脱硫石膏-粉煤灰协同复配胶凝材料制备高固废混凝土及其抗盐侵蚀性能研究

Desulfurization gypsum (DG) and fly ash (FA) are difficult to be utilized on a large scale, which leads to their large accumulation and thus polluting the environment and wasting land resources. Therefore, in this paper, FGD gypsum and fly ash are used as cementitious materials instead of cement (OPC), and steel slag is used as aggregate for the preparation of concrete, which not only can efficiently utilize the solid waste, but also can save cement and gravel and protect the environment. In this paper, the effects of cement content and the ratio of desulfurization gypsum to fly ash on Preparation of high solid waste concrete by desulfurization gypsum-fly ash synergistic compounding cementitious materials and its resistance to salt erosionthe mechanical properties of concrete were systematically investigated and its durability performance was examined. The results show that the higher the cement content, the stronger the mechanical properties of concrete. The lower the ratio of desulfurization gypsum to fly ash, the more excellent the mechanical properties and durability performance of concrete. Taken together, the concrete prepared when cement, FGD gypsum and fly ash accounted for 45%, 18.3% and 36.7% of the cementitious materials respectively had excellent performance, with a compressive strength of 40.5 MPa and the highest solid waste utilization rate of 74%. After boiling NaCl salt solution for 8 hours, the compressive strength only decreased by 4.3 MPa, and the volumetric expansion rate was 0.48%, which was lower than the standard limit value of 0.5%. This is because the addition of desulfurization gypsum and fly ash induced the generation of hydrated calcium silicate and ettringite within the concrete, which filled the internal voids and enhanced the strength of the concrete. The experimental process provides a reference for the large-scale utilization of DA and FA in concrete production and construction.