Production and performance of CO2 modified foam concrete

CO2 capture and utilization is an important environmental protection measure to reduce greenhouse gas (GHG) emissions. In order to realize the carbon fixation of cement and optimize the performance of foam concrete, ordinary Portland cement (OPC), fly ash (FA), CO2 gas and animal protein foaming agent were used as the main raw materials to prepare CO2 foam concrete (CFC). The diffusion principle of CO2 gas in the bubble was analyzed and the performance of CFC was investigated by testing the mechanical, thermal, water absorption and drying shrinkage properties, and microscopic characterization. The results showed that the compressive strength of CFC with 20% CO2 volume could reach 3.32 MPa, which was 24.8% higher than that of the control group (2.66 MPa), and the 70d drying shrinkage rate of CFC was 2.56 mm/m, which was 23.1% lower than that of the control group (3.33 mm/m). The thermal conductivity and water absorption of CFC were also reduced. XRD analysis revealed that intensity of CaCO3 was enhanced with the increase of CO2 gas content in the bubble. SEM analysis also corroborated the XRD results and a large number of CaCO3 crystals were observed in the samples of different ages with the increase in CO2 concentration, which enhanced the density of C-S-H gel pores and refined the microstructure.