TECHNICAL SPECIFICATIONS ITEM 200 AGGREGATE SUBBASE COURSE 200.1 DESCRIPTION This item shall consist of furnishing, placing and compacting an aggregate course on a prepared sub grade in accordance with this Specification and the lines, grades and cross sections shown on the Plans, or as directed by the Consultant. 200.2 MATERIALS REQUIREMENTS Aggregate for sub base shall consist of hard, durable particles or fragments of crushed stone, crushed slag, or crushed or natural gravel and filler of natural or crushed sand or other finely divided mineral matter. The composite material shall be free from vegetable matter and lumps orballs of clay, and shall be of such na ture that it ca n be compacted readi ly to form a fir m, stable sub base. The sub base material shall conform to Table I. Table I GRADING REQUIREMEMENTS The fraction passing the 0.075 mm (No. 200) sieve shall not be greater than 0.66 (two thirds) ofthe fraction passing the 0.425 mm (No. 40 sieve. The fraction passing the 0.425 mm (No. 40) sieve, shall have a liquid limit not greater than 35 and plasticity index not greater t han 12 as determined by AASHT O T 89 and T 90, respective ly. Sieve Designation Mass Percent Passing Standard (mm) Alternate US Standard 50 25 9.5 0.075 2” 1” 3/8” No. 200 100 55-85 40-75 0-12
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The course portion, retained on a 2.00 mm (No. 10) sieve, shall have a mass percent of wear not
exceeding 50 by the Los Angeles Abrasion Tests as determined by AASHTO T 96.
The material shall have a soaked CBR value of not less than 25% as determined by AASHTO T
193. The CBR value shall be obtained at the maximum dry density as determined by AASHTO T180, Method D.
200.3 CONSTRUCTION REQUIREMENTS
200.3.1 Preparation of Existing Surface
The existing surface shall be graded and furnished as provided under Item 105, Sub grade
Preparation, before placing the sub base material.
200.3.2 Placing
The aggregate sub base material shall be placed as a uniform mixture on a prepared sub grade in a
quantity which will provide the required compacted thickness. When more that one layer isrequired, each layer shall be shaped and compacted before the succeeding layer is placed.
The placing of material shall begin at the point designated by the Consultant. Placing shall be fromvehicles especially equipped to distribute the material in a continuous uniform layer or windrow.
The layer or windrow shall be of such size that when spread and compacted the finished layer be
in reasonably close conformity to the nominal thickness shown on plans.
When hauling is done over previously placed material, hauling equipment shall be disperseduniformly over the entire surface of the previously constructed layer, to minimized rutting r
uneven compaction.
200.3.3 Spreading and Compacting
When uniformly mixed, the mixture shall be spread to the plan thickness compaction.
When the required thickness is 150 mm or less, the material may be spread and compacted in one
layer. When the required thickness is more than 150 mm, the aggregate sub base shall be spreadand compacted in two or more layers of approximately equal thickness, and the maximum
compacted thickness of any one layer shall not exceed 150 mm. All subsequent layers shall be
spread and compacted in a similar manner.
The moisture content of sub base material shall, if necessary, be adjusted prior to compacting by
watering with approved sprinklers mounted on trucks or by drying out, as required in order to
obtain the required compaction.
Immediately following final spreading and smothering, each layer shall be compacted to the full
width by means of approved compaction equipment. Rolling shall progress gradually from thesides to the center, parallel to the centerline of the road, and shall continue until the whole surface
has been rolled. Any irregularities or depressions that develop shall be corrected by loosening the
material at these places not accessible to the roller; the sub base material shall be compactedthoroughly with approved tamper or compactors.
If the layer of sub base material, or part thereof, does not conform to the required finish, the
Contractor shall, at his own expense, make the necessary corrections.
Compaction of each layer shall continue until a field density of at least 100 percent of the
maximum dry density determined in accordance with AASHTO T 180, Method D has been
achieved. In place density determination shall be made in accordance with AASHTO T 191.
Before sub base construction is started, the Contractor shall spread and compact trial sections as
directed by the Consultant. The purpose of the trial sections is to check the suitability of the
materials and the efficiency of the equipment and construction method which is proposed to be
used by the Contractor. Therefore, the Contractor must use the same material, equipment and procedures that he proposes to use for the main work. One trial section of about 500 m 2 shall be
made for every type of material and/or construction equipment/ procedure for use.
After final compaction of each trial section, the Contractor shall carry out such field density tests
and other required as directed by the Consultant.
