers with or without the use of additional material.

Sub-base layers constructed from crushed-stone material recovered from existing crushed-

stone pavement layers shall be placed and paid for as gravel material, unless otherwise

determined by the Engineer. Where the Engineer determines, in writing, which the material

shall be processed and placed as crushed stone.

5111 CONSTRUCTION TOLERANCES

The completed subbase shall conform to the dimensional tolerances stated below:

(a) Levels

The lot shall be deemed to comply with the requirements specified for surface levels if, before

any repair work is undertaken, at least 90% of the level measurements are within + 25 mm of

the specified levels.

Isolated spots , where the surface levels deviate by more than 33 mm of the specified levelsshall be repaired to bring the deviation to within the + 25 mm tolerance.





(b) Width

The average width of the sub-base shall not be less than the specified width and nowhere shall

the outer edge of the sub-base be more than 75 mm inside the lines shown on the Drawings.

(c) ThicknessThe lot will be considered to comply with the requirements for layer thicknesses if:

At least 90 % of all the thickness measurements taken before any thickness repairs are made

is equal to or greater than the specified thickness minus 27 mm; and

The mean layer thickness of the lot is not less than the specified thickness minus 5 mm

Isolated spots where the actual thickness is less than the specified thickness less 35 mm shall

be repaired so as to fall within the 27 mm tolerance.

(d) Cross Section

At any transverse section the difference in level between any two points shall not vary by

more than 20 mm from their difference in level as computed from the cross sections as shown

on the Drawings.

5112 TESTING

(a) Process Control

The minimum testing frequency that will be required from the Contractor in terms of Clause

1202, for the purpose of process control, shall be as shown on Table 5112/1 below.

Table 5112/1 Testing Frequency

Testing Frequency

Test One test

every

Minimum number of tests per lot

Materials

Field density and OMC

Atterberg limits and gradings

2 510 m2

2 510 m2

4

4

20 m (3 points per cross section)Construction Tolerances

Surface levels

Thickness

Width

Cross section

20 m

20 m

20 m

(3 points per cross section)

-

-

(b) Routine Inspection and Testing.

Routine inspection and testing will be carried out by the Engineer to test the quality of

materials and workmanship for compliance with the requirements of this Division.





The density requirements specified in Clause 5105 for compaction of subbase shall be deemed

to have been complied with if the minimum dry densities as shown in Table 5112/2 are

equaled or exceeded.

In calculating the mean, density values differing by more than 5 percentage points from the

mean shall be disregarded and a new mean calculated.

Any material or workmanship that does not comply with the specified requirements shall be

removed and replaced with materials and workmanship complying with the specified

requirements, or if the Engineer permits, be repaired as specified in Clause 1208 so that after

being repaired it will comply with the specified requirements.

Table 5112/2 Density requirements

Specified density (% of

AASHTO T 180 MDD)

Number of tests

per lot

Minimum mean

density (% of

AASHTO T 180

MDD)

Minimum density for

any single test (% of

AASHTO T 180 MDD)

95 (unstabilized) 3 & 4

5

6

95. 6

95. 8

95. 9

92. 0

91. 8

91. 6

Note: The determination of field dry density expressed as a percentage of AASHTO T 180

MDD implies an AASHTO T 180 density determination for each field density. Where

material is homogeneous, this ratio can be decreased to one laboratory determination for up to

four field densities.

5113 MEASUREMENT AND PAYMENT

Items 51.08, 51.09 and 51.012 are applicable solely to work that has to be executed in a

restricted area of which the width is less than 3.0 m or the length is less than 150.0 m.

Item 51.01 Sub-base layer constructed from gravel or Crushed stone:

a) Gravel sub-base (unstabilized gravel) compacted to:

(i) 95% of modified AASHTO density

(specify compacted layer thickness) ....................................................cubic metre (m3)

(ii) 97% of modified AASHTO density(specify compacted layer thickness) ...................................................cubic metre (m

3)

b) Gravel sub-base (chemically stabilized material) compacted to:

(i) 95% of modified AASHTO density

(specify compacted layer thickness) ....................................................cubic metre (m3)

(ii) 96% of modified AASHTO density

(specify compacted layer thickness) ...................................................cubic metre (m3)

(c) Crushed stone Sub-base 95% of modified AASHTO density (specify compacted

layer thickness) .................................................................................................cubic metre (m3)





The unit of measurement shall be the cubic metre of compacted pavement layer, and the

quantity shall be calculated from the authorized dimensions of the completed layer.

