Detection of crack propagation in concrete with embedded ultrasonic sensors

• A crack is detected before it crosses between the embedded transducers.
• The correlation between signals is a sensitive method to detect material changes.
• Micro cracks are detected before they shape into a surface breaking macro crack.
• A clear distinction between crack opening and crack closing can be made.
• The crack propagation can be monitored without access to the concrete’s surface.

This study evaluates the sensitivity of embedded ultrasonic sensors to detect propagating cracks within concrete. Because of the sensors constant coupling to the medium, highly sensitive data analysis techniques, such as the correlation between signals and their attenuation, are applied to detect changes in the signal due to propagating cracks.The accuracy of the detected onset of the crack is evaluated with the nondestructive testing methods acoustic emission and Digital Image Correlation. It shows that with embedded ultrasonic sensors crack propagation can be detected before it is visible on the surface of the concrete.