2CaOSiO2

2CaO·SiO2, commonly written as 2CaO·SiO2 or Ca2SiO4, is known in chemistry as dicalcium silicate and is a key calcium silicate phase. In cement science it is more widely referred to as belite (C2S). Belite is one of the principal mineral components in ordinary Portland cement clinker, typically forming alongside alite (Ca3SiO5) during high-temperature kiln processing.

In natural form, Ca2SiO4 exists as a mineral belite, which shows several polymorphs that depend on temperature and cooling history. At ambient conditions the beta form is commonly encountered in cement chemistry contexts. The precise stability of these forms influences setting behavior and hydration characteristics.

Hydration and properties are central to belite’s role in cement. When cement hydrates, belite reacts with water to form calcium silicate hydrate (C-S-H) and calcium hydroxide, albeit more slowly than alite. This slower reaction rate means belite contributes to strength development at later ages and generally produces lower early strength but lower heat of hydration. Consequently, belite-rich cements can be engineered for reduced heat evolution and improved performance in large-scale pours or mass concrete.

Applications and significance center on cement climatology and performance. Belite-rich clinkers yield low-heat cement, useful for large structures where excessive exothermic rise must be avoided. By adjusting raw materials and firing conditions, manufacturers can increase the belite content to tailor hydration behavior and long-term strength while balancing workability and setting characteristics.