Crack sealing and damage recovery monitoring of a concrete healing system using embedded piezoelectric transducers

The autonomous healing performance of concrete is experimentally verified by applying a technique based on the ultrasonic pulse velocity method using embedded piezoelectric transducers. Crack opening which deteriorates the mechanical capacity of concrete infrastructure is traditionally studied by different monitoring techniques that adequately provide a direct estimation of damage. Conversely in this research, an ultrasonic pulse velocity method is applied in order to monitor the crack closure and sealing of small-scale concrete beam elements. Short glass capsules filled with healing adhesive break due to crack formation and release those healing additives which fill the crack void and reset the element continuity. The damage index based on the early part of the wave arrival observes any emitted signal shape differentiation indicating the crack formation and development under two-cycle three-point bending loading tests (in the first cycle, the crack forms and healing release takes place, and consequently, after few hours of curing and crack reset, the beam is reloaded leading to crack reopening).