301ASPHALT CONCRETE BASE

301.01 Description

301.02 Composition

301.03 Mixing

301.04 Spreading and Finishing

301.05 Spreading and Surface Tolerances

301.06 Basis of Payment

301.01 Description. This work consists of constructing a base course of

aggregate and asphalt binder, mixed in a central plant and spread and compacted on a prepared surface. The requirements of Item 401 apply, except as modified by this specification.

301.02 Composition. Furnish aggregate for the mix that conforms to the

following gradation: Sieve Size Total Percent Passing 2 inch (50 mm) 100 1 inch (25.0 mm) 75 to 100 1/2 inch (12.5 mm) 50 to 85 No. 4 (4.75 mm) 25 to 60 No. 8 (2.36 mm) 15 to 45 No. 16 (1.18 mm) 10 to 35 No. 50 (300 µm) 3 to 18 No. 200 (75 µm) 1 to 7 Submit for OMM’s approval the desired percentage of the aggregate passing the No. 4 (4.75 mm) sieve and blend of individual components. The Contractor may use reclaimed asphalt concrete pavement according to 401.04. OMM will establish the required binder content within a range of 4.7 to 7 percent. Do not make changes in these JMF v alues due to unsatisfactory results or other conditions except as authorized by OMM. Obtain a new JMF approval for any desired change to an existing JMF.

301.03 Mixing. If using a batch plant, use screens with openings of sizes that

result in a reasonably balanced separation of the dried and heated aggregate into a minimum of two bins.

301.04 Spreading and Finishing. Ensure that the maximum compacted depth

of any one layer is 6 inches (150 mm). Ensure that the temperature of the mixture when delivered to th e paver is a minimum of 250 °F (120 °C). Ensure the temperature of the mixture is sufficient for the roller coverage to be effective in compacting the mixture .

301.05 Spreading and Surface Tolerances. Do not exceed 3/8 inch (10 mm)

in surface variation fro m the testing edge of a 10 -foot (3 m) straightedge. If using Item 301 Asphalt Concrete Base as a subbase for a rigid pavement or base, do not exceed a variation of 1/4 inch (6 mm).