Sorel cement

Sorel cement is a hydraulic cement mixture of magnesium oxide (burnt magnesia) with magnesium chloride with the approximate chemical formula Mg4Cl2(OH)6(H2O)8, corresponding to a weight ratio of 2.5-3.5 parts MgO to one part MgCl2. This material, which is also called "magnesia cement," is usually combined with filler materials such as sand or crushed stone. A variant uses zinc oxide with zinc chloride instead of the magnesium compounds.

Sorel cement was developed since the middle of the 19th century. It is used for grindstones, tiles, artificial stone (cast stone), cast floors, and even artificial ivory (e.g. for billiard-balls). Magnesia cement floors are credited a high resistance to wear. Its chief drawback is its poor water resistance, making it unsuitable for construction applications.