Today, isothermal heat flow calorimetry is a routine method for cement characterization due to the availability of modern multi-channel instruments . The heat flow signal of cement hydration is a superposition of all ongoing reactions, namely, the dissolution of the cement phases and the nucleation and crystal growth of the hydrate phases. The reproducibility and reliability of the calorimetry data obtained with different isothermal calorimeters have been confirmed in an extensive round-robin test and a recent study of the age and model of different calorimeters . Importantly, it was recognized that the heat of hydration of a binder, accessible through calorimetry, is directly linked to the Heat [J g -1 ] Compressive Strength Figure : Correlation between compressive strength of mortar determined between 1 to 7 days for 10 different cements and the heat of hydration, adapted from . The strength is determined according to EN 196-1 at a w/c of 0.5. degree of hydration. Therefore, calorimetry is connected with the onset of hardening , chemical shrinkage and, most importantly, strength development (Figure ) . Consequently, isothermal heat flow calorimetry is specified in standards like the European standard and the American standard ASTM standard C1702-23 .