Bentonite (Bentonite, E558) is a natural clay mineral.
It has the ability to swell when hydrated by 14-16 times. When the space for free swelling is limited, a dense gel is formed in the presence of water, which prevents further penetration of moisture. This property, as well as its non-toxic and chemical resistance, makes it indispensable in manufacturing, construction and many other areas of activity.
There are two types of bentonite:
- calcium, with a low degree of swelling;
- sodium, with a high degree of swelling (swelling rate less than 7 ml / g or more than 12 ml/g).
Some naturally occurring bentonites may have characteristics that differ from these values; where this is the case, it is generally assumed that bentonite is activated.