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SECTION 645

ASPHALT CONCRETE SURFACE COURSE,

TYPES I-1, I-2, AND HDS

645-1 DESCRIPTION.

The work covered by this section consists of the construction of a asphalt plant mix surface course composed of a mixture of coarse and fine aggregates, asphalt cement, and mineral filler and other additives when required, properly laid upon a prepared surface, in accordance with these specifications and in conformity with the lines, grades, thickness, and typical sections shown on the plans.

645-2 MATERIALS.

All materials shall meet the requirements of Division 10 shown below:

Coarse aggregate Article 1012-1

Fine aggregate Article 1012-1

Mineral filler Article 1012-1

Stone screenings Article 1012-1

Natural sand Article 1012-1

Asphalt cement, Grade AC-20 (See Standard Special Provisions) Article 1020-2

Non-strip additive Article 1020-8

645-3 COMPOSITION OF MIXTURE.

(A) General Requirements:

A combination of graded coarse and fine aggregates will be required which will produce an acceptable mix. The coarse aggregate shall consist of standard size aggregates.

At least 1/2 of the fraction passing the No. 200 sieve shall be mineral filler or stone screenings.

The percentage of natural sand in Asphalt Concrete Surface Course, Type HDS shall not exceed 20 percent by weight of total aggregate in the mixture.

(B) Job Mix Formula:

A job mix formula will be established by the Engineer for the particular materials the Contractor proposes to use in accordance with Article 610­3 or Article 611­3. The job mix formula target values will be established such that when the tolerances (where applicable) are applied, the mixture values will be within the design criteria listed in Table 645.

TABLE 645

ASPHALT CONCRETE SURFACE COURSE DESIGN CRITERIA
Gradation Design Limits (Percent Passing by Weight)
Sieve Size
Types I-1 and HDS
Type I-2
JMF Tolerance
3/4"
100
100
0
1/2"
96 - 100
96 - 100
± 2
3/8"
85 - 100
85 - 100
± 5
No. 4
50 - 85
67 - 92
± 7
No. 8
33 - 67
55 - 75
± 5
No. 16
22 - 53
± 5
No. 40
9 - 40
15 - 45
± 5
No. 80
2 - 20
7 - 22
± 5
No. 200 (Dust)
2.0 - 8.0
3.0 - 9.0
± 2.0
AC Content
4.0 - 7.5%
4.5 - 8.5%
± 0.5%
Mix Temperature
250 - 325F.
250 - 325F.
± 15F.
4" Marshall Method Design Requirements
Requirement
Type I-1
Type I-2
Type HDS
Number of Blows, each end (4 inch specimen)
50
50
75
Stability, Minimum (lbs.)
1300
750
1500
Flow (0.01 in.)
7 - 18
7 - 18
7 - 14
Voids in Total Mix, VTM, (%)
4 - 6
4 - 7
4 - 6
Voids in Mineral Aggregate, VMA (% Minimum)
15
16
15
VMA Filled with Asphalt, VFA, (%)
60 - 75
60 - 75
60 - 75
**Retained Tensile Strength, TSR (% Minimum)
75
75
75

** ASTM D 4867 "Effect of Moisture on Asphalt Concrete paving Mixtures" as modified by the Department.

In addition to the requirements of Table 645, the amount of material between any adjacent sieves, except between the 1/2 inch and the 3/8 inch sieves shall not be less than 4 percent.

Additives may be utilized to achieve the required tensile strength ratio, subject to approval of the Engineer.

(C) Requirements for Completed Plant Mix:

The completed plant mix shall conform to the job mix formula within the tolerances shown in Table 645.

When a mix has been tested and has been found to be outside of the design criteria, the Engineer may require the removal from the road of any of this mix which has been placed and which is represented by the test results. All such mix which has been removed shall be replaced with plant mix which is within the job mix formula and allowable tolerances at no cost to the Department.

645-4 CONSTRUCTION REQUIREMENTS.

The asphalt plant mix shall be produced, transported to the site, placed, and compacted in accordance with the applicable requirements of Section 610.

The asphalt plant mix shall be compacted to a density of at least 95% of the laboratory density as determined by the Marshall method of test.

Density control and determination shall be as specified in Article 610­11.

645-5 METHOD OF MEASUREMENT.

The quantity of surface course to be paid for will be the actual number of tons of surface course which has been incorporated into the completed and accepted work. The surface course will be measured by being weighed in trucks on certified platform scales or other certified weighing devices.

645-6 BASIS OF PAYMENT.

The quantity of surface course, measured as provided in Article 645­5, will be paid for at the contract unit prices per ton for "Asphalt Concrete Surface Course, Type I-1", "Asphalt Concrete Surface Course, Type I-2", and "Asphalt Concrete Surface Course, Type HDS".

Furnishing asphalt cement for the mix will be paid for as provided in Article 620­5 for "Asphalt Cement for Plant Mix".

Furnishing asphalt laboratory facilities will be paid for as provided in Article 615­3 for "Field Laboratory Rental, Asphalt Plant Mix".

Furnishing non-strip additive will be paid for as provided in Article 622­5 for "Non-Strip Additive".

The above prices and payments will be full compensation for all work covered by this section, including but not limited to producing, weighing, transporting, placing, and compacting the plant mix as specified in Section 610; furnishing the asphalt cement and all other materials for the plant mix; furnishing and applying tack coat as specified in Section 605; furnishing scales; maintaining the surface course until final acceptance of the project; and making any repairs or corrections to the surface course that may become necessary.

Payment will be made under:

Asphalt Concrete Surface Course, Type I-1 Ton

Asphalt Concrete Surface Course, Type I-2 Ton

Asphalt Concrete Surface Course, Type HDS Ton

OPEN-GRADED ASPHALT FRICTION