Effect of montmorillonite organic modification on ultraviolet aging properties of SBS modified bitumen

Montmorillonite (MMT)/SBS modified bitumen was prepared by melt blending. The microstructures of the binders were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and atomic force microscopy (AFM), respectively. The effect of MMT on ultraviolet (UV) aging properties of SBS modified bitumen was investigated. The Na+-MMT/SBS modified bitumen forms a phase separated structure, while the OMMT/SBS modified bitumen forms an intercalated structure according to FTIR and XRD analyses. AFM analysis indicates that a network structure is formed in SBS modified bitumen. The phase contrast between the dispersed domains and the matrix is decreased with the introduction of MMT. Na+-MMT shows a different influence on the SBS modified bitumen phase image, while the phase image of OMMT/SBS modified bitumen is more homogeneous. As a result of UV aging, both viscosity aging index and softening point increment of SBS modified bitumen decrease due to the introduction of Na+-MMT, which can be further reduced under the influence of OMMT. The micro-morphology of the binders becomes solid-like after UV aging, as indicated by the single phase trend of the phase images. However, these changes can be effectively prevented under the influence of MMT. Compared with Na+-MMT, the single phase trend of SBS modified bitumen can be prevented more obviously, indicating the good aging resistance of OMMT/SBS modified bitumen.