Isothermal calorimetry is a useful tool for the time-resolved investigation of cement hydration. The temperature change in the sample induced by endothermic or exothermic reactions is transferred into a heat flow signal. This allows investigation of e.g. the retarding or accelerating effect of additives.
The Erlangen Applied Mineralogy Group operates three commercial TAM Air isothermal calorimeters with eight twin-type channels, each consisting of a measurement and a reference cell.
Special tools were developed for internal stirring (InMixEr – Injection & mixing device for internal paste preparation, FAU Erlangen, Mineralogy). Here, injection of the mixing liquid and stirring of the cement paste is performed directly in the measurement channel, whereas tools containing four syringes further allow the simultaneous addition of different mixing liquids. By this means, reliable calorimetry data can be obtained even for the initial part of cement reactions.