Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020)

3 PAVEMENT

This work shall consist of furnishing, placing, spreading, and compacting pavements for new
construction and rehabilitation works including asphaltic and Portland cement types in accordance
with these specifications and conforming to the lines, grades, and dimensions shown in the Contract
documents.

3.1 Reference Standards and Codes

Standards and codes shall be as specified in these specifications, in the Contract documents, if any,
and the following, in their latest edition:

AASHTO

Standard Specifications for Transportation Materials and Methods of Sampling
and Testing;

ASTM

American Society for Testing and Materials;

BSI

British Standards Institution;

BS EN

European Standards;

AIM

Asphalt Institute Manual;

AI MS-2

Mix Design Methods for Asphalt Concrete and Other Hot Mixes;

ITE

Institute of Traffic Engineers;

ITE

Equipment and Material Standards of the Institute of Transportation Engineers,

2001.

Table 3-1 and Table 3-2 presents American Association of State Highway and Transportation
Officials (AASHTO), American Society for Testing and Materials (ASTM), British (BS), and European
(BS EN) Standards that are related to materials for pavement works. It also includes designations
and titles.

Table 3-1: Designations and titles for AASHTO and ASTM standards that apply to pavement

works

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

AASHTO T96

Standard method of test for resistance to
degradation of small-size coarse aggregate by
abrasion and impact in the

ngeles machine.

ASTM D75 / 75M - 09

Standard practice for sampling aggregates.

ASTM C131 - 06

Standard test method for resistance to
degradation of small-size coarse aggregate

abrasion and impact in the L

os Angeles machine.

ASTM C535

– 12

Standard test method for resistance to
degradation of large-size coarse aggregate by
abrasion and impact in the los Angeles machine.

ASTM C88-05

Standard test method for soundness of
aggregates by use of sodium sulfate or
magnesium sulfate.

ASTM D2419 - 09

Standard test method for sand equivalent value of
soils and fine aggregate.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

ASTM D4318-10

Standard test methods for liquid limit, plastic limit,
and plasticity index of soils.

ASTM D1883-07e2

Standard test method for CBR (California bearing
ratio) of laboratory-compacted soils.

ASTM C128-12

Standard test method for density, relative density
(specific gravity), and absorption of fine
aggregate.

ASTM C127-12

Standard test method for density, relative density
(specific gravity), and absorption of coarse
aggregate.

ASTM D1559-89

Test method for resistance of plastic flow of
bituminous mixtures using Marshall apparatus
(withdrawn 1998).

ASTM C25 - 11

Standard test methods for chemical analysis of
limestone, quicklime, and hydrated lime.

ASTM C50 / C50M - 12

Standard practice for sampling, sample
preparation, packaging, and marking of lime and
limestone products.

ASTM C51 - 11

Standard terminology relating to lime and
limestone (as used by the industry).

ASTM D244 -09

Standard test methods and practices for
emulsified asphalts.

ASTM D1075-11

Standard test method for effect of water on
compressive strength of compacted bituminous
mixtures.

ASTM D2172 / D2172M

- 11

Standard test methods for quantitative extraction
of bitumen from bituminous paving mixtures.

AASHTO M 208

ASTM D2397

Standard Specification for Cationic Emulsified
Asphalt

ASTM D6307 - 10

Standard Test Method for Asphalt Content of Hot-
Mix Asphalt by Ignition Method.

ASTM D3387 - 11

Standard test method for compaction and shear
properties of bituminous mixtures by means of the
U.S. Corps of Engineers gyratory testing machine
(GTM).

ASTM D3142 / D3142M

- 11

Standard test method for specific gravity, API
gravity or density of cutback asphalts by
hydrometer method.

ASTM D6927 - 06

Standard Test Method for Marshall Stability and
Flow of Bituminous Mixtures.

ASTM D6926 - 10

Standard Practice for Preparation of Bituminous
Specimens Using Marshall Apparatus.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

ASTM D5821

– 01

(2006)

Standard Test Method for Determining the
Percentage of Fractured Particles in Coarse
Aggregate.

ASTM D4791 - 10

Standard Test Method for Flat Particles,
Elongated Particles, or Flat and Elongated
Particles in Coarse Aggregate.

ASTM D3042 - 09

Standard Test Method for Insoluble Residue in
Carbonate Aggregates.

ASTM C1077 - 13

Standard Practice for Agencies Testing Concrete
and Concrete Aggregates for Use in Construction
and Criteria for Testing Agency Evaluation.

