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 CO 2 as modifiers to enhance its properties. In this research, CFBFA and CS assumed the role of cementitious constituents, with EVA and CO 2 serving as the modifying agent. A comprehensive exploration of the mechanism underlying the CO 2 + EVA modified composite cementitious system was undertaken, delving into the differences of its compressive, bending, and flexural strengths. The addition of CO 2 further improved the flexibility and rigidity of the materials and effectively improve the material's microstructure. It was worth noting that when CO 2 + 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. This study employs CFBFA and CS activated by the synergistic effect of EVA and CO 2 , significantly enhancing the rigidity-flexibility balance of grouting filling materials. The composite system exhibits substantial improvements in flexural, bending, and compressive strengths by 166.7 %, 48.76 %, and 40.56 %, respectively. • CO 2 overcame the shortcomings of EVA modification and the holes more uniform. • CO 2 +EVA improved the CFBFA-CS system flexibility and rigidity together. • CO 2 +EVA reduced the density and improved microstructure of the CFBFA-CS system.