Reinforced concrete: Application of acoustic nondestructive testing for safety evaluation

Abstract

The inhomogeneous nature of reinforced concrete makes it challenging to nondestructive testing applications. One of the major safety issues concerning the bond stress of concrete structures under external loads has been investigated. Significant changes in acoustic wave velocity were observed as the bond stress exceeded a certain level. The splitting and slipping actions of the reinforcing bar induce not only cracks at the steel-concrete interface, but strain softening of the concrete which may explain the decrease in acoustic wave velocity. This study pioneers the combination of pull-out tests for standard concrete and mortar specimens with through-transmission measurements. The correlation between bond stress and acoustic wave velocity is established such that the structural safety of concrete structural elements can be evaluated using through-transmission measurements.