Preparation of slag-based foam concrete and its carbon dioxide sequestration performance

•Combining industrial solid waste resource utilization and CO2 sequestration technologies.•Constructing connected multi-stage pore storage materials.•Increase CO2 diffusion and reaction rates.•Achieve high efficiency and high-capacity CO2 sequestration. In this study, high-porosity foamed concrete was prepared using blast furnace slag as the raw material, CaO as the alkali activator, and sodium dodecyl sulfate (C12H25NAO4S, SDS) as the foaming agent. The effects of the water-cement ratio, sequestration time, and CO2 pressure on the curing and sequestration of CO2 in the foamed concrete were explored. When the water-cement ratio was 0.7, the specific surface area of the sample was 28.42 m2/g, the pore volume was 0.16 cm3/g, the average pore size was 10.45 nm, and the CO2 sequestration capacity was 55.82 kg/m3. With increasing sequestration time and pressure, the CO2 sequestration capacity of foamed concrete increased, and the maximum sequestration capacity up to 69.32 kg/m3. Flocculating hydration products hold the slag particles together, forming a tightly bound three-dimensional space; after the carbonization reaction, the sample's specific surface area, pore volume, and pore size increased. According to the results, it was seen that slag-based foam concrete could be used in the sequestration of carbon dioxide.