Optimising waste cooking oil and waste engine oil as rejuvenators: a comprehensive study on recycled mixtures

The construction industry faces sustainability challenges, notably in asphalt production, contributing to environmental unfriendly technologies. Reclaimed Asphalt Pavement (RAP) offers a solution, but its aged binder presents stiffness issues affecting performance. Waste cooking oil (WCO) and waste engine oil (WEO) have shown potential as effective rejuvenators, but method to determine the ideal amounts for their use are still to be determined, particularly concerning varying RAP content. This study investigates the rejuvenating effects of optimal WCO and WEO dosages on asphalt binders and mixtures across different RAP concentrations. Results show WCO's superior performance over WEO in restoring high-temperature grades and critical temperatures. Optimal dosages of WCO were found to be lower than WEO, determined through rheological and volumetric parameters, varied with RAP content, indicating higher rejuvenation potential of WCO. Rejuvenated binders exhibited improved rutting and cracking resistance, surpassing conventional asphalt observed from master curves. Additionally, WCO rejuvenator modified mixtures displayed superior volumetric properties and moisture resistance compared to WEO. Despite WEO's efficacy in lower RAP scenarios, it showed limitations with higher RAP content. This research underscores WCO's potential as a sustainable rejuvenator for asphalt production, offering insights into optimising dosages for varying RAP concentrations, thereby advancing eco-friendly road infrastructure.