ASTM C295 / C295M -

Standard Guide for Petrographic Examination of
Aggregates for Concrete.

ASTM C33 / C33M - 11a

Standard Specification for Concrete Aggregates.

ASTM C186 - 05

Standard Test Method for Heat of Hydration of
Hydraulic Cement.

ASTM C114 - 11b

Standard Test Methods for Chemical Analysis of
Hydraulic Cement.

ASTM C1240 - 12

Standard Specification for Silica Fume Used in
Cementitious Mixtures.

ASTM D1751

– 04

(2008)

Standard Specification for Preformed Expansion
Joint Filler for Concrete Paving and Structural
Construction (Nonextruding and Resilient
Bituminous Types).

ASTM C494 / C494M -

Standard Specification for Chemical Admixtures
for Concrete.

ASTM C881 / C881M -

Standard Specification for Epoxy Resin Base
Bonding Systems for Concrete.

ASTM C1260 - 07

Standard Test Method for Potential Alkali
Reactivity of Aggregates (Mortar Bar Method).

ASTM C136 - 06

Standard Test Method for Sieve Analysis of Fine
and Coarse Aggregates.

AASHTO T 176-

Plastic Fines in Graded Aggregates and Soils by
Use of the Sand Equivalent Test.

AASHTO T2

Standard method of test for sampling of
aggregates.

AASHTO M 145

Standard specification for classification of soils
and soil-aggregate mixtures for highway
construction purposes.

AASHTO T 104

Standard method of test for soundness of
aggregate by use of sodium sulfate or magnesium
sulfate.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

AASHTO T 89-

Determining the Liquid Limit of Soils

AASHTO T 90

Standard Method of Test for Determining the
Plastic Limit and Plasticity Index of Soils.

AASHTO T 100

Standard Method of Test for Specific Gravity of
Soils.

AASHTO T 85

Standard Method of Test for Specific Gravity and
Absorption of Coarse Aggregate.

AASHTO T 180

Standard Method of Test for Moisture-Density
Relations of Soils Using a 4.54-kg (10-lb) Rammer
and a 457-mm (18-in.) Drop.

AASHTO T 193

Standard Method of Test for The California
Bearing Ratio.

AASHTO. T 96-

Resistance to Degradation of Small-Size Coarse
Aggregate by Abrasion and Impact in the Los
Angeles Machine.

AASHTO T112-

00 (2008)

ASTM C142-97

Standard method of test for clay lumps and friable
particles in aggregate.

AASHTO T 191

Standard Method of Test for Density of Soil In-
Place by the Sand-Cone Method.

AASHTO T 11

Standard Method of Test for Materials Finer Than
75-µm (No. 200) Sieve in Mineral Aggregates by
Washing.

AASHTO T 27-

Sieve Analysis of Fine and Coarse Aggregates.

AASHTO M 85

Standard specification for Portland cement.

AASHTO T 22-

Compressive Strength of Cylindrical Concrete
Specimens.

AASHTO T 205

Standard Method of Test for Density of Soil In-
Place by the Rubber-Balloon Method.

AASHTO T 165

Standard method of test for effect of water on
compressive strength of compacted bituminous
mixtures.

AASHTO M 17

ASTM D242

Standard specification for mineral filler for
bituminous paving.

AASHTO M 20

Standard specification for penetration-graded
asphalt cement.

AASHTO M 33-

Preformed Expansion Joint Filler for Concrete
(Bituminous Type).

AASHTO M 82

Standard specification for cutback asphalt
(medium-curing type).

AASHTO M 140

Standard specification for emulsified asphalt.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

AASHTO M 208

Standard specification for cationic emulsified
asphalt.

AASHTO M 226

Standard specification for viscosity-graded asphalt
cement.

AASHTO M 320

Standard specification for performance-graded
asphalt binder.

AASHTO M 323

Standard specification for superpave volumetric
mix design.

AASHTO MP2

Standard specification for superpave volumetric
mix design.

AASHTO MP 19

Standard Specification for performance-graded
asphalt binder using multiple stress creep recover
(MSCR) test.

AASHTO R 12

Standard Specifications for bituminous mixture
design using the Marshall and

veem procedures.

AASHTO R 35

Standard practice for superpave volumetric design
for hot mix asphalt (HMA).

AASHTO PP 28

Standard specification for superpave volumetric
design for hot mix asphalt (HMA).

