Study on 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 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. In this paper, based on the traditional air foam cement slurry preparation technology and ordinary cement-based carbon fixation mechanism, carbon dioxide foam cement slurry was prepared with carbon dioxide instead of air, which was 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 were 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 increased 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 material formed after curing are approximately linearly increasing with the content of foam slurry, while the permeability coefficient is approximately linearly decreasing 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.