Enhancing mechanical properties and microstructural integrity of silica fume-based self-compacting geopolymer concrete through municipal solid waste incineration fly ash incorporation

This study examines the impact of municipal solid waste incineration fly ash (MFA) on silica fume-based self-compacting geopolymer concrete (SGC). MFA replaced silica fume at 0–40 % by weight across five mixes. Results showed that workability improved with MFA incorporation, as shown by slump flow, V-funnel, and L-box tests. The highest compressive (44.12 MPa) and splitting tensile strengths (3.87 MPa) were achieved at 20 % MFA replacement after 28 days, with further increases reducing strength due to altered geopolymerization and shrinkage. SEM confirmed reduced voids, while TGA showed 1.18 % higher mass loss, indicating improved geopolymerization. Excess MFA (≥30 %) increased porosity and cracking, reducing performance due to unreacted particles and carbonation effects.