Swelling properties of natural and modified bentonites by rheological description

Barast, Gilles, Razakamanantsoa, Andry-Rico, Djeran-Maigre, Irini, Nicholson, Timothy and Williams, David (2016) Swelling properties of natural and modified bentonites by rheological description. Applied Clay Science, 142 60-68. doi:10.1016/j.clay.2016.01.008


Author Barast, Gilles
Razakamanantsoa, Andry-Rico
Djeran-Maigre, Irini
Nicholson, Timothy
Williams, David
Title Swelling properties of natural and modified bentonites by rheological description
Journal name Applied Clay Science   Check publisher's open access policy
ISSN 0169-1317
1872-9053
Publication date 2016-02-09
Sub-type Article (original research)
DOI 10.1016/j.clay.2016.01.008
Open Access Status Not Open Access
Volume 142
Start page 60
End page 68
Total pages 9
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 1907 Geology
1906 Geochemistry and Petrology
Abstract Bentonite is used for landfill application because of its high sealing ability. Following the swelling phenomenon the water reacts with the bentonite and expands the solid particles. The voids are filled and this reduces permeability of the soil. However, the drawback is the long time needed to assess the hydraulic performance, whereas the engineers require simple and rapid characterization parameters to design the hydraulic barrier. Present paper investigates the possibility of use of rheology testing to describe the swelling properties of bentonite used for geotechnical engineering issues. Rheology testing is proposed to investigate the swelling properties of different nature of bentonite. Different types of bentonite are tested: natural sodium, natural calcium and sodium-activated-calcium bentonites. Rheological measurements are performed in steady and dynamic conditions. Free swell and oedometer swell tests are also performed and compared. A simple model is proposed to unify the output parameters of the liquid-state bentonite from two rheology tests, with the ones obtained from two swelling tests. This approach propose a single parameter: the swelling ratio β that describes the layer of water surrounding the particles based on the aspect ratio of bentonite packed particles. The method highlights the correlation between swelling characteristics and rheological parameters of bentonites. The results of swelling ratio underline distinctly the difference of mineralogy between the groups of bentonites. A linear equation fits the values of β obtained from the two swelling tests and the values of β obtained from the rheology tests, for all bentonites. Low correlations are observed between the oedometer swelling ratio and the rheology ratio. But, the free swelling ratio is in good agreement with rheological ratio and demonstrates a stronger correlation between the steady state rheology ratio than the dynamic state rheology ratio.
Formatted abstract
Bentonite is used for landfill application because of its high sealing ability. Following the swelling phenomenon the water reacts with the bentonite and expands the solid particles. The voids are filled and this reduces permeability of the soil. However, the drawback is the long time needed to assess the hydraulic performance, whereas the engineers require simple and rapid characterization parameters to design the hydraulic barrier. Present paper investigates the possibility of use of rheology testing to describe the swelling properties of bentonite used for geotechnical engineering issues. Rheology testing is proposed to investigate the swelling properties of different nature of bentonite. Different types of bentonite are tested: natural sodium, natural calcium and sodium-activated-calcium bentonites. Rheological measurements are performed in steady and dynamic conditions. Free swell and oedometer swell tests are also performed and compared.

A simple model is proposed to unify the output parameters of the liquid-state bentonite from two rheology tests, with the ones obtained from two swelling tests. This approach propose a single parameter: the swelling ratio β that describes the layer of water surrounding the particles based on the aspect ratio of bentonite packed particles. The method highlights the correlation between swelling characteristics and rheological parameters of bentonites. The results of swelling ratio underline distinctly the difference of mineralogy between the groups of bentonites. A linear equation fits the values of β obtained from the two swelling tests and the values of β obtained from the rheology tests, for all bentonites.

Low correlations are observed between the oedometer swelling ratio and the rheology ratio. But, the free swelling ratio is in good agreement with rheological ratio and demonstrates a stronger correlation between the steady state rheology ratio than the dynamic state rheology ratio.
Keyword Modified clays
Free swelling index
Oedometer swelling index
Rheology steady state swelling ratio
Rheology dynamic state swelling ratio
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Civil Engineering Publications
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