The tendered rates shall include full compensation for procuring, crushing or soft excavation

or pits, breaking down, placing and compacting the material, including transporting the

material for a distance of 1.0 km and its removal, disposal and transporting for a distance of

1.0 km, of up to 5% by volume of oversize material, and the protection and maintenance of

the layer and the conducting of control tests, all as specified.

Item 51.02 Extra over Pay item 51.01 for excavation of material in:

(a) Intermediate excavation ..................................................................... cubic metre (m3)

(b) Hard excavation................................................................................... cubic metre (m3)

The unit of measurement shall be the cubic metre of material obtained from intermediate or

hard excavation.

The tendered rates shall include full compensation for the additional costs involved for taking

material from classes of material harder than soft excavation and for the additional costs, ifany, for processing such material in the pavement layers.

Item 51.03 Sub-base layer constructed from gravel or crushed stone obtained from

existing pavement layers:

(a) Gravel sub-base (unstabilized gravel) compacted to 95% of modified AASHTO

density, using:

(i) Non-cemented material (specify compacted layer thickness) ... cubic metre (m3)

(ii) Cemented material (specify compacted layer thickness)........... cubic metre (m3)

(b) Gravel sub-base (unstabilized gravel) compacted to 97% of modified AASHTO

density using:



(c) Gravel sub-base (chemically stabilized material) compacted to 95% of modified

AASHTO density, using:



(d) Gravel sub-base (chemically stabilized material) compacted to 96% of modified




(e) Crushed Stone sub-base (unstabilized) compacted to 95% of modified AASHTO

density using:






(ii) Cemented material (specify compacted layer thickness) ...........cubic metre (m3)

(f) Crushed Stone sub-base (chemically stabilized material) compacted to 95% of

modified AASHTO density, using:

(i) Non-cemented material (specify compacted layer thickness) ....cubic metre (m3

)(ii) Cemented material (specify compacted layer thickness) ...........cubic metre (m

3)

The unit of measurement shall be the cubic metre of compacted pavement layer, the quantity

of which shall be calculated in accordance with the authorized dimensions of the completed

layer if the underlying layer has also been reconstructed or reworked. Where the underlying

layer has not been reconstructed or reworked but only rolled, or where no work has been done

on it, quantities shall be calculated with the aid of cross-sections taken of the layer before and

after construction. Where the material consist of recovered pavement material in part and

imported material in part the quantity of imported material obtained from cut or borrow shall

be paid for under pay item 51.01, calculated in accordance with the volume relation of therespective materials.

The tendered rate shall include full compensation for breaking up the existing pavement layer,

excavating the material in the existing pavement, procuring, breaking down, placing and

compacting the material, including haul for a free-haul distance of 1.0 km, and for the

protection and maintenance of the layer as well as for the performance of control tests, all as

specified.

Where excavation is executed over sections of the road payment shall also include

compensation for the proper measuring and marking-off of the excavation, and the protection

of the adjacent existing pavement and its repair should it be damaged.

The tendered rate for cemented material shall include full compensation of breaking down the

material to comply with the specified grading requirements.

Item 51.04 In situ reconstruction of existing Sub-base layer as:

(a) Gravel sub-base (unstabilized gravel) compacted to 95% of modified AASHTO

density, using:

(i) Non-cemented material (specify compacted layer thickness) ....cubic metre (m3)


(b) Gravel sub-base (chemically stabilized material) compacted to 95% of modified

AASHTO density using:



(c) Gravel sub-base (chemically stabilized material) compacted to 96% of modified



(ii) Cemented material (specify compacted layer thickness) ..........cubic metre (m3

)





(d) Crushed stone Sub-base (unstabilized) compacted to 95% of modified AASHTO

density, using:


(ii) Cemented material (specify compacted layer thickness) ......... cubic metre (m3)

(e) Crushed stone Sub-base (chemically stabilized) compacted to 95% of modified

AASHTO density using:



The unit of measurement shall be the cubic metre of compacted pavement layer reworked in

situ, the quantity of which shall be calculated in accordance with the authorized dimensions of

the completed layer.

