The Preparation and Thermal Behavior of Calcium Monocarboaluminate

The synthesis of calcium monocarboaluminate starting from mixtures comprising gibbsite or boehmite, portlandite and limestone was carried out at 80 °C with synthesis times of 24 and 48 hours. Products were characterized by powder Xray diffraction, thermogravimetric analysis, IR spectroscopy and scanning electron microscopy. Products differed in calcium monocarboaluminate content, unreacted portlandite and limestone contents also varied. The differences in X-ray diffraction patterns and IR spectra were less pronounced. Scanning electron micrographs showed two different sizes of calcium monocarboaluminate hexagonal platy crystals. Thermogravimetric curves revealed three or four dehydration steps of calcium monocarboaluminate indicating different water contents, depending on starting materials combination and, to a lesser extent, on synthesis conditions. The main effect on the formation of calcium monocarboaluminate from the above starting materials was a combination of aluminum source and limestone particle size.