When water is added to cement, each of the compounds undergoes hydration and contributes to the final state of the concrete.
This reaction typically is expressed as: also written in cement chemist notation, (CCN) as: or, tricalcium silicate + water → calcium silicate hydrate + calcium hydroxide + heat The stoichiometry of C-S-H in cement paste is variable and the state of chemically and physically bound water in its structure is not transparent, which is why "-" is used between C, S, and H.[4] Synthetic C-S-H can be prepared from the reaction of CaO and SiO2 in water or through the double precipitation method using various salts.
The C-S-H from cement phases can also be treated with an ammonium nitrate solution in order to induce calcium leaching, and so to achieve a given C/S ratio.
The silicates in C-S-H exist as dimers, pentamers and 3n-1 chain units [9][10] (where n is an integer greater than 0) and calcium ions are found to connect these chains making the three dimensional nano structure as observed by dynamic nuclear polarisation surface-enhanced nuclear magnetic resonance.
[citation needed] The scanning electron microscope micrographs of C-S-H does not show any specific crystalline form.