Assessment of the Effect of Pore Pressure Cycles on Moisture Sensitivity of Hot Mix Asphalt Using MIST Conditioning and Dynamic Modulus

In this study, a recently developed Moisture Induced Sensitivity Tester (MIST) is used for moisture conditioning of asphalt concrete samples, and then dynamic modulus testing is used to assess whether MIST is sensitive to moisture-induced damage in asphalt. MIST applies a pumping action by generating repeated pore pressure in a compacted asphalt sample; however, it is not known yet whether MIST affects the dynamic modulus of asphalt concrete. In essence, the dynamic moduli (E*) of a Superpave mix were determined with and without MIST conditioning. Dynamic moduli at different temperatures and frequencies as well as dynamic modulus mastercurves were compared for with and without MIST conditioning cases using a dynamic modulus ratio (DMR). Computed DMR results consistently show that dynamic modulus decreases due to MIST conditioning, which indicates that MIST conditioning causes moisture damage in asphalt samples. Considering the consistency of DMR results and the added benefit provided by MIST to simulate cyclic pore water pressure due to traffic on wet pavement, MIST conditioning with a dynamic modulus test is found to be a good option to study moisture sensitivity of asphalt mixes.