If a trial section shows that the proposal material, equipment or procedures in the Consultant’s
opinion are not suitable for sub base, the material shall be removed at the Contractor’s expenseand a new trial section shall be constructed.
If the basic conditions regarding the type of material or procedure change during the execution of
the work, new trial sections shall be constructed.
200.3.5 Tolerance
Aggregate sub base shall be spread with equipment that will provide a uniform layer which when
compacted will conform to the designated level and transverse slopes as shown on the Plans. Theallowable tolerance shall be as specified hereunder:
Permitted variation from design
THICKNESS OF LAYER +/- 20 MM
Permitted variation from design
LEVEL OF SURFACE + 10 MM
Permitted SURFACE IRREGULARITY
MEAUSURED by 3-m straight-edge 20 mm
Permitted variation from designCROSSFALL or CAMBER +/- 0.3%
Permitted variation from design
LONGITUDINAL GRADE over 25 m length +/- 0.1%
200.4 METHOD OF MEASUREMENT
Aggregate sub base course will be measured by the cubic meter (m3). The quantity to be paid shall
be the design volume compacted in place as shown on the Plans, and accepted in the completedcourse. No allowance will be given for materials placed outside the design limits shown on the
cross-sections. Trial sections shall not be measured separately but shall be included in the quantity
of sub base herein measured.
200.5 BASIS OF PAYMENT
The accepted quantities, measured as prescribed in Section 200.4, shall be paid for at the contract
unit price for Aggregate Sub base Course which price and payment shall be full compensation for furnishing and placing all materials, including all labor, equipment, tools and incidentals necessary
This item shall consist of preparing and treating an aggregate base course with material inaccordance with the Plans and Specifications, preparatory to the construction of a bituminous
surface course.
301.2 MATERIAL REQUIREMENTS
Bituminous material for prime coat shall be cut-back asphalt and shall be either rapid Curing type,
Grade RC-70 or Medium Curing Type, Grade MC-30 or MC-70. Cut-back asphalts shall conform
to the requirements of the following:
Rapid Curing ----- AASHTO M 81
Medium Curing ----- AASHTO M 82
301.3 CONSTRUCTION REQUIREMENTS
301.3.1 Surface Condition
Prime coat shall be applied only to surfaces which are dry or slightly moist. No prime coat shall be
applied when the weather or foggy or rainy.
301.3.2 Equipment
The liquid bituminous material shall be sprayed by means of a pressure distributor of not less than1,000 liters capacity, mounted on pneumatic tires of such with and number that the loud produced
on the road surface will not exceed 1 kN (100 kgf) per cm width of tire.
The tank shall have a heating device able to heat a complete charge of bituminous liquid to 180ºC.
The heating device shall be such that overheating will not occur. Consequently, the flames must
not directly touch the casing of the tank containing the bituminous liquid. The liquid shall beinsulated in such a way that the drop in temperature when the tank is filled with bituminous liquid
at 180ºC and not heated will be less than 2ºC per hour. A thermometer shall be fixed to the tank in
order to be able to measure continuously the temperature of the liquid. The thermometer shall be
place in such a way that the highest temperature in the tank is measured. The tank shall befurnished with a calibrated dip-stick to indicate the contents. The pipes for filling the tank shall be
The distributor shall be able to vary the spray width of the bituminous liquid in maximum steps of
100 mm to a total width of 4m. The spraying bar shall have nozzles from which the liquid is
sprayed fan-shape on the road surface equally distributed over the total spraying width.
For adding the liquid bituminous material, the distributor shall have a pump either driven by aseparate motor or with a device to synchronize its speed with the speed of the distributor. The
pump shall be furnished with an indicator showing the rate of flow. The suction side of the pumpshall have an easily changeable filter. A thermometer shall be fixed, such that it indicates the
temperature of the liquid immediately before it leaves the spraying bar.
The distributor shall be furnished with a tachometer, indicating its forward speed, which shall be
visible from the driver’s seat. The distributor shall be designed so that the deviation from the
prescribed rate of application does not exceed 10% and shall be equipped with a device for handspraying of the bituminous liquid.
301.3.3 Application of Bituminous Material
Immediately before applying the prime coat, the full width of surface to be treated shall be swept
with a power broom an if necessary, scraped to remove all dirt and other objectionable materials.Where required by the Consultant, immediately prior to the application of the prime coat, the
surface shall be lightly spread with water but not saturated. Bituminous material shall be applied by means of a pressure distributor at the temperature given in Table I below. The rate application
of the bituminous material shall be within the range of 1 to 2 liters/m2, the exact rate to be ordered
by the Consultant.
