Abstract
This study evaluated potential improvements in the physical and rheological properties of asphalt binders modified with crumb tire rubber (CTR), microcrystalline synthetic wax (MSW), and nanosilica (NS). Asphalt binder with 85/100 penetration grade was used. A statistical analysis of the experimental data was performed to determine the effect of using CTR, MSW, and NS on 60/70 and 85/100 asphalt binder grades and to detect any differences. Both physical and rheological tests of pure and modified asphalt binders were conducted. The physical tests were the penetration test, softening point test, and flash and fire points test, whereas the rheological tests included the rotational viscometer (RV) test, dynamic shear rheometer (DSR) test, and bending beam rheometer (BBR) test. The results showed that adding CTR and NS enhanced the high-temperature performance, but it had no effect on low-temperature performance. The results did not indicate enhancement by MSW of high-temperature performance but indicated a negative effect on low-temperature performance. The experimental results were compared and analyzed statistically by ANOVA to find any significant differences between the effect of modifier type, binder grade, and test temperature. Based on the one-way ANOVA results, the modifier type had a significant effect on physical properties and rotational viscosity. The two-way ANOVA results revealed that the change in modifier type and binder grade together had a significant effect on flash point and rutting parameter for unaged samples at 58 degrees C only. The three-way ANOVA indicated that changing the modifier type, binder grade, and test temperature all together had a noticeable effect on the BBR m-value test results. (C) 2019 American Society of Civil Engineers.