SBS (styrene-butadiene-styrene block copolymer) modified bitumen is one of most widely used polymer modified bitumens in China. It is also not satisfactory when subjected to extreme conditions. Multiple-walled carbon nanotubes, as a type of advanced nanomaterial, are investigated extensively because of their strong adsorption capacity. Little research has been done about MWCNTs/SBS modified bitumen, and in view of this, the performance and modification mechanism of MWCNTs/SBS modified bitumen was investigated in this paper. Conventional bitumen tests, Brookfield viscosity, bending beam rheometer, and dynamic shear rheometer tests showed improved performance at high and low temperature. The optimum MWCNTs content was determined as 1.0%. FT-IR, bitumen four components, and thermal analysis tests were conducted and revealed that the addition of MWCNTs led to a decrease in the content of light components. In addition, the rate of decomposition and volatilization of saturates and aromatics was reduced and better thermal stability of bitumen was found. Fluorescence microscopy tests showed that MWCNTs improved the dispersion of SBS and storage stability of the binder. Finally a schematic was proposed to explain how MWCNTs improved the performance of SBS modified bitumen through their strong adsorption property created by π-π intermolecular forces.
Keywords: MWCNTs; SBS modified bitumen; modification mechanism; rheological properties.