Characterisation of magnesium silicate hydrate (M-S-H)
In a recently published study, the structure of synthetic magnesium silicate hydrated phases (M-S-H) and the distribution of water as a function of the Mg/Si ratio were investigated.
Different analytical techniques indicated that M-S-H phases are nano-crystallite hydrated phyllosilicates with relatively short coherence length (1.2 nm) and small particle size (>200 m2/g). Zeta potential and cations exchange capacity measurements showed a negative surface charge on M-S-H from the deprotonation of the silanol groups.
Characterisation of water distribution in M-S-H
The negative surface charge is compensated by exchangeable magnesium or others cations. Combined analyses were used to characterise the water distribution in M-S-H revealing the following:
i) confined water; its amount depends mainly on the relative humidity
ii) very confined water (or possibly water coordinated to magnesium), and
iii) hydroxyl groups bound to magnesium and to silicon.
The study is published in: Cement and Concrete Research Volume 116, February 2019, Pages 309-330.
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