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

3.3.4 Cold Planning

Cold planning shall be performed as shown on the plans or directed by the Engineer to areas which
will receive an overlay.

3.3.4.1 Surface Preparation

Prior to cold planning begins, the Engineer will approve that the existing pavement surface is sound
and it does not exhibit any structural failure. Any structural failure based on the Engineer

’s judgment

shall be removed in accordance with Section 2.3.2 of Chapter 2, Earthworks, of these Standard
Specifications.

If the existing pavement will be overlaid, the Contractor shall profile the pavement as follows, unless
otherwise directed by the Engineer.

1. Contractor shall remove the required thickness of asphalt by means of cold planning.

Contractor is responsible for controlling dust to the approval of the Engineer.

2. Final surface elevation of the milled surface shall not vary more than 4 mm from the final

surface elevations in profile and cross-section.

3. Milled material shall be stockpiled off-site for future use by the department, if directed by the

Engineer. Otherwise, the removed asphalt shall become the property of the Contractor.

3.3.4.2 Surface Preparation for Overlays/ Rehabilitation

Contractor shall prepare the existing pavement as shown on the Contract plans for an application of
overlay. Preparation shall include, but not by way of limitation, all cleaning, scraping and performing
various types of repairs necessary to correct structural failures, deterioration, drainage and grade
elevations in compliance with lines, grades, thicknesses and typical sections shown on the Contract
plans, or as required by field conditions, and shall be carried out as required herein or as directed
by the Engineer.

a. Materials

Materials required for various repairs shall be in accordance with the requirements of applicable
sections of these specifications.

b. Construction

Before the application of an overlay, the existing pavement surface shall be swept clean of all dirt,
loose and foreign matter by the use of hand brooms or mechanical sweepers of approved type in a
manner approved by the Engineer. All sand, mud, dust and other loose material so swept off shall
then be disposed of in accordance with Section 2.3.2 of Chapter 2, Earthworks, of these Standard
Specifications.

Filling and compacting of ruts and depressions with wearing course material to the general level of
the surface shall immediately follow the operation of cleaning the surface. Contractor shall check
the level of patch work with a straight edge and make corrections as required.

When directed by the Engineer, the Contractor shall make all necessary repairs to the existing
pavement surface (potholes, failed areas, depressed areas, utility cuts, cracks, or other damaged
areas).

Immediately prior to the placement of the overlay, tack coat material shall be applied to the areas to
be resurfaced.

Care shall be exercised to prevent spraying tack coat materials upon adjacent sidewalks, structures,
plants and shrubbery, adjacent property and improvements, and any other improvements and
facilities not specifically mentioned. Any of the above mentioned facilities so damaged shall be
cleaned or replaced to the satisfaction of the Engineer at the expense of the Contractor.

Contact surfaces of kerbs, gulleys, inlets, catch basins, manholes and other structures shall be
painted with a thin uniform coating of tack coat material immediately before asphaltic material is
placed against them. Tack coat shall be carefully applied and in such a manner that the tack coat
shall not show above the surface of the finished pavement, all in accordance with Section 3.4.2.

In executing the construction of the single lift surface treatment, the Contractor shall adhere to the
steps described above. However, in left or right turning areas the following steps shall be followed,
unless otherwise directed by the Engineer.

1. Comply with the applicable requirements of maintenance of traffic and related work, of these

specifications.

2. Contractor shall remove completely the existing kerb, including haunching and blinding at the

road shoulder or median, and the resulting excavation shall be filled with borrow material
compacted to 95 % maximum dry density as specified in Section 2.5.3 of Chapter 2,
Earthworks, of these Standard Specifications.

3. Cut the existing pavement to neat lines at a distance of 250 mm from the removed kerb edge

of the pavement. Remove the existing wearing and base courses in accordance with Section
2.3.2 of Chapter 2, Earthworks, of these Standard Specifications. Exposed 250 mm of
existing subgrade shall be prepared prior to placing asphaltic concrete overlays, as specified
in Section 3.62.6 of Chapter 2, Earthworks, of these Standard Specifications

4. Subgrade area shall be compacted and prepared in compliance with lines, grades, thickness

and typical sections shown on the Contract plans and as specified in Section 2.5.3 of Chapter
2, Earthworks, of these Standard Specifications.

5. Prior to placement of permanent pavement, the Contractor shall prime coat the subgrade

area  as  shown  on  the  Contract  plans  and  as  specified  in  Section  3.4.1.  Where  existing
pavement  has  been  removed,  the  top  300  mm  of  subgrade  shall  be  compacted  to  95  %
modified proctor density as specified in  Section 3.62.6 of Chapter 2, Earthworks, of these
Standard Specifications.

6. Final surface of the subbase course shall be finished so that after final compaction and just

prior to placement of base or pavement courses, the surface elevation shall not vary more
than 10 mm from a five-meter straight-edge at any location. Surface shall be completed to
the above tolerance and approved by the Engineer prior to any work at a given location or
placing an overlying course, all in accordance with Sub-article b of Article 3.2.2.3.

7. Place tack coat as directed by the Engineer on the sand-asphalt subbase course immediately

prior to placing an asphaltic base course, or on the base course in those cases where the
base course has been utilized by traffic prior to the placement of the wearing course, all in
accordance with Section 3.4.2.

