Accelerated Diagenesis via Mechano-Chemo-Carbonation for Carbon Sequestration and Municipal Solid Waste Incineration Fly Ash Valorization

Abstract

Large-scale and safe utilization of municipal solid waste incineration fly ash (MSWI FA) remains a pressing global challenge, due to its dual nature as a hazardous waste and a potential resource. Inspired by natural rock formation processes, this study proposes an innovative triple-field synergistic strategy integrating mechanical compaction, chemical hydration, and carbonation treatments, aiming to achieve the accelerated diagenesis of MSWI FA into artificial MSWI FA-based geomaterials (MFBGs). The mechano-chemo-carbonation led to a breakthrough in early-age strength performance, with the 7-day compressive strength of MFBGs reaching 21.4 MPa, approximately 80% of the 28-day strength, while keeping the environmental risk of critical heavy metals under a safe limit. The mechanism revealed that vaterite, ettringite, and Friedel's salt were the main hydration products. Chemical hydration provides the initial strength framework, and mechanical and carbonation treatments act as supplementary enhancers. The synergistic order of the tri-fields is observed as follows: mechano-chemo-carbonation, mechano-chemical, chemo-carbonation, chemical, carbonation, and mechanical. This work not only elucidates the multi-field coupling mechanism underlying rapid, stable artificial rock formation but also establishes a short-process, low-carbon pathway for scalable resource recovery from MSWI FA, offering a viable route toward carbon sequestration and environmentally safe construction aggregates.