Effect of Different Aggregate and Binder Grades on the Moisture Resistance of Asphalt Mixes in Oklahoma

Moisture-induced damage can be detrimental to asphalt pavements. Several laboratory tests have been introduced to simulate the field performance of asphalt mixes under moisture damage. There is no consensus on the most appropriate lab test for moisture sensitivity of asphalt mixes. In this study, the modified Lottman test, as outlined in the AASHTO T 283 standard, and the moisture-induced stress tester (MiST) are used to evaluate the moisture susceptibility of three asphalt mixes prepared using different aggregates, and binders sampled from different sources in Oklahoma. The results indicate that no direct correlation can be established between the two methods since they involve different failure mechanisms. The different moisture tests resulted in different rankings between the mixes. For the mixes tested, the tensile strength ratios (TSRs) for the AASHTO T 283 conditioned specimens were lower than the MiST conditioned specimens, indicating that the AASHTO T 283 method was more severe. It was also shown that there was a correlation between the tensile strength ratio (TSR) from the MiST and the percentage change in volume.