Civil Engineering Reference
In-Depth Information
Figure 14.
Calorimetric curves showing the effect of phosphonic acid on the rate of
hydration of tricalcium silicate.
Phosphonic acid had a retarding effect on C
3
A hydration (Fig. 15).
The reference C
3
A produced the maximum heat effect at 3.6 minutes with
a value of 113.7 cals/g/h. At an addition of 0.03% acid, the peak occurred
at 19.2 minutes producing 76 cals/g/h.
DSC investigations showed that the addition of phosphonic acid to
the C
3
A + gypsum mixture, in the presence of water, retards the hydration
and inter-conversions in the system.
[31]
