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

c. Plant Mixed

a. Mixing

Thoroughly mix materials in the proportions designated on the mix design, in a plant that
meets the requirements “Mixing Plant.” Mix at optimum moisture content, unless otherwise
directed, until a homogeneous mixture is obtained.

b. Placing

Place  lime-treated  base  on  a  subgrade  or  subbase  prepared  in  accordance  with  details
shown on the plans. Bring the prepared roadway to the moisture content directed. Haul lime-
treated base to the roadway in clean trucks and begin placement immediately. Spread and
shape  in  a  uniform  layer  with  an  approved  spreader.  Construct  individual  layers  to  the
thickness shown on the plans, the same day as delivered, unless otherwise approved. Do
not place lifts exceeding a compacted depth of 20 cm.  Correct or replace segregated areas
as directed.

d. Compaction

Compact the mixture using density control, unless otherwise shown on the plans. Multiple lifts are
permitted when shown on the plans or approved. Bring each layer to the moisture content directed.
Determine the moisture content of the mixture at the beginning and during compaction.

Begin rolling longitudinally at the sides and proceed toward the center, overlapping on successive
trips by at least one-half the width of the roller unit. Operate rollers at a speed between 3 and 10
KMPH, as directed.

Rework, recompact, and refinish material that fails to meet or that loses required moisture, density,
stability, or finish before the next course is placed or the project is accepted.

e. Reworking a Section

When a section is reworked within 72 hours after completion of compaction, rework the section to
provide  the  required  density.  When  a  section  is  reworked  more  than  72  hr.  after  completion  of
compaction,  add  additional  lime  at  25%  of  the  percentage  determined  “Mix  Design.”  Reworking
includes  loosening,  adding  material  or  removing  unacceptable  material  if  necessary,  mixing  as
directed, compacting, and finishing. When density control is specified, determine a new maximum
density of the reworked material and compact.

f. Construction joints

Construct vertical joints between segmented areas of lime-treated base. The vertical face may be
created by using a header or by cutting back the face to approximately vertical. Place successive
base courses using the same methods as the first course. Offset construction joints by at least 15
cm.

g. Curing

Cure for 5 days with wet hessian cloth and watered so as to keep moist at all time or by applying an
asphalt emulsion at a rate of 0.2 to 0.50 kg/m2 as directed. Maintain moisture during curing.

No equipment or traffic will be permitted on the completed cement stabilized subbase/base during
the first 7 days unless otherwise permitted by the Engineer

At final compaction the finished surface of the lime stabilized base/subbase shall be uniform and
shall not deviate at any point more than 6 mm from the bottom of 3 m straightedge laid in any
direction.

Top of the layer shall not vary from the required elevation by more than 6 mm. All bumps and
depressions exceeding the specified tolerance shall be corrected by removing the defective work
and replacing it with new material as directed by the Engineer, all at the expense of the Contractor.

i. Thickness Requirement

Thickness  of  the  completed  lime treated  subbase/base  shall  not  vary more than  10 mm from  the
thickness shown on the Contract plans.  Sufficient measurements of thickness shall be taken before
and  after  compacting  to  establish  the  relationship  between  the  thickness  of  the  un-compacted
material and the completed work.  Thickness shall be controlled first by measurements taken of the
un-compacted  material.    When  the  measurements  indicate  that  an  area  will  not  be  within  the
allowable  tolerance  for  the  completed  work,  the  un-compacted  area  shall  be  corrected  while  the
material is still in workable condition.

Immediately after final compaction the thickness shall be measured at one or more points in each
300 m of the laid lane width of stabilized subbase/base layer.  Measurement shall be made by means
of test holes or other approved methods.  Points for measurement shall be selected by the Engineer
at random locations within each 300 m sections of the laid lane width in such a manner as to avoid
any regular pattern.  Various points on the cross section shall be covered.

Whenever a measurement indicates a variation from the thickness shown on the Contract plans of
more than the allowable tolerance, additional measurements shall be taken at intervals of
approximately 50 m until the measurements indicate the thickness is within the allowable tolerance.
Any area not within the allowable tolerance shall be corrected by removing the defective work and
replacing it with new material as directed by the Engineer all at the expense of the Contractor. Cutting
of test holes and refilling with materials properly compacted shall be done by the Contractor as
observed and approved by the Engineer.

j. Compaction Control and Testing

Compaction of the cement stabilized subbase/base shall be controlled as the work progresses by
means of field density tests.

Field density tests shall be carried out immediately after compaction and before hardening of the
material in accordance with AASHTO T 191(1) or AASHTO T 205(2) or as directed by the Engineer.
Frequency of testing shall be 1 test every 100 lin. m of laid lane width. Field density of the compacted
cement stabilized subbase/base shall not be less than 98% of the reference design maximum dry
density.

k. Weather Limitation

Lime stabilized subbase/base shall not be mixed or placed when the atmospheric temperature is
over 30° C or when the weather is rainy.

