Study on Preparation and Performance of CO₂ Foamed Concrete for Heat Insulation and Carbon Storage

Environmental problems caused by large amounts of CO₂ generated by coal-electricity integration bases have raised concerns. To solve these problems, this study develops a CO₂ foam concrete (CFC) material with both heat insulation and carbon fixation characteristics to realize CO₂ in situ storage and utilization. In this study, a Portland-cement-based CO₂ foam concrete (PC-CFC) with good thermal insulation performance and carbon fixation ability is prepared using carbonation pretreatment cement and a physical foaming method. The effects of CO₂ on the compressive strength, thermal insulation, and carbon fixation properties of PC-CFC are studied. The internal relationship between the compressive strength, thermal insulation, and carbon fixation performance of PC-CFC is analyzed, and the feasibility of PC-CFC as a filling material to realize the in situ mineralization and storage of CO₂ in the coal-electricity integration base is discussed. The experimental results show that the compressive strength of PC-CFC is significantly improved by CO₂ curing. However, CO₂ in the PC-CFC pores may weaken the strength of the pore structure, and the compressive strength decreases by 3.62% for each 1% increase in PC-CFC porosity. Using CO₂ as a foaming gas and the physical foaming method to prepare CFC can achieve improved thermal insulation performance. The thermal conductivity of PC-CFC is 0.0512-0.0905 W/(m·K). In addition, the compressive strength of PC-CFC increases by 19.08% when the thermal conductivity of PC-CFC increases by 1%. On the premise of meeting the thermal insulation requirements, PC-CFC can achieve improved compressive strength. The carbon sequestration rate of the PC-CFC skeleton is 6.1-8.57%, and the carbon storage capacity of PC-CFC pores is 1.36-2.60 kg/ton, which has obvious carbon sequestration potential; however, the preparation process and parameters of PC-CFC still require further improvement. The research results show that PC-CFC has great potential for engineering applications and is of great significance for realizing carbon reduction at the coal-electricity integration base.