Study on the viscoelastic behaviour of the modified asphalt containing multi-walled carbon nanotubes (MWCNTs) and crumb rubber (CR)

Asphalt binder plays an important role on the performance of asphalt mixture, especially for the hightemperature performance. The purpose of this research is to investigate the viscoelastic behaviours of the modified asphalt containing multi-walled carbon nanotubes and crumb rubber. By adding multi-walled carbon nanotubes and crumb rubber to the base asphalt, the multi-walled carbon nanotubes modified asphalt, crumb rubber modified asphalt and multi-walled carbon nanotubes and crumb rubber composite-modified asphalt were prepared. The high-temperature viscosity and rheological property indices were obtained through the viscosity test and small amplitude oscillatory measurement. Besides, multiple stress creep recovery test and stress relaxation test were utilized to explore creep recovery behaviours and stress relaxation characteristics of the asphalt samples. Based on the time-temperature superposition principle, the master curves of complex shear modulus and phase angle were generated. Han curves of the asphalt samples were established based on superposition principle of Blotzmann. Furthermore, the Burgers model was used to model the creep-recovery data. The relaxation functions of Maxwell model and Burgers model were applied to fit stress relaxation curves of the asphalt samples. Results indicate that, the addition of multi-walled carbon nanotubes and crumb rubber caused an increase in high-temperature viscosity, and reduce the temperature susceptibility of base binder. In addition, the permanent deformation resistance, creep-recovery behaviours and stress relaxation characteristics of asphalt were enhanced remarkably by the two modifiers modification. Lastly, the composite-modified asphalt exhibited better viscoelastic behaviours than asphalt modified with either crumb rubber or multi-walled carbon nanotubes alone.