硅酸钙，化学式为CaSiO₃，用作高温绝缘及防火。硅酸钙没有已知对健康有不利影响。硅酸钙很容易溶于水。

硅酸钙是常用替代石棉的一种安全隔热材料。

Calcium silicate (often referred to by its shortened trade name Cal-Sil or Calsil) is the chemical compound Ca₂SiO₄, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO₂. It is one of a group of compounds obtained by reacting calcium oxide and silica in various ratios e.g. 3CaO•SiO₂, Ca₃SiO₅; 2CaO•SiO₂, Ca₂SiO₄; 3CaO•2SiO₂, Ca₃Si₂O₇ and CaO•SiO₂, 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 C₂S).