Effect of Short-Term Aging on Wax-Modified Crumb Rubber Binder Based on Rutting Performance and Chemical Characterization

Abstract

Abstract Waste tires are processed to modify asphalt binders. Asphalt pavement constructed using crumb rubber modified (CRM) binders have shown good rutting and fatigue performance. However, the use of CRM involves high construction temperature. High temperature leads to aging and successive degradation of CRM binders and also causes significant emission of greenhouse gases. To address this concern, Fischer-Tropsch (FT) wax-based warm mix additive has been used in the present study. CRM binder was modified using three dosages (1 %, 2 %, and 3 % by weight of asphalt binder) of FT additive. CRM binder and CRM binder with FT additive were short-term aged (STA) at 163°C and 143°C, respectively, using a thin-film oven. To evaluate the effect of FT modification on aging susceptibility of CRM binder, physical and chemical properties of CRM binder with and without FT additives were examined. CRM binders with and without FT additives were evaluated in unaged and STA conditions using physical (multiple stress creep recovery [MSCR] test to assess rutting performance) and chemical characterization (Fourier transform infrared [FTIR] spectroscopy test to assess change in chemical compounds/groups). Based on MSCR parameters, FT modification improved rut resistant, elastic performance, and ranking of CRM binder in unaged and STA conditions. On the other hand, FT modified CRM binders were observed to be more temperature susceptible and more stress sensitive as compared to the control CRM. FTIR results showed an increase in absorption values of Carbon-Hydrogen (C-H) long chain, C-H methyl rocks, and carbonyl compound of CRM binder after FT modification. Also, the absorption values of FTIR functional groups were found to be directly proportional to R and inversely proportional to Jnr values of CRM binders with and without FT additive in unaged and STA conditions at tested temperatures. Considering aging sensitivity, FT modified CRM binders were less prone to aging. Therefore, FT additive modification improved rut resistant performance as well as worked as an antioxidant for CRM binder.