Statistical research on phase formation and modification of alite polymorphs in cement clinker with SO₃ and MgO

The design of experiments (DoE) was adjusted in cement clinker chemistry, with alite polymorphisms in the clinker taken into account. The additions of SO₃, MgO, as well as two other factors, sintering temperature and time, were included to study clinker formation and alite polymorphisms. XRD quantitative analyses and thermal analysis (DSC-TG) were used to collect quantitative data from the samples and to investigate the clinkerization of the raw meal. The central composition design was used to design the experiments and the response surface methodology was used to evaluate the results. The addition of SO₃ inhibited the formation of alite in the clinker, while MgO compensated for any negative effects caused by the SO₃. A contour plot interpreted the combination effects of these four factors. The amount of C₄AF was then increased with a likewise increasing SO₃ content. MgO favored the formation of M3 type alites, while SO₃ stabilized the M1. Alite modification, which is related to hydration properties, could be helpful for efficient use of high MgO content calcite in cement production.