Heat Flux Calorimetry

Heat-flux Differential Calorimetry

Toni Cal 7338

For the calorimetry experiments, a heat-flux-differential calorimetry (Toni Cal) is employed. Hereby, water and cement are mixed in the test chamber and the heat-flux and the heat-flux rate required to keep the hydrating sample at a pre-specified temperature (e.g. 30°C) are recorded from the first moment of reaction.

The energy required to keep the pre-specified temperature is monitored for both an inert reference sample and the hydrogenated sample, giving the heat flow Q(t) [J/g] associated with the hydration process (see, e.g., Figure 1).

Left: the heat flux rate over 160 hours, with the maximum reached after 10 hours and the rate decreasing thereafter. Right: he cumulative line of this heat flux. This increases steadily, with hardly any increase after about 60 hours.

Figure 1: Output of differential-calorimetry test: history of (a) heat-flow rate and (b) heat flow

The left picture shows a cylindrical measuring device, the differential calorimeter, with the control computer.
 The right picture shows a screen with the displayed measured values and the corresponding computer.