Calciumsilikathydrat

CalciumSilikatHydrat, often abbreviated C‑S‑H, is the principal binding phase formed during the hydration of Portland cement. Chemically it is a poorly crystalline, poorly defined calcium silicate hydrate whose idealized composition can be expressed as CaO·SiO₂·H₂O, though the actual Ca/Si ratio varies between 0.6 and 2.0 depending on the cement formulation and curing conditions. The structure consists of layered silicate sheets linked by calcium ions and interlayer water molecules, giving rise to a gel‑like material with high specific surface area.

During cement hydration, tricalcium silicate (C₃S) and dicalcium silicate (C₂S) react with water to produce calcium hydroxide and C‑S‑H. The former contributes to early strength development, while C‑S‑H provides the long‑term mechanical strength and durability of concrete. Its nanoscopic porosity governs permeability, shrinkage, and resistance to chemical attack. Modifying the Ca/Si ratio, for example by adding pozzolanic materials or supplementary cementitious binders, can tailor these properties for specific applications.

CalciumSilikatHydrat also appears in natural settings as the mineral tobermorite and related phases in hydrothermal veins and altered volcanic rocks. In the construction industry it is studied for low‑carbon cement alternatives, such as calcium‑silicate‑based binders derived from industrial by‑products, which aim to reduce the CO₂ emissions associated with traditional Portland cement production.