Effect of aging on structure and properties of self-healing-enhanced SBS modified asphalt with dual dynamic chemical bonds

The introduction of dynamic chemical bonds (disulfide bonds, hydrogen bonds, etc.) into the network structure of SBS modified asphalt (SMA) can notably improve its healing properties. However, aging may break the dynamic chemical bonds in self-healing SMA, thereby deteriorating its healing ability. Therefore, it is crucial to investigate the effects of aging on the structure and properties of self-healing SMA with dynamic chemical bonds. Herein, self-healing SBS modified asphalts (SD/SMA and DDH/SMA) containing single disulfide bonds (SD) and dual disulfide bonds and hydrogen bonds (DDH) were prepared by free radical reaction, respectively. The SD/SMA and DDH/SMA were subjected to Thin Film Oven Test (TFOT) aging and Pressurized Aging Vessel (PAV) aging. Chemical structure analysis showed that the disulfide bonds underwent partial break after PAV aging. Nevertheless, the results of the healing tests indicated that compared to SMA, SD/SMA and DDH/SMA maintained superior healing properties after aging under the break-reorganization effect of dynamic chemical bonds. The fatigue healing indices of SD/SMA and DDH/SMA were 51.9 % and 95.8 % higher than those of SMA after PAV aging. The rheology tests revealed that SD/SMA and DDH/SMA had higher recovery rates and low-temperature cracking resistance than SMA before and after aging. Compared with SMA, SD/SMA and DDH/SMA had superior anti-aging performance. After PAV aging, the ductility retention rate of SD/SMA and DDH/SMA was 72.9 % and 98.9 % higher than that of SMA. Furthermore, compared to SD/SMA, DDH/SMA containing dual disulfide and hydrogen bonds had better healing capability, rheological properties and anti-aging performance.