REVIEW OF ACOUSTIC EMISSION CORROSION MONITORING OF PRESTRESSED CONCRETE BRIDGES

摘要

Corrosion of steel reinforcement is a major deterioration mechanism in reinforced concrete structures that has led to highway bridge failures in the recent past. While prestressed and post-tensioned concrete structures offer a natural protection to the reinforcement by limiting crack development, the high stresses in prestressing strands and their geometry facilitates crevice corrosion which accelerates corrosion deterioration and may increase the risk of sudden failure. Traditional methods for corrosion detection, such as visual inspection and electrochemical measurements, are local, time consuming and may not be feasible in post-tensioned concrete structures. This study summarizes recent efforts that utilize the acoustic emission technique for corrosion detection in prestressed and post-tensioned concrete structures. Acoustic emission is sensitive to ongoing damage and can detect it on both the micro- and macro-level. The method is non-intrusive and can enable global assessment of the structural condition. The methodology is reviewed and the results of accelerated corrosion experiments on specimens with different sizes and configurations are reported. In these studies, acoustic emission results are validated using electrochemical results and micro-graphs from scanning electron microscopy. A newly developed acoustic emission based corrosion classification chart is also presented.