Corrosion damage identification in concrete underwater based on time reversal of stress waves

Abstract

The time reversal method (TRM) of stress waves is capable of identifying damage in concrete due to its self-adapting spatial and temporal focusing characteristics. However, the application of TRM in identifying the damage of underwater concrete structures is rarely reported. In this study, TRM is further utilized to identify corrosion damage (introduced by hydrochloric acid solution) in order to characterize the mechanical degradations of concrete underwater. First, as one of the innovations of this work, the existence of non-zero initial values of damage indexes (DIs) is numerically proved, and two modified damage indexes (MDIs) are correspondingly defined. The correctness of MDIs obtained by TRM is verified by a carefully designed experiment. On one hand, one concrete beam with embedded modified piezoelectric aggregate (MPA) transducers is immersed in a hydrochloric acid solution to mimic the long-term corrosion damage of concrete underwater. TRM is experimentally used to determine the MDIs representing the corrosion damage identification. On the other hand, the compressive strength and elastic modulus of concrete cubes with the same degree of corrosion damage are measured in compression tests. The good agreements between the degradations of these representative mechanical properties and the evolutions of MDIs demonstrate the feasibility of TRM in identifying damage in underwater concrete structures.