CASH II is a Swiss-Danish research project investigating the effect of aluminum, potassium and sodium on the structure and solubility of calcium silicate hydrates (C-S-H) using innovative experimental methods and computational modelling.

The (partial) replacement of Portland cement by supplementary cementitious materials (SCMs) is an efficient to reduce CO₂emissions associated with Portland cement product. The industrial application of SCMs based materials is hampered by the fact that low-CO₂ cementitious materials have different chemical composition resulting in other hydrates than in Portland cements, where Ca-rich calcium silicate hydrates(C-S-H) is the main hydrate. The composition of C-S-H changes in the presence of silica rich SCMs such as blast furnace slag, fly ash, silica fume or calcined clays, where C-S-H with a low Ca/Si ratio and high aluminum and alkali content is the most important hydrate that forms. The work includes  experimental investigations of the influence of varying Ca/Si ratios, the presence of aluminum and alkali ions on the solubility, structure, and composition of synthetic C(-A)-S-H gel and on aqueous complex formation and the development of a thermodynamic model of C(-A)-S-H based on the solubility of C-S-H and on the structural information and surface properties.

Calcium silicate hydrates with aluminum (CASH II) – This project has received funding from the Swiss National Foundation (SNF), project No. 200021_169014 / 1 and the Danish Council for Independent Research, Technology and Production, grant no. DFF-7017-00097.