Effect of expanded vermiculite on aging properties of bitumen

Expanded vermiculite (EVMT) clays modified bitumen was prepared by using EVMT, cetyltrimethyl ammonium bromide (CTAB)–EVMT and octadecyl dimethyl benzyl ammonium chloride (ODBA)–EVMT as modifiers. The morphology characteristic of the modified bitumen was investigated by X-ray diffraction (XRD). The binders were aged by pressure aging vessel (PAV), situ thermal aging and ultraviolet (UV) radiation. The phase-separated structure is observed in EVMT modified bitumen, while CTAB–EVMT and ODBA–EVMT modified bitumen form the intercalated and exfoliated nanostructure, respectively. The mass change rate, viscosity aging index and softening point increment of the binders can be effectively decreased after PAV simulation and situ thermal aging. The improved aging resistance of the binders after thermo-oxidative aging (PAV simulation and situ thermal aging) is more obvious than that after UV aging. Compared with EVMT, organic expanded vermiculites (OEVMTs) have more pronounced improvements in aging resistance of bitumen. In addition, the morphology and aging resistance of OEVMTs modified bitumen depend on the nature of the organic modifiers in OEVMTs.