Hydration Products in Water Suspension of Portland Cement Containing Carbonates of Various Solubility

Simona Medvešček,^a* Roman Gabrovšek,^b Venčeslav Kaučič,^b Anton Medena

^a Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia
^b Laboratory for Inorganic Chemistry and Technology, National Institute of Chemistry, Hajdrihova 19,
SI-1001 Ljubljana, Slovenia

Absrtract
The development of hydrated phases and overall microstructure were studied in the course of the hydration of portland cement containing carbonates of various solubility. Phase composition of hydrated samples was examined by powder diffraction and thermogravimetric analysis (TG/DTG). The development of hydrated surfaces was assessed by the measurement of surface area.
The addition of a constant amount of slightly soluble (CaCO₃, MgCO₃), medium soluble (Li₂CO₃) and highly soluble (K₂CO₃ and KHCO₃) carbonates significantly influenced both the degree of hydration and final phase composition of hydrated cement. Anhydrous mineral, tilleyite, was formed in samples containing medium- and highly soluble carbonates.