8. Construct new kerbs in accordance with Section 7.6.3 of Chapter 7, Incidental construction,

of these Standard Specifications.

9. Place and compact asphaltic concrete base, thickness of 160 mm or as shown on the

Contract plans, placed in the widened areas, in two lifts of 80 mm each, all in accordance
with the requirements for Section 3.3.3.

10. Place tack coat as directed by the Engineer immediately prior to placing any new asphaltic

material over a previously placed asphaltic course, where the previous course has become
“dirty” as the result of traffic using the surface, all in accordance with Section 3.4.2.

11. Place and compact asphaltic concrete wearing course, 60 mm minimum thickness over the

turn area in one lift unless otherwise shown on the Contract plans or directed by the Engineer,
all in accordance with the requirements for 3.3.3.

12. Place and compact asphaltic concrete wearing course, 40 mm minimum thickness, over the

turning lanes and existing pavement in one lift unless otherwise shown on the Contract plans
or directed by the Engineer, all in accordance with the requirements for Section 3.3.3.

13. Install pavement markings in accordance with Chapter 8, Traffic markings and signs, of these

Standard Specifications

3.4 Bituminous Prime and Tack Coats

3.4.1 Medium Cure Liquid Asphalt Prime Coat

3.4.1.1 Description

This work shall consist of furnishing and applying liquid asphalt prime coat to previously prepared
and approved granular sub-base/ aggregate base courses or wet mix macadam prior to placement
of hot mix overlay. Such work shall be performed as specified herein or as directed by the Engineer.

3.4.1.2 Materials

a. Liquid Asphalt

Liquid asphalt shall be of the medium curing type MC-70 grade and shall comply with AASHTO M-
82 as modified by the Table 3-37. Application rate shall be between 0.6 and 1.0 kg/m

However the

exact rate of application will be determined by the engineer following trials to be carried out by the
contractor.

Table 3-37: Medium cure liquid asphalt

Description

MC-70

Min.

Max.

Saybolt furol viscosity @ 50



C, sec.

120

Flash point (tag open cut),



Distillation:

Distillate (% of total distillate to 360



To 225



To 260



To 315



20
65

20
60
90

Residue from distillation to 360



C, percent by volume

Tests on residue from distillation:

Penetration 25



100 g, 5 sec.

Ductility, 25



C, cm

Solubility in Trichloroethylene, %

Water, %

120
100

250

0.2

The surface to be prime coated shall be uniformly smooth and firm and true to the grades and cross-
section shown on the drawings within specified tolerances, and so maintained throughout prime
coating. Prime coat shall not be placed on a soft, uneven base. When required, the surface to be
primed shall be lightly bladed and compacted and the Engineer may instruct a light application of
water to facilitate penetration. Priming will not be permitted when the surface is wet.

Prime coat shall not be applied when the ambient temperature is less than 13 deg. C or during rain,
fog, dust storms or other unsuitable weather. The application temperature for MC-70 liquid asphalt
shall be between 50deg. C and 80 deg. C as approved by the Engineer.

prime coat or as otherwise directed by the Engineer. The required period of time for penetration of
the prime coat shall be determined by site trials conducted by the contractor to allow a minimum of
10mm of penetration of prime coat into the subbase, base or wet mix macadam course with no visible
wet spots at the surface.

The Contractor shall furnish and spread at his cost sufficient clean fine sand, of an approved quality,
to blot up areas which show an excess of prime coat.

The primed surface shall be maintained in a good, clean condition at all times until the next course
is placed. Any surface irregularities or holes in the primed surface, however caused, shall be repaired
and corrected to the Engineer's satisfaction.

b. Blotter Material

Blotter material, if required, shall be clean natural sand and shall comply with the requirements of
the specifications given in Paragraph 4 of Sub-article b of Article 3.3.2.5.

3.4.1.3 Construction Requirements

a. Weather limitations

Prime coat shall not be applied when the ambient temperature is less than 13



C nor during rain,

fog, dust-storms or other unsuitable weather.

b. Application Temperature

Application temperature for the MC-70 liquid asphalt shall be between 60



C and 85



C as directed

by the Engineer.

c. Equipment Required

Equipment used by the Contractor shall include an asphalt distributor in accordance with Sub-article
d  of  Article  3.3.3.1  as  well  as  a  power  broom  and  a  power  blower.    Power  broom  shall  be  self-
propelled  and  equipped with  a  cylindrical,  rotating  nylon  bristle  brush  of not  less than  760  mm  in
diameter and not less than 1.8 m in length.  Brush shall be capable of being angled to the right and
left with adjustable ground pressure.  Where necessary for the proper preparation of the surface,
motor graders, rollers, water trucks, and other related equipment shall also be provided.

d. Surface Preparation

Immediately  before  applying  the  prime  coat,  all  loose  dirt,  earth  and  other  objectionable  material
shall be removed from the surface with a power broom of approved design and/or a power blower
as required, and any ruts, soft spots or unacceptable irregularities in the surface shall be repaired in
accordance with the instructions of the Engineer.  If the Engineer so requires, the surface shall be
lightly  bladed  and  rolled  immediately  prior  to  the  application  of  the  prime  coat,  in  which  case
brooming or blowing may not be required.  Engineer may direct that a light application of water be
made  just  prior  to  the  application  of  liquid  asphalt  to  facilitate  penetration.    Priming  will  not  be
permitted by the Engineer when there is free water present on the surface.

e. Method of Operation

After preparing the road surface as above, the liquid asphalt shall be applied by means of the
distributor at the temperature and rate directed by the Engineer. Hand-spraying of restricted,
inaccessible areas is permitted, subject to the approval of the Engineer.

