Storage stability characterization and improvement of SBS and crumb rubber composite modified asphalt

Abstract

The styrene–butadiene-styrene (SBS) and crumb rubber (CR) composite modified asphalt (SBS/CRMA) possesses favourable mechanical performance but poor storage stability. The purposes of this study are aiming to investigate the changes in storage properties of SBS/CRMA and propose a corresponding improvement approach in the laboratory and further provide a storage guidance for the field application. The Fluorescence Microscope and the Fourier Transform Infrared Spectroscopy were applied to investigate the phase distribution state of SBS. While the phase distribution state of CR was investigated by visual inspection of fractural surfaces. The softening point, rutting factor and Zero Shear Viscosity (ZSV) were used to evaluate the storage properties. It was concluded that the CR sank and the obvious separation occurred within 6 h. The SBS floated up and the evident separation happened within 12 h. In terms of performance, the separation was most distinct in 12 h. Additionally, The effects of Sulphur and Naphthenic oil on storage stability were evaluated. The verification of the feasibility was conducted in a field project. It was verified that the binder prepared in the construction site possessed better high-temperature performance and storage stability due to different production processes and tank truck storage. The little difference in the high-temperature performance of SBS/CRMA indicated the feasibility of the storage performance optimisation method.