Temperature requirements may be waived but only when so directed by the Engineer. When
temperature is higher than 30° C, particular care shall be exercised in order to minimize water
evaporation from the mixture.

In this case a test section shall be executed at the high temperature foreseen during the working
period in order to evaluate the water content necessary to compensate evaporation and to establish
actual setting time.

According to such test section the Engineer may order pre-moistening of aggregates before cement
mixing and watering of the granular subbase finished surface level.

Engineer will give approval of the test section not before 7 days from the completion of curing.

3.2.7 Recycled Crushed Aggregate Base Course

3.2.7.1 Description

This specification has been prepared to meet the requirements of the order issued by the Executive
Council of the Emirate of Abu Dhabi, dated 26th of July 2010, under number BT9G25/2010 requiring
the mandatory use (subject to availability) of a minimum of 40% aggregate (by volume) of recycled
construction and demolition waste in roads projects, as well as any other infrastructure projects
throughout the Emirate of Abu Dhabi.

The works described below shall consist of furnishing and placing one (1) or more layers of recycled
crushed aggregate (RCA), including additives if required on a prepared surface in accordance with
the specifications and in conformity with the lines, grades, thicknesses and typical cross-sections
shown on the plans or established by the Engineer.

3.2.7.2 Materials

Materials shall conform to the requirements for the class of “Recycled Crushed Aggregate Base
Course” specified on the plans or directed by the Engineer. All RCA for base course shall consist of
crushed rock, crushed concrete stone fragments including sand.

a. Components

Crushed concrete aggregates shall consist of clean, hard, durable, angular fragments of rock,
concrete and sand fragments of uniform quality complying with the general requirements specified
in Section 3.2.2 and its use limited as stated in Section 4.3.10 of Chapter 4, Concrete Works, of
these Standard Specifications.

The use of crusher fines passing the 4.75 sieve which are not produced from crushing concrete shall
be subject to approval in writing by the Superintendent to the proposed source and nature of these
materials and the proposed amounts to be added.

b. Physical requirements

All base course RCA shall conform to the physical requirements described, for each Class of
Aggregate.

Foreign material in the fraction retained on the 4.75 sieve shall not exceed the percentages by mass
specified:

Table 3-14: RCA Base Physical requirements

Foreign Material Type

High density materials such as glass, brick and asphalt

Metallic items such as steel, aluminum and iron

Low density materials such as plastic, rubber, plaster, clay lumps and other
liable material

Wood and other vegetable or decomposable matter

0.2

c. Grading requirements

Course materials for aggregate base course shall conform to the following requirements:

Table 3-15: RCA Base testing requirements

Properties

Value

50mm

100

37.5mm

95-100

Value

19mm

70-92

9.5mm

50-70

4.75mm

35-55

0.60mm

12-25

0.075mm

0-8

Loss by Abrasion Test (AASHTO T 96)

40% maximum

Liquid Limit (AASHTO T89)

25 maximum

Plasticity Index (AASHTO T 90)

4 maximum

Sand Equivalent (AASHTO T 176)

35 minimum

CBR on remolded sample (BS 1377 Test 16) after 4 days soaking

120% minimum

Soundness (Magnesium)

– AASHTO T104

15% maximum

Flakiness

– BS 812

35% maximum

Elongation

– BS 812

35% maximum

Sulfate Content

– BS 812

2% maximum

Chloride Content

– BS 812

2% maximum

3.2.7.3 Acceptance

When  the  stationary  plant  method  is  used,  the  aggregate  will  be  accepted  immediately  following
mixing, based on periodic samples taken from the pug mill output. When a road mix method is used,
the aggregate will be accepted after necessary blending and before laying, based on samples taken
from  the  combined  windrow  for  each  layer.  When  the  aggregate  is  a  total  aggregate,  it  may  be
accepted at the crusher. Acceptance of the material by the Engineer does not constitute acceptance
of the base course, only that the material is approved for use in the base course.

3.2.7.4 Equipment

Equipment shall be according to the type and number outlined in the Contractor’s detailed
Programme of work as approved by the Engineer.

3.2.7.5 Construction requirement

a. Groundwater levels and protection

The contractor must establish the high water table levels (HWT) along the length of the road, relative
to the accepted National benchmark (New Abu Dhabi Datum

– NADD) should the base of the

proposed road be within 1 meter of the HWT, an impermeable barrier will be required to be installed
to prevent groundwater coming in contact with the RCA.

b. Sub-grade preparation

Unless other sub-grade preparation is called for on the plans or appears as a pay item in the bill of
quantities, the contractor shall, as part of the work and prior to the delivery of materials for the base
course, prepare the roadbed surface by sprinkling blading, rolling and lightly scarifying where
necessary, until the proper crown is obtained. However, in the process of shaping the roadbed, the
originally compacting crust or top portion of the roadbed shall be disturbed as little as possible. When
completed and ready for base course construction the roadbed shall be well compacted, smooth,
hard and uniform, all irregularities having been bladed out and rolled down.

1. Handling of RCA

Handling of RCA, including the loading of trucks and stockpiling, shall be effected in such a
manner as to minimize segregation.

