MEASUREMENT OF THE VARIATION OF THE DIELECTRIC CONSTANT OF WATER WITH EXTENT OF ADSORPTION

1935 ◽  
Vol 13b (3) ◽  
pp. 156-166 ◽  
Author(s):  
G. H. Argue ◽  
O. Maass
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Experimental Technique ◽  
Liquid Water ◽  
Adsorbed Water ◽  
Dielectric Constants ◽  
Saturation Point ◽  
Cellulosic Materials

An experimental technique has been devised for the measurement of the dielectric constants of cellulosic materials containing various amounts of adsorbed water. From measurements made with standard cellulose the dielectric constant of the adsorbed water was calculated over the concentration range 0 to 18% of water. The dielectric constant of the water initially adsorbed is less than one-quarter of that of liquid water, but it increases with the amount of water subsequently adsorbed, until the dielectric constant approximates that of liquid water as the water content of the fibre approaches the saturation point. These results are shown to be in agreement with the hypothesis concerning the nature of the system cellulose–water.

Ground Penetrating Radar for Water Content and Compaction Evaluation: A Laboratory Test on Construction Material

2020 ◽  
Vol 25 (2) ◽  
pp. 169-179
Author(s):  
Hashem Ranjy Roodposhti ◽  
Mohammad Kazem Hafizi ◽  
Mohammad Reza Soleymani Kermani
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Ground Penetrating Radar ◽  
Large Scale ◽  
Construction Material ◽  
Construction Materials ◽  
Dielectric Constants ◽  
Base Layer ◽  
Subsurface Water ◽  
Ground Penetrating

With the aid of ground penetrating radar (GPR), it is possible to evaluate physical properties of a constructed base layer in engineered structures (pavement, land consolidation projects, etc.) non-destructively, quickly, and accurately. High spatial variations of subsurface water content and deficient compaction can lead to unexpected damage and structural instability. In this research, we established a relationship between the dielectric constant, water content, and compaction, whereby, an interactive relationship between these parameters is presented. To achieve this, large-scale laboratory experiments were carried out on construction materials to simulate field conditions. According to USCS, the tested soil type was GW-GM (type E base layer according to Iran's highway specifications code). Furthermore, water content and compaction were changed between 4% -12.9% and 84.7% -94.9%, respectively. The travel-times in each test, including three profiles with more than 210 traces, are measured automatically. Additionally, the calculated dielectric constants were compared with the Topp and Roth equations. R-square and RMS error of the final interactive equation between dielectric constant and water content-compaction were 0.95 and 0.41, respectively. Moreover, the sensitivity analysis of the proposed interactive equation shows that changes in water content of soil have greater impact on dielectric constant than soil compaction changes. The data also indicate the importance of considering the compaction changes of soil to reduce the error in dielectric constant estimation.

scholarly journals Experimental Determination of TDR Calibration Relationship for Pyroclastic Ashes of Campania (Italy)

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3727 ◽  
Author(s):  
Giovanna Capparelli ◽  
Gennaro Spolverino ◽  
Roberto Greco
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Organic Matter Content ◽  
Free Water ◽  
Time Domain Reflectometry ◽  
Dielectric Constants ◽  
Phase System ◽  
Three Phase ◽  
The Relationship

Time domain reflectometry (TDR) is one of the most widely used techniques for indirect determination of soil volumetric water content (θ). TDR measures the relative dielectric constant (εr) which, in a three-phase system like the soil, depends on water, air, and solid matrix dielectric constants. Since dielectric constant of water is much larger than the other two, εr of bulk soil mainly depends on water content. In many cases, the application of TDR requires a specific calibration of the relationship θ(εr) to get quantitatively accurate estimates of soil water content. In fact, the relationship θ(εr) is influenced by various soil properties, such as clay content, organic matter content, bulk density, and aggregation. Numerous studies have shown that pyroclastic soils often exhibit a peculiar dielectric behavior. In Campania (Southern Italy) wide mountainous areas are covered by layered pyroclastic deposits of ashes (loamy sands) and pumices (sandy gravels), often involved in the triggering of landslides induced by rainwater infiltration. Reliable field measurements of water content of such soils are therefore important for the assessment of landslide risk. Hence, in this paper, the θ(εr) relationship has been experimentally determined on samples of typical pyroclastic soil of Campania, collected around Sarno, reconstituted with different porosities. The aim of the study is to identify specific calibration relationships for such soils based not only on empirical approaches. In this respect, a three-phase dielectric mixing model with a variable exponent is introduced, and the variable value of the exponent is related to the different dielectric properties of bond and free water within the soil pores.

