Hygrothermal characteristics of aerogel-enhanced insulating materials under different humidity and temperature conditions

Since aerogel-enhanced materials provide significantly higher thermal resistance than conventional materials, they have received increasing attention over the past few years. In this study, a variety of aerogel-enhanced materials including aerogel-enhanced plasters, blankets, and boards, with different percentages of aerogel were prepared and investigated. The consistency of the thermal properties under a wide range of temperatures and humidity conditions was studied. In particular, the temperature and moisture-driven changes of the thermal conductivity of the samples were quantified. In addition, to characterize the permeability and hydrophobicity behaviour of the samples, water sorption curves, moisture storage capacity, and the vapour permeability were studied. The test conditions swung temperature ranges from −20 °C to +60 °C and moisture content ranges from 0% to 95% in Relative Humidity (RH). The results show that the aerogel-enhanced insulating materials have remarkably low thermal conductivity under different hygric conditions. This study shows that compared to the standard testing condition, the maximum increase in the thermal conductivity was 100% under 95% RH, while the greatest temperature-driven increase in the thermal conductivity was 12% at the maximum tested temperature. Both these effects were recorded in the aerogel gypsum board samples. The humidity-driven changes in the thermal conductivity of aerogel-based products are significantly greater than temperature-driven changes. The thermal resistance of the investigated materials decreased under extreme humidity condition, therefore, drying mechanism or providing a protection layer must be considered to prevent moisture accumulation and performance attenuation.