Optimized process window for fresh concrete carbonation curing

The feasibility of using captured carbon dioxide as an enabling starting material for fresh concrete carbonation curing was studied. Carbonation curing of fresh concrete accelerates hydration, shortens production time, and recycles carbon dioxide recovered from cement kiln. The challenge is if an optimized process window can be established that can compete with steam curing. The carbonation reactivity of fresh concrete was reduced by high water content and internal relative humidity. It was found that water content was more dominant at a fresh state. When the water content was reduced to 40%, the internal relative humidity was still over 95%. A novel process including a high water to cement ratio mix, a precondition drying, and a static carbonation curing was developed to establish an optimized process window for enhanced carbon dioxide uptake and concrete early strength within an 8 h work shift.