Evaluation on the fatigue and self-healing properties of aged and rejuvenated SBS-modified asphalt

To investigate the fatigue and self-healing properties of aged and rejuvenated SBS-modified asphalt, soybean oil (SBO), epoxidized soybean oil (ESO), and commercial rejuvenators (LBS) were selected as asphalt rejuvenators. The fatigue performance of the asphalt was assessed through a time sweep procedure using a dynamic shear rheometer (DSR) instrument. Subsequently, a series of fatigue-healing-fatigue tests were conducted with varying healing times and damage degrees to analyze the self-healing characteristics of the asphalt. The rejuvenation and self-healing mechanisms were elucidated through a fluorescence microscope, Fourier transform infrared spectroscopy (FTIR), and thin-layer chromatography with flame ionization detection (TLC-FID) tests. The results revealed that the fatigue life of aged SBS asphalt deteriorated by more than 17% compared to unaged asphalt, and the self-healing properties were also weakened. However, both the fatigue life and self-healing properties could be significantly restored through the addition of rejuvenators, with SBO exhibiting the most pronounced effect in their restoration, followed by LBS and ESO. Furthermore, the self-healing capacity of the asphalt was notably affected by both the healing time and damage degree. Microstructure test results showed that in aged SBS-modified asphalt, lighter components dissipated, and the polymer deteriorated, contributing to the decline in self-healing performance. The presence of a substantial quantity of lightweight components in SBO expedited wetting and molecular diffusion at the damaged interface within the asphalt, thereby restoring the self-healing properties of the aged asphalt.