The present invention relates to a process for producing calcium silicate hydrate under hydrothermal conditions, wherein an organic compound is added in at least one of the process steps and wherein the organic compound has a molecular weight of 100 to 600 g/mol and from 0.02 to 0.035 functional groups per gram of the organic compound, wherein the functional groups being selected from OH, COOH, COOM.sub.a, SO.sub.3H or SO.sub.3M.sub.a, or C(O)H, wherein M is hydrogen, a mono-, di- or trivalent metal cation, ammonium ion or an organic amine radical and a is , or 1. Further the invention is directed to the calcium silicate hydrate produceable according to the process of the present invention and its use as curing accelerator for hydraulic binders.

The present invention relates to the use of an additive which is an aqueous system of specific polyether silicones in clinker and cement preparation. The additive improves the grinding efficiency and also results in an improvement in the cured properties of cementitious compositions employing cement so produced.