Rheological properties of asphalt binder modified by nano-TiO2/ZnO and basalt fiber

Nanomaterials and fibers have gradually become widely used modifiers in asphalt to improve the performance of pavements. However, studies have been focusing on the improvement of individual properties, while comprehensive analyses are still not available. In this study, different contents of nano-TiO2/ZnO and basalt fiber were used to prepare composite-modified asphalt binders. Using scanning electron microscopy (SEM), dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests, Fourier transform infrared (FTIR) spectroscopy, and other experimental methods, the rheological properties and microstructure of modified asphalt binders were determined. The tests results indicate that incorporation of nano-TiO2/ZnO and basalt fiber can significantly improve the high-temperature performance and fatigue life of composite-modifier asphalt binder before aging and after short-term, long-term, and ultraviolet (UV) aging. In addition, an improved permanent deformation resistance was obtained for asphalt pavement with basalt fiber and nano-TiO2/ZnO additives. However, low-temperature performance of asphalt binder was weakened by the addition of basalt fiber, while the appropriate amount of nano-TiO2/ZnO could eliminate negative effects. Moreover, the FTIR results suggest that there was no chemical reaction between basalt fiber, nano-TiO2/ZnO, and asphalt, and the modification mechanism is mainly of physical nature. Furthermore, the nanoparticles were more evenly distributed in the asphalt, which, together with the basalt-fiber-forming network structure hindered the propagation of internal microcracks. The conclusion of the tests is that the optimal content of nano-TiO2/ZnO is 4 wt% of the asphalt, while the content of basalt fiber is 6 wt%.