Properties of calcium silicate briquette improved by pretreatment of raw materials of coal ash
Ashida Toshifumi; Nakabayashi Ichiro; Okamoto Teruhiko; Hirashima Yasushi
Abstract:Calcium silicate briquettes were hydrothermally made from the raw materials of waste coal ash which were activated by pretreating with 0.05 mol/l-HCl solution or 0.1 mol/l-NaOH solution at 80 degree for 4 hours. After curing for 72 hours, the briquette consisted of hydrogarnet, C-S-H, and tobermorite. The briquette made from the pretreated coal ash had lower bending strength and lower bulk density than those made from untreated coal ash. To improve the strength, waste silica containing 85 wt% a-quartz was added with the pretreated coal ash. The pretreatment of coal ash indirectly improved the reactivity of waste silica, since hydrothermal solution easily invaded into the briquette through pore developed by the reaction of coal ash. The briquettes having bending strength of 18.7 MPa and bulk density of 1.42 Mg/m3 were obtained. Key Words:calcium silicate briquette, pretreated coal ash, hydrothermal treatment