2. Combining aggregates and water

Aggregates for base course shall be combined into a uniform mixture and water added only
in a central mixing plant before final placement of the material. Mixing and watering by
windows will not be permitted. When binder is to be added, it shall be combined with the
aggregate base by thoroughly mixing binder and aggregate base in the central mixing plant.

The moisture added to the aggregates shall be that required, as designated by the Engineer
to  obtain  the  specified  density  thereby  preparing  an  aggregate  completely  ready  for
compaction  after  spreading  on  the  roadbed.  In  no  case  will  be  wetting  of  aggregates  in
stockpiles or trucks be permitted.

3. Spreading and combining aggregates

Unless otherwise specified, aggregate for base course shall be delivered to the roadbed as
an  uniform  mixture  and  shall  be  placed  on  the  existing  roadway,  prepared  sub-base  or
prepared sub-grade, as the case maybe in an uniform later or layers not exceeding fifteen
(15) centimeters in compacted depth, including any binder that is to be blended on the road.
Spreading  shall  be  done  by  means  of  approved  self-propelled  stone  box  spreaders,
distributing the material to the required width and loose thickness. When the required base
thickness is greater than fifteen (15) centimeters, the materials shall be spread in layers of
equal thickness.

The material shall be so handled as to avoid segregation, if an aggregate spreader causes
segregation in the material, or leaves ridges or other objectionable marks on the surface
which cannot be eliminated easily or prevented by adjustment of the spreader operation, the
use of such spreader shall be removed and replaced with well-graded

material. No “skin”

patching shall be permitted.

No hauling or placement of material will be permitted when, in the judgment of the Engineer,
the weather or road conditions are such as hauling operations will cause cutting or rutting of
the road surface or cause contamination of the base course material.

4. Compaction

If directed by the Engineer, prior to starting the aggregate base operation, the contractor shall
construct the trial lengths in accordance with Section 3.2.1 and Sub-article e of Article 3.2.8.8.

RCA shall be laid and compacted in a manner which will not result in segregation of the
material and at a moisture content which allows the compaction stated.

Immediately after placing, the base course material shall be compacted. The material shall
be compacted to an average density of 100% of M.D.D. as determined according to AASHTO
T 180 Method D with no single value below ninety-eight (98%) percent. The field
determination of density shall be made in accordance with AASHTO T 191. The percent of
density shall be adjusted to compensate for the weight and volume of aggregate larger than
the aggregate used in the compaction control test where acceptable.

Rolling shall be continued until the entire thickness of each layer is thoroughly and uniformly
compacted to the density specified. The final rolling of the compacted base course shall be
done  with  a  self-propelled  roller.  Rolling  shall  be  accompanied  by  sufficient  blading  in  a
manner  approved  by  the  Engineer,  to  insure  smooth  surface  free  from  ruts  or  ridges  and
having the proper section and crown. When additional water is required, it shall be added in
the  amount  and  manner  approved  by  the  Engineer.  Each  layer  of  base  course  must  be

The surface of the finished base course will be tested with a three (3) metre straight-edge by
the Engineer at selected locations. The variation of the surface from the testing edge of the
straight-edge between any two (2) contacts with the surface shall at no point exceed six (6)
millimetres  when  measured  in  any  direction.  The  base  course  shall  be  compacted  to  the
thickness and cross-section as shown on the plans and shall not vary by more than five (5)
millimetres  from  the  required  elevation.  All  humps  and  depressions  and  thickness
deficiencies exceeding the specified tolerances shall be corrected by removing the defective
work or by adding new material as directed by the Engineer.

If  the  material  for  the  base  course  is  laid  and  compacted  in  more  than  one  (1)  layer,  the
contractor shall plan and coordinate the work in such a manner that the previously placed
and  compacted  layers  be  allowed  ample  time  for  drying  and  development  of  sufficient
stability,  before  vehicles  hauling  materials  for  the  succeeding  layers  or  other  heavy
equipment are permitted on the base. Prior to placing the succeeding layers of material, the
top of the under layer shall be made sufficiently moist to insure bond between the layers. The
edges and edge slopes of the base course shall be bladed or otherwise dressed to conform
to the lines and dimensions shown on the plans and present straight, neat and workmanlike
lines and slopes as free of loose material as practicable.

The contractor shall also plan the work and handle the various operations so that the least
amount  of  water  will  be  lost  by  evaporation  from  uncompleted  surfaces.  If  the  contractor
delays placing of succeeding layers of base course material to the extent that additional water
must be applied to prevent raveling or excessive dripping, the application of such water shall
be at the contractor’s expense not to be considered as the basis for a claim for additional
compensation. Water shall be applied at such times and in such quantities as directed by the
Engineer  and  the  Engineer  shall  have  full  authority  to  require  the  suspension  of  all  other
works on the project to ensure the proper maintenance of previously compacted material. If
after the base is compacted, any areas are above or below proper grade and true elevations
such  areas  shall  be  loosened  and  after  having  had  additional  materials  added  or  excess
material  removed  as  the  case  may  require,  shall  be  reconstructed  as  described  herein.  If
after  the  base  is  compacted  any  areas  fail  to  meet  the  specified  density  and  gradation
requirements,  they  shall  be  loosened  ore  removed  as  directed  by  the  Engineer  and
reconstructed as described herein.

