Norman Wagner

Norman Wagner
Bauhaus-Universität Weimar · Materials Research and Testing Institute

Dr. rer. nat. (PhD)

About

90
Publications
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1,104
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Publications

Publications (90)
Article
Full-text available
A shielded and guarded capacitor for non-destructive measurement of the complex permittivity of cylindrical rock samples has been developed. In combination with a vector network analyzer, the measurement system allows for rapid determination of spectral permittivity. The geometrical construction of the capacitor allows for scanning the properties o...
Article
Full-text available
The performance of high-frequency ground-penetrating radar (GPR) for high-resolution imaging of the near surface can essentially be controlled by the soil electromagnetic (EM) properties. One of these properties influencing sensing depth and image resolution of GPR is the intrinsic attenuation. We investigated the frequency-dependent electrical and...
Article
Full-text available
The thermal conductivity and complex dielectric permittivity of soil are highly correlated and are both affected by changes in chemical composition, grain structure and soil hydro-mechanical conditions. Moisture content in particular plays a predominant role in the thermal and dielectric behaviour of soils. Moreover, the relationship between therma...
Article
Water content is a key parameter to monitor in nuclear waste repositories such as the planed underground repository in Bure/France in the Callovo-Oxfordian (COx) clay-formation. High frequency electromagnetic (HF-EM) measurement techniques, i.e. time or frequency domain reflectometry (TDR, FDR), offer useful tools for quantitative estimation of wat...
Article
Impedance and vector network analyzer measurements are combined in order to measure frequency dependent conductivity and permittivity of two different saturated clays: montmorillonite and illite chlorite. In the low frequency range, the complex conductivity is determined over the 10 mHz to 45 kHz frequency range using a complex impedance analyzer w...
Article
Full-text available
A new integrated experimental and theoretical framework to simultaneously measure mechanical, hydraulic and high frequency dielectric properties of soil during shrinkage was designed aiming at the development, verification and validation of constitutive electromagnetic material relationships. The electromagnetic response of a soil to a high frequen...
Conference Paper
Clay is a key mineral phase in soil science and geotechnical engineering due to its ubiquitous appearance in soils and sedimentary rocks. Under moist conditions exchangeable cations at clay mineral interfaces dissociate and form an electrostatic double layer. Hence, clay dielectric relaxation spectra contain valuable information of the material due...
Conference Paper
Geotechnical application of high frequency (radio to microwave) electromagnetic (HF-EM) techniques is based on the relationship between constitutive HF-EM material properties and soil structural or state parameters such as water content, density, temperature and stress strain state. An unresolved problem in the theoretical modeling of HF-EM propert...
Conference Paper
Coaxial transmission line technique is widely used to deduce broadband dielectric spectra from measured scattering parameters. The inversion algorithm in frequently used proprietary software to determine electromagnetic properties of materials remains unknown as part of a commercial closed code. Against this background, we combine a forward operato...
Article
This paper reports the design, the calibration and the application of a multiple open-ended coaxial probe. The objective behind development of this new sensor is to characterize the spatial and temporal distribution of electromagnetic properties of materials in frequency domain (radio to microwave region). Complex permittivity has been computed fro...
Conference Paper
Full-text available
Collapsible soils, widely regarded as problematic soils, undergo large volume changes when subjected to saturation by water, which in turn causes damage on the structures unwittingly built on such deposits. In this work, a new approach for the monitoring of water caused deterioration process in collapsible soils based on experimental high frequency...
Article
Full-text available
A broadband soil dielectric spectra retrieval approach (1 MHz-2 GHz) has been implemented for a layered half space. The inversion kernel consists of a two-port transmission line forward model in the frequency domain and a constitutive material equation based on a power law soil mixture rule (Complex Refractive Index Model-CRIM). The spatially-distr...
Article
Full-text available
In this paper, we propose a novel approach to broadband model relative effective complex permittivity of soils (augmented broadband complex dielectric mixture model). The approach involves a combination of mixture equation and relaxation model. The mixture equation is an extension in frequency domain developed from a volume average approach. The re...
Conference Paper
Full-text available
A broadband soil dielectric spectra retrieval approach (1 MHz to 2 GHz) has been implemented for a layered half space. The inversion kernel consists of a two port transmission line forward model in the frequency domain and a constitutive material equation based of a power law soil mixture rule (Complex Refractive Index Model - CRIM) considering (i)...
Article
Knowledge of the frequency-dependent electromagnetic properties of coarse-grained materials is imperative for the successful application of high frequency electromagnetic measurement techniques for near and subsurface monitoring. This paper reports the design, calibration and application of a novel one-port large coaxial cell for broadband complex...
