Investigation of Tar-Rubber Pavement Overlays

The purpose of this study was to determine why tar-rubber pavements are experiencing failures from usage by aircraft with high tire pressures. Failures are in the form of depressions and rutting, raveling of joints, and deterioration from fuel spillage. The study was accomplished by performing pavement field studies and sampling at 10 selected airfields and subjecting the tar-rubber pavement samples from these airfields to a laboratory testing program. The investigation indicated the following: (1) performance of tar-rubber pavements is dependent upon the quality of construction and subsequent usage of the pavement; (2) spillage of JP-4 fuel is more detrimental than spillage of hydraulic fluid on a short-term basis; (3) use of heavy rubber-tired rollers appears to be necessary during construction in order to meet the density requirements; and (4) tar-rubber pavements perform poorly in all areas adjacent to refueling pits. Based on these findings the following recommendations are considered warranted: (1) very strict quality control should be enforced during construction so that proper densities can be obtained; (2) portland cement concrete pavements should be placed in refueling pit areas instead of tar-rubber pavements. (3) tar-rubber pavements should not be used in aircraft parking areas where tire contact area is less than 100 sq in. and tire pressure is greater than 250 psi; and (4) better housekeeping rules should be enforced to minimize deterioration from fuel spillage.