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Monitoring of drying of cement screed with the help of ultra-wideband microwaves and air-coupled antennas

 
: Manavipour, Maryam; Sklarczyk, Christoph; Szielasko, Klaus

:
Volltext urn:nbn:de:0011-n-3995632 (639 KByte PDF)
MD5 Fingerprint: 8a2b6802ce38ea7a4d5d7f4d3139b9f3
(CC) by-nd
Erstellt am: 28.6.2016

Poster urn:nbn:de:0011-n-399563-17 (63 KByte PDF)
MD5 Fingerprint: 4b3fea25182669c7fe388e18af2c4afb
Erstellt am: 6.7.2016


International Committee for Non-Destructive Testing -ICNDT-; Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin:
19th World Conference on Non-Destructive Testing, WCNDT 2016 : Munich, Gemany, 13-17 June 2016; Proceedings; USB-Stick
Berlin: DGZfP, 2016
ISBN: 978-3-940283-78-8
Paper P105, 7 S.
World Conference on Non-Destructive Testing (WCNDT) <19, 2016, Munich>
Englisch
Konferenzbeitrag, Elektronische Publikation
Fraunhofer IZFP ()

Abstract
The drying behaviour of freshly prepared anhydrite screed and cement screed samples was investigated non-destructively and in contact-free way using ultra-wideband microwave signals in the frequency range between about 1 GHz and 10 GHz. The measurements have been performed using a vector network analyser and air-coupled wideband horn antennas in reflection mode. Both entry echo and back wall echo at the interfaces of the samples were analysed. The amplitudes of the entry signals decreased within few weeks as the real part of the relative permittivity decreased with drying. Finally a plateau level was reached. At the beginning of the tests the back wall signal of the specimen was not recognizable since the attenuation of the microwaves resp. the imaginary part of the permittivity in the moist sample was too high. After a few weeks of drying, a back wall signal was detected. It increased with continued desiccation and thus lowered attenuation, until here again a constant level was reached. At the same time, the temporal position of the back wall signal moved to smaller times since the propagation velocity of the microwaves increased until a constant value was reached as well.

: http://publica.fraunhofer.de/dokumente/N-399563.html