Rheological behaviors and microstructure of SBS/CR composite modified hard asphalt

Abstract The rheological behavior and microstructure of SBS/CR composite modified asphalt including base asphalt, crumb rubber (CR), SBS copolymer and hard asphalt have been investigated in this study. The influences of CR, SBS and hard asphalt on the failure temperature, temperature sensitivity, compatibility and microstructure of modified asphalt were evaluated by rheological tests, Cole-Cole plots, fluorescence microscopy and FTIR, respectively. The results show that the CR, SBS and hard asphalt have great different influences on the performance of composite modified hard asphalt. Compared to base asphalt, the addition of CR and SBS to asphalt makes a remarkable improvement in viscoelastic behavior and temperature sensitivity. Although the failure temperature of composite modified hard asphalt decreases and the composite modified hard asphalt is more sensitive to temperature with the increase of hard asphalt content, hard asphalt improves the compatibility and workability of composite modified asphalt and decreases the compact temperature. Furthermore, there is a significant variation in the morphology of composite modified hard asphalt during preparation. With addition of CR, SBS and hard asphalt, phase morphology is converted from a continuous asphalt phase with dispersed polymer phase to two twisted continuous phases, and then to a continuous asphalt phase with dispersed polymer phase again. Meanwhile, the chemical reaction between asphalt and SBS does exist and the hard asphalt could promote the degree of chemical reaction.