The tendered rate shall include full compensation for breaking up the existing pavement layerto the specified depth, breaking down and preparing the material, placing and compacting the

material as well as the protection and maintenance of the layer, conducting control tests,

measuring and demarcating the work where layers are reprocessed partly, protecting the

adjacent pavement and its repair should it be damaged.

The tendered rate shall also include full compensation for spreading and mixing in any

additional material should the existing layer thickness be inadequate and it be specified or

instructed by the engineer that the thickness be increased.

Material which is temporarily bladed to windrow for the removal of an underlying layer and

then bladed back and compacted, will be classed as in situ reconstruction and paid for under

this item. The temporary blading of the material to windrow will be paid for under Pay item

51.07.

The tendered rate for cemented material shall include full compensation for breaking down

the material to comply with the specified grading requirements.

Item 51.05 Sub-base layer constructed Extra over Pay item 51.03 (a),(b),(c)&(d) and

Pay item 51.04 (a),(b)&(c) from recovered pavement material mixed with

existing bituminous surfacing material

The unit of measurement shall be in cubic metre (m3).

The tendered extra-over rate for constructing the pavement layers from material recoveredfrom existing pavements and mixed with existing bituminous surfacing material shall include

full compensation for breaking down the surfacing material into fragments not exceeding 37.5

mm in size, uniformly mixing it with the other material, manually removing any over-sized

fragments, and for any other incidentals.

Item 51.06 Extra over Pay item 51.04 for adding extra material as specified below:

(a) Gravel sub-base ................................................................................... cubic metre (m3)

(b) Crushed stone Sub-base....................................................................... cubic metre (m3)

Where the thickness of any existing pavement layer requires to be supplemented and the

thickness of the added material after compaction will be less than 100 mm, the existing layershall be scarified to a depth that will give a layer thickness of at least 100 mm after





compacting together the loosened existing and added material. In the case of gravel or

crushed-stone sub-bases the engineer may direct the existing layer to be broken down to its

full depth.

The composite layer shall be watered mixed and compacted as determined in the clause for

placing and compaction. Payment for adding the material will be made as per this pay item.

The unit of measurement shall be a cubic metre of material added on the instruction of the

engineer, which quantity shall be taken as 70% of the loose volume measured in trucks, unless

instructed by the engineer that the quantity be determined by way of cross-sections.

The tendered rate shall include full compensation for procuring and adding the material to the

in situ broken- down pavement layer and for haul over a free-haul distance of 1.0 km.

Item 51.07 Extra over Pay item 51.04 for temporarily blading the material to windrow

The unit of measurement shall be a cubic metre (m3) of material from an existing pavement

layer, temporarily bladed to windrow and measured in its original position before removal.

The tendered rate shall include full compensation for all additional costs involved intemporarily blading the material to windrow and later blading back and also for all clearing-

up work which may be necessary after the material has been bladed back.

Only material bladed to windrow on the instruction of the engineer in order to expose the

underlying layer shall be measured and paid for.

Material bladed or cut from restricted areas to windrow, and material temporarily stockpiled,

will not be paid for under this item.


layers in restricted areas:

(a) Non-cemented material........................................................................cubic metre (m3)

(b) Cemented material ...............................................................................cubic metre (m3)

The unit of measurement shall be a cubic metre of material excavated in a restricted area, the

quantity of which shall be calculated in accordance with the area and the average thickness of

the layers excavated.

The tendered rate shall include full compensation for all additional costs for excavating the

material in restricted areas.

Item 51.09 Compacting the floors of pavement excavations (5 roller passes) with:

(a) Vibratory rollers .................................................................................square metre (m2)

(b) Oscillatory rollers .............................................................................. square metre (m2)

(c) Grid rollers .........................................................................................square metre (m2)

(d) Flat-wheeled rollers ...........................................................................square metre (m2)

(e) Pneumatic-tyred rollers...................................................................... square metre (m2)

The unit of measurement shall be a square metre of floor of pavement excavations compacted

by 5 roller passes. Payment will differentiate between the above types of rollers.

The tendered rate shall include full compensation for supplying the roller, applying 5 roller

passes, and removing the roller after completion of the compacting process. The engineer may





increase or decrease the number of roller passes, in which case payment will be adjusted in

accordance with pay item 51.11.

Item 51.10 Watering the pavement excavation floor.