Article
Full-text available
We combined two completely different methods measuring the frequency-dependent electrical properties of moist porous materials in order to receive an extraordinary large frequency spectrum. In the low frequency (LF) range, complex electrical resistivity between 1 mHz and 45 kHz was measured for three different soils and sandstone, using the spectra...
Article
An experimental set-up was developed in order to determine the coupled hydraulic, dielectric and mechanical properties of granular media under hydraulic loading. The set-up consisted of a modified column for permeability tests involving a flow meter and pressure transducers along the sample to quantify the hydraulic gradient. A newly developed open...
Article
Full-text available
The interaction of electromagnetic waves with matter is sensitive to various temporal and spatial scales. This allows probing the dynamics and structure of molecular processes at interfaces, macroscopic structural states of porous materials as well as altering of rock formations in the subsurface. Hence, high-frequency (radio to microwave) electrom...
Article
The mechanical compaction of soil influences not only the mechanical strength and compressibility but also the hydraulic behavior in terms of hydraulic conductivity and soil suction. At the same time, electric and dielectric parameters are increasingly used to characterize soil and to relate them with mechanic and hydraulic parameters. In the prese...
Conference Paper
Full-text available
Two completely different methods, which both can measure the frequency-dependent properties of moist soil, had been combined in order to receive an extraordinary large frequency spectrum for the electromagnetic (EM) response. On the one hand, complex electrical impedance of different soils had been measured using the spectral induced polarization (...
Conference Paper
Full-text available
The mechanical compaction of soil influences not only the mechanical strength and compressibility but also the hydraulic behavior in terms of hydraulic permeability and soil suction. Hence, in addition to conventional and standardized compaction tests, the hydraulic and dielectric soil properties were measured under those conditions. The objective...
Conference Paper
Full-text available
An experimental rig was developed in order to determine the coupled dielectric and mechanical properties of soil under hydraulic load. In this paper, a modified column for permeability experiments and a self-designed Open Ended sensor are described. During experiments, the hydraulic gradient, the water flow, the shear resistance, the porosity and t...
Article
The broadband dielectric measurement method based on the vector network analysis technique, in combination with an open-ended coaxial probe, was applied to the determination of the dielectric relaxation behaviour of one- and two-component backfilling grout materials in the frequency range from 40 MHz to 2 GHz. The cement hydration process and the g...
Article
Full-text available
Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain...
Article
Full-text available
The knowledge of constitutive broadband electromagnetic (EM) properties of porous media such as soils and rocks is essential in the theoretical and numerical modeling of EM wave propagation in the subsurface. This paper presents an experimental and numerical study on the performance EM measuring instruments in soil for broadband EM wave in the radi...
Conference Paper
Full-text available
Soil thermal properties such as thermal conductivity and resistivity, thermal diffusivity and specific heat capacity are vital in conducting analysis and modeling in various fields of geo-mechanics, agriculture, hydrology and others. Heat and water transfer problems in geo-mechanics are strongly coupled processes, thus producing transient temperatu...
Conference Paper
Full-text available
A new approach for monitoring of water caused deterioration process in unsaturated, stressed collapsible soils based on experimental high frequency electromagnetic (HF-EM) investigations with an open ended coaxial line technique is presented. The tests were performed in a one dimensional controlled loading cell under simultaneous measurements of co...
Conference Paper
This paper presents a new technique of deterioration monitoring of water caused soil collapse based on experimental investigations on the physical relation between electromagnetic properties and collapse mechanism by wetting of collapsible soils at different levels of vertical stress. In this work, an open ended coaxial line, which measures time-de...
Conference Paper
The use of electromagnetic sensors such as Time Domain Reflectometry (TDR) probes has gained increasing importance for long term monitoring of the water content in radioactive waste repositories. TDR probes are sensitive to changes in electromagnetic properties of the surrounding material, a clay rock in our case. Prior to the in situ application,...
Conference Paper
Full-text available
The relationship between thermal conductivity and water content is fundamental for quantitative investigation of heat and water transfer processes in both unsaturated and saturated soils. Accurate determination of thermal conductivity can be achieved through measurements of soil parameters which are strongly coupled to thermal conductivity. One suc...
Chapter
In diesem Beitrag wurden systematische Untersuchungen variierender Anfangsparameter an einem Ton vorgenommen, um den Einfluss der Änderungen der hydraulisch-mechanisch gekoppelten Eigenschaften im Schrumpfungsprozess sowie deren dielektrische Charakteristik zu analysieren. Es wurden Saugspannungs- und freie Schrumpfversuche durchgeführt. An den Sch...
