Sustainable asphalt innovation: harnessing treated waste cooking oil for enhanced warm mix rubberized pavement

This study investigates the effectiveness of waste cooking oil (WCO) as a sustainable warm mix asphalt (WMA) additive, particularly in rubberized asphalt mixtures modified with cup lump rubber (CLR). Five asphalt mixtures were evaluated namely; conventional hot mix asphalt concrete with 14 mm nominal size aggregate (AC14), cup lump modified asphalt (CMA), warm mix asphalt using WCO additive (AC14 + WCO), rubberized warm mix asphalt (CMA + WCO) and warm mix asphalt using commercial additives namely CMA + CX. CX is a commercial liquid WMA additive which is derived from waste materials. Performance was assessed through resilient modulus, dynamic creep, indirect tensile strength, moisture susceptibility, and Cantabro loss tests. This study is using 2% WCO pre-blend with 60/70 penetration grade bitumen and rubber modified bitumen prior to mixing with the aggregate. Results indicate that CMA exhibited the highest resilient modulus (4864 MPa), significantly outperforming AC14 (3205 MPa). CMA + WCO demonstrated superior cracking resistance at lower compaction temperatures, achieving a tensile strength ratio (TSR) of 93% at 120 °C, compared to 89% for AC14 + WCO. The dynamic creep modulus of CMA + WCO (59.46 MPa at 120 °C) was higher than that of AC14 + WCO (22.77 MPa), highlighting enhanced deformation resistance. Moisture susceptibility testing revealed that CMA + WCO retained 76% of its stability at 120 °C, outperforming AC14 + WCO (62%). Furthermore, Cantabro loss values showed that CMA + WCO exhibited superior durability (1.61% at 120 °C) as compared to AC14 + WCO (2.49%). These findings suggest that WCO-modified WMA mixtures provide a viable, cost-effective, and environmentally friendly alternative to commercial additives, ensuring durability and enhanced mechanical performance for sustainable pavement construction.