For the isothermal heat flow calorimetry experiments at low w/s values, a dry mix containing 60 wt.% CA-cement (CAC1) and 40 wt.% filler (Al 2 O 3 ) was preparded in an overhead shaker. We used a fine aluminum oxide (>99.7 %) with a surface area of approximately 7 m 2 /g to improve the reproducibility of the duration of the dormant period (as recommended by Götz-Neunhöffer ). The samples for the calorimetry experiments were prepared as follows: 40 ± 0.01 g of the dry mix was weighted into a 250 mL polyethylene cup. Afterward, 12 ± 0.01 g liquid (w/s = 0.3) (water or diluted acidic solution)