The unit of measurement shall be kilolitre (kl) of water applied to the floor of the excavation

to be compacted on the instruction of the engineer.

The tendered rate shall include full compensation for procuring and applying the water,

including all hauls.

Item 51.11 Variations in the number of roller passes applicable to pay item 51.09:

(a) Vibratory rollers ............................................................. square metre- pass (m2

-pass)

(b) Oscillatory rollers ............................................................ square metre- pass (m2

-pass)

(c) Grid rollers ...................................................................... square metre- pass (m2

-pass)

(d) Flat-wheeled rollers ......................................................... square metre- pass (m2

-pass)

(e) Pneumatic-tyred rollers ................................................... square metre- pass (m2

-pass)


restricted areas

The unit of measurement shall be a square metre (m2) of pavement excavation floor

compacted in restricted areas.

The tendered rate shall include full compensation for all additional costs for compacting the

pavement excavation floor in a restricted area irrespective of the compaction plant used.



Division 5200: Road Bases


DIVISION5200: ROADBASES

5201 SCOPE

This Division covers the specifications of materials for, and the construction of road base

pavement layers from approved base materials. It includes the use of crushed, screened or

crushed and screened stones or gravels, natural gravels, and stabilized base materials.

5202 DIMENSIONS

The road base layer shall be constructed to the dimensions and cross sectional profiles shown

in the Contract.

5203 MATERIALS

(a) Sources of Material

Road base material shall be obtained from sources located by the Contractor and approved by

the Engineer.

(b) Road Base Material Types

The materials used for the construction of road base layers shall be one of the following as

described in the Contract:

Crushed Rock or Stone;

Naturally occurring Granular Materials, Boulders, Weathered Rock;

Dense Bitumen Macadam.

5204 MATERIAL REQUIREMENTS FOR CRUSHED ROCK OR STONE

(a) General

Graded crushed stone (GB1):

This material is produced by crushing fresh, quarried rock (GB1) and may be an all-in

product, usually termed a 'crusher-run', or alternatively the material may be separated byscreening and recombined to produce a desired particle size distribution, as per the

specifications. The material shall be clean and free from organic matter, lumps of clay or other

deleterious substances. The material shall be of such a nature that it can be readily

transported, spread and compacted without segregation.

(b) Grading

The combined grading of the material shall be a smooth continuous curve falling within the

grading limits shown in Table 5200/1 when determined in accordance with the requirements

of AASHTO T-27. The mass of material passing the 0.075mm sieve shall be determined in

accordance with the requirements of AASHTO T-11.





Table 5200/1: Grading Limits for Graded Crushed Stone Base Course Materials (GB1)

Percentage by mass of total aggregate passing test sieve

Nominal maximum particle size

Test sieve (mm)

37.5 mm 28 mm 20 mm50 100 - -

37.5 95 100 100 -

28 - - 100

20 60 80 70 - 85 90 100

10 40 60 50 - 65 60 75

5 25 - 40 35 - 55 40 60

2.36 15 30 25 - 40 30 45

0.425 7 19 12 - 24 13 27

0.075(1)

5 12 5 - 12 5 12

Note 1. For paver-laid materials a lower fine content may be accepted.

(c) Plasticity Index

The fine fraction of a GB1 material shall be non-plastic or shall have a maximum Plasticity

Index of 6 when determined in accordance with AASHTO T-90.

(d) Californian Bearing Ratio (CBR)

The in- situ dry density of the placed material should be a minimum of 98% of the maximum

dry density obtained in the ASTM Test Method D 1557 (Heavy Compaction). The compacted

thickness of each layer should not exceed 200 mm.

Crushed stone base courses constructed with proper care with GB1 materials described above

should have CBR values in excess of 100 per cent.

(e) Aggregate Crushing Value (ACV)

Requirements expressed in terms of the results of the Aggregate Crushing Value (ACV)

(British Standard 812, Part 110) may be used: the ACV should preferably be less than 25 and

in any case less than 29.

Other simpler tests e.g. the Aggregate Impact Test (British Standard 812, Part 112, 1990) may

be used in quality control testing provided a relationship between the results of the chosen test

and the Ten percent Fines Value (TFV) has been determined.

