Effect of particle size and thermal activation on the coal gangue based geopolymer

Abstract To better improve the preparation processing of coal gangue based geopolymer and understand the influence of particle size and thermal activation on the coal gangue based geopolymer, this paper introduces two kinds of geopolymers prepared by different methods using coal gangue and blast furnace slag as raw materials. The influence of particle size and activation temperature on the coal gangue was analyzed by XRD, FTIR, SEM, and TG-DTA. Then the mineral composition, microstructure and pore structure on the properties of the coal gangue based geopolymer were studied through XRD, MIP, and SEM. The results show that the optimum particle size is 200 mesh and the optimum activation temperature is 700 oC; Both geopolymers have obvious mechanical characterization; The main change of coal gangue under mechanical grinding is that the original structure is destroyed, the active reaction site and the potential gelling activity are both increased; While the main change of coal gangue under thermal activation is the crystal structure of Al2O3·2SiO2·2H2O in the coal gangue is destroyed and a phase transformation occurs; The analysis of XRD and SEM-EDS manifested that both the final products are composed of N-C-A-S-H gel and some unreacted crystalline phases are still present.