Superior CO2 uptake and enhanced compressive strength for carbonation curing of cement-based materials via flue gas

Carbonation curing of cement-based materials is an important pathway for CO2 utilization and sequestration. Most previous studies focused on pure CO2 carbonation curing. In this work, we demonstrate superior CO2 uptake and enhanced compressive strength with flue gas (20% CO2 concentration) carbonation curing. The flue gas carbonation rate is smaller at the beginning of curing, but the CO2 uptake and compressive strength are larger than that of pure CO2 curing at 12 h carbonation. Moreover, the growth rate of the post hydration strength is inversely proportional to the CO2 uptake, but under proper combination of carbonation and hydration curing, the 28d strength of the flue gas carbonated specimen can be higher than that of the hydration specimen. The carbonation curing mechanism for the flue gas and pure CO2 is discussed from a microscopic perspective. The higher carbonation capacity of lower concentration CO2 in cement carbonation curing may inspire new pathways in carbonation management.