Synergistic rejuvenation of aged asphalt utilizing polymers and epoxidized soybean oil: Rheological and microscopic performance characterization

With the growing global awareness of sustainable development, asphalt rejuvenating has become an indispensable part of green development in road construction. This study explored the rejuvenation mechanism and impact of composite rejuvenators, composed of various contents of polymers (Styrene-butadiene-styrene (SBS) and SINOTPS (TPS)) and epoxidized soybean oil (ESO) on aged asphalt. To achieve the objective, a combination of service performance studies and micro-nano characterization were employed. The results indicated that the addition of ESO helped to improve the low-temperature performance of aged asphalt. The service performance of all rejuvenated asphalts was improved and gradually increased with the addition of rejuvenators dosage. SBS-RA (rejuvenated asphalt contain ESO with SBS) and TPS-RA (rejuvenated asphalt contain ESO with TPS) exhibited excellent rutting resistance, elastic recovery, anti-aging performance, fatigue resistance, and thermal stability. Using an independent samples t-test analysis, it was found that when the dosages of SBS polymer and TPS polymer were the same, SBS-RA exhibited superior high-temperature, low-temperature, and fatigue performance. Fourier transform infrared spectroscopy (FTIR) results indicated that ESO provided an abundance of unsaturated fatty acids for the aged asphalt, the sulfoxide index slightly decreased with the increase in the dosage of two different rejuvenated asphalts. The results of Atomic force microscopy (AFM) and Thermogravimetric analysis (TGA) indicated that the high content of composite rejuvenators significantly improved the bonding, self-healing properties and thermal stability of aged asphalt. This study was expected to further extend the service life of aged asphalt, reduce environmental impact, and provide theoretical support for sustainable construction of high-grade pavements.