TABLE I
APPLICATION TEMPERATURE FOR BITUMINOUS PRIME COAT
The prime coat shall be left undisturbed for at least 24 hours and shall not be opened to traffic
until it has penetrated and cured sufficiently so that it will not be picked up by the wheels of the
passing vehicles. The contractor shall maintain the prime coat until the next course is applied.Care shall be taken that the application of bituminous material is not in excess of the specified
amount, any excess shall be blotted with sand or removed as directed by the Consultant. All areas
inaccessible to the distributor shall be sprayed manually using the device for hand spraying. The
surface of structures and trees adjacent to the areas being treated shall be protected in such manner
as to prevent their being spattered or marred.
301.4 METHOD OF MEASUREMENT
Bituminous Prime Coat shall be measured by the tone (t). The quantity to be paid for shall be thenumber of tones of bituminous material applied and accepted in the completed work.
301.5 BASIS OF PAYMENT
The accepted quantities, measured as prescribed in Section 301.4, shall be paid for at the contract
unit price for Bituminous Prime Coat which priced and payment shall be full compensation for
furnishing and placing materials, including all labor, equipment, tools and incidentals to complete
this Item.
Payment will be made under:
Pay Item Number Description Unit of Measurement
301 Bituminous Prime Coat Tone
ITEM 310
ASPHALT CONCRETE SURFACING – PLANT MIX
310.1 DESCRIPTION
This work shall consist of furnishing and mixing aggregates and asphalt binder at a central mixing
plant, transporting the mixture and spreading and compact it on a prepared base in accordance
with the Specifications and Drawings.
310.2 MATERIAL REQUIREMENTS
310.2.1 Aggregates
1. Course and fine aggregates shall be clean, hard, tough, sound principles free from
decomposed material, vegetable matter and other deleterious substances.
2. Course aggregate, which is material retained on a 4.75 mm (No. 4) sieve, shall consist of
crushed rock or crushed river grade. At least 50 percent by weight of the course aggregateshall have at least one fractured face.
3. Fine aggregate, which is material passing a 4.75 mm (No. 4) sieve, shall consist of sand or
stones screening or a mixture thereof. At least 50 percent by weight of the fine aggregates
shall be angular or fractured particles. Sand shall not comprise more than 25% by weight
of the total aggregate.4. The combined aggregate shall conform to the one of the grading shown in Table I. When the
combined grading of the course and fine aggregate is deficient in material passing the No.
200 sieve, additional filler material shall be added. The filler material shall consist of
finely divided rock dust, hydrated lime, Portland cement of other suitable material matter
and shall conform to the grading shown in Table II. However, the grading shall beadjusted to take account of the results of the trials to allow the asphalt concrete mix to
conform in all respects to the requirements for the job mix specified in Clause 310.3.7.Table I
5. The course and fine aggregates shall meet the following requirements.
a. The percent of wear by the Los Angeles Abrasion Test (AASHTO T 96) shall not be
more than 40.
b. The loss when subjected to five cycles of the Sodium Sulphate Soundness test(AASHTO T 104) shall be less than 12%.
c. The Sand Equivalent (AASHTO T 176) determined after all processing except for
addition of asphalt cement shall not be less than 45.
d. All aggregates shall be non-plastic.
e. The flakiness index of the aggregate retained on the 9.5 mm (3/8 in) sieve whentested in accordance with BS812 shall not exceed 35%. (the flakiness index of an
aggregate is the percentage by weight of particles in it whose least dimension
(thickness) is less than three fifths of their mean dimension. The test is not applicable
to material passing a 6.3 mm (1/4 in) sieve.
310.2.2 Asphaltic Material
Asphalt binder to be mixed with the aggregate shall be asphalt cement penetration grade
1. Asphalt cement shall be oil asphalt, or a mixture of refined liquid asphalt and refined solid
asphalt, prepared from crude asphaltic petroleum. It shall be free from admixture with any
residues obtained by the artificial distillation of coal, coal tar, or paraffin oil and shall be
homogeneous and free from water. No emulsification shall occur when a 30g sample is boiled
for 2 hours with 250 cc of distilled water in a 500 cc Erlenmeyer flask equipped with a refluxcondenser.
