Original paper(Vol.49 No.3 pp.348)
Hardening treatment of muddy soil with coal fly ashes
Sawa Kohei; Tomohisa Seishi; Inazumi Shinya; Tachibana Mari
Abstract:Recently, the amount of muddy soil produced from various kinds of construction sites has been increasing. Most of the soils are difficult to reuse as construction material owing to low strength, and the disposal site of the soil has been decreasing. Therefore, it is very important to reuse the soil from the view point of natural resource preservation and environmental impact mitigation.
The purpose of this study is to reuse the muddy soil effectively stabilized with cement, and to clarify the possibility of application of coal fly ashes as hardening additives to the soil stabilization. In this study, the hardening effects of four coal fly ashes are examined by an unconfined compression test, and the hardening reaction products of stabilized soil were measured by SEM observation and X-ray diffraction analysis.
As a result, it has been found that coal fly ashes, especially fluidized bed combustion coal fly ash, are effective on the muddy soil stabilization as a hardening additive. The quality control of coal fly ash is very important, because the hardening activity of the coal fly ash changes due to the storage condition. Furthermore, the main reaction products which contribute to strength development are ettringite and calcium silicate hydrate compound.
Key Words:Cement, Coal fly ash, Hardening additive, Muddy siol, Soil stabilization, Unconfined compression test