Abstract

This thesis presents the results from a series of experiments in which moisture is transported across several bonded and natural contact interfaces between two materials, i.e. autoclaved aerated concrete (AAC) and mortar. All experimental results conclusively show that an assumption of perfect hydraulic contact is an over simplification of the interfacial phenomena. Instead, this thesis recommends "imperfect hydraulic contacts" in all situations, bonded as well as natural contact. Based on the above recommendation, this thesis introduces a concept of "mismatching resistance" to mathematically describe the imperfect contact. Physically it corresponds to a resistance offered by the interface to moisture transport due to misalignment of the pore structures on either side of the interface. A mathematical model of moisture transport was developed and the mismatching resistance was incorporated in it to account for interfacial phenomena. A numerical model was subsequently used to simulate moisture transport in building assemblies. The moisture transport experiments conducted with AAC and mortar were simulated with the numerical model. The results from the gamma ray measurements were used to optimize the mismatching resistance for each experimental situation. The mismatching resistance so optimized was found to depend on moisture content and also showed directionality. With one set of optimized mismatching resistances for each experimental situation, excellent agreement was found between the measured and simulated transient moisture distributions in all cases. This thesis also presents the results of a parametric study to investigate the sensitivity of predictions regarding material properties and interface imperfection. (Abstract shortened by UMI.)