Hysteresis and Temperature Dependency of Moisture Sorption – New Measurements

It is well known that sorption characteristics of building materials exhibit hysteresis in the way the equilibrium curves develop between adsorption and desorption, and that the sorption curves are also somewhat temperature dependent. However, these two facts are most often neglected in models for combined heat and moisture transport in materials.

There is a need for further elaboration of the importance of these issues, and it is the intent of this paper to contribute to such elaboration. The paper seeks to contribute to the knowledge base about such sorption characteristic by presenting some new measurements of hysteresis and temperature dependency of the moisture sorption characteristics of three different porous building materials: aerated concrete, cement paste and spruce.

Scanning curves are measured for all three materials where periods with adsorption and desorption interrupt each other intermittently. For one of the materials, aerated concrete, the sorption curves are determined at three different temperatures.