The Polishing of Road Stones on a Drum Apparatus

摘要

In preliminary tests, the effects of slider wear and temperature on the Drag Tester No. were determined. The principal tests showed that the Drag Tester No. decreases linearly with the logarithm of the number of passes. In the polished state, pure limestone produced the lowest friction level followed by uncrushed gravel, slag and crushed gravel, in this order. The Drag Tester No. of limestone-crushed gravel mixtures of uniform gradation was found to increase linearly with the volume percentage of the more skid resistant aggregate. At least 25% gravel must be added to pure limestone surfaces to achieve satisfactory friction levels. The skid resistance of polished limestone can also be increased by quartz sand roughening and, to a lesser extent, by chemical etching. (Author)