AASHTO T 2

Standard Method of Test for Sampling of
Aggregates.

AASHTO T 11-

Materials Finer Than 75-

μm (No. 200) Sieve in

Mineral Aggregates by Washing.

AASHTO T 30

Standard specification for mechanical analysis of
extracted aggregate.

AASHTO T 96-

Resistance to Degradation of Small-Size Coarse
Aggregate by Abrasion and Impact in the Los
Angeles Machine.

AASHTO T 99

Standard Method of Test for Moisture-Density
Relations of Soils Using a 2.5-kg (5.5-lb) Rammer
and a 305-mm (12-in.) Drop.

AASHTO T 104-

Soundness of Aggregate by Use of Sodium
Sulfate or Magnesium Sulfate.

AASHTO T 164

Standard method of test for quantitative extraction
of asphalt binder from hot mix asphalt (HMA).

AASHTO T 168

Standard method of test for sampling bituminous
paving mixtures.

AASHTO T 219

Standard method of test for testing lime for
chemical constituents and particle sizes.

AASHTO T 230

Standard method for determining the degree of
pavement compaction of a bituminous-aggregate
mixture.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

AASHTO T 245

Standard method of test for resistance to plastic
flow of bituminous mixtures using Marshall
apparatus.

AASHTO T 308

Standard method of test for determi

ng the

asphalt binder content of hot-mix asphalt (HMA)
by the ignition method.

AASHTO T 304-

Standard Method of Test for Uncompacted Void
Content of Fine Aggregate.

AASHTO M 303

Standard Specification for Lime for Asphalt
Mixtures.

AASHTO R 14-

88 (2007)

ASTM D4552-92 (2004)

Standard Recommended Practice for Classifying
Hot-Mix Recycling Agents.

AASHTO TP 61

Standard Method of Test for Determining the
Percentage of Fracture in Coarse Aggregate.

AASHTO T 85-

Specific Gravity and Absorption of Coarse
Aggregate.

AASHTO T 84-

ASTM C 128-07a)

Standard Method of Test for Specific Gravity and
Absorption of Fine Aggregate.

ASTM C150 / C150M -

Standard Specification for Portland Cement.

AASHTO M 140

Standard Specification for Emulsified Asphalt.

AASHTO T

19M/T 19-00

(2004)

Standard Method of Test for Bulk Density ("Unit
Weight") and Voids in Aggregate.

AASHTO T 182

Standard Method of Test for Coating and Stripping
of Bitumen-Aggregate Mixtures.

AASHTO T 210-

Aggregate Durability Index.

AASHTO T 112

Standard Method of Test for Clay Lumps and
Friable Particles in Aggregate.

AASHTO M

195-06

Lightweight Aggregates for Structural Concrete.

AASHTO T 27

Sieve Analysis of Fine and Coarse Aggregate.

AASHTO T 89

Standard Method of Test for Determining the
Liquid Limit of Soils.

AASHTO M 43-

Sizes of Aggregate for Road and Bridge
Construction.

AASHTO M 254

Standard Specification for Corrosion-Resistant
Coated Dowel Bars.

AASHTO M

284M/M 284-09

Epoxy-Coated Reinforcing Bars: Materials and
Coating Requirements.

AASHTO

DESIGNATION

ASTM DESIGNATION

TITLE

AASHTO T 97

Standard Method of Test for Flexural Strength of
Concrete (Using Simple Beam with Third-Point
Loading).

AASHTO PP 50

Standard Practice for Operating Inertial Profilers
and Evaluating Pavement Profiles.

AASHTO PP 51

Standard Practice for Pavement Ride Quality
When Measured Using Inertial Profiling Systems.

AASHTO PP 52

Standard Practice for Developing a Quality
Assurance Plan for Hot-Mix Asphalt (HMA).

ASTM C618 - 08a

Standard Specification for Coal Fly Ash and Raw
or Calcined Natural Pozzolan for Use in Concrete.

ASTM A615 / A615M -

09b

Standard Specification for Deformed and Plain
Carbon Steel Bars for Concrete Reinforcement.

ASHTO M

31M/M 31 - 10

Deformed and Plain Carbon-Steel Bars for
Concrete Reinforcement.

