What is Gypsum?

Building gypsum, chemically known as calcium sulfate hemihydrate (CaSO₄·0.5H₂O), is produced through the calcination process of natural gypsum stone or as a byproduct of flue gas desulfurization in coal-fired power plants. In the construction industry, it is used as a binding material, for cement production, and in various other applications. Gypsum can be easily cut, dissolves well in hot water, and has multiple industrial and artistic uses.

Gypsum, or calcium sulfate compounds, has been known for thousands of years. It naturally occurs as gypsum stone, alabaster (a pure fine-crystalline variety), and anhydrite. Through the firing of gypsum stone, gypsum binders are produced, mainly in the form of hemihydrate gypsum or soluble anhydrite. Gypsum binders are chemically reactive, hardening quickly when mixed with water to form a solid gypsum structure equivalent to its original dihydrate form.

Uses of Gypsum

Gypsum is widely used in construction and architecture, but also in:

• Fine arts – as a sculpting, modeling, and decorative material
• Surgery and dentistry – for casts and molds
• Ceramic industry – in mold-making
• Chemical industry – in paints, varnishes, and paper production
• Food industry – for clarifying wine
• Agriculture – as a soil fertilizer and conditioner

Gypsum remains indispensable in the building industry, valued for its ease of shaping, smooth surface finish, and eco-friendliness. Alongside lime and ceramics, gypsum is one of the oldest human-made building materials, proving its effectiveness and durability in residential construction.

Key Properties of Gypsum

• Fast setting time (even within a few minutes), easily modified with additives
• No shrinkage – in fact, it slightly expands during setting
• High compressive and flexural strength
• Fire resistance – chemically bound water (≈20% of its mass) is released as steam above 140°C, absorbing heat and slowing fire spread
• Helps maintain stable humidity levels indoors

Gypsum’s versatile applications, environmental benefits, and excellent physical properties make it an ideal material for various construction, artistic, and industrial purposes