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

Abstract

This study introduces a novel strategy for carbon capture and utilization by incorporating CO<inf>2</inf> into foams to develop CO<inf>2</inf> foam concrete (CFC) with high performance. A conceptual design approach for CFC was first proposed by incorporating tailor-made CO<inf>2</inf> foam into an optimized cement-based paste. The engineered CO<inf>2</inf> foam exhibited fine size and good stability, but increasing CO<inf>2</inf> concentration decreased stability. Then, the CO<inf>2</inf> 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 CO<inf>2</inf> foam induced positive internal carbonation effects to further enhance the CFC performance. These effects included promoting cement hydration efficiency and generating CaCO<inf>3</inf> on the foam wall for strength enhancement. Also, the rational use of CO<inf>2</inf> 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 CO<inf>2</inf> 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.