Page 294 - Handbook of Thermal Analysis of Construction Materials

272 Chapter 7 - Superplasticizing Admixtures

The relative effects of superplasticizers on the hydration of C S has
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been compared in the presence of 1% SMF, 1% SNF, and 0.25% LS
(lignosulfonate). The rate of hydration was determined by TG technique
(Fig. 7). [18] The amount of calcium hydroxide formed in pastes with these
admixtures was distinctly lower than those in reference samples, indicating
significant retardation effects. It was also found that the C-S-H formed in
the presence of the admixtures had a higher C/S ratio. It is evident from the
figure that the retardation effect of even 0.25% LS is significant.

Figure 7. Effect of SMF, SNF, and LS on the amount of Ca(OH) formed in the hydration
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of C S.
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