Centrifuge experiments for the determination of the moisture storage and transport properties in the overhygroscopic range

Abstract

This study explores the potential of a centrifuge experiment for hygric property determination. In this method, a core sample is placed in a tube which is spun at different rotational speeds to create a distribution of moisture contents and capillary pressures. This way, a simultaneous determination of the moisture retention curve and moisture permeability curve is possible. Measurements performed in the petroleum industry and in soil science already showed the technique to be an appropriate substitute for the pressure plate method. In building physics, the potential of the centrifuge method is currently still unexplored. Therefore, in this study, preliminary desorption measurements on brick samples are performed. To infer the moisture retention curve, an approximate data analysis method is applied. This approach is compared to a more sophisticated parameter estimation technique, which is also used to infer the moisture permeability curve. From a theoretical point of view, the centrifuge method allows a simultaneous determination of the moisture storage and transport properties of building materials. In practice, however, experimental inaccuracies make the experimental results unusable for a reliable determination of the moisture transport properties.