The Influence Mechanism of Molar Ratio on the Performance of Phosphogypsum-Modified Geopolymer Material

Comprising a relatively large amount of industrial solid waste, the high-value utilization of phosphogypsum (PG) is closely related to the sustainable development of resource materials and the protection of the ecological environment. PG can improve some of the shortcomings of geopolymers, but there is a lack of systematic research on the specific influencing factors as well as the mechanism of the two in a hydration reaction. In this study, the effects of the Si/Al, Na/Al and Ca/Al ratios on the micropores as well as the hydration products of phosphogypsum-modified geopolymer material (PMGM) are systematically explored via macroscopic and microscopic tests from the molar ratios of the raw material’s target components. By changing the molar ratio, the generation of hydration products is affected, thereby altering the properties of the material. The effects of each molar ratio on paste workability, capillary water absorption, drying shrinkage and self shrinkage are systematically analyzed, while the types, productions, and micropores of hydration products are analyzed via XRD and SEM. This study provides a new idea for the large-scale recycling of PG and makes a systematic investigation of its hydration mechanism, which can provide a reference for the reaction principle of PG with geopolymers.