Preparation and mechanism of rubber-plastic alloy crumb rubber modified asphalt with low viscosity and stabilized performance

Recycled rubber and plastics for asphalt modification are gaining increasing attention for sustainable pavements. However, the high viscosity and low stability of modified asphalt are the primary reasons limiting its widespread application. In this work, the rubber-plastic alloy crumb rubber (ACR) was prepared with the twin-screw extruder using crumb rubber (CR) and polyethylene (PE). The properties influence of the preparation process on ACR modified asphalt (ACRMA) was investigated by fluorescence microscopy, basic properties, and storage stability tests. The viscosity reduction characteristics of asphalt and asphalt mastic were assessed at different temperatures. Differential scanning calorimetry (DSC) and contact angle tests were used for modification mechanism analysis. Results showed that, compared with CR modified asphalt (CRMA), the thermal stability of ACRMA was improved, and its cohesion energy was not significantly reduced. The high-temperature viscosity of asphalt and its mastic was decreased by 35.1% ∼ 69.1%. But it had the same mid-temperature viscosity as CRMA. The rutting factor, high-temperature PG grade of ACRMA increased, and the phase angle decreased. The optimum dosage of PE was 15 wt% in ACR, ACR was 15 ∼ 20 wt% in asphalt, and the stabilizer was 0.05 ∼ 0.1 wt%. Compared with traditional CRMA, ACRMA with low viscosity and stabilized performance. It has good application potential, which can effectively reduce construction temperature and promote factory production.