Thermo-oxidative aging performance of mechanochemical activated rubber powder modified asphalt

Although waste rubber powder modified asphalt improves the high-temperature performance, low-temperature performance and fatigue performance of asphalt, the poor aging resistance of waste rubber powder modified asphalt limits its wide application. To address this issue, this study uses tetraethylenepentamine as the activator of waste rubber powder, and the activated rubber powder prepared by mechanochemical technology to modify asphalt. In order to verify the thermo-oxidative aging performance of activated rubber powder modified asphalt, this study simulated the thermo-oxidative aging process of activated rubber powder modified asphalt (ARMA) and non-activated rubber powder modified asphalt (RMA) by indoor accelerated aging test. The conventional and rheological properties of ARMA and RMA under thermo-oxidative aging conditions were investigated using conventional and rheological performance test techniques, respectively. The chemical structure and molecular weight changes of modified asphalt during thermo-oxidative aging were also investigated using attenuated total reflectance Fourier transform infrared spectrophotometer and gel permeation chromatography. The macroscopic results showed that with the increase of aging intensity, the amount of changes in conventional performance indexes (permeability, ductility, softening point) and rheological performance indexes (complex shear modulus, rutting factor, fatigue life, creep stiffness, and phase angle, m) of ARMA were smaller than those of RMA. The microscopic results showed that the asphalt was gradually oxidized with increasing aging, but the changes in the content of the characteristic functional group index and macromolecular size were less significant for ARMA than for RMA. Based on these findings, it can be concluded that ARMA exhibits excellent anti-aging performance. Gray correlation entropy analysis showed that the sulfoxide index had the strongest correlation with phase angle and m, while the molecular weight had the strongest correlation with complex shear modulus, rutting factor, fatigue life, and creep stiffness.