Sorel cement
Sorel cement (also known as magnesia cement) is a non-hydraulic cement first produced by Frenchman Stanislas Sorel in 1867.
The cement is a 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.[1] A variant uses zinc oxide with zinc chloride instead of the magnesium compounds.
In use it is usually combined with filler materials such as sand or crushed stone. It is used for grindstones, tiles, artificial stone, and even artificial ivory (e.g. for billiard balls). It can withstand 10,000 – 12,000 psi (69 - 83 MPa) of compressive force whereas standard Portland cement can typically only withstand 7,000 - 8,000 psi.
Other differences between magnesium-based cements and portland cement include water permeability, preservation of plant and animal substances, and corrosion of metals. These differences make different construction applications suitable. With few functioning mines, and Chinese limits on export, magnesium-based cements are relatively expensive compared to portland-cement based concrete outside Asia.