for an empty sample cell, ensuring that the thermal drift is lower than 2 µW h -1 and the standard deviation of the heat flow is below 4 µW for a period of 20 min. Five minutes after the cement was mixed with water (t = 0 s), the sample ampoules were loaded into the calorimeter. The instrument software records the data at a sampling rate of approximately 1 s -1 . After the data acquisition, the instrument software is used to down-sample the raw data to 6000 data points, which are exported to a CSV file. Here, we use the instrument software's adaptive mode, which ensures high sampling rates during large and fast heat flow changes and low sampling rates during periods of minor heat flow changes.