AASHTO M

42M/M42

ASTM A996 / A996M -

09b

Standard Specification for Rail-Steel and Axle-
Steel Deformed Bars for Concrete Reinforcement

Table 3-2: Designations and titles for BS and BS EN standards that apply to pavement

works

Designation

BS EN

Designation

Title

BS 1377-

2:1990

Methods of test for soils for civil engineering purposes.
Classification tests.

BS 1377-

3:1990

Methods of test for soils for civil engineering purposes.
Chemical and electro-chemical tests.

BS 812-

110:1990

Testing aggregates. Methods for determination of
aggregate crushing value (ACV).

BS 812-105-

105.1:1985

Testing aggregates. Methods for determination of
particle shape. Flakiness index.

BS 1377-4:

1990

Methods of test for soils for civil engineering purposes.
Compaction-related tests.

BS 1377-

9:1990

Methods for test for soils for civil engineering
purposes. In-situ test.

BS EN 1744-1+A1

Tests for chemical properties of aggregates. Chemical
analysis.

BS 812-

117:1988

Testing aggregates. Method for determination of
water-soluble chloride salts.

BS EN -

12620:2002+A1:2008

Aggregates for concrete.

3.2 Subbase and Bases

3.2.1 Granular Subbase Course

3.2.1.1 Description

Granular subbase shall consist of furnishing, spreading, and compacting subbase in accordance
with the details shown on Contract plans and these specifications or as established by the Engineer.

3.2.1.2 Materials

Granular subbase material shall consist of hard, durable natural, screened gravel or crushed stone,
and shall be free from clay balls or other deleterious substances. Granular subbase type I shall be
used under footpath and type II under roads. Granular subbase shall be well graded and lie within
the grading envelope shown in Table 3-3 when tested in accordance with

AASHTO T27

Table 3-3: Granular subbase gradation

Sieve size

Percentage passing

Type I (Under Footpath)

Type II (Under Roads)

50 mm

100

37.5 mm

– 100

85-100

25.4 mm

– 96

70-90

19.0 mm

– 92

62-82

9.5 mm

40 - 82

40-70

4.75 mm

25 - 70

25-55

0.6 mm

8 - 32

8-28

0.075 mm

0 - 10

0-10

a. Sampling and Testing

One sample every 1000 m

Type II and One sample every 2000 m

of Type I

, or part of as

directed by the Engineer shall be tested for grading, plasticity index, maximum dry density, CBR and
loss by abrasion. Three in-situ density tests shall be made every unit of granular subbase laid (one
unit being 300 m

) or as directed by the Engineer.

Materials  shall  meet  the  minimum  requirements  per  the  testing  standards  listed  in  Table  3-4.
Materials  that  do  not  comply  with  the  requirements  of  these  specifications  will  be  rejected  and
removed  immediately  from  the  site  unless  otherwise  instructed  by  the  Engineer.    No  rejected
materials, the defects of which have been corrected, shall be used until approval has been given by
the Engineer.

Table 3-4: Granular subbase test requirements

Test

Standard

Limit

Sampling

AASHTO - T2

Min. One sample
every 1,000 m

Los Angeles Abrasion

AASHTO-T96

30 % max.

Soundness (Magnesium Sulphate Solution - 5
cycles)

AASHTO-T-104

15% max.

Liquid Limit

AASHTO-T-89

35 % max.

Test

Standard

Limit

Plasticity Index

AASHTO-T-90

6 max.

Compaction Test (Dry Density / Moisture
Content test)

AASHTO-T-180 D

2.00 Mg/m

min

Particle size sieve analysis of fine and coarse
aggregate

AASHTO T27

Table 3-3

C.B.R. at 98 % of Maximum dry density (96
hour soaked)

AASHTO-193

45% min Type I
60% min Type II

Field Density

AASHTO T191

Avg.100% min. at
MDD

for Type II

Avg.98% min. at
MDD for Type I

Linear Shrinkage

BS 1377: Part 2 Method
6.5

3 % max.

Sulphate Content (Acid soluble)

BS EN 1744-1

0.5 % max.

Chloride Content (Acid soluble)

AASHTO T260

1 % max.

