Production of Foam Glass Made from Glassy Volcanic Ashes as Main Material Resources

This report describes the formation of foam glass made from abundant glassy volcanic ashes existing in south Kyusyu (Kagosima-ken), Hokuriku (Ishikawa-ken), and Hokkaido. A specified batch composition in the system volcanic ash, sodalime-silica glass, and sodium silicate (anhyd.), has been calcinated at 900°C for 10 minutes in an electric furnace to obtain foam glass. This experiment has provided various usefull foam glasses with desired quality, for insulating materials (bulk density: 0.23Mg/m3, thermal conductivity: 0.07W/m·K) and inner or/and outer sawing materials (bulk density: 0.65Mg/m3, thermal conductivity: 0.14W/m·K). All volcanic ashes used in this experiment has satisfied requirements for raw materials. When the six definite straight lines are extrapolated to find by plotting the physical properties (bulk density, thermal conductivity, average pore diameter) of foam glass on various amounts of the soda-lime-silica glass at the right-angled coordinates definates x-axis as the amount of sodium silicate (anhyd.) including the glass batch, and y-axis as the physical properties, every lines intersected and converged on one point. When the intersectional coordinates are the bulk density and thermal conductivity of foam glass, all the values of x-axis are the same. And, when the intersectional coordinates are the average pore diameter of foam glass except Sample No. 2, all the values of y-axis are the same. It was found that all the glassy volcanic ashes used in this experiment have essentially the same property ranging from south Kyusyu to Hokkaido.