Synergistic enhancement of asphalt mixtures with novel high-elastic modifiers and waste cooking oil

This study investigates the synergistic effects of Waste Cooking Oil (WCO) and three types of High-Elastic Modifiers (HEM-S, HEM-C, and HEM-G) on the mechanical and rheological performance of asphalt mixtures. The modified AC-13C mixtures were evaluated through Marshall Stability, rutting, low-temperature cracking, moisture susceptibility, and aging tests. The findings demonstrate that the combined use of HEMs and WCO significantly enhances both high- and low-temperature performance compared with conventional binders. The HEM-S + 6% WCO mixture exhibited the most balanced performance, achieving a 27% increase in Marshall Stability, 87% improvement in Dynamic Stability, and 46% increase in tensile strain, alongside superior moisture, and aging resistance. HEM-C + 4.5% WCO achieved the highest rutting resistance (4900 passes/mm) but displayed slightly higher stiffness at low temperatures. Rheological analysis confirmed that WCO acts as a plasticizer, reducing binder stiffness and improving stress relaxation, while HEMs provide an elastic network that enhances load-bearing capacity. The integration of WCO and HEMs effectively replaces conventional SBS modification, offering a sustainable and high-performance alternative for asphalt pavement applications. Moreover, a 1% adoption of HEM-WCO asphalt in China annual production could prevent approximately 31,300 tonnes of CO 2 emissions and recycle over 6,200 tonnes of waste oil annually, underscoring the environmental and circular-economy potential of this technology.