Evaluation of the influence of environmental conditions, load levels, and fillers on the self-healing performance of dynamic covalent network modified asphalt

This study investigates the enhancing effect of a self-healing promoter (SHP) based on dynamic disulfide bonds on asphalt healing. Using the Healing-Linear Amplitude Sweep (HLAS) test, the healing efficiency of SHP modified asphalt (SHP-MA) and base asphalt (BA) was evaluated across varying strain levels, durations, temperatures, and filler proportions. Results indicate that the healing enhancement of SHP-MA depends on a strain threshold, which was identified from HLAS tests at maximum strain levels of 10% to 30%. Specifically, at low-to-moderate strain levels (≤25%), SHP-MA achieves a healing improvement of up to 35.36% over BA. However, beyond a critical strain of 30%, extensive cracking restricts the spatial proximity required for disulfide bond reformation, causing the efficiency to fall below the intrinsic recovery of BA. Furthermore, SHP-MA exhibits significant time-dependence, as prolonged healing intervals increase molecular chain mobility and bond recombination probability. Temperature analysis reveals that the chemical induction mechanism is most effective between 10 °C and 25 °C, where it effectively compensates for the restricted viscous flow of the binder. Notably, the self-healing performance advantage of SHP-MA is amplified in asphalt mastics. These findings demonstrate that dynamic covalent bonds can partially overcome environmental constraints, providing a robust mechanism for asphalt damage recovery.