Surface Modification of Multiwalled Carbon Nanotube on the Performance of SBS Asphalt

Multiwalled carbon nanotubes (MWCNTs) improve ultraviolet (UV) aging resistance and storage stability of asphalt modified with styrene-butadiene-styrene (SBS). However, MWCNTs have the disadvantages of poor dispersivity, easy agglomeration, and insolubility in various solvents, which greatly affect the modification effect. The application of silane coupling agent KH550 has the potential to improve the dispersion of original MWCNTs in asphalt. In this research, the high-speed shearing method was used to prepare KH550–modified MWCNTs/SBS composite–modified asphalt, and then Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to observe and evaluate the MWCNTs before and after surface modification. Sensitivity analysis was conducted on the impact of MWCNTs on the performance of SBS-modified asphalt. The softening point test, ductility test, dynamic shear rheology test, and UV aging resistance test were carried out, and the optimal content of MWCNTs after surface modification was determined after comparing with the composite-modified asphalt without coupling agent modification. The results showed that oxidized MWCNTs could be grafted with silane molecules to have a molecular bridging effect on the surface after chemical modification by the silane coupling agent KH550. When the content of SBS was 5% unchanged, the asphalt with 1% surface-modified MWCNTs had excellent performance in softening point, ductility, complex modulus, rutting factor, and UV aging resistance.