Civil Engineering Reference
In-Depth Information
Figure 16.
Calorimeter output of hydrated CA at different scanning rates after 28 days
hydration.
[10]
The DSC curves for hydration of CA
2
are presented in Fig. 15b.
Primarily the CAH
10
and AH
3
phases appear after 1 day of hydration (165°
and 295°C). C
2
AH
8
appears after 3 days of hydration. The strength of
hydrated CA
2
increases up to 14 days (maximum period measured). This
behavior suggests that use of mixtures of CA and CA
2
may be of practical
benefit. In this work,
[11]
there was no indication of the formation of C
3
AH
6
.
DSC curves for hydrated C
12
A
7
are shown in Fig. 15c. The
broadening of the dehydration peak at 310°C indicates that C
3
AH
6
together
with AH
3
phases are formed within 1 day of hydration. The peak at 170°C
corresponds to the dehydration of CAH
10
. A significant amount of the
C
3
AH
6
phase is formed after 14 days of hydration. There is also a significant
decrease in strength after 1 day, corresponding to the formation of the
C
3
AH
6
phase.
