In this study, we aimed to clarify that modification condition when unburned carbon of Fly Ash which quality differ is removed by flotation method, physical properties of Fly Ash which was modified by that condition and properties of mortar and concrete with it. As a result, properties of modified Fly Ash by flotation method are superior to original ash, and unburned carbon of Fly Ash was removed, particle size of it had become fine down. Therefore, fluidity of mortar and concrete with it improved. In addition, durability of concrete with it was superior to normal concrete.