5. Maintenance of base course

Following the construction of the aggregate base, the compacted base course shall be
maintained by the contractor at his expense. The contractor shall blade, broom and otherwise
maintain the base, keeping it free raveling and other defects until such time as the bituminous
prime or other surface is applied. Water shall be applied at such time and in such quantities
as directed by the Engineer.

The Engineer shall determine when the surface of the base course is in the proper condition
to permit the bituminous prime and/or surfacing to be applied. If the contractor chooses not
to apply the bituminous prime and/or surfacing at the time, he must continue to maintain the
surface of the base curse, including the application of the necessary water at his expense
until such time as the bituminous prime and/or surfacing is applied. Any additional expense
incurred by the contractor because of his failure to apply the bituminous prime and/or
surfacing when so permitted by the Engineer will not be considered as the basis for a claim
for additional compensation.

3.2.7.6 Minimum test requirements

The Contractor shall test the crushed concrete and any approved components at a frequency which
is sufficient to ensure that the material supplied under the contract complies with the specified

a. Minimum frequency of testing

Table 3-16: RCA Base Minimum Testing requirements

Test

Minimum Frequency of Testing

Grading

On each day

– one per 300 tonnes if part thereof

Foreign Material Content

On each day

– one per 300 tonnes if part thereof

Moisture Content

On each day

– 3 No.

One per 200 tonnes or part thereof on each day

Plasticity Index

In each month

– one per 5000 tonnes or part thereof

California Bearing Ratio

Prior to the commencement of work and when in the opinion of the
Engineer the nature of the material has changed significantly

Los Angeles Abrasion

Once per month or when in the opinion of the Engineer the nature
of the material has changed significantly.

3.2.8 Recycled crushed aggregate sub-base

3.2.8.1 Description

This Specification has been prepared to meet the requirements of the Order issued by the Executive
Council of the Emirate of Abu Dhabi, dated 28th July, 2010, under number BT9G25/2010 requiring
the mandatory use (subject to availability) of a minimum of 40% aggregate (by volume) of recycled
construction and demolition waste in roads projects, as well as any other infrastructure projects
throughout the Emirate of Abu Dhabi.

The works described below shall consist of furnishing and placing one (1) or more layers of Recycled
Crushed Aggregate (RCA), including additives if required, on a prepared surface in accordance with
the Specifications and in conformity with the lines, grades, thicknesses and typical cross sections
shown on the plans or established by the Engineer.

3.2.8.2 Materials

Materials shall conform to the requirements for the class of "Recycled Crushed Aggregate Base
Course" specified on the plans or directed by the Engineer. All RCA sub-base material shall be free
from dirt, organic matter, shale or other deleterious matter and shall be of such quality that it will bind
readily to form a firm stable sub-base.

3.2.8.3 Components

Crushed  concrete  aggregates  shall  consist  of  clean,  hard,  durable,  angular  fragments  of  rock,
concrete  and  sand  fragments  of  uniform  quality  complying  with  the  general  requirements  of  the
Section 3.2.1 and its use limited as stated in Section 4.3.10 of Chapter 4, Concrete Works, of these
Standard Specifications.

The use of crusher fines passing the 4.75 sieve which are not produced from crushing concrete.
Shall be subject to approval in writing by the Superintendent to the proposed source and nature of
these materials and the proposed amounts to be added,

3.2.8.4 Physical requirements

All base course RCA shall conform to the physical requirements described below, for each Class of
Aggregate.

Foreign material in the fraction retained on the 4.75 sieve shall not exceed the percentages by mass
specified:

Table 3-17: RCA Sub-base Physical requirements

Foreign Material Type

High density materials such as glass, brick, and asphalt

Metallic items such as steel, aluminum and iron

Low density materials such as plastic, rubber, plaster, clay lumps and other
friable materials

Wood and other vegetable or decomposable meter

0.2

3.2.8.5 Grading requirement

a. Sub-base

Sub-base shall consist of well-graded RCA with sand and silt, conforming to the following
requirements:

Table 3-18: RCA subbase requirements

Properties

Value

50mm

100

37.5 mm

95-100

65-95

9.5mm

30-65

4.75mm

25-55

2.00mm

15-40

0.425mm

8-20

0.075mm

2-8

Loss by Abrasion Test (AASHTO T 96)

40% maximum

Liquid Limit (AASHTO T89)

25 maximum

Plasticity Index (AASHTO T 90)

4 maximum

Sand Equivalent (AASHTO T 176)

25 minimum

CBR on remolded sample (BS 1377 Test 16) after 4 days soaking

120% minimum

Soundness (Magnesium)

– AASHTO T104

15% maximum

Flakiness

– BS 812

35% maximum

Elongation

– BS 812

35% maximum

Sulphate Content

– BS 812

2% maximum

Chloride Content

– BS 812

2% maximum

When  the  stationary  plant  method  is  used,  the  aggregate  will  be  accepted  immediately  following
mixing based on periodic samples taken from the pug mill output. When a road mix method is used,
the aggregate will be accepted after necessary blending and before laying, based on samples taken
from the combined  windrow  for  each  layer.  Acceptance  of  the  material  by  the  Engineer  does  not
constitute acceptance of the sub-base, only that the material is approved for use in the sub-base.

