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 tomodify the physical, mechanical and rheological properties of warm mix asphalt (WMA). WMA iscontaining 2 wt.% of Sasobit (mixture of long-chain 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 Nano-silica from 2 to 6 wt%.Phase angle and rut factor for the Nano-silica modified bitumen have also decreased significantly. Fromrheological analysis, 6 wt% Nano-silica has been selected as the optimum content. Results of investigationson the asphalt mixtures demonstrated the fact that by increasing Nano-silica content, the quality of the warmmix asphalt has been improved. By increasing the Nano-silica content, the resilient modulus of WMA hasincreased; as such, the pavement response under the traffic loading has decreased. By adding Nano-silica tothe Sasobit WMA, the depth of cracking has decreased dramatically. So, fatigue life of WMA has beenextended in the presence of Nano-silica. Also, the results of wheel tracking test demonstrated that the ruttingdepth of modified samples have been reduced. The results on WMA showed that 6 wt.% of Nano-silica is theoptimum content. This result was in compliance with the rheological investigations.

کلیدواژه ها:

WMA ، Sasobit ، nano-silica modified bitumen ، rheological properties ، resilient modulus ، fatigue ، rut depth