Hydrogamet phases formation

The effect of aluminum ions on the transformation of C-S-H into 1.1 nm tobermorite was investigated by Mitsuda and Taylor [184], The solid solution of aluminum ions in tobermorite enlarges also the stability field of this phase in relation to xonothte [185], Diamond [186] found the maximum Al/(Si+Al) ratio in tobermorite to be 0.15 above this value the hydrogamet phase is appearing. Aluminum is tetrahedrally coordinated and accelerates the formation of 1.1 nm tobermorite. Finally, Mitsuda and Taylor [184] revealed that alkalis (l%Na20+1.7%K20) are activating the tobermorite formation from zeolite and calcium hydroxide. 

According to Ding and Beaudoin (1996), the addition of small amounts of sodium silicate promotes the formation of strathngite (C2SAHg) in calcium aluminate cement pastes. At the same time the hydration of the cement is strongly retarded. The additive delays, but does not prevent completely, the formation of the hydrogamet phase in the cement paste. 

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