Static Dielectric Constant as a Textural Index of Snow

1985 ◽  
Vol 6 ◽  
pp. 203-206 ◽  
Author(s):  
A. Denoth
Keyword(s):  
Dielectric Constant ◽  
Liquid Water ◽  
Strong Dependence ◽  
Liquid Water Content ◽  
Dielectric Constants ◽  
Least Square ◽  
Static Dielectric Constant ◽  
Shape Factors ◽  
Least Square Fit ◽  
Snow Samples

The dielectric constants of alpine snow samples with different stages of metamorphism and with different liquid water saturations have been measured in the frequency range of 10Hz to 50MHz using a plate condenser and network-analyzer. The limiting static dielectric constant, €s’, has been derived from the measured frequency dependence of the complex permittivity of snow by a least-square-fit using the model of Cole-Cole. A strong dependence of e on porosity, liquid water content and on the shape of the snow grains was found. Calculations of shape factors from the measured static permittivity based on the model of Polder and van Santen are given, and are compared to shape factors derived from an analysis of photographs of the snow samples.

scholarly journals Measurements of Daily Variations in the Subsurface Wetness Gradient

1985 ◽  
Vol 6 ◽  
pp. 254-255
Author(s):  
A. Denoth ◽  
A. Foglar
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Liquid Water ◽  
Field Measurements ◽  
Liquid Water Content ◽  
Strip Line ◽  
Snow Surface ◽  
Dielectric Sensor ◽  
Different Depths ◽  
Destructive Measurement

A flat condenser in strip-line technique has been developed to measure the gradient in liquid water content near the snow surface. This dielectric sensor is connected to a twin-T-bridge with an operating frequency of 27 MHz. The special design of the sensor allows the non-destructive measurement of the mean dielectric constant of underlying material at two different depths of 0 to 2 cm, and of 2 to 4 cm below the snow surface. Based on the model of Polder and van Santen, changes in the gradient of liquid water content can be calculated from measured changes in the dielectric constant in different depths; the density has to be measured separately. Results of measurements of wetness gradient with this flat capacitative sensor are given. Field measurements have been carried out in the Stubai Alps (3100 m a.s.1.) and at the Hafelekar (2256 m a.s.l.) near Innsbruck.

scholarly journals Measurements of Daily Variations in the Subsurface Wetness Gradient

1985 ◽  
Vol 6 ◽  
pp. 254-255 ◽  
Author(s):  
A. Denoth ◽  
A. Foglar
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Liquid Water ◽  
Field Measurements ◽  
Liquid Water Content ◽  
Strip Line ◽  
Snow Surface ◽  
Dielectric Sensor ◽  
Different Depths ◽  
Destructive Measurement

A flat condenser in strip-line technique has been developed to measure the gradient in liquid water content near the snow surface. This dielectric sensor is connected to a twin-T-bridge with an operating frequency of 27 MHz. The special design of the sensor allows the non-destructive measurement of the mean dielectric constant of underlying material at two different depths of 0 to 2 cm, and of 2 to 4 cm below the snow surface. Based on the model of Polder and van Santen, changes in the gradient of liquid water content can be calculated from measured changes in the dielectric constant in different depths; the density has to be measured separately. Results of measurements of wetness gradient with this flat capacitative sensor are given. Field measurements have been carried out in the Stubai Alps (3100 m a.s.1.) and at the Hafelekar (2256 m a.s.l.) near Innsbruck.

scholarly journals Static Dielectric Constant as a Textural Index of Snow

1985 ◽  
Vol 6 ◽  
pp. 203-206
Author(s):  
A. Denoth
Keyword(s):  
Dielectric Constant ◽  
Liquid Water ◽  
Strong Dependence ◽  
Liquid Water Content ◽  
Dielectric Constants ◽  
Least Square ◽  
Static Dielectric Constant ◽  
Shape Factors ◽  
Least Square Fit ◽  
Snow Samples

The dielectric constants of alpine snow samples with different stages of metamorphism and with different liquid water saturations have been measured in the frequency range of 10Hz to 50MHz using a plate condenser and network-analyzer. The limiting static dielectric constant, €s’, has been derived from the measured frequency dependence of the complex permittivity of snow by a least-square-fit using the model of Cole-Cole. A strong dependence of e on porosity, liquid water content and on the shape of the snow grains was found. Calculations of shape factors from the measured static permittivity based on the model of Polder and van Santen are given, and are compared to shape factors derived from an analysis of photographs of the snow samples.

