Carbonation curing for precast Engineered Cementitious Composites

The ultra-durable Engineered Cementitious Composites (ECC) provides an opportunity for sequestering CO2 during construction while reducing operational emissions in use phase. Here, ECC carbonation curing was investigated as a precast route of CO2 sequestration. Results suggest that ECC sequesters 29.6% CO2 by cement mass through early-age carbonation. The ultimate tensile and compressive strengths at 2 days were increased by 57.2% and 40.9%, respectively, while the tensile strain capacity attained 3.7%. Carbonation curing was found to densify the fiber/matrix interface resulting in higher interfacial bond, tighter crack widths, and more robust fiber bridging capacity. Consequently, the composite ultimate tensile strength increased by 22.7% while maintaining comparable strain capacity at 28 days. The tighter crack widths further decrease the material water permeability in loaded condition. These findings prove the feasibility of ECC carbonation curing and establish the scientific foundation of carbon utilization and permanent sequestration in ECC for precast construction elements.