f. Opening of Traffic and Traffic Control

i. The pavement, undergoing surface treatment, shall not be opened to traffic, until the bituminous material has dried, and in the opinion of the Employer, will not pick up under the traffic.
ii. Provided that if it becomes necessary to permit traffic, prior to the drying time, which in no case shall be sooner than 24 hours, after the application of bituminous material; fine sand shall be applied, as directed by the Employer, and then the traffic shall be permitted to use the road so treated.

29.5 SCOPE OF WORK
This work shall consist of manufacture, transportation, placing, spreading, finishing and compacting the asphaltic concrete (plant-mixed) surfacing for pavement, in accordance with these specifications and in conformity with the lines, grades and cross-sections shown in the Drawings or as directed by the Employer.




29.5.1 MATERIAL REQUIREMENTS
29.5.2 Mineral Aggregates
29.5.2.1 General
The aggregates shall consist of coarse aggregates, fine aggregates and filler material, if required. The aggregates shall comprise clean, tough, durable and sound particles, of uniform quality and shall be free from decomposed materials, vegetable matter, shale lumps and other deleterious substances.

29.5.1.2 Coarse and Fine Aqqreqates
Course aggregate, which is the material retained on an AASHTO No.4 Sieve, shall consist of crushed rock or crushed gravel, having at least 2 faces mechanically crushed.
Fine aggregate which is the material passing AASHTO No.4 sieve, shall consist of 100% crushed material from rock or boulder. Fine aggregate shall be stored separately and no natural sand will be allowed in the mix.

The coarse 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 30.
b. The loss when subjected to five cycles of the Sodium Sulfate 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 have a liquid limit of not more than 25 and a Plasticity Index of not more than four 4, as determined by AASHTO T-89 and T-90, respectively.
e. The portion of aggregate retained on the 9.5 mm (3/8") sieve shall not contain more. than 15% by weight of flat and/or elongated particles (ratio of maximum to minimum dimension = 5:1).

The three dimensions of particles shall be nearly equal. For at least 80% of the particles, the proportion between the largest and smallest dimension shall be 2.5 or less and for at least 95% of the particles the same proportion shall be 3 or less.

The percentage of particles having certain proportions between their largest and smallest dimensions (i.e. between the largest distance the particles can fill out between two parallel planes that will permit the particle to pass), shall be determined in the following way:

I. Form a sample of course aggregates, all particles passing No.4 sieve shall be eliminated. The sample shall be of sufficient quantity that at least 100 particles remain.
ii. By means of a sliding caliper, the largest and smallest dimensions, as defined above, shall be determined for each particle and its proportion calculated.
iii. The total weights of particles having the proportions 2.5 or less and 3 or less, are determined and their percentage in relation to the total sample are calculated.

29.5.1.3 Filler Materials: When the combined grading of the coarse and fine aggregates is deficient in material passing the AASHTO NO.200 sieve, mineral filler material shall be added as approved by the Employer. The filer shall consist of finely divided mineral matter such as rock dusts, hydrated lime, hydraulic cement or other suitable mineral matter free from lumps, balls or other deleterious material and shall confirm to the following gradation:
US Standard Sieve Percent Passing by Weight
No.30 (0.600 mm) 100
No.50 (0.300 mm) 95-100
NO.200 (0.075 mm) 70-100

29.5.2 Asphaltic Material
Asphaltic binder to be mixed with the aggregate to produce asphaltic concrete shall be asphalt cement, with Penetration Grade of 40-50 or 60-70 as specified by the Employer. Generally it shall I meet the requirement of AASHTO M-20.

