2017 Volume 73 Issue 3 Pages 271-290
The purpose of this study was to clarify the mechanism of transformation of cement minerals and the property of ions diffusivity in hardened cement paste on the basis of the results of the diffusion cell tests. The aqueous solutions enclosed in the cells were sulfuric acid, hydrochloric acid, sodium sulfate and sodium chloride. As a result, this study provided an explanation about the mechanism of the dissolution of portlandite and other cement minerals caused by pH decrease due to the action of proton and the penetration of anions. Furthermore, based on the explanation, this study considered the mechanism of the expansion failure caused by ettringite formation in case that monocarboaluminate is a main cement minerals in AFm phase. In addition, this study provided the evidence that the effect of Co-existence of cations on the diffusivity of anions should be taken in to account when considering the expansion failure of hardened cement paste due to chloride ions diffusivity and sulfate ion penetration.
