Preparation of Geopolymers with Enhanced Mechanical Properties Using High-Content (>50%) Municipal Solid Waste Incineration Fly Ash

This study investigates the feasibility of incorporating high-volume municipal solid waste incineration (MSWI) fly ash into geopolymers, with a focus on its effects on mechanical performance and fragmentation behavior. A systematic experimental program was conducted in three stages. Geopolymer mixtures were first prepared with MSWI fly ash substitution rates ranging from 50% to 100% at seven distinct levels. Uniaxial compression tests were then performed to evaluate mechanical properties, followed by sieve analysis to examine fragment size distribution. The fractal dimension (D) was adopted to quantitatively characterize the degree of fragmentation. The results indicate that dry density, compressive strength, and elastic modulus all decrease progressively with increasing MSWI fly ash content. Specifically, as the fly ash content increased from 50% to 100% the compressive strength decreased from 9.57 MPa to 3.18 MPa. Notably, even at a 100% substitution rate, the compressive strength reached 3.18 MPa, which is 59% higher than the 2.0 MPa minimum requirement specified in the JTG/T F20-2015 standard. These findings demonstrate that MSWI fly ash can be effectively utilized at high replacement levels to produce sustainable geopolymers with satisfactory mechanical properties. This approach presents a viable strategy for recycling industrial solid waste into value-added construction materials.