The kinetics and even the mechanism of cement reaction with water can be successfully investigated by use of microcalorimetry.
In this study this method was applied to follow the hydration of the new family of portland cements containing C12A7* and C11A7·CaF2 addition as well as special cement with C3A replacement by calcium sulphoaluminate. It has been found that C11A7·CaF2 acted as hydration retarder. The heat evolution curves for C12A7 containing samples without CaF2 are very similar to those for the reference portland cement samples. XRD and SEM studies confirm the results described above,
relating to the retardation of alite hydration. The process is positively modified by the addition of anhydrite. In the presence
of calcium sulphoaluminate (4CaO·3Al2O3·SO3) the hydration at early stage occurs with the rapid formation of large amount of the ettringite phase. The calcium fluoride
acts as a set retarder. The full compatibility of calorimetry with SEM and XRD results should be underlined.