Effective permittivity of porous media: a critical analysis of the complex refractive index model

Brovelli, Alessandro; Cassiani, Giorgio

doi:10.1111/j.1365-2478.2008.00724.x

Cited by 86 publications

(47 citation statements)

References 53 publications

(90 reference statements)

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“…The main advantage of these techniques is that they are rapid field-scale and noninvasive surveys (Roth et al 1990;Brovelli and Cassiani 2008). However, the information obtained during the test is complex, so there is need for insight into the fundamental mechanisms of the dielectric spectral responses, to facilitate the interpretation of measured data into useful subsurface information, such as moisture content, soil composition, solute concentration, consolidation parameters, cementation, and petrophysical geotechnical properties of the porous medium (Klein and Santamarina 1997;Brovelli and Cassiani 2008).…”

Section: Introductionmentioning

confidence: 99%

Complex dielectric permittivity of organically modified bentonite suspensions (0.2–1.3 GHz)

Bate

Burns

2014

Can. Geotech. J.

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To quantify the impact of organic carbon on the complex dielectric permittivity of organoclays, nine organically modified clays were synthesized with controlled organic carbon structure and density of loading. Resonance polarization responses were observed for six of the organoclays at resonant frequencies from 0.74 to 1.37 GHz; however, organoclays synthesized with the smallest organic cations did not exhibit resonant frequency. A structural model of water molecules near the surface of organoclay and in the diffuse layer was proposed, which consists of a surface-bound water layer, an organic cationinteractive zone, and bulk water. The Cole-Cole equation was used to fit the resonance response. Increasing the density of loading (30% to 100% of the cation exchange capacity of the base clay) on the clay surface led to a reduction in the resonance time of the clay, while increasing the size of the organic cation led to a longer dielectric resonance time for the clay, which indicates that altering the structure and density of the organic carbon phase changed the degree of constraint of water molecules within the clay's interlayer. However, the impact of organic carbon content on real permittivity was not significant. Water content had no obvious effect on the resonant frequency of the organoclays at high water content (porosity ranging from 0.7 to 1.0) in this study. In addition, it was shown that a linear approximation was sufficient in relating real permittivity of organoclay suspensions to porosity, and the effective conductivity decreased linearly proportional to porosity. That is, the real permittivity and effective conductivity were dominated by that of the aqueous phase until the inception of resonance polarization.Résumé : Afin de quantifier l'impact du carbone organique sur la permittivité diélectrique complexe d'organo-argiles, neuf argiles modifiées organiquement ont été synthétisées avec une structure de carbone organique et une densité de charge contrôlée. Les réponses de résonance polarisée ont été observées pour six des organo-argiles à des fréquences de résonance de 0,74 à 1,37 GHz; cependant, les organo-argiles synthétisées avec les cations organiques les plus petits n'ont pas démontré de fréquence de résonance. Un modèle structural de molécules d'eau près de la surface de l'organo-argile et dans la couche diffuse a été proposé, qui consiste en une couche d'eau liée à la surface, une zone d'interaction du cation organique, et le volume d'eau. L'équation Cole-Cole a été utilisée pour représenter la réponse en résonance. L'augmentation de la densité de charge (de 30 % à 100 % de la capacité d'échange cationique de l'argile de base) sur la surface de l'argile a entraîné une réduction du temps de résonance de l'argile, tandis que l'augmentation de la taille du cation organique a entraîné un temps de résonance diélectrique plus long pour l'argile, ce qui signifie que l'altération de la structure et de la densité de la phase de carbone organique change le degré de contrainte des molécules d'eau à l'intérieu...

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Section: Introductionmentioning

confidence: 99%

Complex dielectric permittivity of organically modified bentonite suspensions (0.2–1.3 GHz)

Bate

Burns

2014

Can. Geotech. J.

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“…If we want error percentage less than 5%, it is clear that the frequency range should start around 200 MHz. It should be noted that the accuracy depends on what you measured whether the sample is low loss material or not [11–17].…”

Section: Resultsmentioning

confidence: 99%

Alkyd–epoxy blends as multipurpose coatings

Dutta

Karak

Dolui

2006

J of Applied Polymer Sci

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“…α is a fitting parameter. The theoretical variation range of α is between −1 and 1 [16,17]. But, common in the literature, α = 0.5, Equation (6) is reduced to the CRIM as…”

Section: Methodology and Experimental Protocolmentioning

confidence: 99%

Epsimu, a Tool for Dielectric Properties Measurement of Porous Media: Application in Wet Granular Materials Characterization

Sabouroux¹,

Ba²

2011

PIER B

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Abstract-The principal aim of this article is the presentation of EpsiMu, a tool for dielectric properties measurement. This general tool can be used to characterize all types of materials, but in this article we apply it to porous or granular materials. The tool consists of a coaxial cell and dedicated software that allow us to reconstruct the permittivity in almost real-time by a de-embedding process. Dielectric permittivity of soils sample was measured using this microwave tool. So, we can then determine the relationship between the dielectric properties and volumetric water content θ of Fontainebleau sand (center of France) and Dune of Pilat sand (Arcachon Bay area, France). The clay effect on Fontainebleau sand is also studied. We discuss the usefulness of several models that link the permittivity to volumetric water content of soil. It is shown that the soil permittivity model is not directly applicable to Fontainebleau sand and Dune of Pilat sand. We find a good match between our results representing the relative permittivity ε r versus the volumetric water content θ and the Complex Refractive Index model (CRIM) between 600 MHz and 1 GHz. Alternative regression formulae are proposed. The implication of the determination of volumetric water content, θ, is discussed. A linear relation between the dielectric loss tangent and volumetric water content θ of soils is established.

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Effective permittivity of porous media: a critical analysis of the complex refractive index model

Cited by 86 publications

References 53 publications

Complex dielectric permittivity of organically modified bentonite suspensions (0.2–1.3 GHz)

Complex dielectric permittivity of organically modified bentonite suspensions (0.2–1.3 GHz)

Alkyd–epoxy blends as multipurpose coatings

Epsimu, a Tool for Dielectric Properties Measurement of Porous Media: Application in Wet Granular Materials Characterization

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