| Summary: | The β-γ polymorphic transition of calcium orthosilicate (C<sub>2</sub>S) is a key phenomenon in cement chemistry. During this transition, the compound expands due to structural changes and a significant reduction in its density is observed, leading to its disintegration into a powder with a very high specific surface area. Owing to this tendency of the C<sub>2</sub>S material to “self-disintegrate”, its production is energy-efficient and thus environmentally friendly. A physicochemical study of the self-disintegration process was conducted with the aim of determining how the amount of dodecacalcium hepta-aluminate (C<sub>12</sub>A<sub>7</sub>) in calcium orthosilicate (C<sub>2</sub>S) affects the temperature at which the polymorphic transi-tions from α’L-C<sub>2</sub>S to β-C<sub>2</sub>S and from β-C<sub>2</sub>S to γ-C<sub>2</sub>S undergo stabilization. The applied techniques included differential thermal analysis (DTA), calorimetry and X-ray diffraction (XRD), and they made it possible to determine what C<sub>2</sub>S/C<sub>12</sub>A<sub>7</sub> phase ratio in the samples and what cooling rate constitute the optimal conditions of the self-disintegration process. The optimal cooling rate for C<sub>2</sub>S materials with a C<sub>12</sub>A<sub>7</sub> content of up to 60 wt% was determined to be 5 K·min<sup>−1</sup>. The optimal mass ratio of C<sub>2</sub>S/C<sub>12</sub>A<sub>7</sub> was found to be 70/30, which ensures both efficient self-disintegration and desirable grain size distribution.
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