Effect of organic layered silicate on microstructures and aging properties of styrene-butadiene-styrene copolymer modified bitumen

A new approach to determine the microstructures of organic layered silicate/SBS modified bitumen was adopted by combining the results from X-ray diffraction analysis of organic layered silicate/SBS modified bitumen and the dissolving-filtrating procedure. The effect of thin film oven test (TFOT) and ultraviolet (UV) aging on the morphology of binders was characterized by using optical microscopy. The results show that organic montmorillonite/SBS modified bitumen and organic rectorite/SBS modified bitumen form the semi-exfoliated nanostructure, while organic expanded vermiculite/SBS modified bitumen forms the exfoliated nanostructure. The high temperature properties of SBS modified bitumen and the compatibility between SBS and bitumen are improved with the introduction of organic layered silicate. Compared with SBS modified bitumen, organic layered silicate/SBS modified bitumen shows the lower viscosity aging index and the higher retained ductility after TFOT and UV aging. Aging influences the morphology of SBS modified bitumen significantly. There is a single phase trend of SBS modified bitumen during TFOT, which is accelerated by UV radiation. However, the morphological changes are prevented obviously with the introduction of organic layered silicate, indicating the good aging resistance of organic layered silicate/SBS modified bitumen. Additionally, the influence of organic layered silicate on these physical properties of SBS modified bitumen before and after aging depends on its nature.