Comparison of Mechanical Performance between Carbonated and Noncarbonated Recycled Aggregate Concrete under Static and Dynamic Loads

Carbonation treatment has emerged as a promising method for improving the quality of recycled aggregate. To support the application of carbonated recycled aggregate concrete (CCRA) in transportation infrastructure, a thorough understanding of the mechanical performance of CCRA under dynamic loading is essential. This study systematically compares the mechanical properties of natural aggregate concrete (NAC), recycled aggregate concrete (RAC), and CCRA under both static loading and dynamic loading conditions. Mechanical performance was assessed through static compressive and flexural strength tests, as well as high-strain-rate split Hopkinson pressure bar (SHPB) experiments. Additionally, scanning electron microscopy (SEM) was used to examine the microstructural changes in the aggregate surface and the interfacial transition zone (ITZ). The results show that carbonation treatment significantly increases the density of recycled aggregates while reducing both water (H2O) absorption and crushing value. Carbonation treatment improves the static compressive strength of CCRA to a level comparable to NAC. Notably, CCRA demonstrates both high strength and ductility under dynamic loading. The dynamic peak stress of CCRA reaches 117.76 MPa, closely matching the 113.73 MPa observed in NAC, while the peak strain of CCRA is 76.2% higher than that of NAC. The findings demonstrate that carbonation treatment effectively improves the pore structure and ITZ of RAC, leading to improved static mechanical performance and greater dynamic impact toughness. This study contributes to a better understanding of the mechanical behavior of CCRA and supports the application of CCRA in transportation infrastructure to promote sustainable construction.