2. Asphalt cements shall be classified by penetration and when tested in accordance with the
AASHTO standard methods of tests, the grades of asphalt shall conform to the requirements
given in Table III. The grade of asphalt to be used shall be as specified in the contract.TABLE III
Loss on heating, percent - 0.8 - 0.8 - 1.0 - 1.3 - 1.5
Penetration, of residue,
percent of original58 - 54 - 50 - 46 - 40 -
Ductility of residue, percent
at 25c (77F) 5 cm per mi.,
cm
- - 50 - 75 - 100 - 100 -
Spot test when and as
specified ( See Note) with:
Standard naphtha solvent
Naphtha-xylene solvent,
percent xylene
Heptane-xylene solvent,
percent xylene
Negative for all grades
NOTE: the use of the spot test is optional. When it is specified, the Consultant shall indicate whether the standard
naphtha solvent, the naphtha solvent, the naphtha-xylene solvent, or the heptane-xylene solvent will be used indetermining compliance of xylene to be used.
3. Mixing Temperature for Asphalt CementThe mixing temperature shall be that temperature to which the asphalt must be treated to
produce a viscosity of 85 +/- 10 seconds Saybolt Furol. A viscosity/temperature curve shall be
supplied for each asphalt cement grade from each source of crude from which the asphaltcement has been manufactured.
The asphalt concrete mixture shall conform to the requirements of Table IV. However the exact
composition of the mixture shall be adjusted to take account of the results of the mix trials to
allow the asphalt concrete mix to conform in all respect to the requirements of Clause 310.3.7.
TABLE IV
ASPHALT CEMENT CONTENT OF ASPHALT CONCRETE MIX
% OF ASPHALT CEMENT OF TOTAL MIX NY WEIGHT
BINDER COURSE WEARING COURSE
Min. Max. Min. Max.
4.0 5.5 5.0 7.0
310.3 CONSTRUCTION REQUIREMENTS
310.3.1 Mixing Plant
1. The plant shall be either a batch plant or continuous mix plant of adequate capacity,
coordinated and operated to produce a mixture within the limits of the Specification.2. The plant scales for any-weigh box or hopes shall be either the beam of the spring less
dial type, sensitive to one-half of one percent of the maximum load that may be required
and shall be of standard make and design. When of the beam type there shall be a
separate beam with tell-tale indicator for each size of aggregate, and a tare beam for
balancing the hopper.
3. Tanks for storage of asphalt cement shall have a capacity of at least 7 days run and shall
be capable of heating the material, under effective and positive control at all times, to thetemperature requirements given in Clause 310.2.2. The method of heating shall be such
that the products of combustion or the flame shall not come into contact with the asphalt
cement. Before the asphalt cement is placed in the mixer shall be heated in a direct fired
heater of such capacity that it need never be less than half full. Heating of material
supplied in barrels shall be subject to the same conditions.
4. The plant shall be provided with accurate mechanical means for uniform feeding of the
aggregates into the dryer so that a uniform production and a uniform temperature of the
heated aggregates are secured.
5. A rotary dryer satisfactory design for drying and heating the aggregates shall be provided.
The dryer shall be capable of drying and heating the aggregates to the temperaturerequirements specified in Clause 310.3.4 for the type of asphaltic material to be used.
6. Suitable screens capable of screening all aggregates to the sizes required, and having
normal capacities slightly in excess of the maximum output of the mixing plant shall be
provided.
7. The plant shall include at least three storage bins for screened aggregates with total
capacity of not less than three times the dead load of the mixer in the case of a batch
mixer, or not less than a run of 10 minutes in the case of a continuous mixer. Bins shall
be divided into compartments arranged to ensure separate and adequate storage of appropriate sizes of aggregate. Each compartment shall be provided for filler, if used, and
satisfactory provisions made for proportioning the filler for each batch of mixture.8. Satisfactory means either by weighing, metering, or volumetric measurement, shall be
provided to obtain the proper amount of asphalt cement, and all measuring devices shall
be sensitive to a two per cent tolerance of the amount required. Means shall be provided
for checking the quantity of rate of flow of asphalt cement into the mixer. Suitable means
shall also be provided, either by steam jacketing or other insulation, for maintaining the
specified temperature of the asphalt cement in the pipe lines, meters, weight buckets,spray bars and other containers or flow lines.
