Non-sintered artificial aggregates made of ternary alkali-activated materials with natural carbonated MSWI fly ash incorporations

This study investigates the utilization of municipal solid waste incineration (MSWI) fly ash (MFA) to produce non-sintered artificial aggregates (AAs) through alkali activation. To enhance its suitability, MFA underwent a six-month natural carbonation process to remove leachable salts and stabilize heavy metals, during which significant phase transformations were observed. The AAs were fabricated using ternary alkali-activated materials (AAMs) with varying MFA proportions through spray pelletization. Although higher MFA content reduced the strength of the AAs, this effect was counterbalanced by increasing the silicate modulus in the activators. The resulting AAs demonstrated mechanical strength comparable to or exceeding that of natural granite aggregates and recycled aggregates derived from concrete demolition waste. Furthermore, the study examined the reaction products and microstructural characteristics of the AAs. Leachate analysis confirmed compliance with environmental standards for heavy metal content, highlighting the potential of these AAs as a sustainable alternative aggregate resource for the construction industry. • Natural carbonation treatment was conducted on MSWI fly ash (MFA) samples. • The evolution of phase assemblage and leaching properties of MFA were characterized. • Carbonated MFA was adopted in AAMs to produce artificial aggregates (AAs). • The mechanical and microstructural properties of AA samples were assessed in detail. • The heavy metal leaching behavior of AA samples was tested to meet the standard.