Feasibility study of percussion–acoustic‐based void identification for underwater concrete.

Summary: Concrete has been widely used in underwater structures. However, accidental voids near the concrete protective layer may weaken the bearing capacity of the structures and can even lead to severe disasters. Therefore, it is necessary to develop an efficient and convenient method for quantitatively identifying voids in concrete and guaranteeing structural safety. A percussion–acoustic method is commonly used to identify voids in concrete exposed to air, owing to its high efficiency and low‐cost. Nevertheless, its feasibility for underwater concrete remains questionable, owing to the complexity of the underwater environment. To address this limitation, this study conducted experimental and theoretical studies by using a percussion–acoustic‐based method to identify voids in underwater concrete while considering the fluid–structure coupling effect. The results demonstrate that the frequency characteristics of percussive sound pressure underwater are significantly different from those in air and are determined by the void scopes and depths. Accordingly, this study provides a potentially applicable method for evaluating the voids in underwater concrete. [ABSTRACT FROM AUTHOR]