Prime coat shall usually be applied to one half or one third of the road width at a time. When applied
in two or more lanes, there shall be a 150 mm overlap of asphalt material along adjoining edges of
the lanes. It should be noted that no overlapping is allowed at the transverse joints and that thick
paper shall be used at the joint to protect the previous application and the joining application shall
begin on the paper. After use, the paper shall be removed and satisfactorily disposed of by the
Contractor. Care shall be taken that the application of bituminous material at the junctions of spreads

is not in excess of the specified amount. Excess bituminous material shall be removed from the
surface.

Prime coat shall be uniformly applied with the distributor within a maximum of 48 hours preceding
placement of asphaltic concrete paving. Do not place plant mix bituminous courses until the prime
coat has set.

f. Maintenance and Traffic

Traffic shall not be permitted on the primed surface until the asphaltic material has penetrated and
dried and, in the judgment of the Engineer, will not be picked up under traffic.  If it becomes necessary
to permit traffic prior to that time, but in no case sooner than 24 hours after the application of the
asphaltic material, blotter material shall be applied as directed by the Engineer and traffic shall be
permitted to use the lanes so treated.  Blotter material shall be spread from trucks operated backward
so that the wheels will not travel in uncovered wet asphaltic material.  When applying blotter material
to an asphalt treated lane that adjoins a lane that has not been treated, a strip at least 200 mm wide
along the adjoining edge shall be left devoid of blotter material in order to permit an overlap of asphalt
material.

Contractor shall maintain the primed surface in a good clean condition and prior to the application of
the next course, any surface irregularities shall be corrected and all excessive blotter material, dirt
or other objectionable materials shall be removed.

3.4.2 Emulsified Asphalt Prime Coat

3.4.2.1 Description

This work shall consist of furnishing and applying emulsified asphalt prime coat to previously
prepared and approved granular subbase/aggregate base courses or wet mix macadam prior to
placement of hot mix asphalt layer. This work shall be performed as specified herein or as directed
by the Engineer.

3.4.2.2 Materials

Emulsified asphalt shall be of slow setting type and shall comply with the following properties as
shown in Table 3-40. Application Rate shall be between .8 l/m2 to 1.2 l/m2.However, the exact rate
of application will be determined by the Engineer following trials to be carried out by the contractor:

Table 3- 40 Emulsified Asphalt Prime Coat

Property

Specification

Test Method

Water content (%m/m)

42-46

ASTM D244

Saybolt Furol Viscosity @
50C

(sfs)

10-35

ASTM D 7496

Residue on Sieving %

<.10

ASTM D 6933

Particles >710 micron
Particles >150 micron

<.25

Particle Charge

Positive

ASTM D244

Emulsified asphalt prime coat shall be kept in a tank with proper agitation facilities to keep it homogenous

3.4.2.3 Construction Requirements

Emulsified asphalt Prime coat shall not be applied when the ambient temperature is less than
10C, or during rain, fog, dust storms or other unsuitable weather. The emulsified asphalt can be

applied cold, or it can be heated up to maximum temperature of 45C. and as approved by the
Engineer.

Traffic shall be kept off the prime coat until it has penetrated the subgrade or road base and fully
cured. It should be left undisturbed for a sufficient period of time to allow adequate penetration of
prime coat or as otherwise directed by the Engineer. The required  period of time for penetration of
the emulsified asphalt  prime coat shall be determined by site trials  conducted by the contractor,
which shall not be less than 6 hours to allow for a minimum of 8mm of penetration  into the
subbase, base ,or wet mix macadam with no visible wet spots at the surface.

The contractor shall furnish and spread at his own cost sufficient clean fine sand of an approved
quality to blot up areas which shows an excess of prime coat.

The primed surface shall be maintained in a good clean condition at all times until the asphalt
course is placed. Any surface irregularities, or holes, in the primed surface, however caused shall
be repaired and corrected to the Engineers satisfaction.

3.4.3 Tack Coat

3.4.3.1 Description

This  work  shall  consist  of  furnishing  and  applying  slow  setting  emulsified  asphalt  tack  coat  to
asphaltic  base  course,  an  existing road  surface, concrete  bridge  deck,  approach  slabs  and  other
concrete  surfaces  prior  to  placing  asphaltic  concrete  wearing  course  in  accordance  with  these
specifications and the Contract plans or as directed by the Engineer.

3.4.3.2 Material

Emulsified asphalt shall be of the slow-setting Cationic or Anionic type of the CSS-1h or SS-1h
grades respectively. Emulsified asphalt CSS 1h shall be in accordance with AASHTO M208 and SS
1h shall be in accordance with AASHTO M 140.

Approved emulsion will be diluted with approximately an equal quantity of water and thoroughly
mixed as directed by the Engineer. Diluted emulsion shall be applied at a rate of 0.18 to 0.35 kg/m

unless shown otherwise on the Contract plans or as directed by the Engineer.

