Hydration of calcium aluminate cements in the presence of calcium carbonate
Kuzel, Hans-Jürgen; Baier, Herbert
European Journal of Mineralogy Volume 8 Number 1 (1996), p. 129 - 142
published: Feb 22, 1996
manuscript accepted: Sep 1, 1995
manuscript received: Feb 21, 1995
ArtNo. ESP147050801014, Price: 29.00 €
Abstract The hydration reactions of mixtures of calcium aluminate cements with calcium carbonate have been studied at 25°C and 60°C using X-ray diffraction methods, conduction calorimetry and SEM. It is shown that the degree of conversion to the cubic phase is directly proportional to the available reactive SiO2. Hydration of calcium aluminate cements low in SiO2 leads to nearly quantitative formation of monocarbonate C3ACaCO311H2O in the presence of CaCO3. The resulting phase assemblage gibbsite-monocarbonate is stable up to 90 ± 5°C at 100 % relative humidity. In cements containing SiO2 bound in phases with hydraulic activity as glass, C2S, gehlenite or related compounds, a hydrogrossular stable in the presence of CaCO3 will be formed. The minimum SiO2- concentration in this hydrogarnet is close to the composition 3CaO·AI2O3 ·0.4SiO2 ·5.2H2O.