Rheological properties, storage stability and morphology of CR/SBS composite modified asphalt by high-cured method

Abstract

To improve the workability and storage stability of crumb rubber (CR) modified asphalt, high-cured method was employed. Styrene-butadiene-styrene (SBS) copolymers were added to compensate the loss of properties in the curing process. The curing process of CR modified asphalt and influence of SBS content as well as asphalt composition on conventional properties, rheological properties, storage stability and morphology of CR/SBS composite modified asphalt were investigated, respectively. The results showed that the curing process with three stages can be quantitatively described by logistic fitting model, which improves the workability, storage stability and quality stability of modified asphalt. High-cured CR modified asphalt shows a great improvement in conventional and rheological properties compared with base asphalt. The addition of SBS enhances the properties of modified asphalt, but the extent of improvement is less obvious than CR. Based on the morphology, the strip-type rubber with large size disappears due to the degradation of CR, resulting in better storage stability of modified asphalt. Moreover, low asphaltenes and high saturates are favorable to the CR degradation and storage stability, while moderate asphaltenes and high aromatics are beneficial for achieving desired properties. As a conclusion, CR/SBS composite modification by high-cured method is a cost-effective approach to produce asphalt binder.