Specific gravity of asphaltic material shall be determined by ASTM D3142 standard which shall
establish the kilograms per liter based on the specific gravity at 15.5° C for the material furnished.

3.4.3.3 Construction

a. Weather Limitations

Tack coat shall not be applied when the ambient temperature is less than 13



C nor during rain, fog,

dust-storms or other unsuitable weather.

b. Application Temperature

Application temperature for the diluted emulsified asphalt shall be between 10



C and 60



C or as

directed by the Engineer.

c. Equipment required

Equipment used by the Contractor shall include an asphalt distributor in accordance with Sub-article
d  of  Article  3.3.3.1,  as  well  as  a  power  broom  and  a  power  blower.    Power  broom  shall  be  self-
propelled  and  equipped with  a  cylindrical,  rotating  nylon  bristle  brush  of not  less than  760  mm  in
diameter and not less than 1.82 m in length.  Brush shall be capable of being angled to the right

and left with adjustable ground pressure. In addition, the Contractor shall supply and utilize efficient
and approved equipment for diluting the emulsified asphalt with water.

d. Surface Preparation

Full width of the surface to be treated shall be cleaned with a power broom or power blower to remove
dust, dirt or other objectionable materials.  All fatty or unsuitable patches, excess cracks or joint filler
and  all  surplus  bituminous  material  shall  be  corrected  in  accordance  with  the  instructions  of  the
Engineer.  Surface shall be dry when treated.

e. Method of Operation

Immediately after cleaning the surface, the diluted emulsified asphalt shall be applied by means of
the distributor truck at the temperature and rate directed by the Engineer. Hand spray of inaccessible
areas is permitted, subject to the approval of the Engineer.

Mixing and placing of the asphaltic material shall progress at a rate so that contamination of previous
lifts by dust and dirt and/or loss of bond capability shall not occur. If, in the opinion of the Engineer,
loss of bond capability has taken place, an additional tack coat shall be applied to the surface of the
previous lifts as directed by the Engineer.

Surface of structures, kerbstones and other appurtenances adjacent to areas being treated shall be
protected in such a manner as to prevent their being spattered or marred.

After application, the surface shall be cured prior to placement of asphalt concrete. Tack coat
surface shall be protected prior to placement of the asphalt concrete.

Tack coat shall be uniformly applied with the distributor within 24 hours preceding the placement of
the covering course.

If the tack coat is unavoidably damaged by rain or dust, or paving operations delayed longer than 24
hours, it shall be allowed to dry, shall be cleaned again by a power broom or power blower and,
when directed by the Engineer, a subsequent light application of tack coat applied to the surface.
No additional payment will be made by the department for this work.

Where, in the opinion of the Engineer, a tack coat is not necessary between layers of freshly placed
courses, he may by written direction eliminate the tack coat, in which case there will be no payment
for tack coat for the areas concerned. Any cleaning required in these areas shall be considered to
be included in the overlaying asphaltic concrete course and no separate payment will be made.

3.5 Bituminous Surface Treatment

3.5.1 Single or Multiple Asphalt Surface Treatment

3.5.1.1 Description

This work consists of constructing a single or multiple asphalt surface treatment with aggregate or
pre-coated aggregate. This work also includes constructing an asphalt fog seal without aggregate

3.5.1.2 Material

a. Aggregates

Furnish hard, durable particles or fragments of crushed stone, crushed slag, or crushed gravel. Use
only one type of aggregate on a project. Size, grade, and combine the aggregate fractions in mix
proportions conforming to the following:

1. Los Angeles abrasion, AASHTO T 96: 40 % max.

2. Sodium sulfate soundness loss, AASHTO T 104: 12 % max.

3. Density, AASHTO T 19M: 1100 kg/m

min.

5. Adherent coating on the aggregate, ASTM D 5711: 0.5 % max.

6. Fractured faces, ASTM D5821: 75 % min.

7. Flakiness index, BS 812: Part 10: Section 105.1.: 30 max

8. Durability index (coarse), AASHTO T 210: 35 min.

9. Durability index (fine), AASHTO T 210: 35 min.

10. Free from Clay lumps and friable particles, AASHTO T 112.

11. Free from organic or other deleterious material

Do not use lightweight aggregate according to AASHTO M 195.

Grading shall be per designation type shown on the Contract plans or as included in the bills of
quantities, as approved by the Engineer and as described in Table 3-38.

b. Asphalt

Asphalt is designated as shown in AASHTO M 20 or M 226 for asphalt binder and AASHTO M 140
or M 208 for emulsified asphalt.

Table 3-38: Target value ranges for single and multiple course surface treatment aggregate

gradation

Sieve Size

Percent by mass passing designated sieve

(AASHTO T 27

and AASHTO T 11)

Grading designation

37.5 mm

100*

25 mm

90-100(3)

100*

19 mm

0-35(5)

90-100(3)

100*

12.5 mm

0-8(3)

0-35(5)

90-100(3)

100*

9.5 mm

0-12(3)

0-35(5)

85-100(3)

100*

4.25 mm

0-12(3)

0-35(5)

85-100(3)

85-100*

2.36 mm

0-8(3)

0-23(4)

75 µm

0-1*

0-10*

*Statistical procedures do not apply.
(X) Allowable deviations (±) from the target values

c. Submittals

Submit the following information and samples for approval at least 21 days before placement:

1. Aggregate samples: 35 kg from each stockpile produced and the gradation range

represented by each

2. Aggregate gradation target values: Proposed percentage of each stockpile to be used and

the proposed target value for each sieve size.

