Utilization of incineration bottom ash amended soft marine clay in land reclamation

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Land reclamation is one of the solutions for enlarging territories, which requires a considerable amount of filling materials. Singapore is now short of conventional filling materials such as sand and gravel. Soft marine clay (MC) is a common geological material in Singapore. However, it is not preferred as a filling material for land reclamation due to its high water content and high compressibility. Meanwhile, incineration bottom ash (IBA) from the waste-to-energy plant is an aggregate-like material, which is currently landfilled in Singapore due to heavy metals. The combination of MC and IBA (IBA-MC) may complement each others limitations. Therefore, this study aimed to explore the utilization of IBA-MC as a potential filling material in land reclamation. The stability of IBA-MC in seawater was studied because it may alter when IBA-MC encounters seawater in the field. The appearance, unconfined compressive strength, water content, mineral compositions, and microstructure of IBA-MC before and after soaking in seawater were investigated. The results showed that after soaking in seawater, IBA-MC tended to develop superficial cracks and had significantly lower strength than those cured in the sealed bag. The mineralogy and microstructure of IBA-MC suggested that the formation and growth of ettringite were responsible for the instability of IBA-MC soaked in seawater.

9th International Congress on Environmental Geotechnics (ICEG2023)

Stabilization