Rutting Performance of Nano-Silica-Modified C320 Bitumen

Nanomaterials exhibit novel properties and profound attributes as an additive in asphalt binder modification. However, the application of nano-silica in asphalt binders and mixture modification is still limited, and further research is required. Along these lines, in this work, nano-silica with a content from 2% to 8% and an increment of 2% was utilized in modifying the bitumen binder type C320, which is considered the most conventional type of bitumen used in Western Australia road asphalt mixtures. Various tests were performed to assess their properties, including complex shear modulus, penetration, softening point, and multiple stress creep recovery (MSCR) test. The extracted results revealed an increase in the strength and stiffness properties by lowering the penetration, improving the softening point, and increasing the complex shear modulus of all the nano-silica-modified bitumen samples. Interestingly, much of the content of nano-silica leads to higher rutting resistance. However, the rutting resistance was affected by the size of the nano-silica coated with the silane coupling agent. The ideal sample of nano-silica-modified C320 was determined as NS-15 nm (NS-A), which can improve the rutting resistance by about 7.1 kPa. In the current study, the results of the penetration and softening point using 6–8% of NS-A resulted in a relatively significant improvement of up to 45% in comparison with the non-modified binders. Nevertheless, the rutting resistance of the modified asphalt mixtures needs to be further investigated in the future to elaborate on the impact of nano-silica as modified binders on the mechanical properties of Australian asphalt mixtures.