Enhancing the carbonation performance of recycled concrete in binary and ternary cementitious systems through pre-curing time

Pre-curing time is a critical factor influencing the properties of concrete; however, investigations into its effect on recycled concrete incorporating binary and ternary cementitious systems remain limited. This study investigates the effect of pre-curing time—varied from 1 to 6 days—on the carbon sequestration capacity of recycled concrete incorporating cement-fly ash-slag blended systems. The results indicate that the optimal carbon sequestration performance for different cementitious systems in recycled concrete is achieved with varying pre-curing time. Specifically, controlling the pre-curing time accelerates the formation of CaCO₃, which constructs a dense microstructure and consequently enhances the mechanical properties. At an equivalent replacement ratio, slag-based recycled concrete achieved optimal performance after a 4-day pre-curing times, attaining a unit carbon sequestration amount of 19.41 g/kg and a 33.19% increase in compressive strength. A correlation between the unit carbon sequestration amount and compressive strength was established, defined by the equation y= 11.50 x 0.38 (R²=0.86). Notably, ternary cementitious systems were observed to reach carbon sequestration saturation more readily. This study aims to provide novel approaches for enhancing the carbon sequestration performance of recycled concrete in binary and multi-component cementitious systems, thereby supporting the development of sustainable, low-carbon construction materials.