Category: Cement

CEMENT
cement,binding material used in construction and engineering, typically made by heating a mixture of limestone and clay until it almost fuses and then grinding it to a fine powder. When mixed with water, the silicates and aluminates in to it undergo a chemical reaction; the resulting hardened mass is then impervious to water. It may also be mixed with water and aggregates (crushed stone, sand, and gravel) to form concrete

 

Modern portland cement is made by mixing substances containing lime, silica, alumina, and iron oxide and then heating the mixture until it almost fuses. During the heating process dicalcium and tricalcium silicate, tricalcium aluminate, and a solid solution containing iron are formed. Gypsum is later added to these products during a grinding process. Cement with a high aluminate content is used for fireproofing, because it is quick-setting and resistant to high temperatures; this with a high sulfate content is used in complex castings, because it expands upon hardening, filling small spaces.