Effect of crumb rubber depolymerisation degree on the properties of modified asphalt

This study aims to explore the effect of the depolymerisation degree of crumb rubber on the properties of pre-depolymerised crumb rubber-modified asphalt (PDCRMA), with the goal of improving the environmental sustainability and performance of asphalt pavements. Pre-depolymerised crumb rubber (PDCR) with various depolymerisation degrees was prepared using aromatic oil as a solvent. The properties of the PDCRMA were evaluated using conventional asphalt tests, dynamic shear rheometer (DSR) tests, bending beam rheometer (BBR) tests, and storage stability assessments. The relationship between the depolymerisation degree and the performance characteristics of PDCRMA was analyzed through correlation studies. Results show a strong linear correlation between the depolymerisation degree and the properties of PDCRMA. Increasing the depolymerisation degree enhances the low-temperature performance, fatigue resistance, and storage stability of PDCRMA. However, the high-temperature performance of PDCRMA declines as the depolymerisation degree increases, with the optimal solubility around 50 % for achieving a balance between performance traits. This work provides novel insights into the optimal degree of depolymerisation for crumb rubber, improving the compatibility and performance of crumb rubber-modified asphalt. • Prepared pre-depolymerised crumb rubber with different degrees of depolymerisation. • Characteristics of PDCR and properties of PDCRMA were studied. • Pre-depolymerisation significantly improved the compatibility and storage stability of PDCRMA. • Correlation between depolymerisation degree of PDCR and properties of PDCRMA was established.