Evaluation of cracking properties of SBS-modified binders containing organic montmorillonite

In recent years, organic montmorillonite (OMMT) has become a popular additive for the Styrene-Butadiene-Styrene (SBS) modified binder to improve its storage stability. Though many studies have examined the effect of OMMT additive on asphalt performance, little research has focused on the cracking properties of SBS/OMMT-modified binders. In this study, SBS/OMMT-modified binders for asphalt were first produced using five SBS contents of 1%, 2%, 3%, 4%, and 5% and then blended with 3% OMMT additives. First, FTIR and XRD tests were performed to verify the structure of the asphalt/SBS/OMMT. Then, the intermediate-temperature fatigue cracking property was determined by the G∗sinδ of pressure aging vessel (PAV) specimen through a dynamic shear rheometer (DSR) test, while the low-temperature cracking performance was characterized by the creep stiffness and m-value for the unaged, short-term aged, and long-term aged specimens through bending beam rheometer (BBR) tests. The results show that the OMMT/SBS modified asphalt has formed an intercalated structure and a nanocomposite. The compound modification of OMMT and SBS generally exhibited more intermediate-temperature cracking resistance than that of the single SBS-modified bitumen, but the influence of SBS and OMMT is statistically insignificant. Both SBS and OMMT play key roles in determining the m-value, and higher SBS contents lead to a lower stiffness under three aging conditions at low temperatures.