Sand Equivalent

AASHTO - T176

25% Min. for
footpath 35% Min.
for Roads

Organic matter content

AASHTO T267

0.2% Max.

b. Material Sources

Contractor shall notify the Engineer of the sources of materials for the Engineer’s approval prior to
delivery of materials to the site. Where the source of material does not meet specified requirements,
the Contractor shall furnish material from other sources. Delivery of materials produced from
commercial manufacturing processes shall be accompanied by the manufacturer's certification and
test report showing the materials comply with the specification requirements.

c. Storage and Handling of Materials

Handling  and  stockpiling  of  aggregates  shall  at  all  times  be  such  as  to  eliminate  segregation  or
contamination  of  the  various  sizes.    Stockpiles  shall  be  kept  flat  and  the  formation  of  high  cone-
shaped piles will not be permitted.  When conveyor belts are used for stockpiling aggregates, the
Engineer  may  require the  use  of  baffle-chutes  or  perforated  chimneys.  When trucks  are  used  to
construct stockpiles, the stockpiles shall be constructed one layer at a time with trucks depositing
their loads as close to the previous load as possible.  The use of tractors or loaders to push material
deposited  at  one  location  to  another  location  in  the  stockpile  will  not  be  allowed  during  the
construction of the stockpile and their use shall be limited to levelling the deposited material only.

3.2.1.3 Construction Requirements

Pavement subbase material shall be delivered to the roadbed as a uniform mixture and shall be
spread in layers or windrows. Segregation shall be avoided and the subbase shall be free from
pockets of coarse or fine materials.

Each pavement subbase layer shall be spread by finisher and/or grader or other approved
mechanical methods, watered, shaped to a compacted thickness not exceeding 150 mm and
compacted to the required grade and cross section.

Compaction procedure and plant shall be to the satisfaction of the Engineer. At the time of
compaction, the moisture content of the laid material shall not vary by more than + 2 % from the
optimum moisture content.

Granular subbase shall be compacted to an average of 100% with no single value less than minimum
value of 98%

for Type II, and an average of 98% with no single value less than minimum value

of 96% for Type I.

Surface on completion of compaction shall be well closed, free from movement

under compaction plant and free from ridges cracks or loose material.  Finished surfaces of the road
subbase  shall  not  vary  at  any  point  more  than  10  mm  above  or  below  the  grade  shown  on  the
Contract plans or established by the Engineer.  Pavement subbase shall be maintained in a condition
satisfactory to receive any subsequent base or surfacing material.  Subbase which does not conform
to the above requirements shall be reshaped or reworked, watered and thoroughly recompacted to
conform to the specified requirements.

3.2.2 Aggregate Base Course

3.2.2.1 Description

Aggregate base course shall consist of crushed mineral aggregates natural mineral aggregates, or
a combination of crushed and natural mineral aggregates of the gradation and thickness specified
in these specifications and shown on the Contract plans. Contractor shall furnish, place and compact
aggregate base course for approach slabs for paved roadways, service roads and parking areas
complying with the lines, grades, thicknesses and typical sections shown on the Contract plans, as
specified herein or as directed by the Engineer.

3.2.2.2 Materials

Natural aggregate base course shall consist of coarse and fine mineral aggregates which have been
screened and blended to the various gradations specified herein and constructed to the thickness
as indicated on the Contract plans.

Crushed aggregate base course shall consist of crushed coarse aggregate and crushed or natural
fine aggregate screened and blended in accordance with the gradation specified herein and
constructed to the thicknesses as indicated on the Contract plans.

Materials for base courses shall comply with the requirements as specified herein and shall be as
approved by the Engineer. Contractor shall submit samples of all materials to the Engineer for
approval prior to furnishing and placing any materials.

One sample every 1000 m

, or part of as directed by the Engineer shall be tested for grading,

plasticity index, maximum dry density, CBR and loss by abrasion. Three in-situ density test shall be
made every unit of aggregate base course laid (one unit being 300 m

) or as directed by the

Engineer.

Material samples shall meet the minimum requirements per testing standards shown in Table 3-5.

Materials that do not comply with the requirements of these specifications will be rejected and
removed immediately from the site unless otherwise instructed by the Engineer. No rejected
materials, the defects of which have been corrected, shall be used until approval has been given by
the Engineer.

Table 3-5: Aggregate base course test requirements

Test

Standard

Limits

Sampling

AASHTO - T2

Min. One sample
every 1,000 m

Classification

AASHTO - M 145

A-1-a

Los Angeles Abrasion

AASHTO - T96

30 Max.

Test

Standard

Limits

Soundness (Sodium)

AASHTO - T104

12% Max.

Soundness (Magnesium)

AASHTO - T104

15% Max.

Sand Equivalent

AASHTO - T176

40% Mini.

Liquid Limit

AASHTO - T89

35% Max.

