Long-Term Effectiveness of Waste Soybean Oil (WSO) to Rejuvenate Aged Asphalt Binder

In the current study, waste soybean oil (WSO) was utilized to retrieve the qualities of aged bitumen to that of virgin bitumen. The viscosity grade 30 (VG30) was employed as the control bitumen. Both rolling thin film oven tests (RTFOT) as well as pressurized ageing vessel tests (PAV) were used to replicate short-term and long-term ageing. The tests were performed at three ageing stages: no ageing, RTFO ageing, and RTFO + PAV ageing. A rejuvenator named WSO as mentioned above was introduced to both types of aged bitumen at varying weight-to-bitumen ratios of 2, 4, 6, 8, and 10%. Physical characteristics, viscosity, and rheology of virgin, short-term aged (STA), long-term aged (LTA), as well as rejuvenated bitumen were investigated. Performance-related tests such as multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) were also conducted at 60 °C and 25 °C respectively. The optimal dose of WSO necessary to rejuvenate both STA & LTA bitumen to the levels of virgin bitumen were found to be 4% and 8–10%, respectively. Furthermore, bitumen rejuvenated with WSO is less prone to long-term ageing, indicating their potential to extend the lifespan of asphalt pavements.