Change in pore structure and composition of hardened cement paste during the process of dissolution

Through observation of the samples after leaching, it was confirmed that ettringite precipitation increased as the dissolution of the portlandite and the C-S-H gel progressed. EPMA performed on cross-sections of the solid phase showed a clear difference between the altered and unaltered parts. The boundary between the two parts was termed the portlandite (CH) dissolution front. As the leaching period became longer, the CH dissolution front shifted toward the inner part of the sample. A linear relationship was derived by plotting the distance moved by the CH dissolution front against the square root of the leaching time. This indicated Ca ion movement by diffusion.