(f) Mechanical Strength Requirements (TFVT)

To ensure that the materials are sufficiently durable, they should satisfy the criteria given in

Table 5200/2. These are a minimum Ten Per Cent Fines Value (TFV) (British Standard 812,

Part 111) and limits on the maximum loss in strength following a period of 24 hours of

soaking in water. The likely moisture conditions in the pavement are taken into account in

broad terms based on annual rainfall.





Table 5200/2: Mechanical Strength Requirements for the Aggregate Fraction of

Crushed Stone Base Course Materials (GB1) as Defined by the Ten Percent

Fines Test

Typical Annual Rainfall

(mm)

Minimum 10%

Fines Values (kN)

Minimum Ratio

Wet/Dry Test (%)>500 110 75





Table 5200/3: Recommended Particle Size Distributions for Mechanically Stable

Natural Gravels and Weathered Rocks for Use as Base Course Material

(GB2, GB3)

Percentage by mass of total aggregate passing test sieve

Nominal maximum particle size

Test sieve (mm)

37.5 mm 20 mm

50 100 -

37.5 80 100 100

20 60 80 80 100

10 45 65 55 80

5 30 50 40 60

2.36 20 40 30 50

0.425 10 25 12 27

0.075 5 15 5 15

(c) Plasticity Index

The fine fraction of a GB1 material shall be non-plastic or shall have a maximum Plasticity

Index of 6 when determined in accordance with AASHTO T-90.

If the PI approaches the upper limit of 6, it is desirable that the fines content be restricted to

the lower end of the range. To ensure this, a maximum PP of 60 is recommended or

alternatively a maximum Plasticity Modulus (PM) of 90 where:

PM = PI x (percentage passing the 0.425 mm sieve)

If difficulties are encountered in meeting the plasticity criteria, consideration should be givento modifying the material by the addition of a low percentage of hydrated lime or cement.

(d) Californian Bearing Ratio (CBR)

When used as a base course, the material should be compacted to a density equal to or greater

than 98 per cent of the maximum dry density achieved in the ASTM Test Method D 1557

(Heavy Compaction). When compacted to this density in the laboratory, the material should

have a minimum CBR of 80% after four days immersion in water (ASTM D 1883).

(e) Aggregate Crushing Value (ACV)

Minimum soaked Ten percent Fines Value (TFV) Value (BS 812, Part 111) shall be 50 KN.

(f) Abrasion

The Los Angeles Abrasion value, determined by testing in accordance with AASHTO T96

shall not exceed 45 at 500 revolutions unless otherwise specified in the Project Specifications.

(g) Flakiness Index

The flakiness index shall not exceed 30% when determined in accordance with BS 812 Part

105-1990.





(h) Crushed Ratio

The crushed ratio shall be a minimum of 60%.

(i) Grading Modulus

The minimum Grading Modulus for material once placed and compacted on the road shall be:

For natural material. . . . . . . . . . . . . . . . . . . . 2.00

For material to be chemically stabilized. . . . . . . . . . 1.75

5206 MATERIAL REQUIREMENTS FOR DENSE BITUMEN MACADAM

(a) Coarse Aggregates

The material shall consist of hard durable particles produced by crushing rock or boulders and

shall be clean and free from organic matter, lumps of clay or other deleterious substances and

complying with the requirements of AASHTO M-80.

Crushed rock or crushed boulders shall be produced from one or more of the following rock

types;

Basalt;

Gabbro;

Granite;

Gritstone;

Hornfels; Limestone;

Porphyry or Quartzite.

Aggregate Crushing Value

The aggregate crushing value of the coarse aggregate shall not exceed 25 when determined in

accordance with BS 812 Part 3.

(i) Los Angeles Abrasion

The Los Angeles Abrasion value shall not exceed 35% when determined in accordance with


(ii) Soundness

The loss of soundness of the coarse aggregate shall not be greater than 12% when tested in

accordance with AASHTO T-104.

(iii) Flakiness index

The flakiness index, shall not exceed 45% when determined in accordance with the

requirements of BS 812 Part 105-1990.

(iv) Crushed RatioThe crushed ratio shall be a minimum of 100%.





(v) Water Absorption

The water absorption shall not exceed 2% when determined in accordance with the

requirements of AASHTO T-85.

(vi) Coating of Chippings

The coating of chippings with binder shall not be less than 60% when determined in

accordance with the requirements of prEN 12697-11:1998E for compatibility between

aggregate and bitumen.

