Calcium silicate (often referred to by its shortened trade name
Cal-Sil or
Calsil) is the chemical compound Ca
2SiO
4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO
2. It is one of a group of compounds obtained by reacting
calcium oxide and
silica in various ratios e.g. 3CaO•SiO
2,
Ca3SiO5; 2CaO•SiO
2, Ca
2SiO
4; 3CaO•2SiO
2, Ca
3Si
2O
7 and CaO•SiO
2,
CaSiO3. Calcium silicate is a white free-flowing powder derived from
limestone and
diatomaceous earth. It has a low
bulk density and high physical
water absorption. It is used in roads, insulation,
bricks, roof tiles, table salt and occurs in cements, where it is known as
belite (or in
cement chemist notation C
2S).