Study on the mixed fracture characteristics of concrete-rock Brazilian disks with different fracture angles

The fracture characteristics of cracked straight-through Brazilian discs for concrete-rock composites (CSTBDCRC) with different fracture inclination angles (Mode I-II) were investigated to evaluate the stability of concrete reinforcement engineering. Acoustic emission (AE) and digital image correlation (DIC) techniques were employed to study crack propagation and fracture modes in CSTBD-CRC Brazil splitting tests, as well as the entropy evolution of AE and DIC. Additionally, 3D scanning technology and fractal theory were utilized to investigate the effect of the fracture mode on the fracture surface morphology. The results indicate that both the fracture energy and peak load of the CSTBD-CRC increase with increasing fracture inclination angle. Moreover, the section fractal dimensions of 0 degrees, degrees , 10 degrees, degrees , 15 degrees degrees and 25 degrees degrees samples are 2.01879, 2.01528, 2.01186, and 2.01072. Shear fracture mode increases as the dip angle increases and the fracture surface morphology decreases in fractal dimension. Notably, sharp increases in entropy values for both AE and DIC occurred at peak load, suggesting their use as failure criteria for CSTBD-CRC specimens. Furthermore, cracks were found to initiate at the tips of preexisting cracks within the concrete. The displacement in the x direction undergoes the most significant changes on both sides of the crack during crack growth, while the strain in the x direction experiences its greatest variations at the crack location.