Grain size effect on electrical properties of dry friable sand
Geophysical Exploration Group, Geophysical Sciences Department, National Research Centre, El-Behoos St., Dokki, Cairo, Egypt
Accepted: 20 September 2022
Published online: 12 October 2022
The current experiment is designed to look into the effect of pore size dispersion on the electrical properties of some friable sand samples at frequencies ranging from 10–4 to 100 kHz. A large amount of friable sand was sieved. Individual grain sizes were collected and compacted under appropriate pressure to create a sample that would later be measured electrically. The grain size dispersion covers a range from 5 mm up to 56 µm (5 mm, 3.15 mm, 2.5 mm, 1.6 mm, 1 mm, 0.75 mm, 0.5 mm, 0.63 mm, 0.4 mm, 0.25 mm, and 0.056 mm). The samples were compressed into a disk of appropriate size. The observed changes will be due solely to grain size dispersion. The electrical properties of the samples were able to recognize different grain size effects. The main dominant and controlling factor on the electrical properties of the specimens is grain size, in addition to texture or surface roughness. The electrical properties of curves revealed that the conductivity and dielectric constant increase as grain size decreases. Conductivity increases due to an increase in conducting clusters between grains, i.e., the formation of apparently semi-conducting clusters between grains. The decrease in porosity between grain sizes, i.e., the volume of air between grains, has resulted in an increase in the dielectric constant. This is accepted logically because grain size decreases the number of pore voids or throats between grains. In addition, as grain size decreases, so does the complex impedance. To the best of our knowledge, this is the first time that relationships between the electrical properties of friable sand and grain size dispersion have been studied.
© The Author(s) 2022
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