Analysis of the system 3CaO•Al2O3-CaSO4•2H2O-CaCO3-H2O by FT-IR spectroscopy

The main interaction of CaCO3 with the cement involves the phase C(3)A (3CaO . Al2O3) resulting in the formation of hydrated carboaluminate, a similar compound to that obtained in the 3CaO . Al2O3-CaSO4. 2H(2)O system. In this work gypsum partially substituted by CaCO3 was studied during hydration and the phases formed as consequence of the competition between CaCO3 and CaSO4. 2H(2)O for the C(3)A at early ages were characterized. Calcium mono- and tricarboaluminato formation (phases Afm and Aft, carbonate) during early C3A hydration are discussed as well as the influence that limestone presence causes in the system. Infrared spectroscopy (FT-IR) technique confirmed the existence and formation of the phases reported during the early hydration step. (C) 2001 Elsevier Science Ltd. All rights reserved.