Article
Full-text available
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 w...
Conference Paper
Our objective is the development of a prognosis system that predicts the soil-dependent GPR performance in landmine and improvised explosive device (IED) contaminated areas. One of the soil properties influencing sensing depth and image resolution of GPR is intrinsic attenuation. We investigated the frequency-dependent electromagnetic properties of...
Chapter
Full-text available
This contribution presents an experimental work in which standardized compaction tests on a fine-grained soil are conducted in combination with dielectric spectroscopy to determine the relative effective complex dielectric permittivity over a broad frequency range (1 MHz to 3 GHz). The idea is to investigate the influence of water content and densi...
Article
The storage of power to cover the partial seasonal requirements of larger urban or industrial regions requires storage capacities in the GWh range. Current technologies are site-dependent and area-wide designable, as well as being cost-inefficient. An innovative concept for large-scale energy storage based on a thermohaline base is presented in thi...
Conference Paper
German collaborators Abstract—Spatial Time Domain Reflectometry (spatial TDR) is a measurement method for determining water content profiles along electrically insulated probes (transmission lines). The method is based on the inverse modeling of TDR reflectograms using an optimisation algorithm. By means of using flat ribbon cables as sensors it is...
Conference Paper
Full-text available
A high-frequency electromagnetic measurement technique is employed to investigate dielectric properties of a fine-grained soil. As a case study, a standardized compacted fine-grained soil was investigated using a coaxial transmission line cell in combination with vector network analyzer technique in a frequency range from 1 MHz to 3 GHz. The measur...
Conference Paper
Full-text available
The frequency dependence of dielectric material properties of water saturated and unsaturated porous materials such as soil is not only disturbing in applications with high frequency electromagnetic (HF-EM) techniques but also contains valuable information of the material due to strong contributions by interactions between the aqueous pore solution...
Conference Paper
The French national radioactive waste management Agency (Andra) is in charge of long-term management of radioactive waste produced in France. Andra has systematically studied the possibility of implementing an underground repository for high-level and intermediate level long-lived waste in the underground research laboratory (URL) in Bure (Meuse di...
Article
Full-text available
Open-ended coaxial line probes (OCs) are systematically analyzed by means of numerical 3-D finite element calculations in combination with experimental investigations for microwave dielectric spectroscopy on fine grained soils. The probes, based on conventional coaxial lines and connectors (N, SMA), are broadband characterized in the frequency rang...
Article
Full-text available
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 abo...
Conference Paper
Full-text available
One of the soil properties influencing the sensing depth of ground-penetrating radar (GPR) is intrinsic attenuation. Especially in high-frequency investigations, as for explosive ordnance and landmine detection, it plays a major role. In many cases attenuation is the limiting factor that determines the applicability of the GPR system. In order to i...
Conference Paper
Full-text available
This contribution presents a dielectric spectroscopy study in which four different devices in combination with five different probes were used in order to measure the complex effective relative permittivity of a fine-grained soil in a frequency range from 1 MHz to 40 GHz. Subsequently, the dielectric measurements were combined to obtain a permittiv...
Conference Paper
Full-text available
The shrinkage behaviour of soils affects the structural and the hydraulic properties of the soil, which results in anisotropic strains and volume change. In order to quantify these shrinkage effects, unstrained desiccated samples were analyzed by standard shrinkage laboratory experiments, observed by PIV displacements measurements. In parallel, the...
Conference Paper
Full-text available
Soil as a complex multi-phase porous material typical exhibits several distributed relaxation processes in the frequency range from 1 MHz to approximately 10 GHz of interest in applications. To relate physicochemical material parameters to the dielectric relaxation behavior, measured dielectric relaxation spectra have to be parameterized. In this c...
Conference Paper
Full-text available
Wireless soil moisture sensor networks provide distributed observations of soil moisture dynamics with high temporal resolution as they typically involve a high number of sensors. Low-cost sensors are preferred for this application. These sensors most often show a sensor-to-sensor variability. Hence, a sensor-specific calibration is advantageous pr...
Conference Paper
Full-text available
Collapsible soils are problematic soils which are susceptible to a large and sudden volume changes (collapse) upon wetting. Fly ash is a chemical stabilization use to strengthening theses soils under pozzolanic reactions. The present paper is aimed to study the effect of fly ash stabilization on collapse behavior to the change of their electromagne...
Article
Full-text available
Water content as a thermodynamic state parameter affects nearly all physical, chemical and biological processes on the earth. Recent Mars observations as well as laboratory investigations suggest that water is also a key factor of current physical and chemical processes on the martian surface, e.g. rheological phenomena. Therefore it is of particul...