3.5.1.3 Application temperatures

Apply asphalt at temperatures according to construction requirements

a. Equipment

Furnish equipment as follows:

1. Asphalt distributor

i. Capable of heating asphalt evenly

ii. Adjustable full circulation spray bar to 4.6 m width

iii. Positive controls including tachometer, pressure gauge, volume measuring device, or

calibrated tank to uniformly deposit asphalt over the full width within 0.08 liter per square
meter of the required rate

iv. Thermometer for measuring the asphalt temperature in the tank

2. Asphalt samples: Two 1-liter samples of asphalt binder or emulsified asphalt from the same

source and of the type to be used for the surface treatment

3. Spread rates: Proposed spread rate for the aggregate and asphalt material.

Table 3-39: Asphalt application temperatures

–

degrees C

Type and grade of asphalt

Temperature ranges

minimum - maximum

Spraying

temperatures

Mixing temperatures a

Cut-back asphalt

MC-30

RC or MC-70

RC or MC-250

RC or MC-800

RC or MC-3000

30 -

50 -

75 -

95 -

110 -

60 - 80

75 - 100

80 - 115

Emulsified asphalt

RS-1

RS-2

MS-1

MS-2, MS-2h

HFMS-1, 2, 2h, 2s

SS-1, 1h, CSS-1, 1h CRS-1

CRS-2

CMS-2, CMS-2h

20 - 60

50 - 85

20 - 70

50 - 85

60 - 85

40 - 70

20 - 70

10 - 70

20 - 70

50 - 60

Asphalt Binder All grades

180 max

Temperature of mix immediately after discharge.

Maximum temperature at which fogging or foaming does not occur.

Temperature may be above flash point. Take precautions to prevent fire or

explosion.

For fog seals and tack coats.

4. Rotary power broom

i. Self-propelled

ii. Capable of controlling the vertical broom pressure

5. Pneumatic-tire rollers. Furnish a minimum of two pneumatic-tire rollers both with the

following capabilities:

i. Self-propelled

ii. Minimum compacting width

– 1.5 m

iii. Gross weight adjustable within the range of 3.5 to 6.5 kg per mm of compaction width

6. Aggregate spreader

i. Self-propelled

ii. Minimum of 4 pneumatic tires on 2 axles

iii. Positive controls to uniformly deposit the aggregate over the full width of asphalt within 10

% by mass of the required rates

7. Other equipment: Other equipment of proven performance may be used in addition to or in

lieu of the specified equipment when approved by the Engineer. Provide two-way
communication between the asphalt distributor and the aggregate spreader if the roadway
alignment does not permit visual contact.

b. Surface Preparation

On existing asphalt surfaces, ensure that the surface is dry.  Immediately before placing the layer,
remove loose dirt and other objectionable material from the surface by approved methods.  Fog seal
patches using a slow setting emulsion diluted with equal part water.  Apply the diluted emulsion at a
rate of 0.65 liters per square meter.

On existing aggregate surfaces, prime the surface according to Section 3.4.1. Allow the primed surface
to cure at least 5 days for cutback asphalt or 24 hours for asphalt emulsions. Ensure that the primed
surface is dry for surface treatments using asphalt binder or slightly damp for surface treatments using
emulsified asphalt.

c. Weather Limitations

Apply surface treatments with aggregate only when ambient air and surface temperatures are above
16



C and rising, when the weather is not foggy or rainy, and when rain is not anticipated for at least

24 hours after application.

Apply fog seals only when the ambient air and surface temperatures are above 10



C and rising,

when the weather is not foggy or rainy, and when rain is not anticipated for at least 24 hours after
application.

Complete all surface treatment applications 2 hours before sunset.

d. Production Start-up Procedures for Surface Treatments

At least 10 days before the start of constructing all surface treatments containing aggregate, arrange
for a pre-surface treatment conference. Coordinate attendance with the Engineer and any applicable
subcontractors. Be prepared to discuss or submit the following:

1. Proposed schedule of operations

2. List of all equipment and personnel to be used in the production and construction of the work

3. Proposed traffic control plan

4. Establish

minimum frequency schedule for process control sampling and testing (to be

performed by the Contractor)

5. Discuss asphalt and aggregate application procedures

6. Discuss spill prevention and safety contingency plan

7. Provide 7 days advance notice before constructing all asphalt surface treatments containing

aggregate. Also use these start-up procedures when resuming production after termination
due to nonconforming work

On the first day of placement of each surface treatment layer, or whenever there is a change in the
surface texture or aggregate gradation, construct a 150-meter control strip that is one-lane wide.

Construct the control strip using material, lay-down, and compaction procedures intended for the
remainder of the surface treatment. Cease production after construction of the control strip until the
material and the control strip are evaluated and accepted.

Acceptable control strips may remain in place and will be accepted as a part of the completed surface
treatment.

