M Mehdinazar - M. Sc. student, Department of civil engineering, University of Guilan, I. R. Iran
M Arabani - Professor, Department of civil engineering, University of Guilan, I. R. Iran

There are several approaches for improving adhesion and moisture strength in asphalt mixtures, one of which is to adding liquid anti-stripping to base bitumen. Two types of aggregates, limestone and granite, and two types of anti-stripping additives, namely Wetfix N422 and ZycoTherm, as well as AC 60-70 as base bitumen were evaluated in this study by the help of surface free energy concept and modified lottman test. The results showed that adding anti-stripping causes the total surface free energy of the bitumen to increase, resulting in a decrease in stripping between the aggregate and bitumen in the presence of water. The results of modified lottman test showed that the ratio of wet/dry values of ITS for mixtures containing anti-stripping was higher than those of the samples with base bitumen. The bitumen treated with ZycoTherm also showed better resistance against moisture damage in both aggregates were used in this study

Hot mix asphalt, Moisture damage, Anti-stripping additives, Surface free energy, Modified lottman t