Municipal solid waste incineration bottom ash in concrete : A systematic review and meta-analysis

Municipal Solid Waste Incineration Bottom Ash (MSWIBA), a byproduct of waste-to-energy (WtE) facilities, has emerged as a promising candidate for use both as a sustainable aggregate replacement in concrete and as a supplementary cementitious material (SCM). This systematic review and meta-analysis, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, evaluates its mechanical, durability, and environmental impacts. A literature search (2000-2025) across PubMed, Scopus, Web of Science, Google Scholar, and Engineering Village identified 38 studies with 312 experimental groups. Random-effects meta-analysis showed that MSWIBA replacement up to 20% results in a modest reduction in compressive strength (Standardized Mean Difference [SMD] = - 0.42, 95% Confidence Interval [CI] - 0.58 to - 0.26, p < 0.001), with substantial heterogeneity (I² = 78%). Tensile strength (SMD = - 0.48, 95% CI - 0.68 to - 0.28, p < 0.001) and flexural strength (SMD = - 0.52, 95% CI - 0.74 to - 0.30, p < 0.001) also decrease moderately. Durability outcomes, including chloride penetration (SMD = 0.33, 95% CI 0.12 to 0.54) and freeze-thaw resistance (SMD = - 0.41, 95% CI - 0.72 to - 0.10), show mixed results due to limited data. MSWIBA reduces landfill use by saving 100 kg CO₂ per ton of concrete and conserves natural aggregates, but variability in composition, potential heavy metal leaching, and reduced mechanical properties at higher replacements (> 20%) pose challenges.