Preparation and performance optimization of coal gangue-based geopolymer

The unreasonable disposal of coal gangue will bring pressure and threat to the ecosystem. In order to solve the problem of difficult reuse and low utilization rate of coal gangue, the high value-added strategy of using coal gangue to produce geopolymers was put forward. In this study, uncalcined coal gangue was used as the raw material, and the effects of the addition amount of blast furnace slag, the modulus of sodium silicate, the addition amount of alkali-activator, the ratio of liquid to solid and the initial 24-hours curing temperature on the compressive strength of geopolymer matrix were studied by single factor experimental design. The results show that the initial 24-hours curing temperature, the addition amount of alkali-activator and the modulus of sodium silicate have significant effects on the properties of coal gangue-blast furnace slag based geopolymer matrix. X-ray diffraction and scanning electron microscope analysis show that the structure of uncalcined coal gangue is destroyed under the action of alkali-activator, and the dense microstructure is formed on the synergic formation of N-A-S-H, C-A-S-H and C-S-H gels with blast furnace slag. This research results provide a reasonable basis for the large-scale resourceful utilization of coal gangue.