The Heat-Box is used for determination of the Adiabatic Heat of Hydration for concrete mixes.

The Adiabatic Heat of Hydration is an essential input-parameter when making thermal analyses of hardening concrete structures.

The system is based on a semi-adiabatic measuring followed by a 3D-dimensional thermal analysis. The analysis takes into account the heating of the Heat-Box itself from inside and the loss of heat to the surroundings.

Before the Heat-Box system is taken into use the software has to be calibrated. Calibration is done by placing a container with app. 5 litres hot water in the Heat-Box. After a few days the data-logger has registered a decay of temperature as shown in figure 1.

The result of the calibration is the thermal properties of the insulation material in the Heat-Box.

Measuring of Heat of Hydration is done in the same manner just with fresh concrete instead of hot water. A typical progress of the measured temperature is shown in figure 2. This progress and the above mentioned thermal properties are the basis for the thermal analysis which is resulting in assessing the Heat of Hydration. The Heat of Hydration is expressed as the accumulated output of energy as a function of the maturity (degree of hydration).

In both cases, also the ambient temperature is registered. The progress of the ambient temperature enters in the thermal analysis when calibrating and measuring.

The resulting Adiabatic Heat of Hydration is shown in Figure 3.

The calibration procedure is described in details here.

The procedure for measuring Heat of Hydration is described in details here.


Fig. 1 Decay of temperature when calibrating




Figure 2 History of temperature when measuring Heat of Hydration




Figure 3 Resulting Adiabatic Heat of Hydration