Detailed investigation of capillary active insulation materials by 1H nuclear magnetic resonance (NMR) and thermogravimetric drying

Abstract

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.