Belay Zeleke Dilnesa - Eawag-Empa Library

CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES
of C3AH6 only even after a reaction time of 3 years. This shows that the synthesized solid
contains no or very little silica.
Fig. 54 The XRD pattern of Al containing Si-hydrogarnet synthesized at 20 °C and 110 °C. * Al-
Si-hydrogarnet with two different compositions (see inlet); o C3AH6; - KNO3 present as
impurity; +CaF2 added as an internal standard.
The TGA-DTG curve shows a weight loss at 145 °C due to the co-precipitation of C-S-H
(see Fig. 55). The water loss of Al-Si-hydrogarnet synthesized at 20 °C corresponds to
that observed for C3AH6 (see Fig. 49) with a main peak at around 300 °C. This supports
the XRD results and indicates that the Al-Si-hydrogarnet synthesized at 20 °C contains
little or no silica. The main water loss of Al-Si-hydrogarnet synthesized at 110 °C
occurred around 330 °C. The presence of C-S-H gel in the samples with the target
composition C3ASH4 was persistent.
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