Polish Resistance of Fine Aggregates in Portland Cement Concrete Pavements

Abstract

Many state agencies have limited the use of some sources of fine aggregates in portland cement concrete pavements because of possible skid issues related to the incorporation of such sands. The Texas Department of Transportation, for example, has adopted the acid-insoluble residue (AIR) test to identify polish-resistant aggregates. Because calcium carbonate is soluble in acid, no carbonate sand passes the AIR test, which has a minimum limit of 60% AIR in Texas. This paper describes research that evaluated the polish resistance of aggregates with a laboratory concrete performance test. Concrete slabs made with different fine aggregates were evaluated for skid with the use of a circular track meter, a dynamic friction tester, and a three-wheel polishing device. For each concrete slab tested, the change in texture and friction was monitored for 160,000 polishing cycles. To ensure that the values obtained in the laboratory related to field performance, test sections constructed with 100% limestone sand and blended sands were also evaluated. Results show that some aggregates that failed the AIR test performed as well as some siliceous fine aggregates that passed the AIR test. Other aggregate tests such as the fine aggregates micro-Deval have been shown to relate more closely to the concrete performance tests performed under laboratory conditions. Results obtained from laboratory and field testing showed that blending small quantities of siliceous sand with limestone sands considerably increased the skid resistance of concrete.