A method to determine the critical moisture level for unsaturated transport of ions

This study describes a method to obtain a certain humidity level by a certain drying treatment. This treatment was applied on cement based materials in order to identify the critical moisture level above which ion transport can occur. The drying is performed in two steps, first in one direction to reach a certain moisture level and then in the opposite direction to identify if ions can move at this lower level. This treatment gives an opportunity to determine ion transport at a well defined humidity, both in terms of moisture content and relative humidity. Ion transport was indicated by analyzing the potassium distribution on slices of mortar by SEM–EDS.