Within the first hour, all heat flow curves are characterized by an intense heat flow peak (see Figure ), which is caused by the initial heat of hydration directly after mixing and the thermal effect caused by the insertion of the sample into the calorimeter. For that reason, the heat flow during this time is usually not considered when the cement paste is mixed outside of the calorimeter . Thus, without in-situ mixing experiments inside the calorimeter, the signal for initial CA dissolution can usually not be separated from external heat contribution.