Ball milling to enhance strength of municipal solid waste incineration bottom ash-based controlled low-strength material

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To promote the sustainable utilization of municipal solid waste incineration bottom ash (MSWI-BA) in controlled low-strength material (CLSM), this study comprehensively investigated the physical properties, chemical composition, reactivity, and influence on compressive strength of MSWI-BA under different ball milling durations. The experimental results show that ball milling for 10-15 min effectively optimized the particle size distribution and fineness of MSWI-BA, increasing its specific surface area by 60.0%-82.2%. Concurrently, ball milling depolymerized the highly polymerized silicate phase, promoted the dissolution of silicon/aluminum in alkaline environments, enhanced the reactivity of MSWI-BA, and accelerated the hydration process. For CLSM using ball-milled MSWI-BA after 15 min as fine aggregates, the 7-day and 28-day unconfined compressive strength were enhanced by 72.9% and 62.8%, respectively. The strength enhancement stemmed from increased reactivity driving the formation of AFt and C-S-H, elevating the degree of hydration, and densifying the microstructure. Although ball milling increased the leaching potential of heavy metals, the assessment of heavy metal leaching toxicity confirmed compliance with relevant specification requirements. This study provides new insights into the efficient utilization of MSWI-BA in CLSM production.