Performance Evaluation of Nano-silica Modified Bitumen

In this study, different contents of Nanosilica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen tomodify the physical, mechanical and rheological properties of warm mix asphalt (WMA). WMA iscontaining 2 wt.% of Sasobit (mixture of longchain hydrocarbons). Various quality control tests have beencarried out to characterize the modified bitumen and WMA. The rheological investigations showed that thecomplex modulus of base bitumen increases by increasing the percentage of Nanosilica from 2 to 6 wt%.Phase angle and rut factor for the Nanosilica modified bitumen have also decreased significantly. Fromrheological analysis, 6 wt% Nanosilica has been selected as the optimum content. Results of investigationson the asphalt mixtures demonstrated the fact that by increasing Nanosilica content, the quality of the warmmix asphalt has been improved. By increasing the Nanosilica content, the resilient modulus of WMA hasincreased as such, the pavement response under the traffic loading has decreased. By adding Nanosilica tothe Sasobit WMA, the depth of cracking has decreased dramatically. So, fatigue life of WMA has beenextended in the presence of Nanosilica. Also, the results of wheel tracking test demonstrated that the ruttingdepth of modified sles have been reduced. The results on WMA showed that 6 wt.% of Nanosilica is theoptimum content. This result was in compliance with the rheological investigations.