Physical and Chemical Properties of Cementitious Materials Undergoing Accelerated Decalcification

A major degradation scenario within safety assessment analysis of nuclear waste repositories is decalcification of cementitious materials due to long-term contact with groundwater. Understanding the changes in Physical and Chemical properties of cementitious barriers is of high importance. In order to decrease the uncertainty in the assessments due to extrapolating short term data sets, acceleration methods enhancing the decalcification process can be used. In this study with application of an accelerating electro-chemical migration method, the calcium leaching effect on cementitious specimens is studied. To account for the changes in chemical and mineralogical properties after leaching, paste specimens of size 75×50Ø mm and to study the ageing effect on physical properties, concrete specimens of size 50×100Ø mm were treated with migration method. LA-ICP-MS, XRD and SEM were employed to perform chemical and mineralogical assessments and permeability and water adsorption tests methods were carried out in order to study the physical properties of the leached samples. The results indicate that total leaching of Portlandite content is expected in leached samples. Moreover, up to 15 times of higher gas permeability coefficient and 4 times higher water adsorption rate are detected in aged samples.