Development of wheel-tracking test method and performance criteria for asphalt pavements

Permanent deformation, or rutting, is a common failure mode of flexible pavements. Many methods have been developed to assess the susceptibility of a hot-mix asphalt (HMA) mixture to rutting and a related failure mode, stripping. Wheel-track testing is currently one of the most common methods.; Wheel-tracking tests subject HMA samples to a loaded wheel that tracks linearly along the sample, producing a rut. When the test is performed in the submerged condition, stripping may also be detected.; The Evaluator of Rutting and Stripping in Asphalt (ERSA) was developed at the University of Arkansas. It is a wheel-tracking device that has the capability of using various wheel types, and utilizes an advanced data acquisition system to describe a complete longitudinal profile of each sample as it ruts. ERSA is capable of detecting both rutting and stripping failures in HMA mixtures.; A total of 442 wheel-tracking tests were performed on field- and laboratory-compacted samples from five sites in order to evaluate the effects of specimen air void content, testing temperature and load, specimen shape, compaction method, and wheel type. The mixtures were ranked, then compared to field rutting measurements at each site after three years of service.; In general, air void contents less than ten percent did not significantly affect ERSA test results. Temperature and load were significant factors, the 50 C (122 F) and 591 (132 lb) load combination providing the greatest discrimination of mixes and the most accurate representation of field rutting characteristics. Field-compacted specimens showed less rutting resistance than laboratory-compacted specimens. Relative to wheel-type, the ERSA steel wheel was the only one able to consistently detect the presence of stripping. Moisture damage test results based on traditional methods were compared to stripping data obtained from the ERSA test, with no correlation evident between the methods.; A standard test method was developed for the ERSA device and rutting criteria were set. Maximum allowable rut depths of 5 mm (0.2 in) and 10 mm (0.4 in) were specified for mixes serving high and low volumes of traffic, respectively.