Study on seepage characteristics of concrete cracks based on CT 3D reconstruction and fractal theory

• Pioneering fractal dimension characterization method based on concrete crack surfaces. • Innovative 3D permeability calculation using CT-based crack reconstruction. • Comprehensive analysis of geometric parameters reveals synergistic mechanisms governing permeability in concrete cracks. This study investigates the permeability characteristics of cracked concrete through splitting tests on C40-C70 specimens. Using 3D profilometry and X-ray CT scanning, we quantified crack morphology parameters and obtained 3D permeability measurements. Analysis of 24 crack surfaces from 12 specimens revealed that individual parameters (width, roughness, tortuosity) showed poor correlation with permeability (R ²<0.3). The tortuosity fractal dimension demonstrated the strongest correlation ( R ²=0.485). Notably, 3D permeability assessment improved the correlation with fractal characteristics by 37.2% compared to conventional 2D methods. These findings provide valuable insights for more accurate permeability prediction and durability assessment in cracked concrete structures, highlighting the importance of fractal-based 3D characterization approaches in concrete materials research.