Repeat the control strip process until an acceptable control strip is produced.

e. Asphalt Application

Calibrate  the  asphalt  distributor  spray  bar  height,  nozzle  angle,  and  pump  pressure  and  check
longitudinal  and  transverse  spread  rates  weekly  according  to  ASTM  D  2995.    If  different  asphalt
distributors are used, calibrate each before use on the project.  Ensure that the length of the spread
is no more than can be covered with aggregate immediately after application.

Protect the surfaces of nearby objects to prevent spattering or marring. Spread building paper on
the surface for a sufficient distance from the beginning and end of each application so the flow
through the distributor nozzles may be started and stopped on the paper.

Engineer  will  approve  the  exact  application  rate,  temperature,  and  area  to  be  treated  before
application and may make adjustments for variations in field conditions.  Apply the asphalt uniformly
with an asphalt distributor.  Move distributor forward at the proper application speed at the time the
spray bar is opened.  Use care not to apply excess asphalt at the junction of spreads.

Correct skipped areas or deficiencies. Remove and dispose of paper or other material used.

f. Aggregate Application

When using asphalt binder, the aggregate surface should be dry. When using emulsified asphalt,
the aggregate surface should be moist.

Engineer will approve the exact application rate and area to be treated before application.  Apply the
aggregate uniformly with an aggregate spreader immediately after the asphalt is applied.  Operate
aggregate spreader so the asphalt is covered with the aggregate before wheels pass over it.  During
part-width construction, leave uncovered a strip of sprayed asphalt approximately 150 mm wide to
permit an overlap of asphalt material.

Immediately correct excesses and deficiencies by brooming or by the addition or removal of
aggregate until a uniform texture is achieved. Use hand methods in areas not accessible to power
equipment.

When pre-coated aggregates are used, they may be mixed on the job or at a central mixing plant.
Uniformly coat the aggregate with 1.0 to 2.0 % residual asphalt, by weight of aggregate.  Maintain
the  flow  qualities  of  the  pre-coated  aggregate,  so  it  is  satisfactorily  spread  with  an  aggregate
spreader.

Operate rollers at a maximum speed of 8 km/hr.  Do not permit the aggregate to be displaced by
pickup  or  sticking  of  material  to  the  tire  surface.    Sufficiently  roll  the  surface  to  uniformly  and
thoroughly bond the aggregate over the full width.  Complete rolling within 1 hour after the asphalt is
applied to the surface.

g. Single-Course Surface Treatment

A single-course surface treatment consists of applying asphalt material onto an existing surface
immediately followed by a single, uniform application of aggregate. Apply the asphalt and aggregate

During the initial 45 minutes after completion of rolling, limit the traffic speeds to 15 km/hr. Limit
traffic speeds to 30 km/hr for 24 hours.

Lightly broom the aggregate surface on the morning after construction. Maintain the surface for 4
days to absorb any free asphalt and by repairing areas deficient in aggregate. Sweep excess
material from the surface using a rotary power broom when the temperature is less than 24



C. Do

not displace embedded material.

Table 3-40 Quantities of material for single-course surface treatment

Designation

Nominal maximum

size of aggregate

Aggregate

gradation

(a)

Estimated

quantity of

aggregate

(b)

kg/m

Estimated

quantity of

emulsified

asphalt

(c)

L/m

Estimated

quantity of

asphalt

binder

(c)

L/m

19.0 mm

– 27

1.8

– 2.5

1.2

– 1.7

12.5 mm

– 16

1.4

– 2.0

0.9

– 1.4

9.5 mm

– 14

0.9

– 1.6

0.6

– 1.1

4.75 mm

– 11

0.7

– 1.0

0.5

– 0.8

Sand

– 8

0.5

– 0.8

0.4

– 0.7

(a)

See Table 3-38 for aggregate gradations.

(b)

Aggregate masses are for aggregates having a bulk specific gravity of 2.65, as determined by

AASHTO T 84 and T 85. Make proportionate corrections when the aggregate furnished has a
bulk specific gravity above 2.75 or below 2.55.

(c)

Adjust the asphalt content for the condition of the road.

Table 3-41: Quantities of material for double course surface treatments

Designation

(Thickness)

Nominal

maximum

size of

aggregate

Aggregat

gradation

(a)

Estimated

quantity of

aggregate

(b)

kg/m

Estimated

quantity of

emulsified

asphalt

(c)

L/m

Estimated

quantity of

asphalt

Binder

(c)

L/m

2A (12.5 mm)

Application

9.5 mm

– 19

0.9

– 1.4

0.5

– 1.0

Application

4.75 mm

– 8

1.4

– 1.8

0.8

– 1.3

2B (16.0 mm)

Application

12.5 mm

– 22

1.4

– 1.8

0.8

– 1.3

Application

4.75 mm

– 11

1.8

– 2.3

1.1

– 1.5

2C (19.0 mm)

Application

19.0 mm

– 27

1.6

– 2.3

1.0

– 1.5

Application

9.5 mm

– 14

2.3

– 2.7

1.5

– 1.9

(a)

See Table 3-38 for aggregate gradations.

(b)

Aggregate masses are for aggregates having a bulk specific gravity of 2.65, as determined by AASHTO T 84

and T 85.

Make proportionate corrections when the aggregate furnished has a bulk specific gravity above 2.75 or below 2.55.

