From waste to sustainable pavement: Rejuvenation of asphalt binder using waste engine oil residue and crumb rubber

Waste recycling is a crucial prerequisite for sustainable road development. This study aims to investigate the rejuvenating impact of waste engine oil residue (WEOR) and crumb rubber (CR) on reclaimed asphalt pavement (RAP) to achieve 100% waste recycling. WEOR and CR modified reclaimed bitumen (WERB) were prepared and tested for rheological properties, environmental impact, and microstructure compared with reclaimed bitumen (RB) adding WEOR, CR, and rejuvenator individually. The results indicated that the 30% premixed agent containing a 4:1 ratio of WEOR to CR yields optimal properties. Furthermore, WEOR and CR contribute to WERB's softness and elasticity, improving fatigue life by over ten times compared to RB. “Reverse segregation” was observed for the first time, suggesting the potential of WEOR for improving environmental stability. Additionally, the maximum HPI of WERB leachate was 0.781, below the drinking water limits. However, elements such as Zn, B, and Cu may inevitably provide a leaching risk after rainfall, contaminating the surrounding fields, water sources, or land. This study provides deeper insights into the potential mechanisms of WERB pavements and sheds light on the future realization of sustainable pavements with the concept of 100% waste recycling.