Performance Evaluation of Recycled Mixtures with Waste Cooking Oil and Waste Engine Oil as Rejuvenators

Utilizing reclaimed asphalt pavement (RAP) is a sustainable approach but compromises the performance of recycled mixtures. Rejuvenators are being adopted to incorporate higher amounts of RAP in asphalt mixtures. This study explores waste cooking oil (WCO) and waste engine oil (WEO) as rejuvenators in recycled mixtures, aiming to enhance sustainability without compromising performance. The study investigates the performance characteristics of recycled mixtures with varying RAP contents and the rejuvenation potential of WCO and WEO. The optimal dosages were determined using the equiviscous concept and Marshall stability criteria. Performance metrics such as rutting, cracking, moisture susceptibility, and durability were assessed through the Marshall rutting test (RT), ideal cracking tolerance (CT), tensile strength ratio (TSR), and modified boiling tests, respectively. Results indicated that recycled mixtures with optimal WCO and WEO dosages determined from Marshall stability criteria showed improved resistance to cracking and moisture damage, and improved durability compared with those without rejuvenators. Additionally, these mixtures performed comparably to or even better than conventional mixtures. Notably, mixtures with optimum WEO demonstrated higher resistance against cracking and rutting compared with WCO. This study underscores the potential of waste oils as sustainable rejuvenators, facilitating higher RAP utilization and promoting a circular economy in pavement construction.