Constructing a novel nano-TiO2/Epoxy resin composite and its application in alkali-activated slag/fly ash pastes

•A novel TiO2/Epoxy resin composite was applied to the manufacture of AASF pastes.•AASF pastes display better mechanical properties because of a densified microstructure.•The drying shrinkage leading to fewer cracks as evidenced by morphology analysis.•The simple manufacturing process would help AASF binders to increase their potential for industrial applications. A novel in-situ synthetic method is developed for fabrication of inorganic-organic hybrid structured TiO2/Epoxy resin composite without adding any surfactants. It is discovered for the first time that the inorganic-organic micro-structured TiO2/Epoxy composite can be homogeneously dispersed in one type of alkali-activated binders: alkali-activated slag/fly ash (AASF) pastes with slag/fly ash at 50/50. Besides, it is found that TiO2/Epoxy composite is capable of enhancing the mechanical properties including compressive and flexural bending strengths, improving porous structures and reducing drying shrinkage of the AASF paste. Moreover, scanning electron microscopy results showed that the AASF binder enhanced by TiO2/Epoxy resin composite has a smooth and flat morphology with fewer cracks as compared to the control paste, leading to a denser microstructure. It is assumed that both TiO2 and epoxy resin are beneficial in improving the microstructure and hence the macroscopic properties of AASF binders were also improved. Since the preparation of TiO2/Epoxy composite through in-situpolymerization method is attractive because of its simple manufacturing procedure and cost-effectiveness, its modified AASF binders have an appealing potential to be used for large-scale production and field applications in the foreseeable future.