Use of acoustic emission signals through steel reinforcement to detect the onset of corrosion.

摘要

Corrosion processes produce elastic energy waves in the form of acoustic emission (AE). For corrosion in reinforced concrete structures, AE waves are emitted beginning with the depassivation of oxide layers of reinforcing steel, the initial stage of corrosion processes. This study examines the feasibility of using AE technique to detect corrosion through steel reinforcement, which has relatively lower attenuation than concrete. Comparison of coupling AE sensors on steel and on concrete was made. Accelerated corrosion regime and two-channel multifunctional AE equipment with piezoelectric sensors were employed for laboratory experiments. The detectable distance from corrosion source to sensor was estimated via the calculation of attenuation coefficient and particle surface displacement. The analysis of source location demonstrates that surface wave is the predominant AE wave propagating in rebars with one-inch diameter. Furthermore, an important experiment was performed to compare AE measurement with half-cell potential measurement. As a result, AE was proved to be a promising tool for corrosion detection in reinforced concrete structures.