Simultaneous control of particle size and morphology of α‐CaSO4·1/2H2O with organic additives

Here we reported a method to simultaneously control the particle size and morphology of α‐CaSO4·1/2H2O (α‐HH) prepared from flue gas desulfurization gypsum by adjusting the succinic acid concentration and glycerol content under mild conditions. Succinic acid controlled the crystal morphology by adsorption onto α‐HH surfaces, and glycerol controlled the crystal particle size, in which an increase in the maximal relative supersaturation (Smax) and nucleation rate of α‐HH was hypothesized to cause the change in α‐HH particle size. Then, based on the method, α‐HH with different particle sizes but with almost the same morphology was prepared, and the influence of the crystal particle size on the mechanical strength of the α‐HH pastes was explored. With decreasing α‐HH particle size from about 26 to 5 μm, the dry compressive strength of the pastes made from the α‐HH decreased remarkably from 68.02 to 34.85 MPa, which was ascribed to an increase in the internal porosity of the pastes.