Plasticity Index

AASHTO - T90

6.0% Max.

Sulphate Content (Acid
soluble)

BS EN 1744-1

0.50% Max.

Chloride Content (Acid
soluble)

AASHTO T260

1.0% Max.

Flakiness Index

BS EN 933-3

35% Max.

Elongation

ASTM D4791

35% Max.

Specific Gravity

AASHTO-T100

& T85

2.20 Min.

Max Dry Density

AASHTO - T180D

2.10 gr/cc Min.

C.B.R. at 98% of M.D.D.

AASHTO - T193

% min.

Fine Aggregates

Fine aggregate (passing the 4.75 mm sieve) shall consist of natural sand and/or crushed sand and
shall be of such gradation that when combined with other required aggregate fractions in proper
proportions, the resultant mixture will meet the gradation specified in Sub-article c of Article 3.2.2.2.

Fine aggregate shall be clean and free from organic matter, clay and other extraneous or detrimental
materials.

Portion of fine aggregates passing the 75 µm sieve shall not exceed 2/3 of the portion passing the
425 µm sieve.

Material passing the 425 µm sieve shall have a maximum liquid limit of 35 and the plasticity index
shall not exceed 6.

When the source of fine aggregates does not meet the above requirements, the  Contractor may,
with the Engineer's approval, add additional fine aggregate and/or filler to correct the gradation or to
change the characteristics of the material passing the 425 µm sieve so as to meet the specifications.
Such  additional  material  shall  be  added  in  a  manner  which  ensures  a  completely  homogeneous
gradation as approved by the Engineer.

Coarse Aggregate

Coarse aggregate (retained on the 4.75 mm sieve) shall consist of crushed stone, crushed gravel or
natural gravel and shall be of such gradation that when combined with other required aggregate
fractions in proper proportion, the resultant mixture will meet the gradation specified in Sub-article c
of Article 3.2.2.2.

When crushed aggregate is required, not less than 50 % by weight of the particles retained on the
4.75 mm sieve shall have at least one fractured face. Flakiness Index of the crushed aggregate shall
not exceed 35 %.

Percentage of wear of coarse aggregate shall not exceed 30% maximum when tested for resistance
to abrasion (AASHTO T-96).

Course aggregate shall be hard and durable and free from organic matter, clay and other extraneous
or detrimental materials.

Coarse aggregate shall have a maximum sodium sulphate soundness loss of 12 % and magnesium
sulphate soundness loss of 15 %.

Aggregate Gradation

Combined gradation including fine and coarse aggregates shall conform to the gradation of Type (A)
or (B) or (C) in Table 3-6.

Table 3-6: Aggregate base course gradation

Percent passing by weight

Sieve size

Gradation A

Gradation B

Gradation C

50.8 mm

100

41.75 mm

100

75-100

25.4 mm

100

70-100

55-85

19.05 mm

70-100

60-90

50-80

9.53 mm

50-80

45-75

40-70

4.75 mm

35-65

30-60

2.00 mm

25-50

20-50

425 µm

15-30

10-30

75 µm

5-15

Note:

The final gradation of aggregate subcase and base course shall be subject to the following
tolerances during construction:

Passing 25mm sieve and larger ± 6%
Passing sieves 4.75mm (No. 4) to 19mm (No. 3/4”) ± 5%
Passing sieves 425μm (No. 40) to 2mm (No. 10) ± 4%
Passing 75μm (No. 200) ± 2%

The gradation of materials to be used in the aggregate base courses as shown in Table 3-6 indicates
the limits within which the material could be accepted. The continuous smooth gradation of materials
used shall be kept within the specified gradation limits and gap grading shall be avoided. Selection
of one of the gradations shown in the table shall be as shown on the Contract plans and approved
by the Engineer. Unless otherwise specified, Gradation B shall be used.

Material Sources

Contractor shall notify the Engineer of the sou

rces of materials for the Engineer’s approval prior to

delivery of materials to the site. Where the source of material does not meet specified requirements,
the Contractor shall furnish material from other sources. Delivery of materials produced from
commercial manufacturing processes shall be accompanied by the manufacturer's certification and
test report showing the materials comply with the specification requirements.

