Monocalcium aluminate
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| Monocalcium aluminate | |
|---|---|
| IUPAC name | Monocalcium aluminate |
| Molecular formula | CaAl2O4 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Monocalcium aluminate (CaAl2O4) is one of the series of calcium aluminates[1]. It does not occur in nature, but is important in the composition of calcium aluminate cements.
[edit] Properties
Monocalcium aluminate is formed when the appropriate proportions of calcium carbonate and aluminium oxide are heated together until the mixture melts. It melts incongruently at 1390°C. The crystal is monoclinic and pseudohexagonal, and has density 2945 kg.m-3. In calcium aluminate cements, it exists as a solid solution in which the amount of minor elements depends upon the bulk composition of the cement. A typical composition[2] is Ca0.93Al1.94Fe0.11Si0.02O4. It reacts rapidly with water, forming the metastable hydrate CaO.Al2O3.10H2O, or a mixture of 2CaO.Al2O3.8H2O, 3CaO.Al2O3.6H2O and Al(OH)3 gel. These reactions form the first stage of strength development in calcium aluminate cements.
[edit] References
- ^ H F W Taylor, Cement Chemistry, Academic Press, 1990, ISBN 0-12-683900-X, p 35
- ^ P. C. Hewlett (Ed)Lea's Chemistry of Cement and Concrete: 4th Ed, Arnold, 1998, ISBN 0-340-56589-6, p715
