Performance and hydration mechanism of β-hemihydrate phosphogypsum with granulated blast furnace slag and carbide slag

Abstract

Β-hemihydrate phosphogypsum (HPG) is a building material produced by low-temperature calcination of phosphogypsum, which has the potential to replace cement. However, some defects limit its utilization. In this research work, a ternary solid waste cementitious material system was established by incorporating granulated blast furnace slag (GBFS) and carbide slag (CS) into the HPG system to improve the working performance, strength, and water resistance. The microstructure and phase composition of the hydration products and the hydration process were investigated by SEM, XRD, thermogravimetric analysis, and hydration heat. The results showed that the 28 d compressive strength and softening coefficient could reach 57.5 MPa and 0.91, respectively. The introduction of CS provided the initial alkalinity for the depolymerization of GBFS to form AFt and C-S-H gel, reducing the hydration heat release rate and optimizing the microstructure. The cost of HPBCM was less than 1/2 of cement, and the carbon emission was only 1/10 of cement, which possessed good environmental and economic benefits. The research results can help the promotion and application of the three solid wastes.