Determination of liquid water content and dielectric constant in porous media by the capacitive method

2004 ◽  
Vol 332 (8) ◽  
pp. 639-645 ◽  
Author(s):  
Teddy Fen-Chong ◽  
Antonin Fabbri ◽  
Jean-Pierre Guilbaud ◽  
Olivier Coussy
Keyword(s):  
Dielectric Constant ◽  
Porous Media ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Capacitive Method

Dielectric properties of aerogels

1993 ◽  
Vol 8 (7) ◽  
pp. 1736-1741 ◽  
Author(s):  
L.W. Hrubesh ◽  
L.E. Keene ◽  
V.R. Latorre
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Bulk Material ◽  
Solid Material ◽  
Adsorbed Water ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
High Porosity ◽  
Microwave Frequencies ◽  
Low Dielectric

We have measured the real (dielectric constant) and imaginary (loss factor) components of the complex relative permittivity at 298 K using microwave frequencies (2, 10, and 18–40 GHz) for bulk SiO2-aerogels and for two types of organic aerogels, resorcinol-formaldehyde (RF) and melamine-formaldehyde (MF). Measured dielectric constants are found to vary linearly between values of 1.0 and 2.0 for aerogel densities from 10 to 500 kg/m3. For the same range of densities, the measured loss tangents vary linearly between values of 2 × 10−4 and 7 × 10−2. The observed linearity of the dielectric properties with density in aerogels at microwave frequencies shows that their dielectric behavior is more gas-like than solid-like. The dielectric properties of aerogels are shown to be significantly affected by the adsorbed water internal to the bulk material. For example, water accounts for 70% of the dielectric constant and 70% of the loss at microwave frequencies for silica aerogels. Because of their very high porosity, even with the water content, the aerogels are among the few materials exhibiting such low dielectric properties. Our measurements show that aerogels with greater than 99% porosity have dielectric constants less than 1.03; these are the lowest values ever reported for a bulk solid material.

scholarly journals Dielectric properties assessment of honey by using non-destructive dielectric spectroscopy

2022 ◽  
Vol 12 (1) ◽  
pp. 189
Author(s):  
Aslina Abu Bakar ◽  
Muhammad Aiman Najmi bin Rodzali ◽  
Rosfariza Radzali ◽  
Azlina Idris ◽  
Ahmad Rashidy Razali
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Measurement Technique ◽  
Water Concentration ◽  
Dielectric Constants ◽  
Effect Of Temperature ◽  
Frequency Range ◽  
Calibration Methods ◽  
Destructive Measurement ◽  
Non Destructive

<p>In this research the dielectric constant of three types of Malaysian honey has been investigated using a non-destructive measurement technique. The objective of this research is to assess the dielectric constant of the three types of honey in Malaysia using a non-destructive measurement technique known as an open-ended coaxial probe in the frequency range from 100 MHz to 10 GHz frequency. Analysis on the effect water concentration in honey on the dielectric constant and the effect of temperature on dielectric constant of honey has been conducted. The three types of honey that have been chosen to be investigated in this project are stingless bee honey, wild honey and commercial (organic) honey and together their water adulterated samples. For this research, the probe had been set up by setting a range of frequency from 100 MHz to 10 GHz and needs to be calibrated with three calibration methods namely open, short and reference water. From the result it was found that the higher the temperature of the honey and the higher percentage of water content in the honey, the dielectric constant is increased. The dielectric constants of all honeys decreased with increasing frequency in the measured frequency range and increased with increase percentage of water content and temperature.</p>

scholarly journals Comment on “investigation of dielectric constants of water in a nano-confined pore” by H. Zhu, F. Yang, Y. Zhu, A. Li, W. He, J. Huang and G. Li, RSC Adv., 2020, 10, 8628

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5179-5181
Author(s):  
Sayantan Mondal ◽  
Biman Bagchi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Constants ◽  
Static Dielectric Constant ◽  
Inherent Anisotropy ◽  
Nanoconfined Water

Neglects of inherent anisotropy and distinct dielectric boundaries may lead to completely erroneous results. We demonstrate that such mistakes can give rise to gross underestimation of the static dielectric constant of cylindrically nanoconfined water.

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