480ASPHALT SURFACE TREATMENT

480.1DESCRIPTION—This work is two applications of emulsified asphalt, with each application of emulsified

asphalt immediately followed by an application of coarse aggregate.

480.2MATERIAL—

Provide aggregate to achieve at least the SRL designation indicated in the Contract Item and from sources supplying aggregate for use in wearing courses. The Contractor may provide a blend of two aggregates if the blend has an SRL equal to or better than that specified. Blends are 50% by weight of each aggregate. Mix the aggregates by an approved method.

480.3CONSTRUCTION—At least 2 weeks before the scheduled start of work, submit a surface treatment

design for the Representative’s review. Design the surface treatment according to Appendix E of Bulletin 27.

at the following rates and according to the following sequence:

FIRST APPLICATION Apply emulsified asphalt at a rate of 0.25 gallon per square yard to 0.50 gallon per square yard. Use a mechanical spreader to spread 25 pounds per square yard to 45 pounds per square yard of No. 67 coarse aggregate. Roll the aggregate as specified below and then sweep off the loose material. Allow the first application to cure to the Representative’s satisfaction before spreading the second application.

SECOND APPLICATION Apply emulsified asphalt at a rate of 0.25 gallon per square yard to 0.50 gallon per square yard. Use a mechanical spreader to spread 15 pounds per square yard to 30 pounds per square yard of No. 8 coarse aggregate. Roll the aggregate as specified below.

from of 40 pounds per square inch to 50 pounds per square inch. Use a sufficient number of rollers to cover the width of stone spread during the first pass. When the emulsified asphalt has a tacky surface, backroll the aggregate with a pneumatic-tire roller or a steel-wheel tandem roller until the aggregate adheres to the emulsified asphalt. If directed, eliminate backrolling. Do not roll in the vibratory mode.

480.4MEASUREMENT AND PAYMENT—