Research on high and low temperature rheological properties of TPU/SBR composite modified asphalt

In road engineering, SBS modifier has been widely applied in China to enhance the quality of asphalt pavement. However, without considering the physical and chemical properties of SBS modifier and the asphalt substrate, alternative polymerization methods for asphalt modification that offer better performance and economic benefits have not been explored. In this study, an approach was taken to compound modify the base asphalt by incorporating Thermoplastic polyurethane (TPU) and Styrene Butadiene Rubber (SBR). The high and low temperature rheological properties of the modified asphalt were examined using tests such as Rotational Viscosity (RV) test, Dynamic Shear Rheological test (DSR), Multiple Stress Creep Rheological test (MSCR), and Bending Beam Rheological test (BBR). The modification mechanism of the mixed modified asphalt, combining SBR and TPU, was investigated through fluorescence microscope testing. The RV test revealed that the inclusion of TPU and SBR enhanced the viscosity of the asphalt to a certain extent, affording it favorable workability during construction and improved resistance against high temperature deformation. DSR and MSCR tests demonstrated that the incorporation of TPU significantly bolstered the external load resistance, deformation recovery, rutting resistance, and overall stability of the SBR modified asphalt under high temperature conditions; The BBR test proves that the composite modified asphalt has excellent low temperature crack resistance. The FM tests have shown that TPU are effective in reducing the segregation that may occur in SBR-modified asphalt, thus improving the performance of the composite modified asphalt.