Citation

Whitehurst EA, Goodwin WA. Highw. Res. Board bull. 1958; 186: 1-7.

Copyright

(Copyright © 1958, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

As a result of a 5-year study of pavement slipperiness in tennessee it was concluded that the type of aggregate used in the surface played a major role in determining the eventual slipperiness. The results of this study have been previously reported. Present investigations are being made to determine what aggregates or combinations of aggregate may be used benefically. To minimize expensive and time- consuming field experiments, a device has been constructed to permit the testing of various surface mixtures in the laboratory. The device consists of an automobile wheel, driven by a variable speed motor, which spins against the test specimen. The specimen, either portland cement or asphaltic concrete, is 38 in. Square and 6 in. Thick. The speed of rotation of the wheel may be varied from below 10 to above 40 mph and the load of the wheel against the specimen may range from about 100 to 1,200 lb. Tests may be made at one point on the specimen or the specimen may be moved in both directions while the wheel is spinning, thus producing a planing action across any desired portion of the specimen. A test on a single location usually requires from 30 min to 2 hrs. The measured parameter is the wattage required to drive the motor at the selected speed, and as the pavement becomes slippery less power is required. A graph of wattage versus time is taken through use of a recording wattmeter, the relative decrease in power demand being indicative of the relative potential slipperiness of various mixtures. Typical power demand curves for several paving mixtures are presented.