Page 266 - Handbook of Thermal Analysis of Construction Materials

Section 7.0 - Conduction Calorimetric Assessment of Retarders 247

Figure 18. The effect of calcium gluconate on the hydration of portland cement. (a) rate of
heat development (b) integral heat development.

Table 3. Minimum Concentrations of Various Retarders (%) Required to
Achieve Desired Induction Periods

Retarding Agent Induction Periods (Hrs)
10 20 30 40
Ca Gluconate 0.10 0.12 0.13 0.14
Glucose <0.10 0.15 0.23 >0.30
Glycolic Acid <0.50 0.55 0.64 0.79
Molasses 0.10 0.13 0.20 >0.20
Na Borate 0.51 0.63 >0.70 <0.10
Na Citrate 0.21 0.32 0.39 <0.50
Na Heptonate <0.10 0.12 0.14 >0.15
Na Hexametaphosphate <0.20 1.00 >1.00 ——
Na Pyrophosphate <0.20 0.38 1.00 >1.20
S.F. Ca Lignosulfonate 0.51 0.52 0.54 0.58
Sucrose 0.04 0.06 0.073 >0.075