Maximising the use of municipal solid waste incineration bottom ash for sustainable and high-performance cementitious composites

Incorporation of municipal solid waste incineration bottom ash (MSWI-BA) as fine aggregates into cementitious materials presents a promising pathway for sustainable construction and waste utilization. This study investigates the effects of MSWI-BA on mechanical performance, mass stability, and alkali-aggregate reaction (AAR) behaviour under various conditions. The results reveal a dual role of MSWI-BA: while higher contents exacerbate AAR – leading to alkali-silica gel formation, crack propagation, and strength loss – careful optimization of particle size and grading can mitigate these effects. Smaller particle sizes and finer gradations reduce stress concentrations and enable a more uniform distribution of reaction products, effectively lowering expansion rates. Removing reactive glass particles or substituting them with engineered glass aggregates further enhances material stability. Extensive alkali-silica gel formation and crack propagation are the primary factors contributing to strength reduction and expansion. Removing glass particles or replacing them with crushed glass significantly lessens the severity of AAR. • Keep content below 40% to minimise reaction damage. • Limit particle size to less than 1.18 mm to minimise reaction damage. • Removing active glass can mitigate damage caused by alkali-aggregate reactions. • Mass change rate strongly predicts early strength loss.