TY  - JOUR
A1  - Chen, Zhen
A1  - Schwing, Moritz
A1  - Karlovšek, Jurij
A1  - Wagner, Norman
A1  - Scheuermann, Alexander
T1  - Broadband Dielectric Measurement Methods for Soft Geomaterials: Coaxial Transmission Line Cell and Open-Ended Coaxial Probe
JF  - International Journal of Engineering and Technology
N2  - Broadband dielectric measurement methods based on vector network analyzer coupled with coaxial transmission line cell (CC) and open-ended coaxial probe (OC) are simply reviewed, by which the dielectric behaviors in the frequency range of 1 MHz to 3 GHz of two practical geomaterials are investigated. Kaolin after modified compaction with different water contents is measured by using CC. The results are consistent with previous study on standardized compacted kaolin and suggest that the dielectric properties at frequencies below 100 MHz are not only a function of water content but also functions of other soil state parameters including dry density. The hydration process of a commercial grout is monitored in real time by using OC. It is found that the time dependent dielectric properties can accurately reveal the different stages of the hydration process. These measurement results demonstrate the practicability of the introduced methods in determining dielectric properties of soft geomaterials.
KW  - Impedanzspektroskopie
KW  - Electromagnetic properties of porous materials
KW  - Koaxialkabel
KW  - Dielectric spectroscopy
KW  - open-ended coaxial probe
KW  - coaxial transmission line
KW  - real-time monitoring
KW  - physicochemical properties of geomaterials
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20210408-43984
UR  - http://www.ijetch.org/index.php?m=content&c=index&a=show&catid=58&id=838
VL  - 2014
IS  - volume 6, number 5
SP  - 373
EP  - 380
ER  - 
TY  - JOUR
A1  - Lorek, Andreas
A1  - Wagner, Norman
T1  - Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy
JF  - Cryosphere
N2  - Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 °C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to −70 °C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m2 g−1, up to 9.4% w / w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g−1, up to 7.4% w / w). Three soil-specific relaxation processes are observed in the investigated frequency–temperature range: two weak high-frequency processes (bound or hydrated water as well as ice) and a strong low-frequency process due to counter-ion relaxation and the Maxwell–Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to −70 °C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.
KW  - Grundwasser
KW  - Eis
KW  - Impedanzspektroskopie
KW  - Boden
KW  - dielectric spectroscopy
KW  - planetary research
KW  - Soil
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170516-31840
UR  - http://www.the-cryosphere.net/7/1839/2013/tc-7-1839-2013.html
SP  - 1839
EP  - 1855
ER  -