Properties of Bitumen Containing Various Amounts of Organic Montmorillonite

The effects of various amounts of organic montmorillonite (OMt) on the morphology and physical properties of bitumen before and after ultraviolet (UV) aging were investigated. The microstructures of OMt modified bitumens were characterized by X-ray diffraction (XRD) analysis. The morphology of the binders was analyzed by atomic force microscopy. According to the XRD results, OMt modified bitumens form an intercalated nanostructure. As a result of UV aging, OMt modified bitumens show lower viscosity aging index and softening point increments than unmodified bitumens, which are further decreased by increasing the OMt content, indicating the satisfactory UV aging resistance of OMt modified bitumen. However, the softening point increments and viscosity aging index decrease slowly when OMt content increases above 6% by weight. UV aging significantly influences the morphology of bitumen. The contrast between the matrix and dispersed domains is decreased and a single-phase trend occurs in the bitumen during UV aging. However, these changes can be prevented effectively with the addition of OMt. The influence of OMt on the morphology of bitumen before and after UV aging depends on its content. According to the results of physical properties and morphology analysis before and after UV aging, the recommended content of OMt is 6% by weight.