Effect of the reclaiming degree of catalytic pre-desulfurization recycled crumb rubber on the properties of modified asphalt

Abstract

The application of crumb rubber (CR) as an asphalt modifier in flexible pavements is an effective way to achieve sustainable utilisation. The performance of crumb rubber modified asphalt (CRMA) can be improved by pretreatment of CR to make it desulfurized to a certain extent. This study aims to determine the optimal regeneration degree of CR to obtain CRMA with better performance. Recycled crumb rubber (RCR) was prepared by catalytic regeneration at low temperatures and used to prepare recycled crumb rubber-modified asphalt (RCRMA). Furthermore, the characteristics of RCR with different regeneration degree and the performance of RCRMA were investigated to determine the reasonable range of regeneration degree. The results showed that solubility was a reliable indicator of the degree of regeneration of RCR and that the solubility of RCR was positively correlated with its regeneration degree. The higher the degree of RCR regeneration, the lower the molecular weight, the more uniform the distribution, and the larger the surface structure. The low-temperature performance, fatigue resistance, and construction workability of the RCRMA were better than those of the CRMA. When the solubility of RCR was greater than 30%, the compatibility and storage stability of RCRMA were significantly improved. As the solubility of RCR increases, the high-temperature performance of RCRMA decreases; however, as long as the solubility of RCR does not exceed 60%, the decrease in the high-temperature performance of RCRMA is very small. According to a comprehensive analysis, the solubility of RCR should be maintained at 30–60%.