As a renewable biomass resource, biochar is new to modify or replace asphalt binder in pavement engineering. This paper focuses on the effect of biochar on the anti-aging performance of asphalt binder. The short- and long-term aging properties of biochar modified asphalt binder were investigated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The modification mechanism was investigated through the Fourier-transform infrared spectroscopy (FTIR) test. The aging tests and viscosity analysis showed that the softening point of biochar modified asphalt binder was higher than base asphalt binder, while the aging index and aging viscosity ratio were lower than base asphalt binder. After aging, the temperature sensitivity of biochar modified asphalt binder decreased and the high-temperature stability, reflected by dynamic shear modulus and resistance to rutting, improved. The BBR test after long-term aging showed that the anti-aging performance of biochar modified asphalt binder decreased with the decrease in temperature, and control of the biochar content could ensure good low-temperature performance of the modified asphalt binder after aging. FTIR spectra analysis showed that biochar in modified asphalt binder is physically blended with asphalt binder.

Asphalt binders have been modified with Crumb rubber (CR) as an effort to fulfil the demand for the development of eco-friendly and sustainable pavements. The objective of this study was to investigate the high temperature rheological behaviors and fatigue performance of crumb rubber modified asphalt (CRMA) binder activated using trans-polyoctenamer (TOR). Long-term and short-term aging tests were performed on samples by thin film oven test (TFOT) and pressure aging vessel (PAV). Rotational viscosity (RV), softening point, and dynamic shear rheometer (DSR) tests were conducted to characterize the rheological and physical performance. A linear amplitude sweep (LAS) test was employed to evaluate the fatigue performance. The results show that TOR-activated CRMA is more capable of hardening the matrix bitumen and improving its high-temperature viscoelastic properties after TFOT. The high temperature viscoelasticity is significantly better than styrene-butadiene-styrene block (SBS) modified asphalt (SBSMA) and CRMA. TOR-activated CRMA exhibits strong rutting resistance, but it is more likely to generate fatigue cracks under the violent advancement of complex modulus. Therefore, TOR active agent has a negative impact on the fatigue performance of CRMA. SBSMA exhibited superior fatigue resistance. The viscosity temperature index (VTS) of TOR-activated CRMA and CRMA was basically identical; the TOR did not significantly improve the temperature sensitivity of CRMA.