Thermal conductivity of geomaterial foams based on silica fume

Abstract

Porous materials have been prepared from a solution containing sodium silicate and sodium hydroxide with the addition of silica fume. Kaolin and diatomite were also tested as additives to the initial formulation. This method yields consolidated geomaterial foams without requiring thermal treatment above $50\,{}^{\circ}\hbox{C}$. The influence of chemical composition on the thermal conductivity was studied. The choice of raw materials was found to play an important role. The accuracy of thermal conductivity measurements was evaluated by comparing the steady state heat flow method with the laser flash technique for five different reference materials giving values within 6%. Using the steady state heat flow method, a value of $0.12 \pm 0.01\,{\rm W}\,{\rm m}^{-1}\,{\rm K}^{-1}$ was then obtained for consolidated foams, made with kaolin as the precursor, containing approximately 70% of porosity.