Preparation & Characterization of Original Phosphogpsum-based Hydraulic Cementitious Materials

Using the original phosphogypsum slurry (PS), cement (P.O 42.5), blast furnace slag (BFS) and fly ash as raw materials, adding the powder of cement, BFS and fly ash directly to PS to mix them, the specimens of PS-BFS-cement (PBC) and PS-BFS-cement-fly ash (PBCF) based hydraulic cementitious materials were prepared. The properties of specimens of PBC and PBCF were characterized. The results show that the specimens of PBC have the lower compressive strength (CS) of 3 d, and their CS of 7 d and 28 d increase firstly and then decrease with the increase of cement content. The specimens with 20% (mass fraction) cement have the highest value of CS at 7 d and 28 d among all the specimens of PBC, and its CS value of 28 d is 26.4 MPa. CS values of 7 d and 28 d for specimens of PBCF firstly increase and then decrease with the increase of fly ash content. The specimens with 15% (mass fraction) fly ash have the highest value of CS at 7, 28 d among all the specimens of PBCF, which are 17.0, 28.7 MPa respectively. The softening coefficient of specimens of PBCF ≥ 0.88.