CO₂ utilization in concrete

Flue gas carbon dioxide collected from cement kiln can be beneficially utilized in precast concrete production to reduce carbon emission, accelerate early strength, and improve durability of the products. It is accomplished through a carbonation curing of precast products at very early age. This paper summarizes a recent study on optimization of the reaction conditions at which carbon uptake can be maximized, performance of the products is competitive and the process can be implemented in large scale. It is found that initial curing plays a critical role in reaction efficiency. In reference to cement content, carbon uptake in 4-hour carbonation reaches 8 -12% by zero initial curing, 22% by 4 to 8 hours initial curing and 24% by 18 hours initial curing. CO₂ curing process can replace steam to reduce embodied energy in concrete products, utilize sufficient amount of carbon dioxide in the vicinity of CO₂ sources, and produce the final products with equivalent performance.