Effects of early-age carbonation curing on the properties of cement-based materials: A review

Climate change and carbon emissions, as one of its causes, have raised increasing concerns, and reaching the carbon peaking and carbon neutrality targets requires the construction industry to reduce its colossal carbon footprint. Early-age carbonation curing can effectively sequester CO2 from the atmosphere while improving the properties of cement-based materials. Thus, this technology has great potential to replace the energy-intensive autoclave curing for prefabricated components (nearly 2500 kJ for each standard carbonated concrete block) as the properties of the cement-based materials can be effectively improved after carbonation curing. Early-age carbonation curing is a complex reaction process involving gas diffusion reaction, ionization hydrolysis, and precipitation. Despite the exponentially growing research over the past decade, the underlying mechanisms through which the various factors restrict the efficiency of early-age carbonation curing are not fully explored. Meanwhile, the influence of early-age carbonation curing on the durability of cement-based materials, especially rebar corrosion, remains unclear. This review first presents the principles of early-age carbonation curing and surveys the various influencing factors, including the water content, carbonation curing time, and pre-hydration time. Then, the latest research progress on the mechanical strength properties, durability, and microscopic characteristics of the early-age carbonation cured cement-based materials is summarized. The perceived improvements in the pore structure, early compressive strength (which can be increased by up to 106 % at 1 d), and durability are highlighted. Finally, the future research directions of early-age carbonation curing are discussed, and the application prospects of this technology in the industrial production practice are proposed.