ITEM 301 ASPHALT 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 the Laboratory’s approval the desired percentage of the aggregate passing the No. 4 (4.75 mm) sieve and blend of individual components that will produce a satisfactory mix. The Laboratory will then establish the required binder content within a range of 4 to 8 percent. Do not make changes in these JMF values due to unsatisfactory results or other conditions except as authorized by the Laboratory. If proposing to change the source of materials, give the Laboratory a one-week notice to allow the Laboratory to take samples and check the JMF before making the change.
In addition to the requirements of 401.04, the Contractor may use 10 to 50 percent of reclaimed asphalt concrete pavement in Item 301 Asphalt Concrete Base. If using greater than 20 percent of reclaimed asphalt concrete pavement, submit the viscosity of the recovered binder from the reclaimed pavement to the Laboratory. The Laboratory will establish the JMF according to 401.02.
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. The Laboratory will determine the sequence in which the several aggregates are drawn or weighed.
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 the paver is a minimum of 250 °F (120 °C), and that the mix temperature 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 from 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).
Correct variations in excess of slope or surface tolerances by adding or removing material in a manner satisfactory to the Engineer. The Contractor may use asphalt concrete approved by the Engineer.
301.06 Basis of Payment. The Department will pay for accepted quantities, complete in place, at the contract price as follows:
Item unit Description
301 Cubic
Yard Asphalt Concrete Base
(Cubic Meter)