3.2.8.7 Equipment

Equipment shall be according to the type and number outlined in the Contractor's detailed
Programme of Work, as approved by the Engineer.

3.2.8.8 Construction requirements

a. Groundwater levels and protection

The Contractor must establish the high water table levels (HWT) along the length of the road, relative
to the accepted National benchmark (New Abu Dhabi Datum (NADD)). Should the base of the
proposed road be within 1 meter of the HWT, an impermeable barrier will be required to be installed
to prevent groundwater coming in contact with the RCA subbase.

b. Preparation of sub-grade

Unless other sub-grade preparation is called for on the plans or sub-grade preparation appears as
a separate item for compensation in the Bill of Quantities, the Contractor shall, as part of the Work
of sub-base, prepare the sub-grade. The formation of the sub-grade will vary by either placing the
"Granular  RCA  Sub-base"  on  the  roadway  surface  as  previously  constructed  or  by  excavating
sufficient  material  from  the  roadway  and  placing  the "Granular  RCA  Sub-base"  on  the  sub-grade
obtained thereby. In  either  case,  the  sub-grade, shall  as  hereinafter  described,  be  brought to the
lines, grades and typical section shown on the plans for the bottom of the "Granular RCA Sub-base".
All soft and yielding material or other portions of the sub-grade, which will not compact readily, when
rolled or tamped, shall be removed, and all loose rock or boulders found In the excavation shall be
removed or broken off to a depth of not less than fifteen (15) centimeters below the surface of the
sub-grade. All holes or depressions made by the removal of material, as described above, shall be
filled with approved material and the whole sub-grade brought to line and grade and compacted to
density designated on the plans or directed by the Engineer.

c. Spreading

Sub-base aggregates shall be spread on sub-grade which has been approved by the Engineer. Sub-
base which has been placed on a sub-grade not approved by the Engineer shall be removed at the
Contractor's expense.

Sub-base aggregate shall be spread on the approved sub-grade in layers not exceeding fifteen (15)
centimeters in compacted depth. Spreading shall be done by means of approved mechanical box
spreaders, distributing the material to the required width and loose thickness. Where the required
sub-base thickness is greater than fifteen (15) centimeters, the material shall be placed in layers of
equal thickness, In no case shall a layer be less than seven and one half (1.5) centimeters thick.
Under no circumstances shall Class A Sub-base be dumped in a pile on the Sub-grade.

The material shall be handled so as to avoid segregation. Segregated materials shall be remixed
until uniform. Suitable precautions shall be taken to prevent rutting of the sub-grade during the
spreading of the sub-base materials. No hauling or placement of material will be permitted when, in
the judgment of the Engineer, the weather or road conditions are such that the hauling operations
will cause cutting or rutting of the sub-grade or cause contamination of the sub-base material.

d. Compaction

The moisture content of the sub-base material shall be adjusted prior to compaction, by watering
with approved sprinkler trucks or by drying out, as directed by the Engineer, to that required to obtain
the specified density for sub-base. Sub-base shall be compacted to an average value of 100% of
the M.D.D. as determined according to AASHTO T 180 Method D with no single value below ninety
eight (98%).

The  sub-base  aggregate  shall  be  compacted  by  means  of  approved  compaction  equipment
progressing gradually from the outside towards the centre with each succeeding pass uniformly over-
lapping  the  previous  pass.  Rolling  shall  continuous  until  the  entire  thickness  of  each  layer  is
thoroughly  and  uniformly  compacted  to  the  specified  density.  Rolling  shall  be  accompanied  by
sufficient blading in a manner approved by the Engineer, to insure a smooth surface free from ruts
or ridges and having the proper section and crown.

The surface of the material shall on completion of compaction be well closed, free from movement
under the compaction plant and free from compaction planes, ridges, cracks, or loose materials.

Any area inaccessible to normal compaction equipment shall be compacted by means of mechanical
tampers until satisfactory compaction is obtained.

Each layer of sub-base course must be completely compacted and approved by the Engineer, prior
to the delivery of materials for a succeeding layer of sub-base.

e. Compaction trials

If directed by the Engineer, prior to the commencement of his sub-base or aggregate base
operations, the Contractor shall construct trial lengths, not to exceed one (1) kilometre. The materials
used in the trials shall be those approved for use as sub-base or aggregate base, and the equipment
used shall be that according to the Contractor's approved detailed Programme of Works.

