Sludge solidification based on carbon dioxide foam cement slurry

River and lake dredging will produce a large amount of dredged sludge with high water content and compressibility. Using the carbon dioxide as the foam gas source to prepare carbon dioxide foam cement slurry and use it as the solidification material to carry out sludge improvement is of great significance to the reuse of dredged sludge resources and to achieve the goal of carbon neutrality. Based on the traditional air foam cement slurry preparation technology and ordinary cement-based carbon fixation mechanism, the carbon dioxide foam cement slurry is prepared with carbon dioxide instead of air, which is used to solidify the sludge. The mechanical properties of stone test blocks formed after the curing of foam slurry and the mechanical properties and microstructure of filler formed after the solidification of dredged sludge are studied experimentally. The results show that the best combination of foaming agent and foam stabilizer is A2 4g/L, C1 5g/L. The conversion rate of Ca (OH)₂ and CO₂ to CaCO₃ in the cement hydration hydrolysis product increases by about 26.1%. The optimal content of fly ash in cement slurry is 30%. The unconfined compressive strength, internal friction angle and cohesion of the solidified materials formed after curing approximately linearly increase with the content of foam slurry, while the permeability coefficient approximately linearly decreases with the content of foam slurry. The research results provide important guidance for the engineering application of sludge solidification and the way to "turn waste into treasure" of carbon dioxide.