With Na2CO3 (Figure and), an increase in intensity and an acceleration of hydration is also visible at the second peak. However, it seems that the first peak was slightly delayed by the increased amount of activator used. Overall, the induction period between the two hydration peaks shortened as the activator quantity increased. When SiO2.Na2O (Figure ) was used as activator, similar observations could be made again. The position of the first hydration peak did not vary but its intensity increased when more activator was added. The appearance of the second peak was accelerated when the amount of Na2O was increased. These results are in agreement with the literature . Furthermore, concerning the modulus of the activating solution, the only significant difference was the position of the second peak, in pastes made with 4 wt% Na2O. Therefore, it seems that the variation of the amount of sodium plays a preponderant role compared to the amount of silicon in solution.