in situ time-resolved x-ray diffraction of tobermorite formation in autoclaved aerated concrete: influence of silica source reactivity and al addition

to investigate the effects of the silica source, reactive quartz from chert and less-reactive quartz from quartz sand were used as starting materials. the effect of al addition on tobermorite formation was also studied. in all cases, c-s-h, hydroxylellestadite and katoite were clearly observed as intermediates.

acceleration of tobermorite formation by al addition was clearly observed. however, al addition did not affect the dissolution rate of quartz. two pathways, via c-s-h and katoite, were also observed in the al-containing system. these results suggest that the structure of initially formed c-s-h is important for the subsequent tobermorite formation reactions.