Elastic waves have been long used for structural integrity evaluation of concrete materials and structures. Ultrasonic parameters are well related to crack density, deterioration of the elastic modulus, even empirical characterization of the strength. Recently, several ultrasonic studies have emerged also in the field of repair monitoring. Manual repair actions or self-healing strongly contribute to the sealing of the crack, and the regain of the mechanical properties. However, the restoration cannot be evaluated in a non-destructive manner, especially in-situ. Ultrasonic parameters exhibit strong sensitivity to the degree of filling of a single crack or of a distributed system of cracks, while they also have the capacity to monitor the self-healing process, due to the increase of elastic modulus of the healing compounds in the crack volume. The present abstract intends to give an overview of the recent developments in the field of ultrasound as a means of fracture and repair characterization. Through-the-thickness wave transmission, ultrasonic mapping, surface waves as well as air-coupled applications are reviewed as standalone methods or in conjunction with simulations in the framework of an optimal material assessment after fracture and consequent repair.
EXTENDED ABSTRACT