PHYSICAL CHARACTERISTICS OF POLISH RESISTANCE OF SELECTED AGGREGATES

The British polishing wheel and the British pendulum tester were used to provide polish values similar to skid resistance information on several construction aggregates potentially usable in bituminous pavements. The aggregates included lightweight aggregates (expanded shales), industrial slags, trap rock, chert, siliceous gravel, and carbonate aggregates. Ranked from good to poor polish values, the aggregates are expanded shale; soft carbonates with high acid-insoluble residue contents, some limestones and dolomites; sandstone; boiler slag; trap rock; hard limestones with low acid-insoluble residue contents; steel slag; siliceous gravels; and chert. Petrographic studies of the aggregates demonstrate the trend of soft or surface-renewing rock providing the best results, grading to harder, or more finely crystalline, aggregates yielding the poorest results within similar lithologic types. More research is needed to determine the potential for better use of several aggregates not currently or commonly used in Kansas bituminous pavements. Future research should include field studies of aggregates that have good potential in the laboratory tests but are not now being used.