A process for producing solid compositions containing calcium silicate hydrate (C—S—H) and a water-soluble comb polymer which is suitable as plasticizer for hydraulic binders, wherein the following process steps are carried out: a) contacting of an aqueous C—S—H-containing suspension with at least one comb polymer, b) optionally setting a suitable solids content of the product from step a) by dilution with water and c) drying of the product from step a) or b). The process products which can be obtained, the use thereof in building material mixtures, in particular, containing cement, the use as grinding aid in the production of cement and corresponding building material mixtures are likewise provided.