Magnesium chloride is composed ofmagnesium and chlorine and is a typical ionic halide, being highly polar and soluble in water. Molar Mass of 95.22 g/mol (anhydrous). Melting Point 714 °C (987 K). Boiling point 1412 °C (1685 K). Appearance white or colorless crystalline solid. It is used in the manufacture of cements. Magnesium chloride can be extracted from brine or sea water.

Cement is a binder, a substance which sets and hardens independently, and can bind other materials together. Materials which set and harden after combining withwater, as a result of chemical reactionswith the mixing water and, after hardening, retain strength and stability even under water.

References:

http://en.wikipedia.org/wiki/Magnesium_chloride

House:

http://www.celblox.com/photos-icf.htm

Cement

http://images.google.com/images?q=of+portland+cement&ndsp=20&svnum=10&hl=en&lr=&start=460&sa=N

Structure

http://www.webelements.com/webelements/compounds/text/Mg/Cl2Mg1-7786303.html