Rheological examination of aging in bitumen with inorganic nanoparticles and organic expanded vermiculite

Abstract

Bituminous pavement is vulnerable to aging during construction and service life, which can seriously affect the rheological properties of bitumen. A novel modified bitumen containing inorganic nanoparticles and organic expanded vermiculite (OEVMT) compound was evaluated in this paper. The binders were aged according to the thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) radiation, respectively. The effect of different inorganic nanoparticles (nano-titania, nano-zinc oxide, nano-silica) and OEVMT compound on rheological properties of bitumen before and after aging is investigated. The base bitumen is modified with 1% OEVMT by mass of bitumen and different content inorganic nanoparticles, which are 1%, 2% and 3% nano-titania (nano-TiO2), 3% nano-zinc oxide (nano-ZnO) and 3% nano-silica (nano-SiO2). The microstructures of expanded vermiculite (EVMT), OEVMT and separated OEVMT from modified bitumen were characterized by X-ray diffraction (XRD). The results show that the OEVMT/bitumen forms the exfoliated nanostructures. The complex modulus of bitumen is increased, while the phase angle is decreased with the introduction of compound modifiers. As a result of TFOT, PAV and UV aging, inorganic nanoparticles and OEVMT modified bitumens show the higher phase angle aging index and the lower complex modulus aging index in comparison with base bitumen, which indicates their good thermal oxidation and UV aging resistance. Moreover, based on nano-TiO2 content effect, the recommended content is 1% OEVMT+3% nano-TiO2 by rheological properties results before and after three aging methods. Under the same compound modifiers content, the compound modified bitumen containing nano-ZnO shows better aging resistance than the compound modified bitumen containing nano-TiO2 or nano-SiO2.