The spectra of the first two stops of the Na2Si1.7O4.4-activated slag pastes (Figure ), at 0.5 and 23 J/g, only showed one resonance on top of the ones of the anhydrous slag. This resonance had a chemical shift of 63.7 ppm, which is identical to the value obtained for the first spectrum of the NaOH-activated paste. As the 29 Si NMR results showed the presence of N-A-S-H at these times for the Na2Si1.7O4.4-activated pastes, this confirms that this resonance can be assigned to tetrahedral Al incorporated in a N-A-S-H gel.