Acoustic emission techniques for rebar corrosion in reinforced concrete

Abstract

Corrosion of reinforcing steel is modeled phenomenologically as corrosion losses of three phases. At the 1st phase, corrosion is initiated in reinforcement. The rate of the corrosion loss decreases at the 2nd phase under aerobic conditions. At the 3rd phase of anaerobic corrosion, the expansion of reinforcing steel due to corrosion product nucleates concrete cracking. In order to identify the onset of corrosion and the nucleation of concrete cracking based on this model, continuous AE monitoring 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 applicable to detect the corrosion in rebar and to identify the corrosion process.