Standard state of soil dispersions for rheological measurements

Zsuzsanna Czibulya, E. Tombácz, Tamas Szegi, Erika Michéli, Adam Zsolnay

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The structural degradation of land is increasing all over the world; hence any effort to characterize it effectively is of great practical importance. By rheology we were able to compare the stability and resilience of structured soils containing the same clay minerals. The shear resistance of soil dispersions can be measured over a limited range of solid to water ratios. A precise methodology for rheological characterization of soil dispersions which contain as much water as they can hold in equilibrium, introduced here as standard state, was developed within a European specific targeted research project (acronym: INDEX-GOCE-CT-2003-505450) to determine parameters indicating structural degradation of European soils. We also aimed to find a measuring method for non specialists to follow structural changes in soils. Based on the entire INDEX sample pool, it was shown that soils with particles smaller than 1. mm can be measured in a reproducible way. First the water content of dispersions in a standard state (WCSDinStS) containing the maximum occluded water had to be determined, which itself is a characteristic of soil quality. Then the method for preparation of dispersions was standardized at 25. +. 0.1 °C and 1. bar, and the rheological measurements were performed with a stress controlled rheometer using plate-to-plate and vane sensors. The flow character of all concentrated soil dispersions was viscoplastic and showed thixotropy, with two exceptions. Rheological parameters, i.e., initial stress, thixotropic hysteresis area, extrapolated (Bingham) yield value, plastic viscosity and absolute yield stress, of soil dispersions were determined. They changed in parallel, and were related to the particle adhesion, sensitivity to mechanical effects, and the strength of the physical network built up during the gradual aggregation of particles in soil dispersions. It was shown that the fragile networks of particles are thixotropic, so that external forces above the measurable limits destroy them, but they recover on standing for a longer time period. In the present paper, the development of a precise methodology for structural characterization of several clayey systems is described in detail showing only some examples from the thousands of rheological measurements, and in the end a useful comparison with field test measurements is shown.

Original languageEnglish
Pages (from-to)594-601
Number of pages8
JournalApplied Clay Science
Volume48
Issue number4
DOIs
Publication statusPublished - May 2010

Fingerprint

Dispersions
Soils
soil
Water
thixotropy
GOCE
degradation
methodology
Degradation
Rheometers
soil quality
hysteresis
adhesion
rheology
structural change
water
Clay minerals
Rheology
clay mineral
Water content

Keywords

  • Deformation
  • Equilibrium sediments
  • Rheology
  • Soil structure
  • Thixotropy

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geology

Cite this

Standard state of soil dispersions for rheological measurements. / Czibulya, Zsuzsanna; Tombácz, E.; Szegi, Tamas; Michéli, Erika; Zsolnay, Adam.

In: Applied Clay Science, Vol. 48, No. 4, 05.2010, p. 594-601.

Research output: Contribution to journalArticle

Czibulya, Zsuzsanna ; Tombácz, E. ; Szegi, Tamas ; Michéli, Erika ; Zsolnay, Adam. / Standard state of soil dispersions for rheological measurements. In: Applied Clay Science. 2010 ; Vol. 48, No. 4. pp. 594-601.
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