Hygrothermal simulations are of major importance for critical problems in building physics, such as the application of internal insulation in heritage buildings. These simulations require numerous material parameters that are challenging to determine. We present measurements of typical internal insulation materials, calcium-silicate and autoclaved aerated concrete, which we expose to a warm, humid climate on one side and a cold temperature on the other side. We measure the moisture gain over time and determine the moisture profile at experiment end. In an inverse modelling approach, the measurements are used to identify material parameters, in particular vapour conductivity and capillary conductivity as a function of moisture content. We found the measurements of crucial importance for the accurate determination of these parameters. When the parameters rely only on isothermal measurements such as the drying experiment, the model fails to predict the capillary condensation process. We demonstrate this on a dataset from another study with interior insulation subjected to changing boundary conditions. The model calibrated with capillary condensation data reliably reconstructs measurements while the drying-calibrated model drastically underestimates the moisture content.
Capillary active interior insulation materials are an important and innovative approach to minimize energy losses of historical buildings. In an experimental setup, we investigate the development of moisture profiles under realistic boundary conditions to determine the liquid moisture conductivity for two different interior insulation materials. The moisture profiles were determined by destructive sample cutting with subsequent thermogravimetric drying as well as directly measured by the non-destructive method NMR, which has a higher spatial resolution and even enables repetitive measurements during the course of the experiments. We observed that the moisture profiles obtained from both methods showed good agreement, when compared at the low spatial resolution of sample cutting. This raises confidence in the method of simple mechanical sample cutting. In the next step, the liquid moisture conductivity was calculated using an inverse modelling approach based on both measured moisture profiles separately. Then, we compared the pore-size distributions of the investigated samples based on NMR T2-relaxation-time distributions, mercury intrusion porosimetry and indirect determination from pressure plate and sorption isotherm measurements. Moreover, the measured T2-relaxation-time distributions across the sample depth may give further insight into the saturation degree of the different pore sizes.
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