CO₂ and ethylene vinyl acetate co-modification of solid waste-based filling materials: An integrated approach for carbon capture and recycling

To improve the rigidity and flexibility of conventional grouting materials, one visionary approach is to replace Portland cement with a composite cementitious system containing circulating fluidized bed fly ash (CFBFA) and calcium carbide slag (CS), while adding ethylene-vinyl acetate (EVA) copolymer and CO₂ as modifiers to enhance its properties. In this research, CFBFA and CS assumed the role of cementitious constituents, with EVA and CO₂ serving as the modifying agent. A comprehensive exploration of the mechanism underlying the CO₂ + EVA modified composite cementitious system was undertaken, delving into the differences of its compressive, bending, and flexural strengths. The addition of CO₂ further improved the flexibility and rigidity of the materials and effectively improve the material's microstructure. It was worth noting that when CO₂ + EVA co-modified CFBFA-CS composite cementitious materials, the flexibility and rigidity of the cementitious materials were significantly enhanced, and the bending strength, flexural strength and compressive strength were significantly increased by 48.76%, 166.7% and 40.56%, respectively, and the 28 d density was reduced by 6.91%. These results provided a theoretical basis for the realization of avant-garde cementitious materials with functional properties.