Civil Engineering Reference
In-Depth Information
•
Estimation of hydrates based on the observation that the
total peak area of the dihydrate is in proportion to the
quantity of the sample dihydrate and that the area ratio of
the first peak to the second peak is approximately 3.00.
• Establishment of a proportional relationship between the
peak area of dehydration (second peak) and the quantity
of the sample.
The following empirical relationship was developed to predict the
relative proportion of calcium sulfate hydrates.
Eq. (9)
1/
γ
= 0.33 + 0.33
R
where
is the area ratio of the first peak to the second peak and
R
is the
mass ratio of hemihydrate to dihydrate.
γ
Figure 26.
DSC curve for hydrated portland cement in a hermetically sealed pan.
[19]
9.2
Gypsum-Based Cements
The utilization of gypsum-based binary and ternary blended ce-
ments has been shown to provide the desired characteristics of early
hardening strength with improved durability.
[21]
This is illustrated in
