Monocalcium aluminate is one of the series of calcium aluminates

Calcium aluminates

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

. It does not occur in nature, but is important in the composition of calcium aluminate cements

Calcium aluminate cements

Calcium aluminate cements are cements consisting predominantly of hydraulic calcium aluminates. Alternative names are "aluminous cement", "high-alumina cement" and "Ciment fondu" in French...

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Properties

Monocalcium aluminate is formed when the appropriate proportions of calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

 and aluminium oxide

Aluminium oxide

Aluminium oxide is an amphoteric oxide with the chemical formula 23. It is commonly referred to as alumina, or corundum in its crystalline form, as well as many other names, reflecting its widespread occurrence in nature and industry...

 are heated together until the mixture melts. It melts incongruently at 1390°C. The crystal is monoclinic and pseudohexagonal

Hexagonal crystal system

In crystallography, the hexagonal crystal system is one of the 7 crystal systems, the hexagonal lattice system is one of the 7 lattice systems, and the hexagonal crystal family is one of the 6 crystal families...

, 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

Cement

In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...

. A typical composition is Ca_0.93Al_1.94Fe_0.11Si_0.02O₄. 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.