Effect of magnesium on the structure and chemical composition of calcium silicate hydrate at elevated temperature

This paper aims to investigate the effect of magnesium on the structure and chemical composition of calcium silicate hydrate at elevated temperature. Magnesium oxide, silica fume and calcium oxide were used in the preparation of MgO modified C-S-H gels with (Ca + Mg)/Si molar ratio of 0.8. The obtained solids were characterized with SEM, TEM-EDS, XRD, FT-IR, TG-DSC and 29Si NMR. The results show that the transformation from M-S-H to C-S-H occurs when Mg to Si molar ratio decreases to 0.4. A concentrated distribution of Mg, Si and Ca elements is observed with TEM-EDS, indicating that a new phase magnesium calcium silicate hydrate (M-C-S-H) is possibly formed. (C) 2019 Elsevier Ltd. All rights reserved.