Development of an environmentally friendly composite rejuvenator for SBS-modified asphalt binder

To recycle the substantial amounts of waste Styrene-Butadiene-Styrene (SBS)-modified asphalt mixtures generated from highway reconstruction and expansion projects, this study developed an efficient and environmentally friendly novel composite rejuvenator using aromatic oil (AO) and 2,2′-(1,3-phenylene)-bis-oxazoline (PBO) as raw materials. To clarify the rejuvenation mechanism, the research delved into the interactions between aged SBS and PBO through detailed analyses using Fourier transform infrared spectroscopy and fluorescence microscopy. It was found that PBO can undergo amidation reactions with the carboxyl groups in aged SBS, thereby linking the SBS molecules. Furthermore, results from fluorescence microscopy and master curves analysis indicated that the rejuvenation effectiveness of SBS is also influenced by the proportion of the component rejuvenator AO. Adequate AO is not only essential for softening the base asphalt binder but also necessary for enabling the rejuvenated SBS to sufficiently absorb light fractions and undergo swelling and development. The study also critically assessed the road performance of the rejuvenated SBS-modified asphalt binder. Overall, by employing the composite rejuvenator for aging SBS-modified asphalt binder, significant improvements were achieved in both high-temperature and low-temperature properties of the rejuvenated SBS-modified asphalt binder.