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Section 23 – Asphalt Concrete

for (3/4”) maximum, medium grading as specified in Section 39, “Asphalt Concrete” of the State

For all asphalt concrete for structural section of one and one-half inches (1-1/2”) or greater

in thickness, the paving asphalt shall be viscosity gage AR-8000 as specified in Section 92,

“Asphalts”, of the State Specifications. All aggregate passing the number 200 sieve shall be

mechanically crushed material and natural sand shallnot exceed 10%.

Unless otherwise shown or specified in the Contract, the aggregate for all other structural

sections shall be Type B and shall meet the specifications for one-half inch (1/2”) maximum,

medium grading as specified in Section 39, “Asphalt Concrete”, of the State Specifications.

Asphalt binder and proportioning shall be as specified in this Section 23, in the Contract, or by

RECYCLED ASPHALT PAVEMENT

At the option of the Contractor, reclaimed asphalt pavement (RAP) may be substituted for

virgin aggregate at a rate of up to fifteen percent (15%) by total weight of aggregate in the

asphalt concrete. RAP shall be permitted for use in all asphalt concrete construction except for

the top four inches (4”) of pavement on major streets. For the purpose of this section, major

streets shall be defined as all County roadways within the limits of work for the Project with two

or more striped vehicular traffic lanes in one direction. A list of any additional streets designated

as major may be indicated on the Plans or provided in the Special Provisions.

RAP stockpiles may be from a single source or multiple sources and shall consist solely of

RAP material. Stockpiling and processing of RAP shall be performed in a manner that will

prevent contamination and segregation, resulting in a uniformly blended and homogenous

material. The height of RAP stockpiles shall be limited to fifteen feet (15’). Heavy equipment

shall not be permitted on RAP stockpiles. Stockpiles shall be located on surfaces that are

smooth and free of debris and organic material. The Agency shall be given unrestricted access

to stockpiles for inspection and testing as deemed necessary.

The amount of virgin asphalt binder to be mixed with the combined virgin aggregate and

RAP will be determined by the Contractor in conformance with California Test Method 367, with

the exception that the C.K.E. test shall be waived and the Test Method ASTM D 2041 shall be

used to determine the Maximum Theoretical Density. In lieu of historical data, the approximate

asphalt demand may be calculated in accordance with the Asphalt Institute Handbook MS-4.

The percentage of RAP and the mixture gradation X values shall be designated at the time

of the asphalt mix design. Subsequent changes in the X values of the aggregate grading and

design asphalt content will not be permitted without additional testing to verify compliance with

the requirements for stability and air voids. Changes will not be allowed without the approval of

The proposed mix design shall be submitted to the Agency for review and approval. In

addition to the requirements of Section 39 of the State Specifications, the Contractor shall

provide the Agency with the following information:

1. Location of RAP stockpile

2. The individual and average asphalt content test results representative of the

proposed RAP stockpile based on a minimum of 1 test per 1,000 tons of material in

the RAP stockpile. The asphalt content shall be determined in accordance with

ASTM D 2172, Method B.

3. The individual and average asphalt-free gradations of the RAP material derived from

the samples used to determine the asphalt content.

4. The individual and average asphalt viscosities of the recovered asphalt derived from

the samples used to determine the asphalt content. Asphalt viscosities shall be

determined in accordance with ASTM D 2170.