Potential Alternative to Styrene–Butadiene–Styrene for Asphalt Modification Using Recycled Rubber–Plastic Blends

The utilization of recycled rubber and plastics for asphalt modification potentially has more social and economic benefits than using typical styrene–butadiene–styrene (SBS). However, the availability, compatibility, and stability issues of recycled plastic and rubber in the asphalt limit their application in the field. This study explored an alternative modifier to SBS for asphalt modification by using recycled rubber–plastic blends consisting of recycled polyethylene and tire crumb rubber. The compatibility and rheological properties of the various modified binder blends were characterized by dynamic shear rheometer and optical microscopy. Both recycled rubber–plastic and SBS-modified binder blends were prepared to evaluate the performance of the asphalt mixtures, including rutting, cracking, and moisture resistance. The results showed that the recycled rubber–plastic-modified asphalt could form interacted continuous phases of rubber and plastic, which improved the compatibility of the binder blends and the performance of the asphalt mixtures. Therefore, the recycled rubber–plastic blends can be considered as a potentially suitable alternative for asphalt modification from both performance and economical points of view.