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The electric emission from mortar and concrete subjected to mechanical impact

: Sklarczyk, C.; Altpeter, I.


Scripta materialia 44 (2001), No.11, pp.2537-2541
ISSN: 1359-6462
Journal Article
Fraunhofer IZFP ()
cement; concrete; elastic; electric property; nondestructive testing

Steel balls dropping on mortar and concrete specimens generate electromagnetic signals (Electric Emission EE) in the frequency range of some 104 Hz which are easibly measurable in noncontact way. They are probably due to rapid movements of double electric layers under the action of the impact. The double layers are generated at the interfaces between cement matrix and filler and thus may depend on the adhesion between the components. Therefore the EE should be correlated to material properties like pressure strength. However experimental investigations have shown a big scattering of EE amplitudes during impact. This is due to the high scattering of the material properties in mm and sub-mm scale as the volume subjected to high mechanical stresses at impact is very small (about 10-9 m³). To get reliable correlations between EE signal parameters and material properties on statistical basis, a very high amount of impacts would be necessary. Therefore the experimental results gained up to now are not very satisfactory with regard to an industrial application of the EE-method in the field of materials characterization.