Effect of geopolymer as an additive on the mechanical performance of asphalt

Geopolymers have strong durability, excellent mechanical properties, and resistance to high-temperatures, freeze–thaw cycles, and chemical corrosion. In this study, alkali activators and aluminosilicate materials were used to prepare a geopolymer that was then used as asphalt modifiers. The mechanical and microscopic properties of geopolymer-modified asphalt binders and asphalt mixtures were investigated. A routine asphalt binder test and Fourier transform infrared (FT-IR) spectroscopy were used to evaluate the modified binders. Micromorphological changes was observed using fluorescent microscopy. Dynamic shear and bending beam rheometers were used to analyse the rheological properties. The conventional test of the asphalt mixture was used to assess its engineering performance. The results show that the fundamental properties, except for ductility, and high-temperature performance of the modified binders improved. The geopolymer in the modified asphalt binder was uniformly dispersed, and the microphase state was stable. The high-temperature performance and water stability of the modified asphalt mixture were enhanced; however, the low-temperature properties were weakened.