ACOUSTIC EMISSION & NDT SCIENTIFIC PUBLICATIONS

 

Acoustic Emission / Acousto-Ultrasonic Data Fusion for Damage Evaluation in Concrete

 

J. of Acoustic Emission, Vol. 18, 2000, pp 21-28

(Initially presented and published at the proceedings of EWGAE 2000 - 24th European Conference on AE Testing, CETIM - France, 24-26 May, 2000, pp. 27-32)
Apostolos Tsimogiannis, Dr. Athanasios Anastasopoulos, Barbara Georgali

 

The nature of concrete posses a number of difficulties to conventional Non Destructive Testing (NDT) methods. Due to the existence of several geometric discontinuities, such as voids and particle interfaces, microscopic damage is not usually evaluated by NDT. To retrieve this information from concrete, techniques such as microscopy and chemical analysis are used. Damage accumulation on a microscopic level may not always affect the static behavior of a structure but is crucial for dynamic loading conditions, experienced by bridges, dams etc. and during earthquakes for all concrete structures. Although Acoustic Emission (AE) techniques can detect damage at early stages on structures that can be loaded to typical loads (bridges, piers etc.), they cannot be applied to structures that are not suitable for loading (buildings). In the present work specimens of standard concrete mixtures, used in the construction industry, as well as laboratory mixture specimens, are monitored using, simultaneously, Acoustic Emission and Acousto-Ultrasonic (AU) techniques, during compressive strength tests. The purpose is to monitor damage by AE and evaluate this damage with AU measurements, a technique independent of load. The results show the efficiency of AU in characterizing the level of microscopic damage in concrete specimens and are in agreement with AE monitoring during loading. AU results are also compared against microscopy findings regarding the amount of damage in the specimens.