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Geotechnical Classification of Gap-Graded Soils Using Geoelectric Measurements: Linking Electrical Conductivity Parameters to Fines Content and Particle Shape.

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Bibliographic Details
Title: Geotechnical Classification of Gap-Graded Soils Using Geoelectric Measurements: Linking Electrical Conductivity Parameters to Fines Content and Particle Shape.
Authors: Mandloi, Pushpraj1 (AUTHOR) p.mandloi@unsw.edu.au, Sufian, Adnan2 (AUTHOR) a.sufian@unsw.edu.au, Scheuermann, Alexander3 (AUTHOR) a.scheuermann@uq.edu.au, Bore, Thierry4 (AUTHOR) t.bore@uq.edu.au
Source: Journal of Geotechnical & Geoenvironmental Engineering. Apr2026, Vol. 152 Issue 4, p1-14. 14p.
Subject Terms: *Electrical conductivity measurement, *Composition of sediments, *Electric conductivity, *Soil granularity, *Porosity, *Geotechnical engineering, *Electrical resistivity, *Soil particles
Abstract: This research presents a simple, noninvasive, and cost effective approach where geoelectric measurements are employed to characterize gap-graded granular soils. Variations in electrical conductivity are measured using a four-point impedance analyzer and a custom-designed sample holder, which enabled geoelectric parameters to be linked to the fines content and particle shape characteristics of gap-graded soils. Experiments were conducted on sand-gravel and glass bead mixtures, representing irregular and spherical particle shapes, respectively. For each mixture, fines content was varied from 0% to 100% in 20% increments. X-ray μCT imaging was employed to quantify the shape parameters of the constituent materials. The combination of X-ray μCT imaging with geoelectric measurements is a particularly novel element of the experimental methodology. From the measured electrical conductivity data, three key geoelectric parameters were defined: formation factor, surface conductivity, and cementation exponent. These parameters are essential for understanding the electrical properties of the soil mixtures and were correlated to the porosity, specific surface area, and particle shape characteristics of the gap-graded mixtures. The surface conductivity was directly linked to the specific surface area of the mixture, and was able to distinguish between fines-dominated behavior and coarse-dominated behavior of gap-graded soils. The formation factor showed the expected inverse relationship with porosity, as per Archie's model, and exhibited the same trend as the relationship between porosity and fines content for gap-graded soils. Most significantly, the formation factor was able to identify the threshold fines content for both the sand-gravel and glass bead mixtures. Additionally, the cementation exponent clearly distinguished between the irregular and spherical shape characteristics of both mixtures. These results highlight the potential of geoelectric measurements to characterize gap-graded soils and the proposed preliminary classification serves as a foundation to further develop these capabilities for a wider array of soils. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
Description
Abstract:This research presents a simple, noninvasive, and cost effective approach where geoelectric measurements are employed to characterize gap-graded granular soils. Variations in electrical conductivity are measured using a four-point impedance analyzer and a custom-designed sample holder, which enabled geoelectric parameters to be linked to the fines content and particle shape characteristics of gap-graded soils. Experiments were conducted on sand-gravel and glass bead mixtures, representing irregular and spherical particle shapes, respectively. For each mixture, fines content was varied from 0% to 100% in 20% increments. X-ray μCT imaging was employed to quantify the shape parameters of the constituent materials. The combination of X-ray μCT imaging with geoelectric measurements is a particularly novel element of the experimental methodology. From the measured electrical conductivity data, three key geoelectric parameters were defined: formation factor, surface conductivity, and cementation exponent. These parameters are essential for understanding the electrical properties of the soil mixtures and were correlated to the porosity, specific surface area, and particle shape characteristics of the gap-graded mixtures. The surface conductivity was directly linked to the specific surface area of the mixture, and was able to distinguish between fines-dominated behavior and coarse-dominated behavior of gap-graded soils. The formation factor showed the expected inverse relationship with porosity, as per Archie's model, and exhibited the same trend as the relationship between porosity and fines content for gap-graded soils. Most significantly, the formation factor was able to identify the threshold fines content for both the sand-gravel and glass bead mixtures. Additionally, the cementation exponent clearly distinguished between the irregular and spherical shape characteristics of both mixtures. These results highlight the potential of geoelectric measurements to characterize gap-graded soils and the proposed preliminary classification serves as a foundation to further develop these capabilities for a wider array of soils. [ABSTRACT FROM AUTHOR]
ISSN:10900241
DOI:10.1061/JGGEFK.GTENG-14216