Page 306 - Handbook of Thermal Analysis of Construction Materials

Section 5.0 - Cement 283

In order to study the effect of SO on slump loss in superplasticized
3
cement, Khalil and Ward [32] adopted the conduction calorimetric tech-
nique. The heat effects were used to explain the workability loss. It was
concluded that for cements cured at 25°C, the optimum SO content was
3
higher in the presence of the superplasticizer.
The rate of hydration of the C S phase in cement (containing a
3
superplasticizer) is influenced by the type of sulfate and alkali present in the
cement. In Figs. 16 and 17, the effect of different types of sulfates on the
hydration of low and high alkali cements is given. [5][33] In the cement
containing high sulfate, the retardation is significant at 1% SNF when
dihydrate or anhydrite are used, but is negligible when hemihydrate is used.

Figure 16. Effect of SNF on the hydration of tricalcium silicate phase in a high alkali
cement.

Figure 17. Effect of SNF on the hydration of tricalcium silicate phase in a low alkali
cement.