Effects of Steel Slag and Flue Gas Desulfurization Gypsum on the Properties of Metakaolin-Based Geopolymer Grouting Materials

In this paper, the performance of steel slag (SS) and flue gas desulfurization (FGD) gypsum modified metakaolin-based geopolymer (MGP) was studied for the purpose of industrial solid waste reuse, and a new geopolymer grouting material was obtained. The setting time, fluidity, bulk density, and compressive strength of MGP containing different mass contents of solid waste materials were studied through a series of tests. In addition, the microstructure mechanism of MGP was analyzed using scanning electron microscopy and Fourier transformation infrared spectroscope. The results show that the setting time of MGP increases with the increase of SS content, whereas the setting time decreases with the increase of FGD content. The addition of SS or FGD slightly reduces the fluidity of MGP. Adding an appropriate amount of SS to MGP can significantly improve the later compressive strength of the specimen, whereas adding an appropriate amount of FGD can improve the compressive strength of the specimen, especially the early compressive strength. When the SS content was 4 %, the hardened MGP exhibited the best properties in compressive strength and bulk density. The formation of amorphous geopolymer gel products in MGP matrix was promoted by the addition of SS and FGD. These results will be beneficial to the production of new environmentally friendly and low-cost MGP grouting materials, which can improve the comprehensive utilization level of SS and FGD and achieve the purpose of protecting the ecological environment.