2017 Volume 71 Issue 1 Pages 2-9
In this study, the influence of calcium chloride in early hydration reaction of alite was discussed from the results of various experiments conducted by solid phase analysis（XRD・Rietveld analysis and 29Si MAS NMR）and liquid phase analysis（pH meter, ICP-AES and ion chromatography）. In addition, similar experiments were carried out for sodium chloride and Portlandite addition systems, and the results were compared and examined with calcium chloride addition system. As a result, it was confirmed that promotion of initial hydration reaction of alite by addition of calcium chloride was not promoted dissolution of silica due to pH rise. Moreover, in the calcium chloride addition system, the amount of calcium silicate hydrate, the hydrated silicate monomer layer thickness, and the degree of alite hydration remarkably increased after the start of calcium silicate hydrate production. It was also confirmed that in the same addition system, the chloride ion concentration in the liquid phase decreased before the start of calcium silicate hydrate production and that the calcium ion concentration in the liquid phase was larger than that of other addition system and no addition systems. These findings suggested that both chloride ions and calcium ions are affected by accelerating the initial hydration reaction of alite by addition of calcium chloride.
