Investigations into magnesium oxide carbon sequestration foamed concrete: Mechanical performance, microstructure and environmental benefits

This paper proposes an innovative preparation measure for magnesium oxide (MgO)-based foamed concrete. Carbon dioxide (CO2) foam has been introduced into the sample as a substitute for air foam, resulting in a novel formulation referred to as MgO carbon sequestration foamed concrete (MCFC). This innovation facilitates the setting and hardening of MgO-based foamed concrete under ambient conditions. Basic mechanical properties were tested at three different ages. At the age of 28 days, the resultant MCFC has demonstrated mechanical performance comparable to conventional Portland cement-based foamed concrete including unconfined compressive strength and stain-stress behavior. Through SEM NMR and X-ray CT, the MCFC sample exhibited an increasingly compact matrix and an evolving distribution of pore structure as time progressed. Furthermore, a comprehensive life cycle assessment has revealed that MCFC has the potential to reduce carbon emissions by up to 50% when compared to conventional cement-based foamed concrete. The results imply that MCFC presents itself as a viable alternative to conventional PC-based foamed concrete, offering equivalent mechanical performance while delivering superior environmental advantages for engineering applications. ●MCFC using MgO, soil and CO2 foam is proposed to realize the sequestration of CO2 and the reduction in carbon emissions.●MgO and CO2 react to generate carbonated phases, and CO2 is consumed to realize its solidification.●MCFC can consume and sequester CO2 and avoid environmental pollution, portraying great social and economic benefits.