The thermal stress restrained specimen test (TSRST) was developed at Oregon State University under the Strategic Highway Research Program (SHRP) A-003A contract as an accelerated laboratory test to evaluate the thermal, or the low-temperature cracking resistance of asphalt concrete mixes. The test system is capable of cooling an asphalt concrete specimen (retangular or cylinder) at a constant rate, while restraining the specimen from contraction and periodically measuring elapsed time, specimen surface temperature, and tensile load. TSRSTs were performed on both short-term and long-term aged specimens to (1) relate fundamental properties of asphalt cement and aggregate to the thermal cracking resistance of asphalt concrete mixtures, and (2) validate the A-002A contractor's hypothesis for low-temperature cracking. Statistical analyses were performed on the test results. A ranking of asphalt concrete mixtures based on fracture temperature compared favorably with a ranking given by the A-002A contractor based on fundamental properties of the asphalt cement. Fracture temperature was highly correlated to the A-002A low-temperature index test results.
Abstract