Fabrication of Porous Solidified Materials from Blast Furnace Slag Using Hydrothermal Hot-pressing Method and Measurement of Thermal Conductivity of Solidified Materials
Nobumitsu Hirai, Soichiro Maeda, Shigeru Katsuyama, Toshihiro Tanaka
To produce insulating construction materials using hydrothermal reaction from blast furnace slag (BF slag) such as air-cooled, air granulated, and water-cooled slags, we investigated the fabrication of porous solidified materials from BF slag by a hydrothermal hot-pressing method. The thermal conductivity of the solidified materials was also investigated. The experimental conditions were; hydrothermal holding time from 0 to 120 min, hydrothermal temperature from 250 to 350°C, hydrothermal pressure from 20 to 80 MPa, and slag powder sizes less than 15 μm, 39±24 μm, 84±21 μm, 178±72 μm, 375±125 μm and more than 500 μm. It was found that growth of the hydrothermally reacted phase led to a higher density and higher thermal conductivity of the solidified materials. It was noteworthy that the thermal conductivity of the hydrothermal solidified materials became smaller when the size of the slag powder was larger. This was because the more porous structure introduced into the solidified materials resulted in a lower density of the solidified materials. It was also found that glassy slag such as water-cooled and air granulated slags can be solidified even if the size of the slag powder was more than 500 μm.
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