A method for the reliable and reproducible precipitation of phase pure high Ca/Si ratio (>1.5) synthetic calcium silicate hydrates (C-S-H)

Various methods have been developed to synthesize C-S-H; however, these methods have only allowed for the successful production of pure-phase C-S-H with Ca:Si of 1.5 or less. Attempts to form higher Ca:Si ratios by these methods gives C-S-H (Ca:Si 1.5 or less) in the presence of Ca(OH)(2). This paper focuses on a reliable method to produce single-phase C-S-H with Ca:Si molar ratios between 1 and 2. Reactant concentrations, temperature, pH, and mixing conditions are carefully controlled to ensure homogeneous precipitation of C-S-H. Guidelines on collection, drying, storage, and handling are also described.