The object of these trials is to determine the adequacy of the Contractor's equipment, the loose depth
measurements necessary to result in the specified compacted layer depths, the field moisture
content, and the relationship between the number of compaction passes and the resulting density of
the material.

f. Finishing

The  Contractor  shall  programme  his  operations  to  avoid  the  drying  out  of  the  sub-base  during
construction. If any layer of sub-base material or part thereof, is permitted to dry out after compaction,
or  does  not  conform  to  the  required  density  or  finish,  the  Contractor.  shall  at  his  own  expense,
rework, water or recompact the material, as directed by the Engineer, to density specified before the
next layer of sub-base or base course is superimposed thereon.

Immediately prior to the placing of the first layer on the sub-base, the final layer of sub-base shall be
at the specified density and to the required grade and section. In order to maintain these
requirements while placing the next course, it may be necessary to water and reshape the surface
of the sub-base, which Work shall be at the Contractor's expense.

The surface of the finished sub-base will be tested with a three (3) meter straight-edge by the
Engineer at selected locations. The variation of the surface from the testing edge of the straight-
edge between any two (2) contacts with the surface shall at no point exceed six (6) millimeters when
measured in any direction. The sub-base shall be compacted to the thickness and cross-section as
shown on the plans and shall not vary by more than six (6) millimeters from the required elevation.
All humps and depressions and thickness deficiencies exceeding the specified tolerances shall be
corrected by removing the defective Work or by adding new material as directed by the Engineer.

3.2.8.9 Minimum test requirements

One sample every 1,000 m

shall be tested for Grading Plasticity index, Sand Equivalent Maximum

Dry Density. C.B.R., Loss by Abrasion. One Situ Density Test every 300 m

of Granular RCA Sub-

base laid.

3.3 Asphalt Concrete Paving Courses

3.3.1 Description

Work constructs an asphaltic concrete paving course on a prepared surface in accordance with these
specifications and in compliance with the lines, grades, thicknesses and typical cross-sections
shown on the Contract plans, as approved by the Engineer.

3.3.2 Materials

The materials used in asphaltic concrete mixes shall meet the requirements specified in the following
sections:

•

Superpave mix design materials: Paragraph 1 of Sub-article (a) of Article 3.3.2.5.

•

Marshall mix design materials: Paragraph 4 of Sub-article b of Article 3.3.2.5.

3.3.2.1 Storage and Handling of Materials

Materials shall be stored and handled so as to assure the preservation of their quality and fitness for
the works.  Materials, even though approved before storage or handling, may again be inspected
and tested prior to use in the work.  Stored materials shall be located so as to facilitate their prompt
inspection.  All storage sites shall be restored to their original condition at

the Contractor’s expense

prior to acceptance of the works.

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 shall 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.  Use of tractors or loaders to push  material
deposited  at  one  location  to  another  location  in  the  stockpile  shall  not  be  allowed  during  the
construction of the stockpile and their use shall be limited to leveling the deposited material only.
Stockpiles of aggregate located at permanent asphalt plant sites shall be separated by bin walls and
shall be constructed on asphaltic or concrete floors.  Stockpile locations and procedures at temporary
asphalt plant sites shall be as approved by the Engineer.

Intermediate storage of hydrated lime and commercial mineral filler for equipment feeding the asphalt
plant shall be silos of adequate size to ensure a minimum of one day's continuous operation.

3.3.2.2 Inspection, Testing and Control of Materials

For verification of weights and measures, character of materials and determination of temperatures
used  in  the  preparation  of  the  asphalt  mixes,  the  Engineer  shall  at  all  times  have  access  to  all
portions of the mixing plant, aggregate plant, storage yards, crushers and other facilities used for
producing and processing the materials of construction.  Engineer will have authority to take samples
and  perform  tests  on  any  material  supplied  to  the  site  from  any  source  whatsoever  in  order  to
establish their compliance with these specifications and to accept or reject as he deems necessary.
Samples will also be taken by the Engineer from completed work to determine compliance with these
specifications.  Frequency of all sampling and testing shall be in accordance with these specifications
or as directed by the Engineer.

3.3.2.3 Unacceptable Materials

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

3.3.2.4 Sources of Materials

Materials  used  in  the  work  shall  be  tested  and  approved  before  use.  Contractor  shall  notify  the
Engineer  of  the  sources  of  materials  and  the  material  shall  not  be  delivered  to  site  before  the
approval  by  the  Engineer.    Where  the  source  of  material  does  not  meet  the  specification
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 these specification requirements.

3.3.2.5 Hot Mix Asphalt Design Requirements

Either the Marshall Method of mix design (Asphalt Institute Manual Series MS-2) or the Superpave
Volumetric Design Method (AASHTO MP 2) shall be used in designing the asphaltic concrete mixes,
as may be required on the Contract plans, in the particular specifications and as approved by the
Engineer.

Bituminous paving course mix designs shall be performed by the Contractor and verified by the
Engineer. A certified technician shall perform the mix design.

a. Superpave Volumetric Method

Furnish mixes of aggregate, asphalt binder, and additives that meet the applicable material
requirements and the appropriate design parameters in Table 3-24 and are capable of being placed
and compacted as specified.

