OVERLAYS FOR PLAIN JOINTED CONCRETE PAVEMENT

This report describes the construction and performance of 4 concrete and 16 asphalt overlay test sections after nine years of traffic. The test sections were placed on I-85 which carries a substantial number of heavy trucks to determine what treatments and overlay type and thickness would give acceptable performance. The concrete overlay sections were placed in 1975 and consisted of 3 inch, 4-1/2 inch, and 6 inch CRC and 6 inch jointed PCC with 15 ft. and 30 ft. joint spacing. The asphalt sections were placed in 1976 with the variables being overlay thickness of 2 inches, 4 inches, and 6 inches and the placement of two geotextiles and strips of a waterproofing membrane for each overlay thickness. An Arkansas base test section was also included in the experiment. The conclusions are that a minimum thickness of 6 inches is required for a CRC or PCC overlay if the original pavement has no major structural problems and a minimum overlay thickness of 4 inches is required for an asphalt overlay with placement of strips of waterproofing membrane over the joint. If the existing concrete pavement system has major structural problems, these minimum values will not be valid. (Author)