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- Title
Electromagnetic properties of natural expansive soils under one-dimensional deformation.
- Authors
Lin, Botao; Cerato, Amy
- Abstract
Macroscopic behavior of expansive soil is governed by surface forces rather than gravitational forces. These physicochemical surface forces can be investigated through two electromagnetic properties in response to an applied electromagnetic field as real (relative) permittivity, κ′, and effective (electrical) conductivity, σ. This paper presents the results of dielectric measurements on four natural expansive soils using 1-100 MHz electromagnetic waves in two different test setups. The equipment setup, calibration process and measurement limitations are evaluated, and the dielectric spectra, in terms of the dispersion of real permittivity/effective conductivity with frequency, are presented. A procedure is presented to quantify the thickness of a fully developed diffuse double layer (DDL). The influence of salt concentration on DDL, as well as the dielectric responses, is assessed. Two parameters of special physical meaning are defined in the article: $${\upkappa} _{{{\text{inf}}}}^{\prime }$$, representative of the dielectric response by sample mineralogy, microstructure and saturation ratio, and σ, combining the roles assumed by both surface conduction and pore fluid conduction. Evaluation is attempted on their magnitudes at the optimum compaction state and evolutions at different one-dimensional deforming stages. Extensive analysis is performed on the roles of $${\upkappa} _{{{\text{inf}}}}^{\prime }$$ and σ on the hydration status and structural anisotropy of an oedometer sample.
- Subjects
ELECTROMAGNETIC fields; DIELECTRICS; SWELLING soils; ELECTRIC conductivity; OEDOMETERS (Soil mechanics); ANISOTROPY; ELECTRIC double layer; MICROSCOPY; DEFORMATIONS (Mechanics)
- Publication
Acta Geotechnica, 2013, Vol 8, Issue 4, p381
- ISSN
1861-1125
- Publication type
Article
- DOI
10.1007/s11440-012-0198-z