Hardening accelerator

A setting and/or curing accelerator obtained by milling a mineral solid in a liquid medium, wherein the setting and/or curing accelerator is present as suspension and comprises the following constituents:

• a) 97-99.9 w % of a dispersed inert mineral solid which is rock or rock flour;
• b) 0.1-3 w % of a dispersed mineral binder which is cement;
• where both the inert mineral solid and the mineral binder are present in dispersed form or in the form of suspended particles;
• the mineral solid is milled to particles having an average particle size of <600 nm, and
• the mineral binder is completely hydrated by the liquid medium during milling.