Application of Acoustic Emission to Detection of Reinforcing Steel Corrosion in Concrete^⋆

Cracking and spalling of concrete due to corrosion of embedded steel is generally recognized as a major technological problem within the state of Florida and nationwide. Typically, this failure mode is detected only after cracks progress to the free surface at an advanced stage of the process. The purpose of the study reported herein has been to determine if acoustic emission techniques might be applicable to detection and characterization of damage that results from reinforcing steel corrosion. For the purpose of assessing this, three groups of experiments have been performed. The first involved polarization scans upon reinforcing steel, the second addressed accelerated corrosion tests upon reinforced concrete specimens and the third involved potential monitoring of naturally corroding reinforced concrete specimens. In all cases, the specimens were instrumented such that acoustic emissions could be recorded during the test. The experiments demonstrated that measureable levels of acoustic emission occur even under freely corroding exposure of reinforced concrete. Various aspects of the experimental results are discussed, and it is concluded that acoustic emission monitoring may represent a useful technique for corrosion damage characterization of reinforced concrete.