Use of CO2 as a controlled foam stabilizer to enhance pore structure and properties of foamed concrete

Foam stabilizer plays a crucial role in foamed concrete production as it alleviates the foams to attain satisfactory pore structure. This paper studies the feasibility of using CO2 as a foam stabilizer by investigating the foams and pore structure development over time and the properties of the resulting foamed concrete. Experimental results revealed that the formation of extensive nano-CaCO3 acted as "skeletons" in foamed concrete, which could help mitigate the disproportionation and coalescence reaction of the foams. As such, the matrix also had an optimized pore structure with small and homogeneous pores, leading to an improved stress transfer path. Consequently, the compressive strength of the CO2-stabilized foamed concrete can be two times higher than that of the foamed concrete without CO2 stabilization, while maintaining a similar or even slightly lower density. From the environmental and economic perspectives, CO2-stabilized foamed concrete mineralized about 8.55 wt% of CO2 and mitigated the greenhouse effect.