(b) Fine Aggregate

Fine aggregate shall comply with the requirements of AASHTO M-6 and shall consist of one

of the following:

(i) Crushed rock or crushed boulders;

(ii) Natural sand;

(iii) A blend of (i) and (ii) above.

(c) Filler

Where necessary to improve the combined grading or other properties of the mix, a filler of

either hydrated lime, cement or crushed rock or crushed boulder dust may be added. Filler

shall be material passing the 0.075mm sieve. If used as an anti-stripping agent, the quantity of

hydrated lime shall be at least 1.5% by weight of total aggregates and in no case shall the

quantity exceed 3% by weight of total aggregates.

(d) Binder

The binder shall be 60/70 penetration grade bitumen complying with the requirements of

AASHTO M-20.

5207 MATERIAL REQUIREMENTS FOR MIXED BITUMEN MACADAM

(a) Combined Aggregate Grading

The combined grading of the aggregates shall be a smooth continuous curve falling within the

grading limits shown in Table 5200/4 when determined in accordance with AASHTO T-27.

The mass of material passing the 0.075mm sieve shall be determined in accordance withAASHTO T-11.





Table 5200/4 Combined Aggregate Grading Limits for Dense Bitumen Macadam

Test sieve (mm) Percentage by mass of total aggregate

passing test sieve

28 100

20 95 10014 65 85

10 52 72

6.3 39 55

3.35 32 46

1.18 -

0.3 7 21

0.075 (1)

2 8

Notes:

1. When gravel other than limestone is used, the anti-stripping properties shall be improved

by including 2% Portland cement or hydrated lime in the material passing the 0.075 mmsieve.

2. Limestone and gravel shall not be used for wearing courses where high skidding resistanceis required.

(b) Mix Design Parameters for Dense Bitumen Macadam

The parameters for dense bitumen macadam shall comply with the requirements as shown in

Table 5200/5.

Table 5200/5 Mix Design Parameters for Dense Bitumen Macadam

Property Unit Value

Bitumen content (1)

(per

cent by mass of total mix)

% 5.0 0.6

Bitumen grade (2)

pen 60/70 or 80/100

Minimum Marshal Stability

(Depending on Design

traffic)

kN 3.5-9

Flow mm 2 - 4

Air Voids % 4.0 - 8.0

Voids in Mineral Aggregate % 16.0 - 22.0

Voids Filled with Bitumen % 65.0 - 85.0

Filler/Bitumen Ratio* % 1.0 - 1.6

Compaction Level

(Depending on Design

traffic)

Number of blows 2x50, 2x75 - To refusal

Note :

1. For aggregate with fine microtexture e.g. limestone, the bitumen content should be reduced

by 0.1 to 0.3%.

2. 60/70 grade bitumen is preferred.





The mix proportions for each type of mixture to be used in the Works shall be determined

initially in accordance with the requirements of the Asphalt Institute Mix Design Manual

(MS2) using at least five binder contents. The Marshall specimens shall be compacted using

75 blows on each face. Trial mixes shall be carried out using various combined aggregate

gradings within the limits stipulated within Table 5200/4 in order to determine the optimum

design within the stipulated parameters in Table 5200/5 for the materials being used.

Prior to final approval of the proposed job mix formula, mixes shall be compacted to refusal

using the extended Marshall compaction method (in accordance with the requirements of BS

598 Part 104 (1989)) and the resulting air voids in the mix shall not be less than 3%.

5208 CONSTRUCTION REQUIREMENTS FOR CRUSHED ROCK AND CRUSHED

BOULDER ROAD BASES

(a) Equipment

The material shall be laid either by a self-propelled paving machine or by means of a grader,as described in the Contract. It shall be so designed and operated as to produce a mixture of

laid material complying with the requirements of this Specification.

The equipment used shall be of adequate rated capacity, in good working order, and subject to

the approval of the Engineer.

Obsolete or worn out equipment will not be permitted on the Site.

The mixing plant shall be either a batch or a continuous type, as approved by the Engineer,

and shall be equipped with satisfactory means of accurately controlling the proportions of all

constituent materials.

The crushing and screening plant shall be capable of crushing and screening the aggregates, tobe used for crushed rock or crushed boulder road base material, into at least four different

sized fractions.

