Conventional, Thermal, and Rheological Properties of Asphalt Binder Modified by Carbon Nanotubes and Crumb Rubber

The purpose of this paper was to investigate the effect of carbon nanotubes (CNTs) and crumb rubber (CR) on the conventional properties, thermal behaviors, and rheological properties of binders. There are four asphalt types employed in this study. Physical property tests were conducted to determine the conventional properties of the asphalts. In addition, thermogravimetry (TG) and differential scanning calorimetry (DSC) were applied to analyze the thermal behaviors of the asphalts. To appraise the high-temperature rheological properties of the asphalts, temperature scanning (TS), frequency scanning (FS), and multiple stress creep and recovery (MSCR) tests were employed. Furthermore, based on the creep characteristics of asphalt, bending beam rheometer (BBR) tests were utilized to evaluate the low-temperature properties of the binders. The results showed that the combination of CNTs and CR modified the physical properties of the binder, which manifested as reduced penetration and increased softening points, viscosity, and elastic recovery rates. CNTs and CR improved the temperature stability of the binder and reduced the amount of asphalt components participating in a phase change at low temperatures. Moreover, the results of the TS, FS, and MSCR tests indicated that CNTs and CR significantly improved the high-temperature rheological properties of the asphalt. Lastly, the results of the BBR test implied that the composite-modified asphalt exhibited better flexibility and stress relaxation ability at low temperatures than asphalt modified with either CR or CNTs alone.