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Calcium aluminates


Calcium aluminates are a range of minerals[1] obtained by heating calcium oxide and aluminium oxide together at high temperatures. They are encountered in the manufacture of refractories and cements.

The stable phases shown in the phase diagram (formed at atmospheric pressure under an atmosphere of normal humidity) are:

In addition, other phases include:

  • Dicalcium aluminate (2CaO.Al2O3), which exists only at pressures above 2500 MPa[2]. The crystal is orthorhombic, with density 3480kg.m-3.
  • Pentacalcium trialuminate 5CaO.3Al2O3, forms only under an ahydrous and oxygen-free atmosphere. The crystal is orthorhombic, with a density of 3067 kg.m-3. It reacts rapidly with water.
  • Tetracalcium trialuminate 4CaO.3Al2O3, is a metastable phase formed by dehydrating 4CaO.3Al2O3.3H2O.


  1. ^ H F W Taylor, Cement Chemistry, Academic Press, 1990, ISBN 0-12-683900-X, pp 34-38
  2. ^ ibid, p 28, 29
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Calcium_aluminates". A list of authors is available in Wikipedia.
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