Compaction shall be carried out using self-propelled 8 10 tonnes deadweight smooth

wheeled rollers having a width of roll not less than 450mm, or by multi-wheeled pneumatic

tyred rollers of equivalent mass, or by vibratory rollers of equivalent compactive

performance, or a combination of these.

Rollers shall be equipped with adjustable scrapers for cleaning the drums and an efficient

means of moistening the drums to prevent adhesion of asphalt. The rollers shall be fitted with

a quick and smooth acting reversing mechanism.

(b) Placing and Compaction

The surface on which the crushed rock and crushed boulder road base is to be laid shall be

free from loose or deleterious material.

The crushed material shall be screened into at least four different aggregate fractions.

The aggregate shall be recombined in a mixing plant in the proportions necessary to produce a

smooth continuous combined grading curve complying with the requirements of Table

5200/1.

The mixing plant shall be an approved type and shall be equipped with satisfactory means of

controlling the mix proportions and the addition of the required quantity of water to achieve

the optimum, which is required for compaction purposes.





The mixed material shall be transported at the required moisture content and in such a way,

that no segregation occurs.

Unless otherwise described in the Contract, the material shall be laid by a self-propelled

paving machine approved by the Engineer. The rate of travel of the paver and its method of

operation shall be adjusted to produce an even and uniform flow of material across the full

laying width free from dragging and without segregation.

The material shall be spread in layers not exceeding 200mm and not less than 100mm

compacted thickness.

The material shall be compacted by the use of approved rollers progressing gradually from the

outside towards the centre of the layer, except on superelevated curves, where the rolling shall

begin at the low side and progress to the high side. Each succeeding pass shall overlap the

previous pass by at least one third of the roller width. Rolling shall continue until the entire

thickness of each layer is thoroughly and uniformly compacted to the specified density.

Any area, which is inaccessible to rolling equipment, shall be compacted by means of

mechanical tampers or other equipment approved by the Engineer.

Upon completion of compaction, the surface of the completed layer shall be tightly bound,

free from movement under the compaction plant, and free from laminations, ridges, cracks or

loose or segregated material.

The in-situ density of the completed layer shall not be less than 98% of the maximum dry

density determined in accordance with the requirements of AASHTO T-180 method D.

The in-situ density of the completed layer shall be determined in accordance with the


Alternatively, if approved by the Engineer, the dry density may be determined by use of a

nuclear densometer in direct transmission mode in accordance with AASHTO T238-86Method B or ASTM D 2992-96. The nuclear densometer shall be accurately calibrated before

use, and at interval thereafter, and correlated against results obtained in accordance with

AASHTO T-191.

(c) Stabilization

When specified in the contract or required by the engineer, base layers shall be stabilized as

specified in Division 4600.

(d) Trial Sections

Prior to the commencement of normal working the Contractor shall construct a trial section of

not less than 1000 square metres using the materials and equipment proposed for the work to

demonstrate compliance with the requirements of this Clause.

(e) Traffic on Road base

The completed road base layer shall not be used by construction or public traffic prior to the

application of the prime coat in accordance with the requirements of Division 6100 of these

specifications and without the prior written approval of the Engineer.

The approval by the Engineer shall not relieve the Contractor of his obligations to maintain

the road base in a satisfactory condition and to undertake any repairs as instructed by theEngineer.





5209 CONSTRUCTION REQUIREMENTS FOR CRUSHED GRAVEL ROAD BASE

(a) Equipment

The material shall be laid either by a self-propelled paving machine or by means of a grader,

as described in the Contract. It shall be so designed and operated as to produce a mixture oflaid material complying with the requirements this Specification.

The equipment used shall be of adequate rated capacity in good working order and subject to

the approval of the Engineer.

Obsolete or worn out equipment will not be permitted on the Site.

Compaction shall be carried out using self-propelled 8 10 tonnes deadweight smooth




Rollers shall be equipped with adjustable scrapers for cleaning the drums and an efficientmeans of moistening the drums to prevent adhesion of asphalt. The rollers shall be fitted with

a quick and smooth acting reversing mechanism.

(b) Placing and Compaction

The surface on which the crushed gravel road base is to be laid shall be free from loose and

deleterious material.

Crushed gravel road base shall be spread on the sub-base material by mechanical means

without segregation.

