3. Hydration and intake

3.1 Plug

Products resulting from the thermal dehydration of gypsum have the property, when in contact with water, of regaining their initial degree of hydration and reconstituting gypsum. This phenomenon is known as gypsum setting. Several mechanisms have been proposed to describe this process, which takes place in three successive stages:

• taking up water to reform the dihydrate ;

• crystallization (the actual setting);

• hardening.