Compact specimens with the gyratory compactive effort specified in Table 3-24 for the specified
ESAL or N

Design

1. Superpave Materials

Superpave hot asphalt concrete pavement nominal maximum size aggregate is designated
as shown in Table 3-21 and Table 3-24. Equivalent single axle loads (ESAL) or number of
gyrations at design (N

Design

) is designated as shown in Table 3-19, Table 3-20, and Table 3-

24.

Asphalt binder is designated as shown in AASHTO M 320. Asphalt binder in asphalt mixes
for road works shall be minimum PG grade 76-22. Asphalt binder in asphalt mixes for high
stress  zones  such  as  intersections,  roundabouts,  steep  inclines,  areas  of  low  speed  with
heavy loads, etc. shall be minimum PG grade 82-22. Modifiers shall be organic, inorganic or
hybrid  types  of  polymers  specifically  designed  and  manufactured  for  use  in  a  dissolved,
dispersed or reacted state within asphalt binders or asphalt mixes. Modifiers should be able
to be dissolved, dispersed in or reacted with bitumen in a laboratory sample preparation to
assess  the  properties  and  performances  of  the  modified  binder.  The  polymer  content  in
asphalt binder or asphalt mixes shall be determined according to AASHTO T 302.

Antistrip additive type is designated as shown in Sub-article a of Article 3.3.2.5. Where no
type is designated, use type 3 (lime).

Mineral filler shall conform to AASHTO M 17.

Superpave Asphalt Concrete Pavement Aggregate

Furnish hard, durable particles or fragments of crushed stone, crushed slag, or crushed
gravel conforming to the following:

i. Los Angeles abrasion, AASHTO T 96: 35% max

ii. Magnesium sulfate soundness loss of coarse and fine aggregate (5 cycles), AASHTO T

104: 12% max

iii. Fractured faces, ASTM D5821: Table 3-19

iv. Fine aggregate angularity, AASHTO T 304, method A: Table 3-20

v. Flat and elongated particles, 3 to 1 ratio, ASTM D4791: Table 3-20

vi. Sand equivalent value, AASHTO T 176, alternate method no. 2, reference method: Table

3-20

vii. Gradation. See Table 3-21. Size, grade, and combine the aggregate fractions in mix

proportions that result in a composite blend between the control points. Nominal maximum
size is one sieve size greater than the first sieve to retain more than 10 % of the combined
aggregate. Test according to AASHTO T 27 and T 11.

For the surface course, do not use aggregates known to polish or carbonate aggregates
containing less than 25 % by mass of insoluble residue when tested according to ASTM
D3042.

Table 3-19 Fractured faces coarse aggregate requirements

Traffic

ESALs (million)

Fractured faces

(1 face % min. / 2 face % min.)

< 0.3

55/-

0.3 to < 3

75/-

3 to < 10

100/85

10 to < 30

100/90

≥ 30

100/100

Note: "100/85" denotes that 100 percent of the aggregate has one fractured surface and 85 percent
has two or more fractured faces.

Table 3-20: Superpave aggregate requirements

Traffic ESALs

(million)

Uncompacted void content

of fine aggregate (%

minimum)

Sand

equivalent

(minimum)

Flat and
elongated
(% max.) 3:1
ratio

Depth from surface



100 mm

> 100 mm

< 3

3 to < 10

10 to < 30



Table 3-21: Superpave aggregate gradation

Sieve size

Nominal maximum aggregate size

– percent passing

grading designation

25.0 mm

19.0 mm

12.5 mm

9.5 mm

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

37.5 mm

100

25.0 mm

100

19.0 mm

100

12.5 mm

100

9.5 mm

100

Sieve size

Nominal maximum aggregate size

– percent passing

grading designation

25.0 mm

19.0 mm

12.5 mm

9.5 mm

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

4.75 mm

2.36 mm

600 µm

300 µm

75 µm

*Contractor specified target values. See Table 3-22 for allowable deviations.

Table 3-22: Allowable deviations for target value gradations

Gradation Range

Allowable deviation

Minimum

Maximum

70.1

89.9

60.1

70.0

55.1

60.0

45.1

55.0

40.1

45.0

30.1

40.0

21.1

30.0

8.1

21.0

8.0

Table 3-23: Coarse and fine gradation classification

Nominal maximum aggregate size

Primary control sieve (PCS) for mixture nominal

maximum sieve size

25.0 mm

19.0 mm

12.5 mm

9.5 mm

PCS

4.75 mm

2.36 mm

PCS control point (% passing)

Table 3-24: Superpave hot asphalt concrete pavement design requirements (AASHTO MP2)

Design

Gyratory compaction level

Minimum voids-in-the-

mineral aggregate (VMA),

(d)

Voids

Filled

with

Dust-

to-

Minimum

Tensile

Strength

ESAL

(million)

(% theoretical maximum

specific gravity, Gmm)

AASHTO PP 28

Nominal maximum size

aggregate

(c)

Asphalt

(VFA),

(e) (f)

Binder

Ratio

(a)

Ratio,

AASHTO

T 283

(b)

Initial

Design

Max

25.0

19.0

12.5

9.5

< 0.3



91.5%

96%



98%

12.0

13.0

14.0

15.0

70-80

0.8-1.6

0.80

0.3 to

< 3



90.5%

96%

115



98%

65-78

3 to

< 30



89%

100

96 %

160



98%

65-75





89%

125

96%

205



98%

(a)

Include non-liquid antistrip, baghouse fines, and other mineral matter added to the mixture.

