The present invention refers to a mixture comprising alpha
CaSO.sub.4.times.1/2 H.sub.2 O, CaSO.sub.4.times.2 H.sub.2 O, a
combination of a hardening accelerator, a hardening retarder and a setting
expansion inhibitor, and optionally a surfactant.
The mixture can be used to prepare a die having an extremely high setting
expansion.
