Early Corrosion Detection in Prestressed Concrete Girders Using Acoustic Emission

Long-term corrosion tests were performed on prestressed T-girders measuring 4.98m (16ft, 4in.). The test program was composed of four specimens, including one control. The specimens were subjected to wet/dry cycles using 3% NaCl solution to accelerate corrosion. Two of the specimens were precracked prior to conditioning to examine the effect of crack presence and/or width. The specimens were continuously monitored using acoustic emission (AE). Half-cell potential (HCP) measurements and linear polarization resistance (LPR) were performed daily to serve as a benchmark for corrosion detection. Acoustic emission can detect the onset of corrosion comparable in time to conventional electrochemical methods. Furthermore, AE intensity analysis has the ability to distinguish between different levels of corrosion. The specimens were load-tested to measure the residual capacity, which can give an indication of AE's ability to detect corrosion damage before it affects the strength of prestressed structures.