Evaluation of properties and modification mechanism of organic expanded vermiculite/waste rubber powder modified asphalt

Severe segregation and poor rheological properties in crumb rubber (CR) modified asphalt (CRMT) were addressed by investigating the performance improvement effect of organic expanded vermiculite (OEV) as a co-modifier, while the modification mechanism of the resulting asphalt was also elucidated. Vermiculite was thermally treated and chemically modified to enhance its interaction with the asphalt matrix and CR, improving dispersion and interfacial properties. CR/OEV/furfural extract oil (OIL) composite modified asphalt (COMT) was prepared in this study. The compatibility and microscopic mechanism of modified asphalt were characterized by dynamic shear rheological test, multiple stress creep recovery (MSCR) test, BBR test, thermal segregation test, fluorescent scanning test, infrared spectroscopy, and gel permeation chromatography. Rheological tests showed that the modified asphalt exhibited improved high-temperature stability, with increased G^*/sin(δ) values, and better low-temperature flexibility. Storage stability tests showed a reduced softening point difference, indicating enhanced homogeneity and reduced segregation. Microscopic analysis revealed that OEV effectively optimized the microstructure of the composite system by promoting the uniform dispersion of CR within the asphalt matrix. Furthermore, the macromolecular weight of COMT was increased by 31.9​%, molecular weight analysis confirmed a higher proportion of large molecular weight fractions, contributing to enhanced rheological properties and compatibility. These findings demonstrated that OEV significantly improved the performance and durability of CRMT, providing a promising approach for sustainable road construction.