SECTION 314—PENETRATION SURFACE COURSES
314.01 Description
This work shall consist of constructing a wearing surface of crushed stone, slag, or crushed gravel pene- trated with asphalt in accordance with these specifications and in conformity with the lines shown on the plans or as established by the Engineer. 314.01
314.02 Materials
a.Asphalt may be changed one viscosity grade by the Engineer during construction at no change in the contract unit price. Asphalt shall conform to Section 210 as applicable.
b.Aggregate shall be crushed stone, slag, or crushed gravel that conforms to Section 203 as applicable. The Contractor shall not haul aggregate directly from a washing plant to be used in the work.
c.Fine aggregate shall be Grading B sand conforming to Section 202.
314.03 Weather Limitations
The Contractor shall not place penetration courses when surfaces are wet, when the air temperature is below 50 degrees F , or when the surface temperature is below 70 degrees F . The Contractor shall furnish a properly calibrated infrared instrument for the purpose of measuring the surface temperature and shall measure the surface temperature for conformance to the aforementioned temperature range prior to placement.
314.04 Equipment
The Engineer will evaluate the Contractor’ s equipment for acceptance in placing the materials prior to performance of the work. Equipment that will handle the materials and produce the completed course or courses in accordance with these specifications is acceptable.
a.Spreaders: Spreaders for coarse aggregate shall be self-propelled spreading and leveling machines or spreader boxes equipped with shoes or runners of sufficient width and length to preclude damage or displacement of the subgrade or other courses. The mechanical spreader for the fine aggregate shall conform to Section 312.03.
b.Distributor: The distributor shall be so designed, equipped, maintained, and operated that asphalt at the specified temperature range may be applied uniformly on variable widths of surface up to 15 feet. The distributor shall be capable of applying the asphalt at readily determined and controlled rates from 0.05 to 2.0 gallons per square yard, with uniform pressure, and with an allowable variation from any specified rate not to exceed 0.02 gallon per square yard. Distributor equipment shall include a tachometer, pressure gages, accurate volume-measuring devices, or a calibrated tank and a thermometer for measuring temperatures of the contents of the tanks. Distributors shall be equipped with a power unit for the pump and full circulation spray bars adjustable laterally and vertically. The distributor shall be equipped with a positive shutoff control that will prevent lapping at the junction of two applications. When necessary, the distributor shall be equipped with a positive means of deflecting the spray to prevent coating of adjacent structures and appurtenances. A connection for attaching hand spraying devices shall be provided and the Contractor shall use hand-spraying equipment to cover variable-width areas, patches, and other areas where spray bar application is impractical or would result in excessive asphalt material.
c.Rollers: The number, type, and weight of rollers shall be sufficient to compact the mixture to the required density. 314.02
314.05 Procedures
Cover material shall be applied in full-lane widths up to 12 feet. The Contractor shall make laps only at lane dividers or at the crown of the roadway. Successive laps at lane dividers and the crown of the roadway shall be staggered from 3 to 6 inches. The Contractor shall condition the road surface to receive the materials in accordance with Section 312.04.
a.Rates of Application: Asphalt Aggregate (gal/sq yd) (lb/sq yd) Light Courses Coarse aggregate No. 56 60-139 Asphalt for penetration 0.75-1.20 Choke aggregate No. 68, or 20-30 No. 78, or 22-28 No. 8, or 18-25 Grading B sand 10-15 Asphalt for seal 0.15-0.30 Seal aggregate, No. 78, or 22-28 Seal aggregate, No. 8 18-25 Heavy Courses Asphalt for tack coat 0.10-0.20 Coarse aggregate, No. 56 140-200 Asphalt for penetration 1.30-1.80 Choke aggregate, No. 68 20-30 Asphalt for seal 0.20-0.35 Seal aggregate, No. 78 or 22-28 Seal aggregate, No. 8 18-25
b.Sequence and Methods:
1.If deemed necessary by the Engineer or specified in the contract, the Contractor shall apply a tack coat in accordance with Section 310 immediately prior to the application of coarse aggregate.
2.The coarse aggregate shall be uniformly spread on the prepared base or surface at the specified rate of application. This application shall be mixed and shaped by the use of multiple-blade road planers or other equipment deemed acceptable by the Engineer. Immediately following mixing and shaping operations, the Contractor shall roll the surface with a 10-ton, three-wheel or tandem steel wheel roller and, for a heavy penetration surface course; the Contractor shall uniformly choke the surface with No. 68 aggregate. The surface will be tested by the Engineer using a 10-foot straightedge. The variation of the surface from the testing edge of the straightedge between any two contacts with the surface shall be not more than 1/4 inch. The Contractor shall correct any humps or depressions exceeding the specified 314.05
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Source: Road and Bridge Specifications, 2020 Edition. Pages 417–419 of 1,065. View official source ↗