Compatibility and rheological characterization of asphalt modified with recycled rubber-plastic blends

• Recycled rubber-plastic blends were explored for asphalt modification. • The compatibility and rheological properties of binder blends were evaluated by DSR and optical microscopy. • The pre-combined rubber-plastic blends could improve compatibility and physical properties of the binder blends. The use of recycled plastic and rubber for asphalt modification is gaining increasing attention for the development of sustainable pavements. However, phase separation among the rubber, plastic, and asphalt remains a major challenge for a large-scale field application. In this study, several approaches were tested to improve the compatibility of the modified binder blends including the increase of recycled rubber content, the addition of compatibilizer, and the use of pre-commingled recycled rubber-plastic blends. The rheological properties and microstructure of the modified asphalt were evaluated by using dynamic shear rheometer tests and optical microscopy, respectively. Furthermore, the compatibility of the binder blends was characterized using the cigar tube test. Compared with adding plastic and rubber independently or with additional compatibilizer, the asphalt modified with the pre-combined recycled rubber-plastic blends showed a significant improvement of the compatibility, resulting in enhanced physical properties, which present a promising pathway to large-scale commercial applications of plastic and rubber modified asphalt.