Anhydrite comes from the Greek word anydros: "waterless"; also anhydrite spar or calcium sulphate, is a frequently occurring mineral from the mineral class of anhydrous sulphates without foreign anions. It crystallises in the orthorhombic crystal system with the chemical formula CaSO4 and in most cases develops coarse-grained, bulky aggregates and has a Mohs' hardness of 3 to 3.5 and a density of 2.8 to 3.

Among other things, it is produced as a by-product during the manufacture of hydrofluoric acid. An "anhydrite binder" is created by grinding anhydrite and adding an activator. These are air-setting, non-hydraulic binders, whose physical and chemical properties are comparable to those of gypsum. Calcium sulphate binders are used, for example, in housing to make calcium sulphate screeds or self-levelling calcium sulphate screeds.

Synthetic calcium sulphate binders are construction materials, which are produced with little energy and therefore, spare environmental resources.

Selected raw materials of the highest quality and processing uniformity during production ensure consistent, outstanding technical properties.

On the basis of these raw materials, HENGE has developed a binder system which enables the manufacturer of an optimised self-levelling screed: ""