Page 429 - Handbook of Thermal Analysis of Construction Materials

406 Chapter 10 - Non-Portland Rapid Setting Cements

Figure 2. DTA and XRD data for a Secar 71 paste hydrated at 10°C for 24 hours. [1]

–
Carboaluminate phases (e.g., C ACH ) can form when hydration
4 11
takes place in normal atmospheres. The presence of this phase is indicated
by a DTA peak in the region 180–200°C, which can overlap with the peak
due to the presence of C AH . A shoulder may be present for the phase
2
8
present in the lesser amount.
Figure 3 is a plot of various DTA thermograms (Secar, Alcoa CA,
– –
Secar + CC) depicting the presence of C AH and C ACH . Thermograms
2 8 4 11
for pastes to which CaCO had been added are included in Fig. 3. Supple-
3
menting Fig. 3 are bar graphs indicating the relative amounts of the phases
determined by XRD.