Assessment of corrosion of reinforcing steel bars in concrete using embedded piezoelectric transducers based on ultrasonic wave

Abstract

The corrosion behavior of steel in concrete is an engineering issue that needs to be monitored to ensure structural safety. Novel cement/polymer-based piezoelectric composites were used to fabricate embedded ultrasonic transducers. This study investigated the corrosion development of reinforcement bar in concrete by employing ultrasonic transmission technique. The transmitted ultrasonic wave and acoustic parameters were extracted to reveal the corrosion process of steel. Results show that ultrasonic time- and frequency-domain spectra have weak amplitude attenuation when the corrosion rate of steel is less than 1%. Corrosion then weakens further when the corrosion rate is higher than 5%. A similar variation is observed on the frequency-domain spectrum. Variations in the corrosion rates of steel bars in concrete can be categorized into three periods based on the acoustic parameters, namely, the initial corrosion period when the corrosion rate is less than 1%, rapid corrosion period at a corrosion rate of 1%–6%, and corrosion development period when the corrosion rate is higher than 6%.