Hydration evolution of MgO-SiO2 slurries in the presence of sodium metasilicate

In order to accelerate the formation of magnesium-silicate-hydrate gel (M-S-H), the sodium metasilicate was added into the MgO-SiO2 slurries. The effect of sodium metasilicate on the hydration process of MgO-SiO2 slurries was investigated in this work. It required a relatively small amount of sodium metasilicate to facilitate the formation of M-S-H and to surpress the brucite formation. In the early 24 h, the M-S-H formed quickly due to the high concentration of magnesium ions and silicate species in solutions. With the further increasing of curing time, the M-S-H gel phase continuously grew. Furthermore, the sufficient silicate ions amount was favorable for the transformation of newly formed brucite to the M-S-H phase. The addition of sodium metasilicate influenced not only the reaction process but also the morphology of hydrates. Instead of the yolk-shell structure, the flowerlike and stacked sheet-like M-S-H formed in the presence of sodium metasilicate.