Evaluating the effect of asphalt binder modification using nanomaterials on the moisture damage of hot mix asphalt

One of the most common damages in asphalt mixtures is due to the destructive effects of moisture on the cohesion of asphalt binder and adhesion of asphalt binder–aggregate which is called moisture damage. There are several different approaches for improving adhesion and reducing moisture sensitivity in asphalt mixtures. One convenient approach is modifying the asphalt binder with a suitable agent. In this research, the effects of two types of nanomaterials in two different percentages (nano AL2O3 and Fe2O3), two types of aggregates (granite and quartzite), and one base asphalt binder were evaluated. To assess the effect of nanomaterials, the tensile strength ratio (in 1, 3, and 5 freeze–thaw cycles) and surface free energy (SFE) tests have been used. Mechanical test results used in this study show that using nanomaterials significantly improves the moisture strength of samples made with the modified asphalt binder in comparison with the control samples. Results of SFE theory show that the nanomaterials increase the cohesion free energy of the asphalt binder that decreases the probability of the occurrence of cohesion failure in the mastic. Also, nanomaterials decrease the acid component and increase the base component of SFE of the asphalt binder which increase its adhesion with the aggregates used in this study with acid properties. Measurement results of debonding energy of the asphalt binder–aggregate in wet conditions show that asphalt binder modification with nanomaterials decreases the absolute value of the debonding energy and, therefore, the moisture damage susceptibility decreased.