Understanding of municipal solid waste incineration (MSWI) bottom ash/cement blends: Impact of natural fiber on mechanical strength and leaching behavior

There are well-known drawbacks to using municipal solid waste incineration bottom ash (BA) as cement substitution materials: low compressive strength and the leaching of contaminant ions from BA. These drawbacks hinder the practical application of MSWI BA in construction. Conventional strategies, such as steel or synthetic fiber reinforcement and BA washing pre-treatment, can improve performance but often involve increased costs, high water consumption, and the risk of secondary pollution. In this context, natural fibers present a more sustainable alternative due to their high stiffness, renewability, and low embodied energy. This work evaluates the effect of natural fiber incorporation to solve the above issues. Effects of natural fiber types (sisal fibers, SF, and oil palm fibers, OPF) and BA replacement levels (15 wt% and 30 wt%) on compressive strength and porosity were evaluated. Hazardous ions leaching changes were examined using inductively coupled plasma atomic emission spectrometry (ICP–AES) and Ion chromatography (IC). It was observed that when the maximum replacement with BA increased to 30 %, the 28-d compressive strength of the blended binder with SF is about 85 % higher than the reference binder. Leaching tests show that most contaminant ions were effectively mitigated under the experimental conditions. In addition, compared with a pure cement binder, BA-based cement binders with natural fibers have lower greenhouse gas (GHG) emissions and production costs. This study provides a promising solution to effectively apply MSWI BA into the cement binders for potential building materials.