Around 39% of domestic power is generated from coal-fired power plants, and coal ash is generated as a by-product. While the amount of domestic coal fly ash is about 8.35 million tons/year, about 80% of which is reported as fly ash (6.84 million tons) and 20% is bottom ash (1.51 million tons). Generally, fly ash is used for concrete admixture, subsidiary raw materials of cement fabrication process, etc. However, it is not used in large scale because of its low early-term strength and the problem of lowering the alkaline of concrete. Therefore, this study aims to increase early-term reactivity of fly ash and to increase cement substitution amount by fabricating the energetically modified fly ash (EMFa) through grinding of fly ash. Experimental results show that the EMFa is more effective in accelerating early-term hydration than when mixed with nongrinding fly ash. Also, when 20% of EMFa was substituted, it showed compressive strength equal to or higher than that of OPC, and the carbonation resistance was also increased in comparison with that of non-grinding fly ash.

Keywords: Fly ash, Cement admixture, Energetically-modified material, Hydration reactivity, Carbonation resistance.