9. If an asphalt bucket is used for weighing the asphalt cement, it shall have a sufficient
capacity to hold not less than twenty per cent of the weight aggregate required from one
batch. It shall be steam jacketed or equipped with properly insulated electric heating units
and shall be suspended on dial scales equipped with a telltale device so that the tare
weight can be accurately measured to al tolerance of two percent of the weight required.The bucket shall be so arranged that it will deliver the heated asphalt cement in a thin
uniform sheet or in multiple streams the full width of the mixer, except in the case of arotary mixer where the asphalt cement will be sprayed into the mix.
10. An armored thermometer to include the range from 93º C to 204º C shall be fixed in the
asphalt cement feed line at a suitable location near the discharge valve at the mixer unit.
The plant shall be further equipped with an approved dial scale mercury actuated
thermometer, and electric pyrometer, or other approved thermometric instrument so place
at the discharge chute of the dryer as to register automatically the temperature of theheated aggregate.
11. The plant shall be equipped with positive means to govern the time of mixing to the
satisfaction of the Consultant. The time of mixing shall be considered as the interval
between the time the asphalt cement is spread on the aggregate and the time the same
aggregate is discharged from the mixer.
12. The plant shall have an efficient dust collecting system. Provision shall be made to waste
the material so collected, or to return it to the mixture.
13. Adequate and safe stairways to the mixer platform and guarded ladders to other plantunits shall be placed at all points requiring accessibility during plant operations. All
gears, pulleys, chains, sprockets and other dangerous moving parts shall be adequatelyguarded and protected. Ample and unobstructed space shall be maintained at all times in
and around the truck loading space, and this area shall be kept free from drippings from
the mixing platform.
405.3.2 Special Requirements for Batching Plants
1. The plant shall include means for accurately weighing each size of aggregate in a weight box
or hopper, suspended on scales, large enough in size to hold a full batch without handraking or running over. The weight box or hopper shall be supported on a fulcrum and
knife edges so constructed that they will not be easily thrown out of alignment or
adjustment. Gates on both bins and hopper shall be so constructed as to prevent fromleakage when they are closed.
2. The plant shall include a batch mixer of an approved twin pugmill type, rotary drum type, or
other type that has proved itself capable of producing a uniform mixture within the limits
of this Specification. It shall have a batch capacity of not less than 900 kg. If of the
pugmill type, the clearance of the blades from all fixed and moving parts shall not exceed20mm. if the mixing tank is closed, it shall be fitted with a lid to prevent the dust from
being dispersed into the air. The mixer shall have an accurate time lock to control the
operation of a complete mixing cycle by locking the weight box gate after charging of the
mixer until the closing of the mixer gate at the completion cycle: it shall lock the asphalt
bucket, throughout the dry mixing period and shall lock the mixer gate throughout the dry
and wet mixing periods. The dry mixing period is defined as the interval of time between
the opening of the weigh box gate and the application of the asphalt cement. The wet
mixing period is the interval of time between the application of asphalt cement and theopening of the mixer gate.
3. The control of the timing shall be adjustable and capable of being set at maximum intervals of 5 seconds for cycles of mixing up to 3 minutes. A mechanical batch counter shall be
installed as a part of the timing device shall be so designed as to register only completely
mixed batches.
310.3.2 Special Requirements for Continuous Mixing Plants
1. The plant shall include a means for accurately proportioning each size of aggregate either by
weighing or by volumetric measurement. When proportioning is by volume, the unit shall
include a feeder mounted under the compartment bins. Each bin shall have an accurately
controlled gate, for volumetrically measuring the material drawn from each respective
bin. The gate shall be rectangular with dimensions of about 300 mm x 250mm with onedimension adjustable by positive mechanical means provided with a lock. An indicator
shall be provided on each gate to show the amount of the gate opening. Filler, if used,shall be proportioned separately from a small hopper mounted directly over the mixer.
2. The plant shall provide for the calibration of gate openings by means of weight test samples.
The materials fed out of the storage bins through their individual offices shall be by-
passed to a suitable test box, each compartment of material being confined in a separate
box section. The plant shall be equipped to handle conveniently samples of about 400 kg
to be weight on accurate scales.3. Means shall be provided in the plant to afford positive interlocking control between the flow
of aggregate from the bins and the flow of asphalt cement from the meter or other
proportioning source to the satisfaction of the Consultant.
4. The plant shall include a continuous mixer of an approved type. The paddles shall be of an
adjustable type for angular position on the shafts and shall be reversible to retard the flow
of the mix. The mixer shall carry a manufacturer’s plate giving the net volumetric content
of the mixer at various feed rates.
