Using energy parameters based on the surface free energy concept to evaluate the moisture susceptibility of hot mix asphalt

Although the conventional laboratory test procedure is helpful in comparative analysis of moisture susceptibility of hot mix asphalt (HMA), it does not focus on measuring the fundamental material properties related to the mechanisms of moisture damage. In this study, comparing results of tensile strength ratio test and surface free energy method resulted in the determination of important energy parameters that can be employed as a quantitative indicator to assess moisture susceptibility of HMA. Three of the four parameters used in this research have a convenient correlation with the laboratory results. The ratio of the difference between the surface adhesion of asphalt-aggregate and the water-aggregate to the surface adhesion of the asphalt-aggregate (EP1) had the best correlation with the tensile strength ratio of 32 types of asphalt mixtures. This parameter can be used as a tool for moisture sensitivity detection with more caution. Also, the ratio of the surface energy of adhesion of the asphalt-aggregate to the difference between the surface energy of adhesion in dry and wet conditions (EP2) had good correlation with laboratory results.