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

Although several studies have been carried to discover the asphalt mixture performance when Alumina Trihydrate (ATH) as a flame retardant was added into, the moisture susceptibility of asphalt mixture containing ATH is still not fully clear. In this study, the moisture susceptibility of binders containing ATH were assessed through the surface free energy (SFE) obtained by the sessile drop method. A commonly used SBS modified asphalt with different dosages (0%, 6%, 8%, 10%, 12%, and 14%) of ATH were 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*/sinδ and limiting oxygen index, but decreased the penetration and ductility. What's more, increases in total SFE, cohesive energy and work of adhesion were observed with the addition of ATH. Conversely, the work of debonding, wettability and energy ratio decrease due to the addition of ATH. It is concluded that the ATH has a significant negative effect on the moisture-induced damage potential of asphalt mixture from the view of micromechanisms. The recommended percentage of ATH was 6-8% in consideration of physical properties, flame retardation and moisture susceptibility