A novel method to improve anti-aging properties of SBS modified bitumen by zinc oxide/expanded vermiculite composite: Influence of zinc oxide particle loadings

Styrene-butadiene-styrene copolymer modified bitumen (SBSMB) has been commonly used in pavement construction for its excellent performance. However, during construction and service life, SBSMB is inevitably subjected to thermal-oxidative or ultraviolet aging as a result of factors in the environment like heat, light and oxygen. This study investigated the effects of zinc oxide/expanded vermiculite composite (Z/E) on SBSMB, in particular the effects of Z/E with different zinc oxide (ZnO) particle loadings on SBSMB. And Z/E with different ZnO particle loadings were prepared and characterized by X-ray fluorescence spectrometer, field emission scanning electron microscope, UV-Visible spectrometer and Fourier transform infrared spectrometer tests. To age bitumen samples, thin film oven test, pressure aging vessel and ultraviolet aging tests were used. Eventually, the effects of Z/E with various ZnO particle loadings on the storage stability, physical, rheological and anti-aging properties of SBSMB were investigated. According to the results, Z/E with different ZnO particle loadings are successfully prepared. There are uniform ZnO particles on the surface of expanded vermiculite and ZnO particle loadings are increased with the concentration of the ZnO precursor solution. Furthermore, the high-temperature performance of SBSMB is enhanced, but the low-temperature performance is slightly affected by Z/E. Whatever the aging mode, the introduction of Z/E can obviously reduce the viscosity aging index, softening point increment, complex modulus aging index and increase phase angle aging index of SBSMB, demonstrating that the aging resistance of SBSMB are significantly enhanced. It was determined that SBSMB with 29.5 wt%Z/E had the best aging resistance.