When we use the fly FA-As a concrete admixture, it is known that the properties of the concrete improve. But when we made concrete with fly FA-Fresh property of concrete is adversely affected by unburnt carbon in the fly ash. If there are much quantities of unburnt carbon in the fly ash, they inhibit air entraining performance and fluidity of flesh concrete. So we developed the device removing unburnt carbon from the fly FA-By flotation method in previous studies. It was succeeded remove of unburnt carbon in the fly FA-And to clean the surface of the fly FA-By used the developed device removing unburnt carbon in the fly FA-By flotation method. In this study, it was purpose to confirm the change in the composition and physical properties between the original fly FA-And the reformed fly FA-By flotation method, and to grasp the effects that the physical properties of fly FA-Gave to the unburnt carbon removal when using flotation method. As a result, the specific surface area of reformed fly ash is larger than original fly ash. However, the change of chemical composition for reformed fly FA-By flotation method was as small as 4% at the maximum. It was considered that the addition rate of kerosene and pine oil and the pre-treatment time were changed by difference in sizes and shapes of unburnt carbon in the fly ash. Percent flow and activity index were influenced by the different of physical properties of original fly ash.
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