29.5.3 Asphalt Concrete Mixture
a. The grading of the combined mineral aggregates for the asphaltic concrete mixtures
(class A and B) for wearing courses shall conform to the following requirements:

US Standard Sieve Sizes Percentage passing by weight for
Mix Designation (Compacted Thickness)
Class-A (50-100 mm) Class-B (35-60mm)
-
1" (25 mm) 100 -
3/4" (19 mm) 90-100 100
1/2" (12.5 mm) - 75-90
56-70 -
3/6" (9.5 mm) 60-80
No.4 (4.75 mm) 35-50 40-60
No.8 (2.38 mm) 23-35 20-40
No.50 (0.30 mm) 5-12 5-15
No.200 (0.075 mm) 2-8 3-8

b. The proportion of asphalt contents shall not be less than 3.5% of the total mix, by
weight, for both Class A and B mixes.

c. The asphalt concrete mixture shall meet the following Marshal Test Criteria:

Compaction, number of blows, each end of specimen 75
Stability 1000 Kg (Min)
Flow, 0.25 mm (0.01 inch) 8 -14
Percent air voids in mix 5-8
Percent voids filled with bitumen 65 - 75
Percent voids in mineral aggregates 14 (Min)
Loss of Stability 20% (Max)

29.5.4 Job-Mix Formula
At least one week prior to production, a Job-Mix Formula (JMF) for the asphaltic concrete wearing course mixture or mixtures, to be used for the project, shall be established jointly by the Employer and the Contractor.
The JMF shall be establishe~ by Marshall Method of Mix Design according to the procedure prescribed in the Asp.halt Institute Manual Series No.2 (MS-20), May 1984 Edition or the latest Editiem.

The JMF, with the allowable tolerances, shall be within the master range specified in Section Each JMF shall indicate a single percentage of aggregate passing each required sieve and a single percentage of asphalt to be added to the aggregates.

After the JMF is established, all mixtures furnished for the project represented by samples taken from the asphalt plant during operation, shall conform'thereto within the following ranges of tolerances:
Combined aggregates gradation Passing No.4 and larger sieves Passing NO.8 to NO.100 sieves

Passing NO.200
Asphalt Content
Weight percent of total mix
:t 6.0 % :t 4.0 % :t 2.0 %
:t 0.3 %
In addition to meeting the afore-mentioned requirements, the mixture as established by
the JMF shall also satisfy the following requirement:.
Loss of Marshall Stability by Immersion of specimen in water at 60 DC, for 24 hours, as compared with the stability measured after immersion in water at 60 DC, for 20 minutes shall not exceed 20%. If the mixture fails to meet this criterion, the JMF shall be modified or an anti-stripping agent shall be used.

Should a change of sources of materials be made; a new Job Mix Formula shall be established before the new material is used. When unsatisfactory results or other conditions make it necessary,

a new job Mix Formula shall be required.

29.5.5 Asphalt Additives
Cellulose Fibers shall be used as an asphalt additive with the aim of eliminating bleeding tendencies. Normally 0.20-0.25% by weight of the total mix will be required. The fibers shall be fed into the plant by a separate feeder system or by hand into every batch. The weight of the fibers shall be determined in accordance with the percentage specified in the job-mix-formula.

29.6 CONSTRUCTION REQUIREMENTS

29.6.1 Asphaltic Concrete Mixing Plant
Plants used for the preparation of asphaltic .concrete mixtures shall be either "Batching Plants" or "Continuous Mixing Plants", conforming to AASHTO M 156, and of adequate capacity, coordinated and operated to produce a mixture within the limits of these specifications.

29.6.2 Preparation of Aggregates
Before being fed to the dryer, aggregates for the asphaltic concrete shall be separated into two or more sizes and stored separately. One storage unit shall contain aggregate of such size that 80 percent will pass Sieve No.4, and" the other unit shall contain aggregate of such size that 80 percent will be retained on Sieve No.4. Should the Contractor elect to use natural fine material, a separate storage unit for material shall be provided in addition to the two aforementioned units. If filler is used as a separate component, it shall also 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 of uncontrolled combination of materials of different grading shall be discontinued and the segregated or degraded material shall be re¬screened, or wasted, and, if necessary passed through the dryer before being mixed.
Fine and coarse aggregates shall be dried and heated so that when delivered to the mixer they shall not be at a temperature not more than 15°C above the mixing temperature for the asphalt cement being used, or as directed by the Employer.

29.6.3 Hauling Equipment
Trucks used for hauling bituminous mixtures shall have tight, clean, smooth metal beds which have been thinly coated with an approved material to prevent the mixture from adhering to the beds. Each truck shall have a cover of canvas or other suitable material of such size as to protect the mixture from the weather. When necessary, so that the mixture will be delivered on the road at the specified temperature, covers shall be securely fastened.