Component Changes and Mechanism of Cold Regeneration of Aged Asphalt Using Waste Vegetable Oils

Abstract

Waste vegetable oil cold mix recycling technology can massively improve the resource utilization rate of solid waste in the road construction industry. This process can also reduce energy consumption and environmental pollutant emissions during road construction, making it an effective approach to achieve the carbon peak and carbon neutral strategy in this industry. This study employs a combination of macroexperiment and microscopic molecular simulation to analyze the component changes and mechanisms in the process of cold regeneration of aged asphalt with waste vegetable oil. The findings provide a scientific basis for the popularization and application of this technology. This study conducted a basic performance test, four-component test, atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), and molecular simulation on waste vegetable oil cold regeneration asphalt (WVOCRA) with varying waste vegetable oil (WVO) content, which aims to determine the optimal amount of WVO for cold regeneration of asphalt and to understand the mechanism behind the change in components and properties of aged asphalt during the process. The study found that the addition of WVO improved the colloidal stability of cold regenerated asphalt. The asphaltene index in the four-component test and the ratio of honeycomb structure in the AFM test indicates that the optimal ratio of light and heavy components in WVOCRA was achieved with a 10% dosage of WVO. Furthermore, the macroscopic properties of WVOCRA were restored to the same level as that of the 70# asphalt. The rejuvenation of aged asphalt through WVO is primarily achieved through physical conditioning, without the generation of new chemical functional groups. WVO can be used to separate asphaltene dimers in aged asphalt, reducing the probability of asphaltene and resin aggregation, and degrading heavy component clusters in aged asphalt. The index of mutual diffusion rate Vv indicates that increasing the temperature of simulated diffusion and the proportion of WVO can enhance the mutual diffusion rate and integration depth of WVO and aged asphalt. However, the increase of WVO will reduce the thermal stability of WVOCRA. Therefore, future research could explore process optimization for the cold regeneration of aged asphalt using WVO or investigate the combined use of WVO cold regeneration asphalt technology and composite modified asphalt technology.