Investigate the effect of using polymeric anti-stripping additives on moisture damage of hot mix asphalt

Moisture damage in asphalt mixtures can be defined as the loss of durability and strength caused by the effect of moisture. In order to improve the strength of asphalt mixtures against this damage, anti-stripping additives are used to increase the aggregate-asphalt binder adhesion and cohesion. In this study, the influence of Polybutylene on the moisture susceptibility of asphalt mixtures is investigated. To evaluate the effects of anti-stripping additives on the specimens made with granite and limestone aggregates, the indirect tensile strength ratio test and the theoretical concepts of surface free energy have been used. The results of the mechanical tests indicated that the PB additive has increased the strength of the asphalt mixtures against moisture damage. The results of the SFE method also indicated that Polybutylene additive improved the adhesion between asphalt binders and acidic aggregates which were susceptible to moisture damage. Also, using Polybutylene increased the cohesion free energy, which increased the asphalt binder film strength against cohesion failure. Moreover, the calculations based on thermodynamic concepts indicated that the asphalt binder modification has reduced the debonding energy, which also represented the reduced tendency of the system to stripping.