Storage and Handling of Materials

Handling  and  stockpiling  of  aggregates  shall  at  all  times  be  such  as  to  eliminate  segregation  or
contamination  of  the  various  sizes.    Stockpiles  shall  be  kept  flat  and  the  formation  of  high  cone-
shaped piles will not be permitted.  When conveyor belts are used for stockpiling aggregates, the
Engineer may  require the  use  of  baffle-chutes  or  perforated  chimneys.  When trucks  are  used  to
construct stockpiles, the stockpiles shall be constructed one layer at a time with trucks depositing
their loads as close to the previous load as possible.  The use of tractors or loaders to push material

3.2.2.3 Construction Requirements

Equipment

1. Spreaders: Spreaders / pavers shall be self-propelled and shall be capable of spreading the

base materials in one operation so as to make it ready for compaction with minimum shaping.
Spreader shall be provided with a screed that strikes off and distributes the material to the
required width and level. Width of each spread shall not be less than a traffic lane wide.
Screed shall be adjustable to the required cross-section. Screed action includes any practical
motion that produces a finished surface texture of uniform appearance.

2. Travel mixers: Travel mixers shall be of a type which is capable of mixing to the full depth of

the layer thickness being processed, by picking up the material, mixing, agitating or otherwise
blending into a homogeneous mass which complies with the required general gradation and
other specifications.  Mixers shall be equipped with an accurate depth control device to avoid
the disturbance of previously accepted layers. After mixing, the material shall be deposited
by  the  mixer  in  its  final  position  so  that  prior  to  compaction  no  spotting,  picking-up  or
otherwise shifting the material will be required.  Mixers may be equipped with pressure spray
bars which can supply a uniform distribution of metered water during the mixing process.

3. Central mixers: A central mixing plant shall be either of an approved drum or pugmill type

with a moisture control system so that the material may be spread without further mixing or
processing.

Surface Preparation

Prior to commencing the construction of the base courses, the Contractor shall make sure that the
subbase complies with the specifications and that the surface thereof complies with the levels and
slopes shown in the longitudinal and cross-section Contract plans. In all cases the approval of the
Engineer must be obtained before commencing spreading of material for the base courses.

Screening and Mixture of the Materials

Screening shall be required for the materials used in aggregate base courses.  Screens shall be of
the  size  and  number  required  to  remove  oversize  aggregate  and,  if  necessary,  to  separate  the
materials into two or more fractions so that they may be combined to meet the required gradation.
When  conveyor  belt  samples  from  the  end  of  the  screening  and/or  crushing-screening  operation
yield a product consistently within the specified gradation, no further mixing shall be required and
the  material  may  be  loaded  and  hauled  directly  to  the  stockpile.    In  the  event  the  material  is
stockpiled, it shall be stockpiled so as to prevent segregation.

Mixing of material shall be achieved through the use of the central mixing plant or travel mixer
specified in sub-article a) of Article 3.2.2.3.

Where separate size materials are to be blended to meet the gradation, such blending shall be as
directed by the Engineer and shall be accomplished prior to delivery to the roadway. Mixing of
separate materials on the roadway by motor grader will not be permitted by the Engineer.

Compaction Trials

Prior to the commencement of aggregate base course operations, the Contractor shall

construct trial length, not less than 30m. Material used in the trials shall be that approved for use

as aggregate base course and the equipment used shall be that accepted as the

Contractor’s approved detailed list of resources.
Aim of this trial is to determine the adequacy of the Contractor’s equipment, the loose

thickness measurements necessary to result in the specified compacted layer thickness, the

resulting density of the material.
Contractor may proceed with aggregate base course work only after the method and

procedures established in the compaction trial have been approved by the Engineer
Method statement shall indicate the width of the pavers, number of pavers, compacting plant and

equipment, number of passes by rollers .

Spreading and Compaction

After carrying out the screening and mixing of aggregate material, samples of the approved material
shall be taken in order to determine the optimum moisture content.

Material shall then be spread on the prepared surface by mechanical paver / spreader in layers not
more than 150 mm compacted thickness to achieve the total thickness as shown on the Contract
plans. After spreading and before compaction the gradation shall be checked by the engineer for its
compliance with specifications.

Care shall be taken in spreading and compacting the aggregate base not to damage the geotextile
fabric, if provided. It is required to use 50 mm thick crushed sand on top of the geotextile to protect
the geotextile during spreading the subsequent aggregate layer.

