Estimation of Corrosion in Reinforced Concrete by Electrochemical Techniques and Acoustic Emission

Deterioration of reinforced concrete caused by corrosion of reinforcing steel under chloride environment is experimentally studied. Onset of corrosion and nucleation of cracking are estimated by acoustic emission (AE), comparing with the chloride content. Corroded areas are evaluated by the half-cell potential and the polarization resistance. To compensate the potentials, the inverse boundary element method (IBEM) is applied. Results show that AE parameters can effectively evaluate the onset of corrosion and the nucleation of cracking, which are remarkably comparable to chloride concentration. The decrease in the half-cell potential is observed, following high AE activities. It is concluded that AE technique give an earlier warning of corrosion than the half-cell potential measurement. In addition, crack types at onset of corrosion and nucleation of cracking are identified from AE parameters. Corroded areas estimated by IBEM solutions are in good remarkable agreement with those of visual inspection, although results of electrochemical techniques are marginally successful.