Study on fluidity and mechanical properties of organic-matter-rich dredged sediment-based flowable solidified soil

Abstract

[Objective] Traditional solidification materials, such as cement and lime, have poor improvement effects on organic-matter-rich dredged sediment, and the sediment needs to be pre-dewatered, which reduces construction efficiency. [Methods] A novel solid waste-based cementitious material, combined with potassium permanganate, were used for the flowable solidification treatment of high-water-content, organic-matter-rich dredged sediment to prepare flowable solidified soil. Flowability tests and unconfined compressive strength(UCS) tests were conducted to investigate the effects of potassium permanganate dosage and organic matter content on the flowability and UCS of solidified sediment. [Results] These findings indicated that when the organic matter content was 7%, flowability of solidified sediment increased with increasing potassium permanganate dosage. At potassium permanganate dosages of 2% and 3%, the flowability of the solidified sediment(170 mm and 204 mm) met the standard requirements. However, when the organic matter content was 8.5% and 10%, the flowability of solidified sediment decreased as potassium permanganate dosage increased. Under the same potassium permanganate dosage, increase in organic matter content significantly reduced UCS of the solidified sediment. When the organic matter content was constant, an increase in potassium permanganate from 0% to 1% resulted in a significant decrease in UCS. Further increases to 3% led to a slower decrease in UCS. [Conclusion] Organic matter and potassium permanganate affect the formation of hydration products of the solid waste-based cementitious material, leading to a reduction in the mechanical properties of the solidified sediment. The research findings provide theoretical guidance for the engineering application of flowable solidified soil made from high-water content, organic-matter-rich sediment.

Keywords

underground space backfilling / dredged sediment / flowable solidified soil / solid waste-based cementitious material / flowability / unconfined compressive strength / influencing factors