Raw material ratio optimisation of magnesium oxychloride cement using response surface method

Abstract To improve the mechanical properties of magnesium oxychloride (MOC) cement, its raw materials ratio was optimized using the response surface method (RSM). The effects of the molar ratios of MgO/MgCl2 and H2O/MgCl2 on the compressive strength of MOC cement was were analysed using single-factor tests. Based on the results of the single-factor analysis, the factors and levels of the response surface test were determined. The response surface was established using a binary cubic equation, which fit well with the experimental data. It was predicted by RSM that when the molar ratio of MgO:MgCl2:H2O is 7.56:1:13.51, the compressive strength of the MOC cement would be the highest. The compressive strength of the samples fabricated according to the predicted ratio was 105.48 MPa, and the experimental value was 6.29% higher than the predicted value. The factors contributing to the high strength of the optimised samples were explained using X-ray diffraction and scanning electron microscopy, and it was proved that RSM had a guiding significance in optimising the performance of MOC cement.