Synthesis and hydration kinetics of calcium aluminate cement with micro MgAl2O4 spinels

Calcium aluminate cement with micro MgAl2O4 spinels (CMA) was prepared using a solid-state reaction. The results indicated that three mineral phases of CaAl2O4, CaAl4O7 and MgAl2O4 could be formed when the calcined temperature reaches 1300 °C. The submicron MgAl2O4 particles are homogeneously distributed among the phases of CaAl2O4 and CaAl4O7. Based on the Krstulovic-Dabic model, the hydration mechanism and kinetic parameters of calcium aluminate cement (CAC) and CMA were respectively studied by isothermal calorimetry. It was determined that the total hydration heats of CAC and CMA are, respectively, 309.756 J/g ± 15.5 and 275.496 J/g ± 13.8. The results showed that these two types of cement have the same hydration process. The nucleation and crystal growth process is the main reaction at the initial stage and then transforms into a diffusion controlled process.