Adjust the asphalt content of the first application for the condition of the road.

h. Double and Triple-Course Surface Treatment

Double-  and  triple-course  surface  treatments  consist  of  applying  multiple  layers  of  asphalt  and
aggregate.  Apply each asphalt and aggregate layer according to the approximate rates shown in
Table 3-41 and Table 3-42.  Determine the exact rates based on approved control strips.

No wait is required between surface treatment applications when using an asphalt binder. Wait at
least 24 hours between applications when using emulsified asphalt.

Table 3-42: Quantities of material for triple-course surface treatments

Designation

(thickness)

Nominal

maximum

size of

aggregate

Aggregate

gradation

(a)

Estimated

quantity of

aggregate

(b)

kg/m

Estimated

quantity of

emulsified

asphalt

(c)

L/m

Estimated

quantity of

asphalt binder

(c)

L/m

3A (12.5 mm)

Application

9.5 mm

14 – 19

0.9 – 1.4

0.5 – 1.0

Application

4.75 mm

5 – 8

1.1 – 1.6

0.7 – 1.2

Application

Sand

5 – 8

0.9 – 1.4

0.5 – 1.0

3B (16.0 mm)

Application

12.5 mm

16 – 22

0.9 – 1.4

0.5 – 1.0

Application

9.5 mm

8 – 11

1.4 – 1.8

0.8 – 1.3

Application

4.75 mm

5 – 8

0.9 – 1.4

0.5 – 1.0

3C (19.0 mm)

Application

19.0 mm

19 – 25

1.1 – 1.6

0.7 – 1.2

Application

9.5 mm

11 – 14

1.4 – 1.8

0.8 – 1.3

Application

4.75 mm

5 – 8

1.1 – 1.6

0.7 – 1.2

(a)

See Table 3-38 for aggregate gradations.

(b)

Aggregate masses are for aggregates having a bulk specific gravity of 2.65 as determined

by AASHTO T 84 and T 85. Make proportionate corrections when the aggregate furnished
has a bulk specific gravity above 2.75 or below 2.55.

(c)

Adjust the asphalt content of the first application for the condition of the road.

i. Acceptance

See Table 3-43 for sampling and testing requirements. Asphalt binder, and emulsified asphalt and
aggregate will be evaluated under Article 3.5.1.2.

Table 3-43: Sampling and testing requirements

Material or

product

Type of

acceptance

Characteristic

Test methods

specifications

Sampling

frequency

Point of

sampling

Split

sample

Report

time

Aggregate
surface
treatment
source
quality

(a)

Measured
and tested
for
conformance

LA abrasion

AASHTO T96

1 per type
and source
of material

Source of
material

Yes, when
requested

Before
using

Sodium sulfate
soundness

AASHTO T104

1 per type

and source
of material

Source of
material

Yes, when
requested

Before
using

Fractured
faces

ASTM D5821

1 per type
and source
of material

Source of
material

Yes, when
requested

Before
using

Flat and

ASTM D4791

1 per type

Source of

Yes, when Before

Material or

product

Type of

acceptance

Characteristic

Test methods

specifications

Sampling

frequency

Point of

sampling

Split

sample

Report

time

elongated

and source
of material

material

requested

using

Durability
index (coarse
and fine)

AASHTO T210

1 per type
and source
of material

Source of
material

Yes, when
requested

Before
using

Clay lumps
and friable
particles

AASHTO T112

1 per type
and source
of material

Source of
material

Yes, when
requested

Before
using

Aggregate
surface
treatment
aggregate

(a)

Statistical

Gradation

AASHTO T27
and T11

1 per 750 t

Production
belt or
spreader

Yes

24
hours

Measured
and tested
for
conformance

Fractured
faces

ASTM D5821

1 per 750 t

Production
belt or
spreader

Yes

24
hours

Liquid limit

(b)

AASHTO T89

1 per 750 t

Production
belt or
spreader

Yes

24
hours

Asphalt
binder

(c)

emulsified
asphalt

(c)

Measured
and tested
for
conformance

Quality

AASHTO M 20
or M 226 for
asphalt binder

AASHTO M
140 or M 208
for emulsified
asphalt

1 per
tanker truck
including
trailer

Point of
shipment
delivery

Two 1-litre
samples

(a)

Applies to each aggregate grade furnished.

(b)

For blotter material only.

(c)

Applied to each asphalt

material furnished.

3.5.2 Micro Surfacing Specifications

Micro Surfacing is a cold mix blend of high quality aggregates, polymer modified emulsions, water
and mineral fillers mixed according to a predetermined mix design from a laboratory.

It is applied to existing, higher volume, heavy traffic roads and highways that are still in fair to good
condition, as a means of a cost effective preventative maintenance. It can reduce deterioration by
sealing, prevents further oxidization, corrects raveling and provides or replaces a high degree of skid
resistance. It can also correct wheel rutting, (up to 38mm thick) or re-profile a road. It has a life
expectancy exceeding seven years.

It is applied to existing pavements using a specialized micro box, (more comparable to a paver
screed than a slurry box) which is connected to the micro mixing unit, as shown on the right. The
micro box is variable width, allowing total coverage of a single lane in one pass.

