Page 297 - Handbook of Thermal Analysis of Construction Materials

Section 5.0 - Cement 275

Table 4. Amounts of Calcium Hydroxide Formed in a Cement Paste
Hydrated in the Presence of SMF Superplasticizer

Mixture 3 h 6 h 9 h 24 h 3 d 7 d 28 d

Reference 2.3 6.8 8.0 13.7 17.8 19.3 19.8
Cem. + 1% SMF 2.1 6.4 7.3 13.1 17.6 19.4 19.6
Cem. + 2% SMF 1.9 3.3 4.0 12.9 17.1 18.8 19.4

The influence of different amounts of SNF on the hydration of
cement has also been studied by conduction calorimetry (Fig. 9). [20] At
0.5% SNF, the peaks appear at earlier times. Improved dispersion is thought
to be responsible for this acceleration effect. As the concentration of SNF
increases, the retardation effect becomes evident by the appearance of
peaks at later times. Uchikawa, [25] however, found only minor changes in
the hydration kinetics when SNF admixtures were used.

Figure 9. Conduction calorimetric curves of cement containing different amounts of SNF
admixture.