This study was performed at the Highway Materials Research Laboratory in Lexington, Kentucky. In this study the various sands were combined with a sphalt cement of penetration 60 to 70 and tested by the Marshall method to determine the physical characteristics of the mixtures. Other variables investigated were the hardness of the asphalt cement and the amount of mineral filler. A coefficient of friction was determined, by means of a laboratory testing device, for each of the mixtures.
Due to the promising results of the laboratory testing, and the successful re-surfacing of bridges with silica sand-asphalt mixtures in the New York area; the Research Division of the Kentucky Department of Highways, in June 1958, recommended silica sand-asphalt for the re-surfacing of Clark Memorial Bridge in Louisville. All laboratory testing of sands up to that time had been of crushed sandstones. The lack of sands tone in the Louisville area led to an investigation of the possibility of blending locally available bank and river sands. Various blends of the river and bank sand were tested, with and without mineral filler; and it was concluded that a satisfactory mixture could be manufactured using these sands
