Physical, Rheological, and Aging Properties of Bitumen Containing Organic Expanded Vermiculite and Nano-Zinc Oxide

This work investigates a novel bitumen modification by use of organic expanded vermiculite (OEVMT) and a nano-zinc oxide (nano-ZnO) compound. The content of OEVMT is 1% by mass of bitumen, while that of nano-ZnO is 1, 2, 3, and 4% by mass of bitumen. 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 the OEVMT and nano-ZnO compound on the physical and rheological properties of bitumen before and after aging was investigated. The results show that the high-temperature stability of bitumen can be enhanced, while the other physical properties of bitumen are slightly influenced with the introduction of OEVMT and the nano-ZnO compound. As a result of TFOT, PAV, and UV aging, OEVMT and nano-ZnO modified bitumens show lower viscosity aging index, softening-point increment, phase angle aging index, and complex modulus aging index, and higher retained penetration in comparison with base bitumen, indicating their good thermal-oxidation and UV-aging resistance. However, this improvement depends on the OEVMT and nano-ZnO content. The recommended content is 1% OEVMT plus 3% nano-ZnO by combining the physical and rheological properties results before and after three aging methods. Such a result suggests that the OEVMT and nano-ZnO compound can be effectively used as modifiers to improve both the thermal-oxidation and UV-aging resistance of bitumen, which will remarkably extend the service time of asphalt pavement.