Effect of cooling rates on the properties of Portland cement clinkers in the presence of Mg

In order to enhance the performance of Portland cement clinker, this study investigates the effect of cooling rates on the mineralogical composition of cement clinkers containing magnesium (Mg), which is the most common minor element in raw materials (e.g., limestone). Three cooling regimes were considered to simulate industrial kiln processing conditions. MgO contents of 0, 3, and 6 wt.% were considered in this study. After synthesis of the clinkers, quantitative X-ray diffraction is used to investigate the mineralogical composition, as well, the phase amounts using the Rietveld method. The results show that rapid cooling and Mg doping can promote the formation of alite, and monoclinic alite can be stabilized via Mg ions. Slow cooling and Mg incorporation can stabilize g- C2S, but a rapid cooling rate is still effective to restrain the transformation from b-C2S to g-C2S in MgO-doped clinker. The cooling rates do not influence the content of ferrite and C3A obviously, but the MgO incorporation can enhance the ferrite formation and reduce the C3A content. At a slow cooling rate, little Mg can dissolve in clinker phases, but the retention of MgO in clinker phases can be increased by a fast cooling rate. Therefore, the effect of MgO on the mineralization and the solubility of MgO is a function of cooling rates.