RH measurements for assessing moisture conditions in concrete structures

Abstract

For assessment of the moisture conditions in concrete structures, measurements of relative humidity are often applied. Since such measurements only are an indirect way of testing the moisture conditions, proper interpretation of such measurements requires a good basic knowledge of thermodynamics in order to make a correct assessment of the moisture conditions. In the present paper, it is shown how thermodynamic relationships can be utilized for obtaining more useful information about the moisture conditions in concrete structures, but this requires combined measurements of both relative humidity and temperature during the condition assessment. In the present paper, current experience with relative humidity measurements for assessing moisture conditions in concrete structures is reported. During field investigations of repaired concrete structures, it was observed that the degree of pore saturation was almost constant, even when the relative humidity in the concrete varied between wide limits due to diurnal and seasonal temperature variations.