5. the mixing shall be determined using the following formula:
Mixing time in seconds = Pugmill dead capacity in kilogramsPugmill output in kilograms per second
310.3.3 Preparation of Aggregates
Before being fed to the mixer, aggregates and filler for binder and wearing courses shall be
separated into two or more sizes and stored separately. One storage unit shall contain aggregate of such size that 80 percent will be retained on a 4.75 mm (No. 4) sieve. Should the Contractor elect
to use natural as a separate component it also shall be stored and measured separately and
accurately before being fed into the mixer.
In placing the materials in storage or in moving them from storage to the mixer any method which
causes segregation or uncontrolled combination of materials of different grading shall be
discontinued and the segregated or degraded materials shall be prescreened, or wasted, and, if
necessary, passed through the dryer before being mixed.
Fine course aggregates shall be fed into the dryer at a uniform rate and the rate of feed shall be
maintained within 10 percent of the amount set. Course and fine aggregates shall be dried to
moisture content exceeding 1 % and heated so that when delivered to the mixer they shall be at a
temperature of 25º C above the mixing temperature for the asphalt cement being used, or as
ordered by the Consultant.
310.3.4 Preparation and Composition of the Mixture
First the aggregate, including filler, shall be loaded into the mixer followed by the asphalt cement.Mixing shall continue until all particles of aggregate are coated uniformly. When the mixture is
prepared in a twin pug mixer, the volume of aggregate shall be not so great as to extend above the
tips of the mixer blades when these blades are in a vertical position. Mixing shall continue until all
1. Prior to commencing the supply of asphaltic concrete for flexible surfacing, the Contractor
shall submit full details of his proposed grading and mixes to the Consultant. On
receiving preliminary approval of his proposals the Contractor shall then arrange to lay
and properly compact trial areas of binder and wearing course materials.
2. The contractor shall place approximately 80t of asphaltic concrete in each trial area whichshall be large enough to demonstrate to the satisfaction of the Consultant that the laying
and compaction equipment complies with the requirements of the Specification and thatthe proposed mixes as laid are acceptable.
310.3.6 Job Mix
1. Marshall Specimens are to be obtained from each of the base and wearing course
materials supplied for trial laying purposes. The marshall specimens shall be formed andcompacted in proper moulds, in accordance with the procedure described in ASTM D
1559.
2. The contractor shall demonstrate to the satisfaction of the Consultant by testing, carried
out in the presence of the Consultant’s Representative, in accordance with the procedures
set out in the Marshall Method of Mix Design in the Asphalt Institute Manual, Mix
Design Methods, for Asphalt Concrete and Other Hot Mix Types, Manual Series No. 2
(MS-2), that the requirements given in Table V are achieved. The loss in Marshall
Stability by submerging specimens in water at 60º C for 24 hours shall be not more than25 percent of the stability of the job-mix. In addition the Contractor shall demonstrate by
approved tests to the satisfaction of the Consultant that the proposed mix is not subjectedto stripping of the asphalt cement from the aggregates.
TABLE V
MARSHALL TEST REQUIREMENT FOR ASPHALT CONCRETE
BINDER COURSE WEARING COURSE
Min. Max. Min. Max.
STABILITY (lbf)
FLOW (0.01 in)
AIR VOIDS (1%)
AGGREGATE VOIDS FILLED WITH
ASPHALT CEMENT (%)
FIELD COMPACTED DENSITY
MARSHALL SPECIMEN DENSITY
1200
8
3
60
97
-
16
8
75
-
1200
8
3
70
97
-
16
6
80
-
3. To determine the Marshall Specimen Density, from each set of six Marshall Specimens,
the highest and lowest densities shall be ignored and the Marshall Specimen Density shall
then be the mean of the densities of the remaining specimens.
4. As compacted densities shall be determined of samples taken from the materials laid and
compacted for the mix trials as specified. At least four samples shall be taken for each of
the binder and wearing course materials, under the direction of the Consultant’s
Representative, and the required percentage of the Marshall Specimen Density shall be
activated in each case. Testing shall be in accordance with ASTM D 2726.5. When the Consultant’s Representative is satisfied that the materials and methods
demonstrated by the Contractor during trial laying comply with the requirements of theContract, the Consultant shall determine the job-mix and shall inform the Contractor in
writing of its composition. On receipt of such information the Contractor may proceed
with the work.
