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Porosity and insulating properties of silica-fume based foams
Graphical abstract Display Omitted
Highlights Silica fume, a by-product, was used both as starting raw powder and as foaming agent. Ultra-macroporous silica-fume based foams were obtained by direct foaming. Lightweight porous foams with good thermal conductivity values were obtained. The foams resulted promising as insulating materials.
Abstract The synthesis of silica-fume based foams, with a multi-range macroporosity, was obtained by alkaline activation. Foams were obtained through an in situ foaming process exploiting the gaseous production of hydrogen caused by the oxidation, in alkaline medium, of metal silicon impurities contained in silica fume. Potassium or sodium alkaline solutions were selected and a temperature of 70°C was sufficient to promote the development of hydrogen bubbles, the increase of the viscosity and the consolidation of the foams. The balance of these reactions allowed to entrap hydrogen bubbles inside the structures creating highly porous foams. The foams were characterized in term of macro- and microstructure, porosity distribution, infrared spectroscopy, thermal and acoustic properties achieved. The foams showed ultra-macroporous structures, with a total porosity of ≈80%. The average values of bulk density (0.5gcm−3), thermal conductivity (0.16Wm−1 K−1), and the acoustic behaviors, highlighted a use of the foams as promising insulating materials.
Porosity and insulating properties of silica-fume based foams
Graphical abstract Display Omitted
Highlights Silica fume, a by-product, was used both as starting raw powder and as foaming agent. Ultra-macroporous silica-fume based foams were obtained by direct foaming. Lightweight porous foams with good thermal conductivity values were obtained. The foams resulted promising as insulating materials.
Abstract The synthesis of silica-fume based foams, with a multi-range macroporosity, was obtained by alkaline activation. Foams were obtained through an in situ foaming process exploiting the gaseous production of hydrogen caused by the oxidation, in alkaline medium, of metal silicon impurities contained in silica fume. Potassium or sodium alkaline solutions were selected and a temperature of 70°C was sufficient to promote the development of hydrogen bubbles, the increase of the viscosity and the consolidation of the foams. The balance of these reactions allowed to entrap hydrogen bubbles inside the structures creating highly porous foams. The foams were characterized in term of macro- and microstructure, porosity distribution, infrared spectroscopy, thermal and acoustic properties achieved. The foams showed ultra-macroporous structures, with a total porosity of ≈80%. The average values of bulk density (0.5gcm−3), thermal conductivity (0.16Wm−1 K−1), and the acoustic behaviors, highlighted a use of the foams as promising insulating materials.
Porosity and insulating properties of silica-fume based foams
Papa, E. (author) / Medri, V. (author) / Kpogbemabou, D. (author) / Morinière, V. (author) / Laumonier, J. (author) / Vaccari, A. (author) / Rossignol, S. (author)
Energy and Buildings ; 131 ; 223-232
2016-09-16
10 pages
Article (Journal)
Electronic Resource
English
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