Effect of Carbon Nanomaterials on the Rheological Characteristics of Crumb Rubber–Modified Asphalt

This research aims at studying the effect of graphite nanoplatelets (GNPs) and carbon nanotubes (CNTs) on the rheological characteristics of crumb rubber (CR)–modified asphalt. For this purpose, the apparent viscosity, temperature sweep, frequency sweep, multiple stress creep and recovery, and beam bending rheological tests were employed. To characterize the low-temperature rheological characteristics of the asphalts, the Zener model was utilized to fit the characterizations. The test results indicated that added CNTs or GNPs increased the apparent viscosity of CR-modified asphalt. Also, the viscosity-temperature index (VTS) values of CR/CNTs composite-modified asphalt and CR/GNPs composite-modified asphalt decreased by 25% and 19% compared with that of CR-modified asphalt, which demonstrated that the two nanomaterials improved the temperature sensibility of the asphalt. Adding the two carbon nanomaterials was helpful for enhancing the permanent deformation resistance and creep-recovery characteristics of CR-modified asphalt at high temperatures. In addition, the CNTs/CR composite-modified asphalt had a better effect on the rheological properties at high temperatures. Lastly, the S and m values of CR/CNTs composite-modified asphalt and CR-modified asphalt met the requirements at −18°C. Besides, the m value of CR-modified asphalt was higher than that of the two composite-modified asphalts at all three test temperatures.