Publication details

Thaumasite formation by hydration of sulphosilicate clinker



Year of publication 2020
Type Article in Periodical
Magazine / Source Materials Today Communications
MU Faculty or unit

Faculty of Science

Keywords Sulphosilicate clinker; Hydration; Ternesite; Thaumasite; Sustainability
Description Extensive research on sulphosilicate clinkers has been performed, primarily given by the ecological aspects. The formation of thaumasite and ettringite has become an important issue due to possible concrete deterioration, and also reducing greenhouse gas emissions. This work was aimed at hydration of ternesite based clinkers at low temperatures, with respect to thaumasite formation. Five clinkers with various compositions corresponding to stoichiometric ratios of elements in thaumasite and ternesite were prepared. Clinker-water suspensions were stored at 5 degrees C for up to 810 days. X-ray diffraction, DSC/TG, and SEM/EDS were used as the analytical tools. All the clinkers contained ternesite, belite, anhydrite, and free lime. As shown by the results, ternesite and belite preferably hydrate to CSH gels, and sulphate ions forming ternesite become a part of gypsum. The remaining portion of gypsum originated from anhydrite hydration. Gypsum reacted with silica and carbon dioxide to form thaumasite. Thaumasite was clearly identified already after 28 days of hydration, and for one sample, its content finally reached approximately 34 wt. %. It should be considered that the application of sulphoaluminate cements may possibly be connected with the sever risk of sulphate attack.

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