Performance of incineration bottom ash amended marine soft clay stabilized by cement in seawater

Abstract

Abstract Incineration serves as an effective waste management method driven by its ability to reduce mass and volume of municipal solid waste. However, this process generates incineration bottom ash (IBA), which is commonly disposed of in landfills in many countries, especially when dealing with fine IBA. To address this issue, recycling fine IBA for soft marine clay (MC) stabilization is a sustainable option compared to landfilling. Previous studies revealed that aggregate-like and weak hydration properties of fine IBA may increase the strength and decrease compressibility of MC. Nevertheless, when using IBA-MC in land reclamation or coastal protection, the performance may deteriorate, particularly in the presence of seawater. Therefore, this study employed chemical stabilization method combined with ordinary Portland cement (OPC), to solidify/stabilize IBA-MC (OPC-IBA-MC). The aim was to improve the performance of IBA-MC in seawater. The appearance, water content, strength, mineralogy, and microstructure of IBA-MC and OPC-IBA-MC soaked in seawater were investigated. The results showed that the strength of OPC-IBA-MC (4075 kPa) cured in air for three months was significantly higher than that of IBA-MC (983 kPa). Nevertheless, after soaking in seawater, OPC-IBA-MC was dismantled, rendering its strength untestable. The mineralogy and microstructure of OPC-IBA-MC revealed that the formation and growth of ettringite caused instability in OPC-IBA-MC in seawater.