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Ultrasonic quality assurance for underground salt shotcrete sealing structures in Teutschenthal mine, Germany

  • Underground sealing structures are necessary to seal radioactive or toxic waste in underground repositories. A special version of MgO concrete is used in the mine in Teutschenthal and applied at a large-scale test with the aim to provide a low permeability barrier. The test structures (up to 10 m long) were created by shotcreting. Besides destructive tests, non-destructive ultrasonic measurements have been evaluated for quality assurance to monitor potential anomalies such as cracks, concrete inhomogeneities, and delamination. We show results of ultrasonic measurements with a multi-transducer system used at the front and from the side of the concrete structure. Images are obtained by synthetic aperture focusing techniques. The boundaries between concreting sections are not visible in the ultrasonic images systematically so that a successful concreting is assumed, which is confirmed by the low permeabilities observed. Several reflectors up to a depth of 1.2 m are identified andUnderground sealing structures are necessary to seal radioactive or toxic waste in underground repositories. A special version of MgO concrete is used in the mine in Teutschenthal and applied at a large-scale test with the aim to provide a low permeability barrier. The test structures (up to 10 m long) were created by shotcreting. Besides destructive tests, non-destructive ultrasonic measurements have been evaluated for quality assurance to monitor potential anomalies such as cracks, concrete inhomogeneities, and delamination. We show results of ultrasonic measurements with a multi-transducer system used at the front and from the side of the concrete structure. Images are obtained by synthetic aperture focusing techniques. The boundaries between concreting sections are not visible in the ultrasonic images systematically so that a successful concreting is assumed, which is confirmed by the low permeabilities observed. Several reflectors up to a depth of 1.2 m are identified and interpreted as potential damages in the concrete. Phase analysis of prominent reflectors reveal a negative impedance contrast thus indicating air filled voids, cracks or delamination. Boreholes through some of the identified reflectors are used to verify the results from ultrasonic measurements. Additionally, an experiment with incorporated artificial defects was undertaken to analyse the reliability of the applied methods. Overall, the conducted tests show the potential of ultrasonic measurements to detect critical anomalies. Despite challenges at small-scale structures (cm-order), large-scale anomalies can be identified. Consequently, implementing ultrasonic monitoring during and after the construction of concrete sealing structures has shown its potential as a tool for quality assurance, but needs further development and validation.zeige mehrzeige weniger

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Autor*innen:Vera LayORCiD, Ute EffnerORCiD, Ernst NiederleithingerORCiD, J. Arendt, W. Kudla
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):International Symposium Non-Destructive Testing in Civil Engineering (NDTCE 2022)
Jahr der Erstveröffentlichung:2022
Organisationseinheit der BAM:8 Zerstörungsfreie Prüfung
8 Zerstörungsfreie Prüfung / 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen
Verlag:NDT.net
Erste Seite:1
Letzte Seite:4
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik
Freie Schlagwörter:Engineered barrier systems; Magnesia shotcrete; Ultrasonic imaging; Ultrasound; Underground
Themenfelder/Aktivitätsfelder der BAM:Energie
Energie / Kerntechnische Entsorgung
Veranstaltung:NDT-CE 2022
Veranstaltungsort:Zurich, Switzerland
Beginndatum der Veranstaltung:16.08.2022
Enddatum der Veranstaltung:18.08.2022
URL:https://www.ndt.net/events/proceedings/topic.php?eventID=292&TopicID=27209
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:28.09.2022
Referierte Publikation:Nein
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