Thermal and Moisture Conditions of Coarse-Grained Fill Layer under a Slab-on-Ground Structure in Cold Climate

Abstract

This paper presents the results of a research program concerning the thermal and moisture conditions of coarse-grained fill layer underneath a slabon-ground structure in Finnish climate. Conditions were studied by laboratory tests and long-term in situ surveys. Results showed that the temperature behavior of the fill layer underneath a heated building is strongly diverged. The effect of the outdoor seasonal temperature variation has a major effect on the edge of the fill layer, but under the center part of the slab the temperature remains almost constant throughout the year. The measured moisture contents of the fill at the survey building were close to the hygroscopic equilibrium moisture content of coarsegrained materials in relative humidity RH 1/4 100% in prevailing temperatures. The temperature and moisture conditions of the fill material were such that the water vapor diffusion flow is directed from the subsoil towards the drier indoor air.