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Novel supplementary cementitious material derived from municipal solid waste–sludge co-gasification slag: Aluminum coordination mechanism governing hydrate assemblage
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DOI：10.1016/j.cemconcomp.2026.106636.png)
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Abstract
En 中文
Vitrified co-gasification slag from municipal solid waste and sewage sludge (GSMSW) is a potential waste-derived supplementary cementitious material (SCM), yet the structural origin of its reactivity remains unclear. Here, the role of Al coordination in controlling the depolymerization behavior of GSMSW and the resulting phase assemblage process is investigated using 27Al/29Si MAS NMR and Rietveld-PONKCS XRD in Ca(OH)2-GSMSW model systems and OPC-GSMSW blends. GSMSW contains a silicate-rich glassy aluminosilicate network with coexisting Al(V) and Al(IV) species. In the model systems, Al(V) dissolves preferentially at early ages, inducing localized network disruption and limited Q0 formation, whereas the slower dissolution of Al(IV) is linked to more extensive depolymerization and substantial generation of monomeric silicate species. The same coordination-dependent dissolution sequence of Aluminum is observed in blended cement systems. Early Al(V) release promotes AFt and hemicarbonate formation, while the later reaction stage is characterized by AFt-to-AFm transformation and progressive C-(A)-S-H development, sustained by continued network depolymerization and reactive Si supply. At 180 days, blends containing 20 wt% and 50 wt% GSMSW reach compressive strengths of 52.88 and 46.83 MPa, corresponding to 106% and 94% of the OPC reference, respectively. Overall, the results identify coordination-dependent dissolution as a key mechanism governing the reactivity of GSMSW and the long-term phase evolution and performance of blended cements.
Keywords:
Aluminum coordination
Supplementary cementitious material
Co-gasification slag
Hydrate assemblage
Depolymerization mechanism
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