Macroscopic behavior and microscopic structure of serpentine-MgO carbon sequestration foamed concrete

Abstract

This paper proposes a novel approach for preparing foamed concrete that involves the substitution of Portland cement with serpentine wastes and magnesium oxide (MgO), along with the utilization of carbon dioxide (CO2) foam instead of air foam. The existence of CO2 foam promotes the dissolution and carbonation of MgO and serpentine. Six distinct sample groups with varying serpentine proportions ranging from 0% to 50% were meticulously prepared. The incorporation of serpentine enhanced the sample fluidity and prolonged the sample setting time. The results demonstrated that the serpentine-MgO samples achieved the highest unconfined compressive strength (1.4 MPa) at a serpentine proportion of 30%, and excessive serpentine content negatively influenced the mechanical performance and microstructure development. The improvements in carbonates content, morphologies and microstructure in samples containing 30% serpentine proved the low-carbon potential of the proposed approach. Overall, serpentine-MgO carbon sequestration foamed concrete (SC-FC) could emerge as a promising sustainable construction material for CO2 sequestration.