High- and Intermediate-Temperature Performance of Crumb Rubber-Nano-Alumina-Modified Asphalt Binder

The purpose of this study is to ascertain the impact of adding nano-alumina (NA) to an asphalt binder that has been modified with crumb rubber (CR). In this work, the nano-alumina content was changed from 1 to 6% while the concentration of CR was held constant at 12% (wt. of base binder) (decided after literature survey). Physical tests like penetration, softening point and ductility were used to assess the impact of different concentrations of nano-alumina (by weight of binder) at different concentrations (1, 2, 3, 4, 5 and 6%). Theological parameters of the base binder and the nano-alumina polymer-modified asphalt binder were analysed using the rotational viscosity (RV) and dynamic shear rheometer (DSR) tests. In addition, the performance of modified asphalt after thin film oven (TFO) (short-term ageing) and pressure ageing vessel (PAV) test (long-term ageing) was assessed as well. Furthermore, the storage stability of modified asphalt binder was evaluated. Results showed that the addition of nano-alumina has a positive effect on rutting performance of CR-modified asphalt binders. Storage stability of the CR-modified asphalt binders improved significantly after the addition of nano-alumina. According to the Superpave rutting metric ( \({\text{G}}/{\text{Sin}}\delta\) ), the addition of 4% of NA and 12% of CR improves the performance of the binder's rutting strength. At a particular percentage of CR and NA, a slight increase in the fatigue measure was also noted. According to a storage stability test, improved asphalt binder does not experience phase separation at high temperatures. On the basis of this, it may be deduced that when a little amount of NA was added to the CR-modified binder, its physical characteristics were successfully enhanced. During rheological characterization, it was found that complex modulus increases, phase angle decreases, Superpave rutting parameter increases and failure temperature increases with increasing nano-alumina content. It was also found that Brookfield viscosity increases with an increasing nano-alumina concentration as binder becomes stiffer. All the test results confirmed the fact that crumb rubber-nano-alumina modifier is effective in enhancing the high-temperature properties (rutting resistance) of the soft grade binders and at the same time, it increases the elasticity of the binders.