Calmetrix I-Cal 8000 User Manual page 28

Calmetrix I-Cal 8000 User Manual
Examples of use of Arrhenius plots.
Figure 1 below shows the effect of temperature on the heat flow rate (power) and the produced energy
(approximation for the overall degree of hydration) for a portland cement paste without admixture, w/c 0.45.
Note that the initial non-isothermal heat flow is excluded from the energy calculation, Figure 1 (b). The
measured data was then fitted mathematically to an S-shaped hydration development curve that is known to
work well for portland cement based mixtures according to Schindler (Ref 1 & 2 below). Figure 2 shows the
corresponding Arrhenius plot as a fitted straight line representing the apparent activation energy.
Figure 1: Effect of curing temperature on rate of reaction (heat flow) and degree of hydration (energy
– integrated heat flow)
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