Response Surface Optimized Synthesis of Eco‐Friendly Anti‐Cracking Asphalt Using Waste Rubber Powder: Performance Evaluation and Microstructure Characterization

ABSTRACT Waste tire rubber powder has become a widely used and sustainable replacement for asphalt modification. The traditional waste tire rubber‐modified asphalt exhibits poor low‐temperature performance, leading to frequent cracking in regions with lower temperatures. To effectively reutilize waste rubber tires and enhance the crack resistance of asphalt pavement, this study utilized styrene‐butadiene‐styrene (SBS) and waste tire rubber powder treated with activated desulfurization to prepare anti‐cracking composite modified asphalt (ACA). ACA was synthesized using the response surface method (RSM). Subsequently, the basic properties and anti‐aging performance were tested and compared, showing that ACA demonstrates superior high‐ and low‐temperature performance and aging resistance. Rheological tests confirmed ACA's outstanding high‐temperature rutting resistance and low‐temperature crack resistance. Notably, ACA exhibited a self‐healing capacity 3.9 times greater than SBS‐modified asphalt, showcasing superior fatigue resistance. Moreover, characterization of ACA's microstructure and morphology revealed that the rubber powder showed good compatibility with asphalt, SBS, and flexibilizer, forming a stable cross‐linked network within ACA. This structural feature is a key factor contributing to ACA's superior overall performance and crack resistance. Finally, pavement performance tests validated ACA's performance in asphalt mixtures, demonstrating a novel approach utilizing SBS and rubber powder to enhance asphalt's anti‐crack performance while recycling waste rubber tires.