Calculate the ratio using effective asphalt content (calculated by mass of mix).

(b)

Prepare specimens in accordance with AASHTO PP 28.

(c)

The nominal maximum size is one size greater than the first sieve to retain more than 10 % of the

combined aggregate.

(d)

When mineral filler or hydrated lime is used, include in the calculation for compliance with the VMA.

(e)

For 9.5 mm nominal maximum size aggregate mixtures with



3 million ESALs, provide a VFA of

73 to 76 %.

(f)

For 25.0 mm nominal maximum size aggregate mixtures with < 0.3 million ESALs, provide a VFA



67 %.

Combined aggregate gradation is classified as coarse graded when it passes below the
primary control sieve control point in Table 3-23. All other gradations are classified as fine
graded.

Antistrip Additive

Contractor shall conform to the following:

Type 1. Furnish commercially produced, heat stable liquid products that when added to
asphalt have the chemical and physical properties to prevent separation of the asphalt
from aggregates.

ii.

Type 2. Furnish cement conforming to Section 4.3.1 or fly ash conforming to Section
4.3.2

iii.

Type 3. Furnish lime conforming to AASHTO M 303.

Recycled Asphalt Pavement Use

Do not use recycled asphalt pavement in the top lift.

Furnish  recycled  asphalt  pavement  that  is  processed  in  some  form  (by  crushing  and
screening)  to  produce  a  well  graded  gradation  and  asphalt  content.    Process  recycled
asphalt pavement so that no particle in the mixture made with recycled asphalt pavement
will exceed the mixture maximum aggregate size at the time of production.  Millings will be
considered processed provided they have a uniform gradation and asphalt content.  Provide
recycled asphalt pavement material with a maximum of 2 % deleterious materials.

Recycling agents shall conform to AASHTO R 14 or use an approved petroleum product
additive that restores aged asphalt to the required specifications

Up to and including 15 % recycled asphalt pavement material by mass may be used in the
mix without adjusting the asphalt binder grade. For mixes with over 15 % and up to and
including 25 %, recycled asphalt pavement material by mass, decrease the asphalt binder
grade one performance level for both the upper and lower grade level of the asphalt binder
specified or use an approved blending procedure with a recycling agent. Do not use more
than 25 % recycled asphalt pavement by mass.

For mixture design, use the specific gravity of the new (virgin) asphalt binder as the specific
gravity of the asphalt binder in the recycled asphalt pavement.  For calculation purposes,
use the effective specific gravity of the aggregate in the recycled asphalt pavement as the
bulk  specific  gravity.    When  the  recycled  asphalt  pavement  contains  highly  absorptive
materials,  estimate  the  amount  of  absorbed  asphalt  from  historical  records,  and  use  the
estimate to back-calculate the bulk specific gravity of the aggregate.

2. Submission

Contractor  shall  submit  written  job  mix  formulas  for  approval  at  least  30  days  before
production.  Include the location of all commercial mixing plants to be used and a separate
job-mix formula for each plant.  Include a signed statement prepared by the testing laboratory
that certifies that the proposed job-mix formula meets the requirements of the Contract and
can be compacted in the field during production to meet  Contract requirements.  For each
job-mix formula, submit the following:

i. Aggregate and mineral filler.

a) Target values:

1) Target value for percent passing each sieve size for the aggregate blend

2) Designate target values within the gradation band specified for the nominal

maximum size aggregate grading shown in Table 3-21.

b) Source and percentage of each aggregate stockpile to be used.

c) Average gradation of each aggregate stockpile

d) Representative samples from each aggregate stockpile. Use split samples of material

taken at the same time samples are taken for testing by the Contractor

’s laboratory

375 kg of aggregates proportioned by stockpile according to the stockpile’s
proportion in the mix

2) 10 kg of bag house fines if proposed for the mix

3) 10 kg of mineral filler if proposed for mix

4) Results of aggregate quality tests for Contractor selected sources. Include the sand

equivalent, fractured faces, Los Angeles abrasion, sodium sulfate soundness,
coarse durability, and fine durability results from tests performed within 1 year of
aggregate use

ii. Asphalt binder:

a) Target asphalt binder content

b) Five 4-liter samples of the asphalt binder to be used in the mix. Do not include antistrip

additives in these samples

c) Recent test results from the manufacturer for the asphalt binder including a

temperature-viscosity curve

d) Material safety data sheets

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 24