Investigation of moisture susceptibility of SBS modified asphalt containing alumina trihydrate by static contact angle measurements

Although several studies have been carried out to assess the performance of asphalt mixture with the addition of alumina trihydrate (ATH) as a flame retardant, the moisture susceptibility of asphalt mixture containing ATH is still not fully clear. In this study, the moisture susceptibility of binders containing ATH was assessed through the Surface Free Energy (SFE) obtained by the sessile drop method. A commonly used Styrene- Butadiene-Styrene (SBS) modified asphalt with different dosages (0%, 6%, 8%, 10%, 12%, and 14%) of ATH was prepared to determine the physical properties, flame retardancy, and SFE parameters. Experimental results indicated that the addition of ATH increased the viscosity, softening point, G= sin , and limiting oxygen index, but decreased any possible penetration and ductility. In addition, an increase in total SFE, cohesive energy, and work of adhesion was observed with the addition of ATH. Conversely, the work of debondifing, wettability, and energy ratio decreased due to the addition of ATH. It was concluded that the ATH had a significant negative effect on the moisture-induced damage potential of asphalt mixture in terms of micromechanisms. The recommended percentage of ATH was 6-8% regarding physical properties, flame retardation, and moisture susceptibility.