Autonomous ultrasonic imaging and crack localisation in concrete beams during the fracture process

Monitoring the fracture process in concrete and detecting cracks at an early stage remains one of the major challenges in non-destructive testing of civil engineering structures. This paper presents a novel methodology for real-time fracture imaging in concrete structures using ultrasonic waves. The proposed approach introduces an innovative damage index that enables precise identification of both the location and onset time of crack initiation. Integrated with ultrasonic transmission tomography, this method forms the basis of an automated structural health monitoring system. To thoroughly assess the method performance, experimental validation was conducted on four concrete beams, three of plain concrete and one reinforced with a steel bar, each representing a distinct damage scenario. The accuracy and effectiveness of ultrasonic fracture imaging were verified using X-ray micro-computed tomography and digital image correlation.