The material shall be loosely spread in layers to give a compacted thickness not exceeding200mm and not less than 100mm. The final compacted layer shall be free from

concentrations of coarse or fine materials.

The surface of each completed layer shall be moistened prior to the construction of the

succeeding layer.

Prior to compaction, the moisture content of the spread material shall be adjusted as necessary

either by the uniform application of water or drying out, to achieve within -1% to +2% of the

optimum moisture content when determined in accordance with AASHTO T-180.

The material shall be compacted by the use of approved rollers progressing gradually from the

outside towards the centre of the layer, except on superelevated curves, where the rolling shall

begin at the low side and progress to the high side. Each succeeding pass shall overlap theprevious pass by at least one third of the roller width. Rolling shall continue until the entire

thickness of each layer is thoroughly and uniformly compacted to the specified density.

Any area, which is inaccessible to rolling equipment, shall be compacted by means of

mechanical tampers or other equipment approved by the Engineer.

Upon completion of compaction, the surface of the completed layer shall be tightly bound,

free from movement under the compaction plant, and free from laminations, ridges, cracks or

loose or segregated material.

The in-situ density of the completed layer shall not be less than 98% of the maximum dry

density determined in accordance with the requirements of AASHTO T-180 method D.





The in-situ density of the completed layer shall be determined in accordance with the


Alternatively, if approved by the Engineer, the dry density may be determined by use of a

nuclear densometer in direct transmission mode in accordance with AASHTO T238-86

Method B or ASTM D 2992-96. The nuclear densometer shall be accurately calibrated before

use, and at interval thereafter, and correlated against results obtained in accordance with

AASHTO T-191.

(c) Stabilization

When specified in the contract or required by the engineer, base layers shall be stabilized as

specified in Division 4600.

(d) Trial Sections

Prior to the commencement of normal working the Contractor shall construct a trial section of

not less than 1000 square metres using the materials and equipment proposed for the work todemonstrate compliance with the requirements of this Clause.

(e) Traffic on Road Base

The completed road base layer shall not be used by construction or public traffic prior to the

application of the prime coat in accordance with the requirements of Division 6100 of these

specifications and without the prior written approval of the Engineer.

Such approval shall not relieve the Contractor of his obligations to maintain the road base in a

satisfactory condition and to undertake any repairs as instructed by the Engineer.

5210 CONSTRUCTION REQUIREMENTS FOR DENSE BITUMEN MACADAM ROAD

BASE

(a) Equipment

All equipment used for the mixing and paving of the Dense Bitumen Macadam Road Base

material shall be so designed and operated as to produce a mixture of laid material complying

with the requirements this Specification.

The equipment used shall be of adequate rated capacity in good working order and subject to

the approval of the Engineer.Obsolete or worn out equipment will not be permitted on the Site.

The mixing plant shall be either a batch or a continuous type complying with the requirements

of AASHTO 156 and approved by the Engineer. It shall be equipped with satisfactory means

of accurately controlling the mix proportions of all constituent materials.

The crushing and screening plant shall be capable of crushing and screening the aggregates, to

be used for Dense Bitumen Macadam Road Base material, into at least four different sized

fractions.

Vehicle used for transporting the mixed material shall have tipping bodies capable of

discharging directly into the paving machine. The bodies of the vehicles shall be capable ofcontaining the mixed material without spillage.





All vehicles shall be equipped with a canvas or other approved type of cover which shall be

used to cover the mixed material upon loading at the mixing plant and shall not be removed

until the mixed material is discharged into the paving machine.

Dense Bitumen Macadam Road Base material shall be laid by an approved type of self-

propelled spreading/finishing machine capable of laying to the required widths, thicknesses

and cross sectional profiles shown in the Contract without causing segregation, dragging or

other surface defects.

All paving machines shall be fitted with automatic electronic screed control. Paving machines

shall be equipped with heated screeds and with 60o

or 45o

angle, confining side plates. Paving

machines shall also be equipped with an infra-red joint heating system.

Compaction shall be carried out using self-propelled 8 10 tonnes deadweight smooth, steel




Rollers shall be equipped with adjustable scrapers for cleaning the drums and an efficientmeans of moistening the drums to prevent a

05-series 5000 base, sub base and gravel wearing course new

Documents

gravel subbase

material requirements

compaction requirements

sub base

crushed stone subbase

construction requirements

grading limits

grading modulus