Acoustic emission evaluation in concrete

A series of studies has been made of acoustic emission (AE) behavior in concrete to demonstrate the usefulness of AE techniques for evaluation of structural integrity. Fracture mechanisms were studied in reinforced concrete (RC) beams with a single reinforcing bar and concrete beams reinforced with fiber plastic sheets by the use of a moment tensor analysis. Cyclic loadings were applied to large repaired RC beams, beams deteriorated due to corrosion of reinforcement and a corner of PC rigid frame. Fatigue tests were made in RC slabs used in a highway bridge. Field tests were conducted in RC beams with different damage levels in an aging dock, RC slabs of a highway bridge in service, RC beams of a high speed railway bridge in service, RC foundations under simulated seismic loadings and an arch dam during construction cooling and grouting. The laboratory tests showed that the Kaiser effect starts to break down when shear cracking starts to play a primary role. It has been demonstrated that high AE activity is observed during unloadings after serious damage (slips between the concrete and the reinforcement or those between the original concrete and the repaired part) has occurred. The moment tensor analysis was shown to be very effective for quantitative evaluation of fracture mechanisms and processes in concrete. This article reviews the results of the laboratory tests and field applications and discusses proper methods for AE evaluation of structural integrity in concrete.