Evaluating the Effect of Mix Design and Thermodynamic Parameters on Moisture Sensitivity of Hot Mix Asphalt

This study is an attempt to identify the effective mix design and thermodynamic parameters for the moisture damage of hot mix asphalt. In the present study, 24 different combinations of asphalt mixtures were made and evaluated using three types of aggregates with different mineralogical composition, two types of asphalt binders, and three types of additives. The components of surface-free energy of asphalt binders and aggregates are measured to provide thermodynamic parameters using the Wilhelmy Plate and Universal Sorption Device, respectively. To determine the performance of moisture sensitivity, environmental conditions simulation according to the modified Lottman test was used, and an indirect tensile strength test has been conducted on asphalt mixtures. The results of statistical analysis presented show that the free energy of cohesion, free energy of asphalt binder-aggregate adhesion, specific surface area of aggregates, and asphalt binder film thickness on the aggregate surface have a direct impact, and the debonding energy of the system and permeability of the asphalt mixture have a reverse impact on asphalt mixture strength against the moisture damage.