Adhesion performance and enhancement mechanism of FA/GGBFS based geopolymer modified bitumen and acidic aggregate

The primary challenge in utilizing acidic aggregates in bitumen mixtures lies in enhancing the adhesive bond between the bitumen and the acidic aggregates. In this manuscript, to investigate the adhesion of different geopolymer modified bitumen with acidic aggregates, fly ash geopolymer (FG), fly ash- ground granulated blast furnace geopolymer (SFG), and ground granulated blast furnace (SG) were prepared by fly ash (FA), ground granulated blast furnace (GGBFS) with alkali activator. The different geopolymers were characterized with SEM, XRD, FTIR. Different geopolymer modified bitumen was prepared by adding geopolymers into virginal bitumen. The conventional properties, viscosity, and rheological properties of modified bitumen were measured and analysed. The adhesion of bitumen to acidic aggregates was tested by Zeta potential test, the improved boiling water test and pull-off test. The results showed that the electronegativity of bitumen and acidic aggregates were weakened significantly by Na + in skeletal structure of fly ash geopolymer. The high temperature stability of fly ash geopolymer modified bitumen was improved and the bond strength of bitumen with acidic aggregates increased remarkably with the addition of 9 % fly ash geopolymer. • The high temperature stability of geopolymer modified bitumen was enhanced. • Better bond strength of fly ash geopolymer modified bitumen with acidic aggregates. • Significant improvement in adhesion area and fracture energy of fly ash geopolymer modified bitumen with acidic aggregates. • Na + in skeletal structure of fly ash geopolymer weakened the electronegativity of bitumen with acidic aggregates.