Abstract
The high pH condition of aqueous solution in the radioactive waste repository can be produced by dissolution of hydrated cement. Many studies have been reported to clarify the mechanism to maintain high pH for a long term, however, these can not represent all phenomena related to the dissolution process of the cement hydrates because of the lack of solid phase analyses. We have studied not only the aqueous phase but the change of the solid phase simultaneously. We have studied the applicability of the permeability test method using centrifugal force to percolate pore water. By using this method, we have investigated the dissolution phenomena of hydrated cement within acceptable period of experiment.
As a result, the solid phase analysis indicated the clear distinction between altered and unaltered area and the existence of a dissolution front was identified. On the altered area of the solid phase, it was confirmed that Ca(OH)2 was dissolved. An obvious change of microstructure was observed. The relation between the volume of percolated water and concentration of the liquid phase composition contained in percolated water through a specimen of hydrated cement was found to be quite similar to that of the test data by Pfingsten et. al.[1] and consequently the dissolving process of cement was found to be identical.
