Performance Evaluation of Nano-Silica Modified Bitumen

In this study, different contents of nano-silica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen to modify the physical, mechanical and rheological properties of warm mix asphalt (wma). wma is containing 2 wt.% of sasobit (mixture of long-chain hydrocarbons). various quality control tests have been carried out to characterize the modified bitumen and wma. the rheological investigations showed that the complex modulus of base bitumen increases by increasing the percentage of nano-silica from 2 to 6 wt%. phase angle and rut factor for the nano-silica modified bitumen have also decreased significantly. from rheological analysis, 6 wt% nano-silica has been selected as the optimum content. results of investigations on the asphalt mixtures demonstrated the fact that by increasing nano-silica content, the quality of the warm mix asphalt has been improved. by increasing the nano-silica content, the resilient modulus of wma has increased; as such, the pavement response under the traffic loading has decreased. by adding nano-silica to the sasobit wma, the depth of cracking has decreased dramatically. so, fatigue life of wma has been extended in the presence of nano-silica. also, the results of wheel tracking test demonstrated that the rutting depth of modified samples have been reduced. the results on wma showed that 6 wt.% of nano-silica is the optimum content. this result was in compliance with the rheological investigations.