Gypsum: what it is, how it is produced, and why cracks appear

Gypsum, also known as calcium sulfate dihydrate (CaSO₄·2H₂O), is obtained through the dehydration of natural gypsum rock. Depending on the processing conditions and the addition of other components, different types of gypsum with specific properties can be produced.

As a result, materials such as plaster, stucco, decorative moldings, technical molds, and even medical gypsum used to immobilize bone fractures are obtained. For a more detailed chemical definition, you can consult the gypsum article on Wikipedia.

What calcined gypsum is and how it is used

During partial dehydration, calcium sulfate hemihydrate is produced. This material is commonly known as calcined gypsum and is sold in powder form. It is widely used in construction, mainly for interior wall finishes.

However, in some applications, calcined gypsum is mixed with other types of gypsum. In rare cases, it may even be combined with dead gypsum, which refers to gypsum that has been insufficiently dehydrated or not calcined at all.

Why cracks appear in gypsum walls

The combination of different types of gypsum, each with distinct degrees of dehydration and mechanical properties, is one of the main causes of cracks appearing on interior walls.

These differences lead to variations in setting and drying times, generating internal stresses that eventually result in visible cracks on the surface.

As explained in more detail in our article about cracks in walls, this issue can also be caused by poor plastering practices, such as using guide strips fixed with gypsum mixes of different characteristics.

In short, when cracks originate from the gypsum itself, they are usually related to incompatible mixtures or gypsum products calcined under different conditions.

Uses of gypsum in modern construction

Gypsum is used in construction in many different ways. One of the least known applications among the general public is its use in drywall systems, commonly referred to as plasterboard.

Although drywall systems are sometimes controversial, they clearly offer advantages in modern construction, such as faster execution times, improved quality control, and greater comfort during installation.

If you are interested in modern building solutions, you can explore more related articles using our construction materials search tool.

Content published by the editorial team of Vilssa Construction and Renovation.

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