310.3.7 Transportation of Plant-Mixture
The mixture shall be transported to the site in steel-plate lined trucks with a minimum capacity of
5 tones. The inside body shall be lightly coated with a soap or detergent solution to prevent
adhesion of the mixture and shall be equipped with covers or tarpaulins to protect the mixture.
310.3.8 Spreading and Compacting
1. Prior to commencing work, the surface to be covered shall be thoroughly cleaned. All
mixtures shall be spread and all initial compaction completed at a temperature such thatthe viscosity of the asphalt cement is within the range of 140 +/- 10 seconds Saybolt
Furol. The mixture shall not be placed on wet surfaces or when weather conditions willotherwise prevent its proper handling or finishing.
2. Asphalt pavers shall be self-propelled mechanical spreading and finishing equipment,
provided with a screed or strike-off assembly capable of distributing the material to not
less than the full width of a traffic lane. Screed action shall include any cutting, crowding
or other practical action which is effective on the mixture without tearing, shoving or
gouging, and which produces a surface texture of uniform appearance. The screed shall
be adjustable to the required section and thickness. The pavers shall be provided with
either a full width roller or tamper or other suitable compacting devices. Pavers that leaveridges. Indentations or other marks in the surface that cannot be eliminated by rolling or
prevented by adjustment in operation shall not be used.
3. The prepared base to be surface shall be marked such that minor irregularities in its surfaceare not repeated in the surfacing. Alternatively approved automatic leveling devices may
be used.
4. The sequence of laying shall be planned in advance and shall be subject to the approval of the
Consultant’s Representative. Where applicable laying of material shall commence on the
lower side of the road. Where a course previously laid is joined to a course to be laidlater, the first course shall be cut back to a vertical face and painted with asphalt cement
as directed by the Consultant.
5. A joint in any layer shall not lie in any lower bituminous layer but shall be laterally displaced
by a minimum of 100 mm.
6. The mix shall be compacted immediately after placing. Initial rolling shall follow the pavers s
closely as possible and shall be with a steel wheeled tandem or three-wheel roller with a
minimum wheel load of 50 knN/m (265 lb/in) or an approved vibrating steel wheeled
roller. Immediately following the sealing of longitudinal joints, rolling shall commenceon the lower side of each strip laid in progress toward the higher side. Intermediate
rolling with a pneumatic tired roller with tire pressures not less than 620 Kn/m2 (90lbf/in2) shall be done immediately behind the initial rolling. Final rolling shall eliminate
marks from previous rolling. All rollers shall incorporate quick reversing mechanisms. In
areas too small for the roller, a vibrating plate compactor or hand tamper shall be used to
achieve the specified compaction.
7. Rolling shall continue as long as required to attain the minimum specified compaction and
1. The material being laid shall comply with the requirements of Table VI.
2. Modifications to the job-mix may only be made with the approval of the Consultant.
Should the Consultant at any time have reason to believe that the materials and methodsof laying are different from those approved, he shall so advise the Contractor in writing
and may order work on flexible surfacing to cease pending further trial laying and testing.3. Following each day’s work the Contractor shall cut core samples from locations chosen
by the Consultant’s Representative. The cores will be used to test the density by either
ASTM D 1188, or ASTM D 2726, whichever is applicable.
TABLE VI
COMPLIANCE WITH ASPHALT CONCRETE JOB-MIX
310.3.11 Pavement Thickness and Tolerance
The asphalt concrete binder and wearing courses shall be laid to the designed levels and transverse
slopes as shown on the Drawings. The allowable tolerances shall be in accordance with Table
1. The quantities of aggregate for asphalt concrete binder or wearing course of aggregate Class
A or B shall be design volume in place as shown on the Drawings. No allowance will be
given for materials placed outside the design limits shown on the cross-sections.
2. The quantities of aggregate for trial sections shall be the weight of the complete mixture lessthe weight of asphalt cement as measured in paragraph 5.
3. The quantities for leveling courses shall be weight of the complete mixture less the weight of
asphalt cement as measured in paragraph 5.
4. Where quantities of aggregate are paid for by weight the complete mix shall be weighed onapproved vehicle scales which have been previously tested, certified and sealed by the
responsible agency of the Philippine Government.
5. The quantity of asphaltic material to be measured shall be the calculated weight determined
from the job-mix and the design volume of asphalt concrete in place as shown on the
Drawings or the volume of asphalt cement ordered for trial sections or leveling.
Quantities of asphaltic material, wasted or remaining on hand after completion of the
work shall not be measured or paid for.
