Insights into long-term environmental oxidation of recycled high-viscosity modified asphalt toward durable and sustainable pavement infrastructure

Abstract

The investigation of long-term environmental oxidation resistance of rejuvenated high-viscosity modified asphalt (HVMA) is of great significance as it unlocks its full potential for recycled utilization, offering improved solutions for sustainable and cost-effective pavement infrastructure. This study aims to comprehensively investigate the long-term environmental oxidation resistance and mechanisms of various oil-based and polymer-based rejuvenated HVMAs. Firstly, the long-term oxidation process of oil-based and polymer-based rejuvenated HVMAs was simulated using the indoor accelerated environmental aging test. Subsequently, a series of rheological tests and X-ray photoelectron spectroscopy (XPS) test were employed to examine the environmental oxidation characterization of rejuvenated HVMAs. Finally, a radar chart was proposed to rank the anti-oxidation capabilities of various rejuvenated HVMAs, accompanied by a detailed oxidation mechanism analysis. The results indicate that polymer-based rejuvenated HVMA exhibits superior environmental oxidation resistance compared to oil-based rejuvenated HVMA. The addition of polymer-based rejuvenators effectively retards the phase angle plateau disappearance and rheological performance deterioration of rejuvenated HVMA during environmental aging. Polymer-based rejuvenators significantly slow down the oxidation rates of carbon and sulfur elements in rejuvenated HVMA. Although the addition of oil-based rejuvenators may not enhance the anti-oxidation capability, the restructuring of the polymer phase structure plays a crucial role in improving the anti-oxidation performance. The ranking of anti-oxidation capabilities among the four polymer-based rejuvenated HVMAs is as follows: SBS-based waste furfural oil (SFO) > SBS-based waste rubber oil (SRO) > SBS-based aromatic oil (SR) > SBS-based waste cooking oil (SWCO). SFO demonstrates the highest resistance to environmental oxidation, primarily attributed to the inherent UV absorption and free radical scavenging capability of furfural oil (FO). SRO exhibits favorable anti-aging performance due to the chemical composition resembling asphalt, which provides enhanced chemical stability. Conversely, waste cooking oil (WCO) contains a significant amount of unsaturated fatty acid esters, which is susceptible to oxidation due to oxygen attack, resulting in the lowest anti-aging capability of SWCO.