How is white gypsum powder made?

Production process of plaster of paris

Gypsum powder is one of the materials that are of particular importance in the construction industry and has been used in construction since ancient times due to its characteristics. Plaster is obtained from baking and grinding gypsum stones. Gypsum is one of the construction materials that contain calcium and is abundantly found in nature almost everywhere. It is the fifth most abundant mineral on earth.

Gypsum with the formula CaSO4, 2H2O is one of the sedimentary stones and cannot be found purely due to its high reactivity. It is mostly found in two forms either bound to carbon and ferric and clay oxides or in the form of anhydrite calcium sulfate. Pure gypsum is colorless, carbonated ones are gray, and those bound to ferric oxides can be light yellow, red, or livid depending on the type of ferric oxides.

al ahli gypsum powder

In order to produce white gypsum powder, pure gypsum is first entered into the production line after two stages of crushing with uniform gradation. This uniform mixture is then baked in rotating horizontal kilns at different temperatures and durations and is so-called calcined plaster. This plaster undergoes two stages of fine crushing and grinding after exiting the kiln. The white gypsum powder ( plaster of paris) is sieved after grinding and is now ready to be packed with homogeneous gradation.

Features of white gypsum powder

fast setting, increased volume during hardening, being acoustic, resistant to fire, cheap and easily accessible, and white and pleasant color are among the most significant features of gypsum powder.

Causes of cracks in gypsum plaster

The wall plaster can crack after drying and hardening. As a result, it can create ugly shapes in the building. Cracking can have many reasons. Some of them are listed below:

  • Using inadequate powder when making mortars.
  • Using a thick mortar on the wall (>7-8 cm) results in the outer layers drying quickly in contact with air but leaves the inner ones wet which may cause cracks.
  • If you plaster the wall in the cold season and the mortar water freezes before expansion, the hardening processes will stop. After melting, the plaster rots and no longer continues to expand which will cause cracks on the surface.
How to render wall plaster with good adhesion?

Lack of adhesion of the gypsum plaster is often heard as a hollow sound and usually occurs in thick layers of the wall. Lack of adhesion is usually caused by inappropriate preparation, so you must:

  • Clean the wall of dust
  • Adequately moisturize the wall
  • Apply cement slurry before starting plastering