Monocalcium aluminate

Monocalcium aluminate (CaAl2O4) is one of the series of calcium aluminates.[1] It does occur in nature, although only very rarely, as two polymorphs known as krotite and dmitryivanovite, both from meteorites.[2][3] It is important in the composition of calcium aluminate cements.

Monocalcium aluminate
IUPAC name
Monocalcium aluminate
Molar mass 158.038676 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


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[4] 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.


  1. H F W Taylor, Cement Chemistry, Academic Press, 1990, ISBN 0-12-683900-X, p 35
  4. P. C. Hewlett (Ed)Lea's Chemistry of Cement and Concrete: 4th Ed, Arnold, 1998, ISBN 0-340-56589-6, p715

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