Strength Characteristics of Cement Treated Hedoro Mixed with Coal Fly Ashes

Abstract

Recently, the generation of unreusable surplus soils from various construction sites has been increasing. The hedoro, one of them, is difficult to reuse as construction materials owing to high water content and low strength, and the disposal sites of the hedoro have been decreasing. Therefore, it is very important to develop the significant improvement of the hedoro from the viewpoint of natural resource preservation and environmental impact mitigation.
The purpose of this study is to clarify the possibility of reuse of coal fly ashes as effective hardening additives which affect the cement treated hedoro. The three kinds of coal fly ashes are used as hardening additives with cement stabilizer to increase the hedoro strength.
As a result, it has been found that the strength of the cement treated hedoro mixed with coal fly ashes have been increasing during aging period, therefore, the coal fly ashes can be applied as hardening additives. In comparison with pulverized coal fly ashes, the fluidized bed combustion coal fly ashes including much SO₃ and CaO give larger strength. So the fluidized bed combustion coal fly ashes are effective on the hedoro as hardening additives. On the other hand, pulverized coal fly ashes containing much SiO₂ and Al₂O₃ have continued the strength development for long term. Furthermore, the main reaction products which contribute to strength are ettringite and calcium silicate hydrate compound.