Crews ahead of the unit set up traffic control, and sweep the road before applying the micro surface.
Operators of the units monitor the mixing and application. After a short curing time traffic will be
allowed to resume use of the freshly rehabilitated lane.

There are 3 different classes of Micro Surfacing, each using different size aggregates:

1. Type I: (fine aggregate) Recommended for Maintenance work.

Recommended application rates are 4.5 - 6.5 kg/ m

2. Type II: (6.4mm aggregate) Recommended for Urban and Residential Streets and Airport

Runways. Recommended application rates are 5.4-10.8 kg/ m2

3. Type III: (9.5mm aggregate) Recommended for highways and wheel ruts.

Recommended application rates are 8.1-16.3 kg/ m2

Description

The Contractor shall furnish all labour, equipment, material, supplies, signage, traffic control, and
other incidentals necessary to provide Micro Surfacing. Micro Surfacing shall consist of a mixture of
an approved polymer-modified emulsified asphalt, mineral aggregate, water, and specified additives,
proportioned, mixed and uniformly spread over a properly prepared asphalt surface. The completed
Micro Surfacing shall leave a homogeneous mat, adhere firmly to the prepared surface, and have a
skid-resistant surface texture throughout its service life.

3.5.2.2

Materials

a. Emulsified Asphalt Material

The emulsion for Micro Surfacing shall be Emulsified Asphalt grade (CQS-1P) conforming to ASTM
D 2397 and AASHTO M 208. The modified emulsion shall contain a minimum of 3% polymer, SBR
latex, or natural latex by weight.

Table 3-44: Emulsified asphalt material requirements

Test on Emulsion

Minimum

Maximum

AASHTO Test

Viscosity, Say bolt Furol, 25o C,s

100

T-59

Storage Stability Test, One day, %

T-59

Particle Charge Test

Positive

Sieve Test, %(a)

0.1

T-59

Distillation:

Oil distillate, by volume, %

T-59

Residue, %

62*

T-59

Test on Residue from Distillation:

Penetration, 25o C, 100g, 5s

T-49

Ductility, 25o C, 50 mm / sec

T-51

Solubility in Trichloroethylene, %

T-44

Softening Point, Ring-and-Ball, C

57.2

T-53

*The standard distillation procedure shall be modified as follows:

The temperature on the lower thermometer shall be brought slowly to 175

C ±5

C and maintained

at this point for 20 minutes. The total distillation shall be completed in 60 ±5 minutes from the first
application of heat.

b. Aggregate

The aggregate shall consist of manufactured granite crusher fines. The smooth textured crusher
fines shall have less than 1.25% water absorption. The aggregate shall be grey in colour and clean
and free from organic matter, other deleterious substances and clay balls.

Oversized granular material and/or presence of clay balls will require the project to be stopped and
shall meet the following requirements:

Table 3-45: Gradation Table

– Aggregate (percent passing)

Type I

Type II

Type III

Tolerance

9.50 mm

100

4.76 mm

100

90-100

70-90

+ or - 5%

2.38 mm

90-100

65-90

45-70

+ or - 5%

1.19 mm

60-90

45-70

28-50

+ or - 5%

0.60 mm

40-65

30-50

19-34

+ or - 5%

0.30 mm

18-30

7-18

+ or - 4%

0.15 mm

10-21

7-18

+ or - 3%

0.075 mm

10-20

5-15

+ or - 2%

Resistance to Degradation

(ASTM C131grading D)

15% maximum loss

Soundness of Aggregate

(ASTM C88)

10% maximum loss

Sand Equivalent Value

(ASTM D2419A)

65 minimum

LA Abrasion

(AASHTO T96)

20% maximum loss

c. Mineral Filler

Cement, or other approved filler meeting the requirements of AASHTO M 17 or ASTM D242 shall
be used if required by the mix design. They shall be considered as part of the dry aggregate.

d. Water

All water used shall be potable and free of dissolved materials which may affect the mix
characteristics or finished characteristics of the product. Filler shall be of the specific type specified
in the mix design.

e. Additives

Additives may be used to accelerate or retard the break-set of the Micro Surfacing or to improve the
resulting finished surface. The use of additives in the Micro Surfacing mix (or individual materials)
shall be made initially in quantities predetermined by the mix design with field adjustments, if
required, after approval by the Engineer.

3.5.2.3 Micro Surfacing Mix Design Specifications

Before work begins, the Contractor shall submit a mix design covering the specific materials to be
used on the project. The manufacturer of the polymer modified emulsion shall develop the job mix
formula and present certified test results for the Contractor's approval. Compatibility of the aggregate
and polymer modified emulsified asphalt shall be certified by the emulsion manufacturer. The mix
design shall be in accordance with the ISSA TB-136 Wet Track Abrasion Loss, Six Day Soak with a
maximum loss of 807.4 grams/m

. The emulsion supplier shall also provide a base line of emulsion

to the Owner for testing of latex percentages. The Micro Surfacing mixture shall meet the
specifications shown in Table 3-46.

Table 3-46: Micro Surfacing Mixture specification

ISSA TEST NO.

DESCRIPTION

SPECIFICATION

ISSA TB-113

Mix Time at 23.9°C

Controllable to 120 seconds minimum

ISSA TB-114

Wet Stripping

Pass (90% Minimum)

ISSA TB-139

Wet Cohesion

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 38