Carbon capture and storage CO2 foam concrete towards higher performance: Design, preparation and characteristics

This study introduces a novel strategy for carbon capture and utilization by incorporating CO₂ into foams to develop CO₂ foam concrete (CFC) with high performance. A conceptual design approach for CFC was first proposed by incorporating tailor-made CO₂ foam into an optimized cement-based paste. The engineered CO₂ foam exhibited fine size and good stability, but increasing CO₂ concentration decreased stability. Then, the CO₂ foam was used to fabricate CFC with high strength (about twice that of normal foam concrete at a similar density), excellent durability (comparable to normal concrete), and low thermal conductivity. Moreover, it was demonstrated that CO₂ foam induced positive internal carbonation effects to further enhance the CFC performance. These effects included promoting cement hydration efficiency and generating CaCO₃ on the foam wall for strength enhancement. Also, the rational use of CO₂ foams optimized the CFC pore structures, including reducing porosity, refining pore size, and improving pore uniformity. The CFC exhibited exceptional carbon capture, sequestering 87 kg of CO₂ per m³ of concrete by internal and external carbonations (active carbon reduction), and could reduce electricity consumption and the corresponding carbon emissions (indirect carbon reduction). This innovative material offers a promising pathway towards sustainable construction and carbon neutrality.