Advanced thermal insulation for energy efficient buildings : structural performance of aerogel composite panels

Abstract

Aerogels are well known as exceptional thermal insulators. Thermal conductivities of 9 to 10 mW/m.K have been achieved at atmospheric pressure, and a moderate vacuum (between 1/3 and 1/10 of an atmosphere) can lower this number even further, to around 5 mW/m.K. However aerogels for insulation purposes are not widespread on the market. One of the major shortcomings of aerogels that prevent them from being more widely used is their extreme mechanical weakness and brittleness. In this thesis, we characterize and explain these low mechanical properties. We then propose a composite structure for a rigid aerogel panel, a sandwich panel with a truss core filled with monolithic aerogel. Mechanical and thermal properties are derived and partially tested for the truss cores. Several designs are studied and mechanical properties are derived in order to compare these designs. Some criteria for an efficient designs are given. Finally, we describe a first attempt to manufacture one of these composite structures on a small scale.