Synthetic compounds related to tobermorite: an electron-microscope, X-ray, and dehydration study

Abstract

Summary Tobermorite-like preparations with Ca/Si ratios in the range 0·8–1·4 have been synthesized at room temperature and hydrothermally, and a systematic study has been made using the methods indicated in the title. The results are compatible with the existence of three phases: tobermorite (5CaO.6SiO₂.5H₂O), CSH(I) (0·8–1·33 CaO.SiO₂.aq.), and CSH(II) (1·5–2·0 CaO.SiO₂.aq.). CSH(II) may have a layer structure in which one surface of each layer is composed of hydroxyl groups, analogous in some respects to the hydrated form of the clay mineral, halloysite. The evidence of the electron microscope gives some clues to possible mechanisms of conversion of CSH(I) and CSH(II) into tobermorite.