Influence of curing temperature on the evolution of magnesium oxychloride cement

Hardening behaviour and strength of oxychloride cement strongly depend on the formation of Phase 3 and Phase 5 from MgO and magnesium chloride water solution, and the initial composition can be chosen accordingly within the corresponding phase diagram. A certain number of reactions occur before the final formation of P5 or P3 crystals, and several parameters influence the transformations kinetic, such as MgO reactivity and temperature. Several articles deal with the first aspect, while no indications can be found with regard to the curing temperature's effect on the formation of noble phases. In this article the evolution of magnesium oxychloride cement pastes is analysed at various curing temperatures between 5 and 40 A degrees C. The study is carried out to simulate typical industrial processing conditions and indicate optimal conditions for the production of high chemical and mechanical resistance oxychloride cement. It is shown that at low temperature, Phase 3 is produced in place of Phase 5, and a certain amount of MgO remains non-reacted. The corresponding cement is characterised by lower mechanical strength and higher water solubility.