Abstract
The discharge amount of coal ash was around 10 million tons every year from pulverized coal-fired steam plants in japan. Alkali activated aluminosilicate material, i.e. fly ash, attracts attention as a new usage for building material. Authors produced zeolite composed hardened material by mixing fly ash with sodium hydroxide solution and curing under hydrothermal condition at 180℃. This material has high strength and cation exchange ability against cesium. This paper discusses the influence of variation in physicochemical property of fly ash on mechanical property and mineralogical aspects of hardened materials. There are suitable range of Si/Al ratio of glassy phase and preferable grain fineness of fly ash to obtain enough strength and production amount of zeolite under constant mixing ratio of fly ash and sodium hydroxide. Gmelinite was the main products in any cases. On the hand, production amount of Zeolite NaP1, Hydroxysodalite and unidentified product with 9-10° broad peak in XRD depended upon the properties of fly ash. Strength showed good correlation with pore size distributing property of hardened materials. The low strength specimen had much porosity at diameter of 1-10μm. On the other hand, high strength specimen showed less porosity in 1-10μm and much porosity in 0.01-0.1μm. Cation exchange capacities of powderized hardened materials were 80-150 cmol/kg, the higher reaction rate of fly ash, the higher cation exchange capacity. The partition coefficients for cecium were 33-71L/g.
