Synergistic effects of zinc oxide and red mud composite material on improving the anti-aging performance of asphalt

Abstract

This research prepared the single zinc oxide (ZnO) modifier, single red mud (RM) modifier, ZnO+RM compound (Z + R) modifier and zinc oxide/red mud composite (Z/R) modifier to investigate the interaction between ZnO and RM in Z/R modifier. The content and type of ZnO in Z/R modifier were characterized using X-ray fluorescence spectrometer and X-ray diffraction, respectively. The microstructures and properties of different modifiers and modified asphalt were measured by field emission scanning electron microscope, UV-Visible spectrometer and Fourier transform infrared spectrometer tests. The effects of different modifiers on storage stability, physical and rheological properties of asphalt were also characterized. Finally, the laboratory simulated aging methods were utilized to simulate the various aging stages of asphalt samples. Based on the results, the interaction between ZnO and RM in Z/R modifier improves UV light absorption. Specifically, the UV light absorption of Z/R modifier reaches 98 % that of the single ZnO modifier in the wavelength range of 220–380 nm. With a softening point difference of only 0.3 °C, the Z/R-modified asphalt exhibits superior storage stability. In addition, new chemical bonds (Si-O-Zn) may be created during the preparation of Z/R modifier, making the structure of Z/R modifier more stable. According to the results of physical and rheological aging indexes, the synergistic effect between ZnO and RM in Z/R modifier can improve the resistance to thermal-oxidative and UV aging of asphalt. The effectiveness varies with the type of aging, as the thermal-oxidative aging resistance of Z/R modified asphalt improves by 19.2 % - 57.6 % while the UV aging resistance improves by 23.2 % - 45.3 % compared with base asphalt.