Acoustic Emission Techniques for Rebar Corrosion in Reinforced Concrete

Corrosion of reinforcing steel is modeled phenomenologically as corro-sion losses of three phases. At the 1 st phase, corrosion is initiated in reinforcement. The rate of the corrosion loss decreases at the 2 nd phase under aerobic conditions. At the 3 rd phase of anaerobic corrosion, the expansion of reinforcing steel due to corrosion product nucleates con-crete cracking. In order to identify the onset of corrosion and the nuc-leation of concrete cracking based on this model, continuous AE moni-toring in reinforced concrete specimens was conducted in a cyclic wet and dry test. High AE activities were characteristically observed twice during the corrosion process. AE parameter analysis of hits, events and locations demonstrates that AE monitoring is readily appli-cable to detect the corrosion in rebar and to identify the corrosion process