The attached report reflects the degree of excellence sought in bituminous concrete pavements in Kentucky during the past several years. In the evolvement of the present state of the art, idealized concepts of mixture design have been dutifully tempered with practical considerations, experience factors, and performance features which may not be altogether apparent from this report alone. In substance, the study has been concerned with aggregate gradations, construction operations, and quality of the pavement surface. The achievement of gradation control in the dust of filler sizes has provided opportunities to further optimize mixture requirements. Permissive blending of sands has enabled the utilization of a broader array of materials. Surface appearance has improved; stability has been increased about four-fold; densities are higher; and enhanced durability already seems evident. From these standpoints, the objectives sought are now seemingly replete. Two factors remain sufficiently ominous and formidable to command further attention.

Report Date


Report Number

No. 239

Digital Object Identifier



The opinions, findings, and conclusions in this report are not necessarily those of the Department of Highways or the Bureau of Public Roads.