In 1969, a 6.6-mile section of relocated KY 15 in Perry and Knott Counties was paved utilizing coal-tar (RT-12) concrete base and surface. This project was authorized under the Appalachian Regional Development Act of 1965 and was designated as experimental as a means of implementing a section of the Act.

Two nearby sections of KY 15, containing asphalt (PAC-5) concrete base and surface, were designated as control sections and used for comparison purposes. With the exception of the bituminous material, the experimental and control sections were purposefully made equal in all other respects. A design soil CBR of 9 was used throughout, and the EWL's were estimated at 40-80 million. Total thickness for each section was 17.5 inches (11 inches DGA base and 6.5 inches bituminous concrete). The coal-tar binder was substituted for the asphalt cement on the basis of equal volume. A project map is shown in Figure 1.

Report Date


Report Number

No. 346

Digital Object Identifier



The contents of this report reflect the views of the author who Is responsible for the facts and the accuracy of the data presented herein. The contents do not reflect the official views or policies of the Kentucky Department of Highways. This report does not constitute a standard, specification, or regulation.