Carbon sequestration material development with coal-based solid waste based on in-situ crosslinked network structures

For coal mine strata control, comprehensive disposal of coal-based solid waste and carbon sequestration/reduction, a systematic approach was designed involving coal-based solid waste pretreatment, material production, and gas sequestration units. Coal gangue, fly ash, and other coal-based solid wastes were crushed and sieved. A three-dimensional (3D) in-situ crosslinked polymer network using a four-arm crosslinker (pentaerythritol glycidyl ether) to immobilize CO₂ was developed, thereby establishing an in-situ crosslinking network-based carbon sequestration method. The influence of the in-situ crosslinked polymer network structure on the slurry properties, mechanical characteristics, hydration products, microstructure and carbon sequestration efficiency of solid waste-based carbon sequestration grouting/filling materials was investigated using various characterization techniques. The coupling mechanism of the in-situ crosslinked polymer network structure in these materials was elucidated. Experimental results demonstrate that the in-situ crosslinked network structure enhanced the CO₂ immobilization capacity from 1.29 mg/g to 2.17 mg/g, achieving highly efficient carbon fixation. Additionally, the in-situ crosslinked network accelerated the hydration rate, promoted the hydration process, and significantly improved mechanical strength, with flexural strength increasing by 128.8% and compressive strength by 118.4%. Field tests further confirmed that the performance of the developed solid waste-based carbon sequestration grouting material in rock reinforcement, high-efficiency carbon sequestration and solid waste disposal.