Impact of viscoelastic properties of twin-screw extruded crumb rubber on the high-temperature performance of modified asphalt

The present study aims to investigate the effects of activated crumb rubber (ACR) on the viscoelastic properties and high-temperature deformation resistance of asphalt. Crumb rubber (CR) derived from large and small tires was activated using a twin-screw extruder under various temperatures and additive dosages to prepare activated crumb rubber modified asphalt (ACRMA). The viscoelastic properties of ACR and the high temperature performance of the ACRMA were evaluated through conventional property tests, dynamic mechanical analysis (DMA), viscosity tests and dynamic shear rheometry (DSR). The results demonstrate that the activation treatment of CR exerts a significant influence on the dynamic mechanical properties of ACRMA, leading to an increase in viscosity and a decrease in elasticity of the ACRMA. Further correlation analysis reveals a strong correlation between the activation degree and the viscosity of asphalt at 135℃, with the coefficient of determination (R²) exceeding 0.9. The viscoelasticity of large sized tire CR demonstrates a moderate correlation with ACRMA viscosity (R²=0.648), while that of small sized tire CR exhibits a strong correlation (R²=0.824). Furthermore, the rutting resistance of ACRMA displays a substantial correlation with its viscoelastic characteristics, with all corresponding R² values exceeding 0.8. This study validates that activation treatment can augment the interaction between ACR and asphalt under elevated temperatures and substantial strain. However, the effect on rutting resistance is negligible, with the resistance primarily depending on the inherent viscoelastic properties of CR.