利用磷石膏制备的CaSO4合成高性能胶凝材料OA

To improve the resource utilization rate of phosphogypsum(PG),in this study,anhydrous gypsum(AH)prepared by the PG crystallization method,hemihydrate gypsum(HPG)prepared by calcining PG,calcium sulfoaluminate(CAS),and calcium oxide(CaO)were used to develop a sustainable,fast-setting,high-strength cementitious material(AHCSO)based on PG.The results indicate that the optimal formulation for the cementitious material—comprising 70%(mass fraction,the same below)AH,20%HPG,0.3%polycarboxylic acid superplasticizer(PCE),7%CAS,and 3%CaO—exhibits excellent rapid-setting properties,with an initial setting time of 0.3 h and a final setting time of 0.5 h.This cementitious material achieves a compressive strength of 20.8 MPa after 1 d(29.0 MPa when completely dry),35.0 MPa after 3 d(38.1 MPa when completely dry),and 39.8 MPa after 28 d(45.7 MPa when completely dry),softening coefficient of 0.89 and a PG utilization rate as high as 90%(AH 70%,HPG 20%).Ultimately,the hydration rate,setting time,and pore structure of this cementitious material are synergistically controlled,leading to the successful preparation of AHCSO with rapid-setting and high-strength properties.