In-situ 4D CT scanning and digital volume correlation for 3D kinematic field analysis in high-toughness recycled aggregate concrete

In the field of green building materials, the development of high-toughness recycled aggregate concrete (HTRAC) is crucial for sustainable construction. This study employs in-situ 4D CT technology to observe the meso-structural changes in HTRAC under uniaxial loading, with a focus on the spatial distribution of pores and fibers, as well as the formation and evolution of cracks. Additionally, digital volume correlation (DVC) is utilized to visually analyze the internal strain environment. The results demonstrate the material's heterogeneity and its localized effects on stress/strain distribution, revealing significant differences in crack morphology and strain distribution between recycled coarse aggregate (RCA) interfaces and fiber regions. The inclusion of microsteel fibers enhances crack resistance and toughness, resulting in an increase of the toughness index by 114 %, effectively dispersing stress and impeding crack propagation, thereby improving the material's overall structural performance. A damage evolution model, derived from strain statistical analysis during the HTRAC failure process, offers theoretical and technical support for the design and application of HTRAC in construction.