ITEM 302 ASPHALT CONCRETE BASE
302.01 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 Items 401, 402, 403, 440 apply with the additional requirements of this specification.
302.02 Composition
A.General. Furnish a mixture that conforms to the following gradation and properties: TABLE 302.02-1 MIX COMPOSITION Property Limits 2 inch (50 mm)[1] 100 1 1/2 inch (37.5 mm)[1] 85 to 100 1 inch (25.0 mm)[1][2] 68 to 88 3/4 inch (19.0 mm) [1][2] 56 to 80 1/2 inch (12.5 mm)[1][2] 44 to 68 3/8 inch (9.5 mm)[1] [2] 37 to 60 No. 4 (4.75 mm)[1] 22 to 45 No. 8 (2.36 mm)[1] 14 to 35 No. 16 (1.18 mm)[1] 8 to 25 No. 30 (600 µm)[1] 6 to 18 No. 50 (300 µm) [1] 4 to 13 No. 200 (75 µm) [1] 2 to 6 Binder Content [3] 3.9 – 6.0 [4] F/A Ratio, max. [5] 1.4 Blows [6] 70 Stability, lb [6] (N) 3000 (13,345) [Min] Flow, 0.25 mm [6] 28 [Max] Design Air Voids [7] 4.0 Voids in Mineral Aggregate % 12.0 [Min] [1] Sieve, Percent Passing [2] Provide aggregate to retain a minimum of 7 percent of the material on each of these sieves. This requirement applies to the gradation of the JMF and the mix production according to Item 403. [3] See tables in 440.05 [4] Percent of total mix [5] Using effective asphalt binder content [6] ASTM D5581 [7] Percent, Supplement 1036 Use equipment that meets the requirements of a Level 3 laboratory as specified in Supplement 1041. Produce batches of asphalt concrete base in the amount that will result in a compacted specimen 3.75 ±0.05 inch (95 ±1.3 mm) in height. This amount is about 4050 grams.
B.Compaction of Specimens. Fill the mold with asphalt concrete base by placing approximately one-half of the batch in the mold and spading it vigorously with a heated spatula or trowel 15 times around the perimeter and ten times in the interior. Place the second half of the batch in the mold and spade the mixture in the same manner.
C.Stability Correlation Ratios. Convert measured stability values for specimens that depart from the standard 3.75-inch (95 mm) thickness to an equivalent 3.75-inch (95 mm) value by multiplying the stability value by the appropriate correlation ratio as follows: TABLE 302.02-2 STABILITY CORRELATION RATIOS Approximate Thickness of Specimen, inches (mm) Correlation Ratio 3 1/2 (89) 1.12 3 9/16 (90) 1.09 3 5/8 (92) 1.06 3 11/16 (94) 1.03 3 3/4 (95) 1.00 3 13/16 (97) 0.97 3 7/8 (98) 0.95 3 15/16 (100) 0.92 4 (102) 0.90
302.03 Placement. Provide and operate anti -segregation equipment in accordance with the
requirements of 401.03.C excluding the use of remixing pavers. Use anti -segregation equipment for all project line items containing 1000 or more cubic yards (766 cubic meters) of Item 302 Asphalt Concrete Base. Ensure that the compacted depth of any one layer is a minimum of 4 inches (100 mm) and a maximum of 7.75 inches (190 mm). If the plan thickness is 7.0-7.75 inches (178 mm – 190 mm) and District Testing confirms the JMF and mixture production has 95% pas sing the 1.50 inch (37.5 mm) sieve, the 302 may be placed in two lifts if requested by the Contractor. One lift of plan thickness will be required if top size aggregate dragging occurs. Ensure that the temperature of the mixture when delivered to the 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.
302.04 Acceptance. The Department will base acceptance of the asphalt concrete mix on the
method specified in the Contract line item description (i.e. 449).
302.05 Basis of Payment. Include the cost of asphalt material to coat vertical faces and seal
joints and gutters in the contract unit price for Item 302. The Department will pay for accepted quantities at the contract price as follows: Item Unit Description 302 Cubic Yard Asphalt Concrete Base (____) (Cubic Meter)
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Source: Construction and Material Specifications, 2023 (rev. 7/17/2026) Edition. Pages 147–149 of 892. View official source ↗