Using the Surface Free Energy Method to Evaluate the Effects of Nanomaterial on the Fatigue Life of Hot Mix Asphalt

AbstractFatigue cracking is the main form of structural damage in hot mix asphalt (HMA) at moderate temperatures. The one of ways to reduce this type of distress is use of nanomaterials as additives in asphalt mixtures. In this study, the effects of using nano-TiO2 as an asphalt binder modifier on the fatigue life of asphalt mixtures are assessed by surface free energy (SFE) method and indirect tensile fatigue (ITF) test. The HMA mixtures containing 0, 3, and 6% of nano-TiO2 are plant prepared with two sources of aggregate (granite and limestone), and one type of asphalt binder with 85/100-penetration grade. The results showed that fatigue lives of mixtures containing nano-TiO2 were higher than the control mixtures. This is attributed to the fact that adding nano-TiO2 leads to decrease of the acid component of SFE and increase of the basic component in SFE of the asphalt binder that enhances the adhesion between asphalt binder and aggregate. Furthermore, the asphalt mixtures made with the modified asphalt binder showed greater fatigue life than the control mixtures because of improved cohesion energy and higher resistance to fatigue cracking in asphalt film.