Page 261 - Handbook of Thermal Analysis of Construction Materials

Section 6.0 - Phosphonates 243

Figure 15. Calorimetric curves showing the effect of a phosphonic acid on the rate of
hydration of the tricalcium aluminate component of cement.

Phosphonic acid-based chemicals such as ATMP, HEDP, DTMP,
and their sodium salts were added to portland cement in dosages of
0.03–0.09% at a constant w/c ratio of 0.35 and their conduction calorimet-
ric and DSC curves were compared. [30] The conduction calorimetric curves
of cement containing sodium salt of ATMP are shown in Fig. 16. [30]
Addition of this salt results in the retardation of cement hydration in terms
of extended induction period and the late appearance of the exothermic
peak. At 72 hours, however, the addition of the salt increases total heat
development.