Evaluation of the effect of nano-TiO 2 on the adhesion between aggregate and asphalt binder in hot mix asphalt

One of the basic parameters upon which the occurrence of distress in hot mix asphalt depends is the amount of adhesion at the contact surface between asphalt binder and aggregate. Therefore, a number of researches have been conducted throughout the last decade to improve the adhesion between asphalt binder and aggregate using different additives. In the present study, the effects of using nano-TiO2 on the adhesion between the asphalt binder and aggregate are assessed using the surface free energy (SFE) method. The SFE components of the aggregates are determined by universal sorption device test, while SFE components of the asphalt binders are calculated using Wilhelmy plate test. The results of the SFE method indicate that nano-TiO2 increases the wettability of the asphalt binder on the aggregate and promotes the adhesion between the asphalt binder and the aggregate. Furthermore, adding nano-TiO2 leads to the decrease in the acid component of SFE and the increase in the basic component of SFE of the asphalt binder, intensifying the adhesion between the asphalt binder and the aggregate.