Evaluation of low temperature performance for SBS/CR compound modified asphalt binders based on fractional viscoelastic model

•Low temperature properties of compound modified asphalt were investigated.•Master curve of creep stiffness is constructed by fractional viscoelastic model.•Dissipated energy ratio is recommended to evaluate the low temperature performance.•Addition of CR in SBS asphalt significantly improves low temperature performance. The paper investigated the low temperature performance of asphalt binders modified by SBS, SBS/crumb rubber (CR) and SBS/TAFPACK-Super (TPS). The bending beam rheometer (BBR) test was utilized to compare the rheological properties of three modified asphalt binders at low temperatures. Firstly, the low service temperature of three asphalt binders was calculated from the BBR test results according to the Performance Grading (PG) protocol. Secondly, the generalized fractional viscoelastic model was introduced to construct the master curve of the flexural creep stiffness based on the time-temperature superposition principle. Then the property of three asphalt binders at low temperatures was compared by three approaches based on the generalized fractional model, including the graph of master curve, the derivation of creep compliance and dissipated energy ratio. The comparison results of different indicators showed that the SBS/CR compound modified asphalt had the best low temperature performance followed by the SBS/TPS asphalt and SBS asphalt. Additionally, the strain energy density of three-point bending test and the fracture temperature of thermal stress restrained specimen test (TSRST) for asphalt mixtures further proved the superiority of low temperature crack resistance of SBS/CR compound modified asphalt mixtures. Finally, the results of grey rational analysis demonstrated that the dissipated energy ratio of asphalt binders had a good correlation with the low temperature performance of asphalt mixtures. The study indicates that the SBS/CR compound modified asphalt binder could better meet the demands of pavement materials in cold regions.