Wearing surfaces of Kentucky rock asphalt applied in thin layers were used extensively in Kentucky for many years. Sand asphalts, which generically include rock asphalt, are now a reemergent generation of surfacings to be investigated (1,2,3). An interim report (4) related the construction and interim performance of trial surfacings in Logan County. Two bridge deck sand-asphalt surfacings have been reported (5). This report covers sand-asphalt construction and performance since 1966. Pertinent project data and comments are contained in Appendix A. The several Special Provisions are included in Appendix B.
Interest in sand-asphalt wearing surfaces issues from the skid-resistant qualities which are inherent in angular (unpolished) quartz sands. Blends of quartz sands together with crushed limestone sands have been employed experimentally to obtain strength and durability--and to evaluate the effect of limestone or carbonate sands on skid-resistance. Quartz concentrations in the order of 50 percent of the combined sand have not provided the desired assurances of persistent skid resistance; therefore, recourse to mixtures richer in quartz has become imperative. Experimental work is continuing in that direction
