Process for producing calcium silicate hydrate

A process for producing a composition comprising calcium silicate hydrate, the process comprising the steps of

• a) reacting a calcium hydroxide source with a silicon dioxide source in the presence of water under hydrothermal conditions at a temperature in the range of from 100° C. to 400° C. for a period of from 1 hours to 30 hours, forming a process product from step a);
• b) bringing in contact
• i) the process product from step a) and
• ii) a water-soluble polymeric dispersant
• in an aqueous medium while introducing kinetic energy, forming a process product of step b;
• and optionally,
• c) adding the process product of step b) to a building material mixture comprising a hydraulic binder or a latent hydraulic binder;
• wherein an organic compound is added in at least one of the steps a), b) or to the process product after completion of step b),
• wherein the organic compound has a molecular weight of 100 to 600 g/mol and from 0.015 to 0.035 functional groups per gram of the organic compound, wherein the functional groups being selected from —OH, —COOH, —COOMa, —SO3H, —SO3Ma, 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 ⅓, ½ or 1,
• wherein when the organic compound is added in step a), the temperature in step a) is chosen below the melting point of the organic compound used and
• wherein when the organic compound is added to the process product after completion of step b), and if the process comprises a step c), the organic compound is added between steps b) and c).