310.5 BASIS OF PAYMENT
The quantities measured as stated above shall be paid for at the appropriate contract unit price for
the pay items shown in the Bill of Quantities, which prices and payment shall constitute full
compensation for furnishing and placing all materials and for all labor, tools and incidentals
The use of calcium chloride as an admixture will not be permitted.
405.4.4 Mixing and Delivery
Concrete may be mixed at the site of construction or by a combination of central point mixing
and truck agitating. Mixing and delivery of concrete shall be in accordance with the appropriate
requirements of AASHTO M 157 except as modified in the following paragraphs of this section,
for or a combination of central point and truck agitating. Delivery of concrete shall be regulated
so that placing is at a continuous rate unless delayed by the placing operations. The intervals
between delivery of batches shall not be so great to allow the concrete in place to harden
partially, and in no case shall such an interval exceed 30 minutes.
When volumetric measurements are authorized, the weight proportions shall be converted to
equivalent volumetric proportions. In such cases, suitable allowance shall be made for variations
in the moisture condition if the aggregates, including the bulking effect in the fine aggregate.Batching and mixing shall be in accordance with the ASTM C 685, Section 6 through 9.
For batch mixing at the site of construction or at a central point, a batch mixer of an approved
type shall be used. Mixer having a rated capacity of less than one-bag batch shall not be used.
The volume of concrete mixed per batch shall not exceed the mixer’s nominal capacity as
shown on the manufacturer’s standard rating plate on the mixer except that an overload up to ten
percent above the mixer’s nominal capacity may be permitted, provided concrete test data from
strength, segregation concrete takes place. The batch shall be so charge into the drum that a
portion of the water shall enter in advance of the cement aggregates. The flow of water shall be
uniform and all water shall be in the drum by the end of the first 15 seconds of the mixing
period. Mixing time shall be measured from the time all materials, except water, are in a drum.
Mixing time shall not exceed 60 seconds for mixers having a capacity of 1.5m3 or less. For
mixers having a capacity greater than 1.5m3, the mixing time shall not less than 90 seconds. If
timing starts, the instant the skip reaches its maximum raised position, 4 seconds shall be added
to the specified mixing time. Mixing time ends when the discharge chute opens.
The mixer shall be operated at the drum speed as shown on the manufacturer’s name plate on
the mixer. Any concrete mixed less than the specified time shall be discarded and disposed off
by the Contractor at his own expense.
The timing device on stationary mixers shall be equipped with a bell or other suitable warning
device adjusted to give a clearly audible signal each time the lock is released. In case of failure
of the timing device, the Contractor will be permitted to continue operations while it is being
prepared, provided he furnishes an approved timepiece equipped with minute and seconds
hands. If the timing device is not placed in good working order within 24 hours, further use of
the mixer will be prohibited until repairs are made.
Retempering concrete will not be permitted. Admixtures for increasing the workability, for
retarding the set, or for accelerating the set or improving the pumping characteristics of the
concrete will be permitted only when specifically provided for in the Contract, or authorized in
writing by the Consultant.
1. Mixing Concrete: General
Concrete shall be thoroughly mixed in a mixer of an approved size and type that will
ensure a uniform distribution of the materials throughout the mass.
All concrete shall be mixed in mechanically operated mixers. Mixing plant andequipment for transporting and placing concrete shall be arranged with an ample
auxiliary installation to provide a minimum supply of concrete in case of breakdown
of machinery or in case the normal supply of concrete is disrupted. The auxiliary
supply of concrete shall be sufficient to complete the casting of a section up to a
construction joint that will meet the approval of the Consultant.
Equipment having components made of aluminum or magnesium alloys, which
would have contact with plastic concrete during mixing, transporting or pumping of
Portland Cement concrete, shall not be used.
Concrete mixers shall be equipped with adequate water storage and a device for
accurately measuring and automatically controlling the amount water used.
Materials shall be measured by weighing. The apparatus provided for weighing the
aggregates and cement shall be suitably designed and constructed for this purpose.
The accuracy of all weighing devices except that for water shall be such that
successive quantities can be measured to within one percent of the desired amounts.
The water measuring device shall be accurate to plus or minus 0.5 percent. All scales
and measuring device shall be tested at the expense of the Contractor as frequently as
the Consultant may be deeming necessary to insure their accuracy.
Weighing equipment shall be insulated against vibration or movement of other
operating equipment in the plant. When the entire plant is running, the scale reading