APPLICATION OF ACOUSTIC EMISSION TO DETECT DAMAGE IN CONCRETE STRUCTURES, ILLUSTRATED WITH FULL SCALE EXAMPLES

Acoustic Emission (AE) is a non destructive testing method allowing to detect in real time growing defects. Many damaging processes can be in the scope of the technique such as crack propagation, delamination, corrosion of reinforced bar,... The AE signature of each phenomenon under interest can be characterised in order first to discriminate genuuine AE from noise but moreover to identify the damaging process and to evaluate the severity of the damage for the integrity of the structure, with often the help of the analysis of the AE signals with statistic tools and pattern recognition processing, to provide a good diagnosis. Intrinsic mechanical properties of concrete give raised high signal to noise emission when damage propagates. The high attenuation coefficient of elastic wave in concrete material was a limitation to apply AE on a large civil structure. The development of specific AE sensors has contributed to overcome this difficulty and nowadays AE can be applied on full scale structures. In real time, AF monitoring detects the occurring of growing damage versus the loading level, displays the trend of its AE activity and locates it. AE is applied during proof test in order to investigate the fitness for service or repair validation, during service to detect a problem of fatigue or corrosion. AE continuous monitoring allows to maintain a damaged structure in service. This paper covers applications from laboratory scale experiments to actual civil structures. For the covering abstract see ITRD E123168.