Besides studying the strength development and setting characteristics of different ce-ments, isothermal heat flow calorimetry is a powerful tool for studying the influence of admixtures on the hydration kinetics of cementitious materials. The influence of admixtures on cement hydration has been studied using calorimetry for at least 90 years . However, the influence of admixtures on the hydration kinetics is typically studied qualitatively, i.e., by comparing the heat flow curves of different mixtures. Quantitative analysis of the influence of admixtures on the hydration kinetics is rare in the literature.