Research on the High‐Temperature Performance of Asphalt Modified With Covalently Crosslinked Polyethylene Waste Plastic

To address the dual challenges of waste polyethylene (WPE) recycling and the demand for road asphalt modifiers, asphalt was modified by constructing covalent crosslinking networks within the WPE, thereby enhancing its high‐temperature performance. A covalently crosslinked polyethylene waste plastic (CP) was synthesized via chemical modification of WPE. The structural characteristics and mechanical performance of CP were characterized by Fourier Transform Infrared spectroscopy (FTIR), proton nuclear magnetic resonance, gel content determination, and tensile test. The interaction mechanism between CP and asphalt components was analyzed by using fluorescence microscopy and FTIR. The basic performances of modified asphalt were evaluated based on the penetration, ductility, softening point, and Brinell rotational viscosity tests. The high‐temperature rheological performance was evaluated through a dynamic shear rheometer and multiple stress creep recovery. Results showed that the CP demonstrated superior mechanical properties relative to pristine WPE. The high‐temperature rheological performance of CP‐modified asphalt was significantly improved, peaking at a 5 wt% CP dosage. This improvement was attributed to the formation of a covalent cross‐linked network, in which ester bonds served as the covalent cross‐linking sites. This strategy achieves a synergistic improvement in asphalt performance and plastic reutilization, contributing to sustainable and low‐carbon goals.