Effects of Metallic Nano Materials on the Cohesion and Adhesion Properties of Asphalt Binders and Aggregates Using Surface Free Energy Method

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 (Xiao et al, 2010). Moisture damage can be divided into two mechanisms, adhesion and cohesion. They are related to the strength loss of asphalt mixtures (Tan and Guo, 2013). Water can penetrate between the surface of asphalt binders and the aggregates. It reduces adhesion between binders and aggregates. Also, water can be absorbed in the asphalt binder. It decreases the cohesion properties of asphalt binders. When the cohesion and adhesion properties of asphalt binder reduce, stiffness of asphalt mixtures reduces. 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. Most of road and transportation agencies have tried to use anti striping additives to increase adhesion at the aggregate-asphalt interface (Kakar et al, 2015). Liquid anti strip additives are chemical surfactants that decrease the aggregate’s surface tension and improve the surface coverage of aggregates. In contrast in this research, the potential of two types of metallic nano materials in two different percentages (nano AL2O3 and Fe2O3) were evaluated.