Research on the anti-aging mechanism of SBS-modified asphalt compounded with multidimensional nanomaterials based on atomic force microscopy

Styrene-butadiene-styrene (SBS)-modified asphalt binders age during road service, affecting the road performance. To improve the anti-aging performance of SBS-modified asphalt, layered silicates (organically expanded vermiculite (OEVMT) and organic montmorillonite (OMMT)), which can reduce the oxidation behavior of asphalt, and nanometer-scale titania (nano-TiO2), which has good anti-ultraviolet aging properties, were selected for the preparation of composite modifiers due to their properties. The composite modifiers are multidimensional nanomaterials, OEVMT/TiO2 and OMMT/TiO2. The asphalt samples were aged by a thin film oven (TFOT) test, pressure aging vessel (PAV) test, and ultraviolet aging test. Through physical performance tests, rheological performance tests, and atomic force microscopy, the performance of asphalt samples before and after aging was analyzed, and the action mechanism of multidimensional nanomaterials was discussed. The test results showed that OEVMT/TiO2 or OMMT/TiO2 increased the viscosity and high-temperature performance of asphalt. The dispersibility and stability of the SBS modifier in asphalt were also improved. The addition of multidimensional nanomaterials to SBS-modified asphalt not only inhibited the oxidation rate of the asphalt but also reduced the impact of ultraviolet light on the asphalt during aging. As the degree of aging increased, the area of the “bee structure” in the asphalt gradually increased, and the surface roughness gradually decreased. However, the addition of OEVMT/TiO2 or OMMT/TiO2 to SBS-modified asphalt inhibited the increase in the area of the “bee structure” and improved the surface roughness of the aged asphalt. The comprehensive analysis found that the multidimensional nanomaterials improved the thermal-oxidative aging resistance and ultraviolet aging resistance of SBS-modified asphalt.