was added to the dry mix within 10 seconds and then stirred with an overhead-stirrer equipped with a 4-blade propeller (5.5 cm in diameter) for 2 minutes at 800 rpm (revolutions per minute). A 20 mL plastic ampoule (27.5 mm in diameter) is charged with 6 ± 0.01 g of the freshly prepared paste and then sealed. The sample ampoule was loaded on an eight-channel isothermal heat flow calorimeter (TAM Air, TA Instruments, USA) within 10 minutes after contact of the cement with water. Measurements of reaction heat were conducted at 20.0 °C for over 48 hours. Quartz sand was used as reference material (11.077 g) matching the heat capacity of the measured samples, calculated according to Wadsö .