Influence of Silica–Alumina-Modified Materials on Mechanical Properties of Fly Ash-Based Geopolymers

When the silico–alumina materials in the raw materials are different, the mechanical properties of geopolymers often show great differences. A series of orthogonal experiments have obtained the strengths of fly ash-based geopolymers and metakaolin/slag–fly ash-based geopolymers with different ratios. The mechanical properties of coal ash-based geopolymers have a good modification effect, and the strength shrinkage of pure fly ash geopolymers is eliminated. Then, the obtained compressive strength data were analyzed for significance to obtain the influence degree of each influencing factor, and the optimal mixing ratio of various geopolymers was obtained through variance and range analysis. Finally, the mineral phase, micro-morphology and chemical bonding were analyzed by combining XRD, SEM, and other means, and the reaction mechanism was explored. It provides new ideas and theoretical basis for improving the performance of building materials and solving the problem of industrial waste stockpiling.