Detection of “zero-volume” defects in concrete repair systems using impact-echo method

Adhesion in this system is one of the most important factors that affect the reliability and durability of repair. According to the many standards and guidelines, a pull-off test is recommended for assessment of a bond quality in repair systems. However, a growing interest in development of non-destructive techniques (NDT) for evaluation of concrete structures is recently noted. A majority of NDT methods mentioned in EN 1504-10 for repair efficiency assessment are based on propagation of stress waves. The impact echo method is considered as a one of the promising. The literature data confirmed that the “non-zero volume” defects containing air are relatively easy to detect with impact-echo method if they are large enough. It is more complex to detect “zero-volume” defects, e.g dust or any other antiadhesion material. In this work usability of impact-echo for detection of “zero-volume” defects in repair systems is discussed.