Article
A new coaxial line cell for the determination of dielectric spectra of undisturbed soil samples was developed based on a 1.625-inch - 50 Ohm coaxial system. Undisturbed soil samples were collected from a soil profile of the Taunus region (Germany) and capillary saturated followed by a step-by-step de-watering in a pressure plate apparatus as well as...
Article
Precise knowledge of the absolute value and frequency dependence of the dielectric permittivity of ice is the basis for interpretation of radio echo sounding data on glaciers and ice sheets. However, in the range of radio-frequencies, data from direct measurements of the permittivity are sparse, and partially lacking uncertainty estimates. Here, we...
Chapter
Mechanical relaxation behaviour of various natural volcanic and synthetic binary, ternary and multicomponent silicate glasses and melts (having NBO/T from 0 to 2, and Tg varying from 468°C to 1148°C) have been studied in the temperature range RT-1000°C using special low frequency flexure (f~0.63Hz) and torsion (f=0.002…20Hz) pendulum experiments. T...
Conference Paper
Full-text available
The frequency dependence of soil electromagnetic properties contain valuable information of the porous material due to strong contributions to the dielectric relaxation behavior by interactions between aqueous pore solution and mineral phases due to interface effects. Soil hydraulic properties such as matric potential are also influenced by differe...
Conference Paper
Full-text available
For monitoring of the hydrological water balance in top and subsoil during plant growth accurate knowledge of the spatial and temporal variation of soil water content is essential. In this context, a new full two port spatial time domain reflectometry (Spatial TDR) technique in combination with elongated microwave transmission line sensors were dev...
Article
At radio-frequencies, measurements of the permittivity of ice are sparse and with unknown or large uncertainty. Coaxial transmission lines have been established for frequency-dependent permittivity determination for a broad variety of materials. Here we present a coaxial transmission line setup originally designed for soil samples, now adapted for...
Conference Paper
Full-text available
Steel Fiber Reinforced Concrete (SFRC) is increasingly being used in civil constructions, especially precast tunnel segment linings. Fibers are mixed with fresh concrete, which results in a more or less random distribution of fibers within the concrete matrix. Because of this, SFRC demonstrates a great challenge when it is being investigated using...
Poster
Full-text available
High frequency electromagnetic measurement techniques such as ground penetrating radar (GPR) are based on the electromagnetic wave interaction with dielectric materials such as soils. The wave propagation velocities and reflection of the electromagnetic wave highly depend on the permittivity of the soil material. The permittivity is mainly controll...
Conference Paper
Full-text available
The frequency dependence of dielectric material properties of porous mineral materials such as soil are not only disturbing in applications with high frequency electromagnetic (HF-EM) techniques but also contain valuable information of the material due to strong contributions by interactions between an aqueous pore solution and mineral phases. This...
Conference Paper
Full-text available
High-frequency electromagnetic (HF-EM) measurement techniques, e.g. dielectric spectroscopy, give inside into soil physical properties which are related to soil/water interactions such as the soil water characteristics. The open-ended coaxial line tech-nique offers a non destructive determination of dielectric spectra of fine grained soil. In this...
Article
Full-text available
Frequency- and temperature-dependent complex permittivity or conductivity of a silty clay loam were examined in a broad saturation and porosity range with network analyzer technique (1 MHz-10 GHz, 5 °C-40 °C, coaxial transmission line and open ended coaxial cells). An advanced mixture model based on the well-known Lichtenecker-Rother model (ALRM) w...
Conference Paper
Full-text available
Recent Mars observations and experimental investigations indicate that water could be 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 analog soils in the temperature range below 0 ◦C....
Conference Paper
Full-text available
For constant atmospheric boundary conditions the process of shrinkage of a cohesive soil is mainly dependent on the mineralogy of the clay particles and the particle size distribution of the soil. They both influence the hydraulic and mechanic as well as dielectric parameters of the soil. Concerning shrinkage, the most important parameters are the...
Conference Paper
Full-text available
Precise knowledge of the frequency dependent electromagnetic soil properties is urgently necessary for successful utilization of high frequency electromagnetic (HF-EM) soil moisture measurement techniques. Thus, there is a need of systematic investigations by dielectric spectroscopy of unsaturated and saturated soils under controlled hydraulic cond...
Conference Paper
Full-text available
The density is an important state variable for soils relevant for the evolution of geomechanical processes and geohydraulic properties. The central role of the density makes it necessary to quantitatively determine the phase contents and thus the porosity in laboratory and in field. A new approach to measure porosity distributions of saturated gran...