Characterization of hygrothermal properties of sandstones—Impact of anisotropy on their thermal and moisture behaviors

• Sedimentary sandstones have directionally dependent properties.
• Hygrothermal properties of four sandstones are experimentally investigated.
• Each sandstone is characterized in two directions by using a material model.
• Higher moisture transport occurs in the direction parallel to the bedding plane.
• Impact of hygrothermal property anisotropy of sandstones is explored.

Sandstones are widely used in historic buildings. To assess energy and moisture performance of these buildings and find suitable retrofit strategies, thermal and hygric properties of sandstones are needed. Sedimentary structure of sandstones leads to their directionally dependent properties. In this paper, hygrothermal properties of four sandstones are experimentally investigated and each sandstone is characterized in the directions parallel and perpendicular to the bedding plane. Thermal properties of the studied sandstones are comparable between two directions, while moisture transport properties have a pronounced directional dependence. Lower liquid water conductivity and water vapor diffusivity occur in the perpendicular direction, which is validated by the phenomena observed from water absorption and drying tests. By conducting a benchmark case, the influence of hygrothermal property anisotropy on the thermal and moisture responses of the construction is illustrated. The results show that the property anisotropy has a weak impact on the thermal behavior, but has a strong influence on the moisture behavior, which further affects the thermal behavior due to material's moisture dependent thermal conductivity.