Calcium sulphate screed, formerly also known as anhydrite screed (AE), consists of sand/gravel (grain size up to 8 mm), calcium sulphate as a binder and water. It does not bowl or crack when drying, resulting in particularly flat surfaces that are also particularly suitable for large-format tiles. Joints only need to be arranged for large and very elongated screed surfaces (e.g. in longer corridors) or for L- or U-shaped surfaces. However, building joints must be incorporated into the screed pane, as with any other screed.
Source: bauwion
