This study evaluates the critical high- and low-temperature rheological properties of a high-viscosity modified asphalt (HVMA) binder by analyzing one neat and three high-viscosity modified binders (B-type, Y-type, and H-type) using temperature sweep tests and multi-stress creep recovery tests (MSCR) through the dynamic shear rheometer (DSR), and low-temperature creep stiffness properties by the bending beam rheometer (BBR). Technical indexes such as the softening point temperature, dynamic viscosity, rutting factor, unrecoverable creep compliance, and the creep recovery rate are measured and calculated for high-temperature properties, while the m/S value, dissipation energy ratio, relaxation time, elongation, creep stiffness, and creep speed are used as technical indexes for low-temperature properties. The results show that the incorporation of high-viscosity modifiers reduces the unrecoverable creep compliance and increases the creep recovery rate of the asphalt binder. Non-recoverable creep compliance is found to be a reliable indicator for high-temperature performance, while at low temperatures, the relaxation time decreases, the dissipation energy increases, and the stress relaxation ability improves. The dissipation energy ratio and m/S value are suggested to evaluate the low-temperature performance of HVMA binders using the Burgers model based on the BBR bending creep stiffness test. Therefore, this study recommends using the unrecoverable creep compliance via MSCR to evaluate high-temperature properties and dissipation energy ratio and m/S value for low-temperature properties in the evaluation of HVMA binders.

Blending behavior is the main factor influencing hot recycled asphalt mixtures’ actual and design performance. The following steps were taken to investigate the above issues. Firstly, the component changes of asphalt mixtures were studied by thin-layer chromatography, with flame ionization detection to obtain the mechanism of asphalt aging and recycling. Secondly, according to the difference in the recycled asphalt components, the hot recycled asphalt mixtures were optimized based on the Marshall design method. Lastly, the hot recycled asphalt mixtures for the three mixing processes were prepared using the optimized design method described above. Laboratory tests were conducted to evaluate the correlation between the degree of blending (DoB) and the high-temperature stability, low-temperature crack resistance, water stability, and fatigue performance. The test results indicate that reducing light components (saturates and aromatics) and increasing heavy components (asphaltenes and resins) are the main reasons for asphalt aging, and asphalt recycling is an inverse process. Additionally, the performance of hot recycled asphalt mixtures is improved with an increase in DoB. Specifically, the DoB is only 50% to 60% under a normal mixing process, but by adjusting parameters the DoB will increase to 80% to 90%.

Using waste engine oil (WEO) to partially replace petroleum-based asphalt binders offers a promising solution to mitigate the environmental impact of waste WEO while reducing the dependence on non-renewable asphalt resources. To enhance the comprehensive properties of a modified asphalt containing 6 wt% WEO, an organic rectorite (OREC) with various contents was introduced to the modified asphalt system. The effect of OREC on the structure, storage stability, rheological properties, and self-healing property of WEO-modified asphalt were evaluated using a Fourier transform infrared spectrometer, softening point instrument, and rheometer. The results demonstrated that that no chemical reaction occurs between OREC and WEO-modified asphalt. The addition of OREC can enhance the storage stability and high-temperature stability while marginally decreasing the low-temperature cracking resistance and self-healing properties of WEO-modified asphalt. When the content of OREC increases to 2 wt%, the 48 h softening point difference value of the OREC + WEO composite-modified asphalt drops to 1.8 °C, and this composite-modified asphalt exhibits superior high-temperature rutting resistance, low-temperature cracking resistance, and self-healing property compared to the corresponding base asphalt. In summary, the addition of OREC can effectively offset the adverse effects of WEO on the properties of base asphalt.