Existing moisture content of materials constituting the base courses shall be determined. If the
existing moisture content is less than the optimum moisture content, the necessary amount of water
must be added to obtain the optimum moisture content allowing for the quantity which may be lost
by evaporation in the process of raking, levelling and compacting. Layer shall be compacted when
the moisture content therein is within ± 2 % of the optimum moisture content and uniform in all parts
of the section and depths within the layer thickness.

Compaction shall start immediately thereafter, by means of pneumatic and steel rollers or vibratory
rollers and in accordance with the Engineer

’s approval or instructions.

Compaction shall start with rollers from extreme sides proceeding gradually toward the road axis.
Rolling shall continue until a relative density of not less than 100% of the maximum dry density has
been obtained as determined by the moisture-density relationship test, AASHTO T-180. CBR of the
base material shall not be less than 70% @ 98% MDD.

Multi-layers

During the operations of mixing, spreading, compacting and levelling of base course material, care
shall be taken so that layers already compacted under the layer being executed are not affected, or
that the finished subgrade or subbase surface is also not affected. This requirement shall be given
special attention in places where equipment makes turns in going back and forth and any such
damage resulting in mixing the various layers constituting the different subgrade, subbase and base
courses shall be carefully made good by the Contractor at his expense and to the satisfaction of the
Engineer.

If more than one base course is required for reaching the required thickness described in the
specifications, each such course shall be constructed as specified herein.

Where the finished total compacted thickness exceeds 150 mm, each layer shall be executed in
composite layers not exceeding 150 mm in thickness after compaction unless otherwise approved
by the Engineer.

Protection of Surface

Contractor shall protect the base course so that it shall be maintained sound during work progress,
after its completion and prior to receiving the bituminous layers or prior to laying the surface overlay
thereon. Any damage caused to the layer if exposed to traffic or natural conditions resulting in
damage to its surface should be made good to the satisfaction of the Engineer.

Base courses shall not be rolled when the underlying material is soft or yielding or when the rolling
causes a wave-like motion in this course.

When the rolling develops irregularities, the irregular surface shall be loosened, then refilled with the
same kind of material as used in constructing the course and again rolled according to specifications.
Along places inaccessible to rollers, the base course material shall be tamped thoroughly with
mechanical tampers.

Work on the base course will not be permitted during rainy weather.

Hauling equipment may be routed over completed portions of the base courses provided no damage
results and provided that such equipment is routed over the full width of the course to avoid rutting
or uneven compaction.

Engineer has the right to stop all hauling over completed or partially completed base courses when
in his opinion such hauling is causing damage.

Acceptance of Aggregate Base Courses

Prior to the application of any prime coat or any other paving course, the aggregate base course
shall have been tested and accepted by the Engineer. The following shall be adhered to in accepting
completed aggregate base courses:

1. Requirements for compaction: the degree of compaction testing values should have an

average of 100% with no single value less than minimum value of 98%. Wherever the degree
of compaction is found to be less than the 98% specified, the area of base course involved
shall be satisfactorily corrected so that the minimum specified density is achieved.

2. Requirements for gradation: Wherever the gradation is found to be outside the limits

specified, the area of base course involved shall be scarified, removed or otherwise reworked
as directed by the Engineer to provide a material within the specified limits.

3. Thickness requirements: The total constructed thickness of aggregate base course used for

new construction, reconstruction or widening of roadways shall not vary more than 8 mm
from the total thickness indicated on the Contract plans.

In the event the constructed thickness of the aggregate base course is 8 mm more than the
total thickness indicated on the Contract plans, the area involved shall be corrected as
directed by the Engineer by removing excess material in an approved manner to provide the
required thickness.

In the event the constructed thickness of the aggregate base course is 8 mm less than the
total thickness indicated on the Contract plans, the Contractor shall provide additional
material in the next course (base course or wearing course). In no case shall the deficiency
of the base course exceed 12mm.

Aggregate base course shall be constructed to the grade level as indicated on the Contract
plans, as specified and as approved by the Engineer.

In no case shall the total sum thickness of the aggregate subbase course, aggregate base
course and asphalt pavements be less than the total sum thickness of all courses as indicated
on the Contract plans.

4. Requirements for evenness of surface and grade level: Final surfaces of the base course

shall be tested by means of a 5 m long straight edge; and no rises or depressions in excess
of 10 mm shall appear on the surface; otherwise such areas shall be stripped, corrected and
re-compacted to comply with all specification requirements and as approved by the Engineer.
Further, the finished surface of the base course shall be constructed to within 12 mm of the
grade levels indicated on the Contract plans.

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 22