Effect of nano-zinc oxide and organic expanded vermiculite on rheological properties of different bitumens before and after aging

A novel anti-aging modifier containing surface modified nano-zinc oxide (nano-ZnO) and organic expanded vermiculite (OEVMT) was used to improve the aging properties of different bitumens (denoted as 70#, 90# and 110#). These aging methods include thin film oven test (TFOT), pressure aging vessel (PAV), ultraviolet (UV) radiation and natural exposure aging (NEA). The aging properties of the binders after different aging methods were evaluated by dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test. The result shows that the rutting resistance of three types of bitumens before the above aging methods is enhanced with the introduction of anti-aging modifiers. As a result of TFOT, PAV, UV and NEA, compared with corresponding blank samples, these modified bitumens containing anti-aging modifier show the lower complex modulus and the higher phase angle, indicating their good thermal oxidation and photo oxidation aging resistance. Moreover, the improvement effect of anti-aging modifier is not only bound up with the aging degree of these bitumens, but also depends on the bitumen nature. Besides, the BBR test result manifests that the anti-aging modifier can improve the low-temperature rheological performance of 90# bitumen after PAV aging, and has little influence on that of 70# bitumen and 110# bitumen after PAV aging.