Incineration Bottom Ash as Aggregate for Controlled Low Strength Materials: Implications and Coping Strategies

Most waste disposal methods in Taiwan involve incineration, the incineration bottom ash (IBA) which is accumulated over the years and needs urgent treatment. Hence, using IBA to create renewable materials is essential for the sustainable development. In this study, natural aggregates in the controlled low strength material (CLSM) were replaced with IBA. Its workability, setting time, unit weight, mechanical behavior, and environmental impact were examined. The study also looked at the characteristics of CLSM and suggested solutions for improvement. The results showed that the substitution of natural fine aggregates with IBA had the most significant impact on the engineering properties of CLSM. IBA significantly improves the workability and reduces the unit weight of CLSM, but the presence of CaSO4 had a detrimental effect on its setting time and mechanical behavior. However, treating IBA at 750℃ before use significantly improved the mechanical properties of IBA-CLSM and shortened its setting time, making it a potential permanent backfill structure. The toxicity test results showed that the IBA-CLSM produced had no threat to environmental safety. The study proved that using IBA produced in Taiwan to replace natural aggregates in CLSM was feasible and an effective way to utilize IBA.