All about gypsum
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Manufacturing process

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From materials to plasterboards, learn about the steps involved in manufacturing gypsum.

Manufacturing gypsum

Gypsum is made from:
  • natural gypsum, sedimentary rock extracted from mines or underground quarries,
  • synthetic gypsum, produced from by-products of energy generation or industrial waste.

 

Making gypsum from natural gypsum involves crushing and grinding the gypsum mineral, then firing it at 150°C. Additives can be mixed with the gypsum in very small quantities:

  • starch improves the adhesion between the gypsum and the cardboard in plasterboard production,
  • retarding agents slow the setting time of gypsum.
Plasterboard plant, Silver Grove, Kentucky, United States

Glossary

Gypsum, crushing, plasterboard... Every profession has its technical jargon!

Glossary

Manufacturing plasterboard

Plasterboard is made up of a thin core of gypsum between 2 cardboard sheets. Its manufacture involves several steps:
  • the gypsum is mixed with water. Various solid and liquid admixtures are introduced until a homogeneous slurry is obtained,
  • 2 layers of cardboard are continuously unrolled, 1 below and 1 above the mixer. The edges of the upper cardboard layer are glued to the edges of the lower layer. The sandwich then passes through a system of rollers that compresses it to the desired thickness,
  • after drying, the sheets are cut into standard lengths,
  • they are then stored, ready to be shipped to building sites.

 

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Supervised manufacturing

Drying time

Extensive R&D programs have been devoted to drying as this stage has an impact on the quality of the finished product.

The drying time must be uniform and very precise:

  • sheets containing too much moisture cannot be stored properly,
  • "burned" sheets lose their mechanical strength because the cardboard and the gypsum tend to come apart.

Last update on 06/05/2008

All about gypsum

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Industrial ecology

How to create value from waste

Large amounts of natural resources, particularly minerals and fossil fuels, are used to manufacture cement. For many years the Group has been working to reduce the environmental impact of its activities by finding ways to obtain value from waste products.

Cement and industrial ecology