Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities

ABSTRACT: The structural strength of soils has been extensively described by physical and mechanical properties evaluated on the mesoscale for different soils and management conditions. However, changes in the organization of the soil matrix at the microstructural level, which can be obtained by rheometry, are still seldom used in soil mechanics. Our aim was to use the amplitude sweep test, a rheometry technique, to investigate the microstructural strength of four subtropical soils (two Oxisols, an Ultisol and a Vertisol) and to discuss difficulties with respect to the samples, water content, soil density and vertical force. The various rheological properties which reveal the soil microstructural strength were determined: deformation at the end of the linear viscoelastic range, LVE range (γLVE), shear stress at the end of the LVE range (τLVE), deformation at yield point, YP (γYP), storage and loss moduli at YP (G′G″YP), maximum shear stress (τmax), and integral z. In general, soil elasticity (γLVE and γYP) and microstructural strength (τLVE and τmax) were greater in the Oxisols and the Vertisol, which both possess high clay content, while the latter also contains expansive clay minerals. The lowest structural strength was observed in the Ultisol which had a high sand content. As rheological properties are related to soil properties such as particle size distribution and carbon content, they can be applied in the evaluation of the microstructural strength of clayey and sandy soils and allows for inferences regarding inter-particle shear strength. However, the test is not applicable to very dry soil samples and sample preparations can affect the results. We suggest a number of approaches to find solutions for these difficulties/problems.

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Main Authors: Pértile,Patricia, Holthusen,Dörthe, Gubiani,Paulo Ivonir, Reichert,José Miguel
Format: Digital revista
Language:English
Published: Escola Superior de Agricultura "Luiz de Queiroz" 2018
Online Access:http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162018000200154
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spelling oai:scielo:S0103-901620180002001542017-12-01Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunitiesPértile,PatriciaHolthusen,DörtheGubiani,Paulo IvonirReichert,José Miguel soil mechanics oscillatory shear amplitude sweep test soil structure ABSTRACT: The structural strength of soils has been extensively described by physical and mechanical properties evaluated on the mesoscale for different soils and management conditions. However, changes in the organization of the soil matrix at the microstructural level, which can be obtained by rheometry, are still seldom used in soil mechanics. Our aim was to use the amplitude sweep test, a rheometry technique, to investigate the microstructural strength of four subtropical soils (two Oxisols, an Ultisol and a Vertisol) and to discuss difficulties with respect to the samples, water content, soil density and vertical force. The various rheological properties which reveal the soil microstructural strength were determined: deformation at the end of the linear viscoelastic range, LVE range (γLVE), shear stress at the end of the LVE range (τLVE), deformation at yield point, YP (γYP), storage and loss moduli at YP (G′G″YP), maximum shear stress (τmax), and integral z. In general, soil elasticity (γLVE and γYP) and microstructural strength (τLVE and τmax) were greater in the Oxisols and the Vertisol, which both possess high clay content, while the latter also contains expansive clay minerals. The lowest structural strength was observed in the Ultisol which had a high sand content. As rheological properties are related to soil properties such as particle size distribution and carbon content, they can be applied in the evaluation of the microstructural strength of clayey and sandy soils and allows for inferences regarding inter-particle shear strength. However, the test is not applicable to very dry soil samples and sample preparations can affect the results. We suggest a number of approaches to find solutions for these difficulties/problems.info:eu-repo/semantics/openAccessEscola Superior de Agricultura "Luiz de Queiroz"Scientia Agricola v.75 n.2 20182018-04-01info:eu-repo/semantics/articletext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162018000200154en10.1590/1678-992x-2016-0267
institution SCIELO
collection OJS
country Brasil
countrycode BR
component Revista
access En linea
databasecode rev-scielo-br
tag revista
region America del Sur
libraryname SciELO
language English
format Digital
author Pértile,Patricia
Holthusen,Dörthe
Gubiani,Paulo Ivonir
Reichert,José Miguel
spellingShingle Pértile,Patricia
Holthusen,Dörthe
Gubiani,Paulo Ivonir
Reichert,José Miguel
Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
author_facet Pértile,Patricia
Holthusen,Dörthe
Gubiani,Paulo Ivonir
Reichert,José Miguel
author_sort Pértile,Patricia
title Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
title_short Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
title_full Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
title_fullStr Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
title_full_unstemmed Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
title_sort microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities
description ABSTRACT: The structural strength of soils has been extensively described by physical and mechanical properties evaluated on the mesoscale for different soils and management conditions. However, changes in the organization of the soil matrix at the microstructural level, which can be obtained by rheometry, are still seldom used in soil mechanics. Our aim was to use the amplitude sweep test, a rheometry technique, to investigate the microstructural strength of four subtropical soils (two Oxisols, an Ultisol and a Vertisol) and to discuss difficulties with respect to the samples, water content, soil density and vertical force. The various rheological properties which reveal the soil microstructural strength were determined: deformation at the end of the linear viscoelastic range, LVE range (γLVE), shear stress at the end of the LVE range (τLVE), deformation at yield point, YP (γYP), storage and loss moduli at YP (G′G″YP), maximum shear stress (τmax), and integral z. In general, soil elasticity (γLVE and γYP) and microstructural strength (τLVE and τmax) were greater in the Oxisols and the Vertisol, which both possess high clay content, while the latter also contains expansive clay minerals. The lowest structural strength was observed in the Ultisol which had a high sand content. As rheological properties are related to soil properties such as particle size distribution and carbon content, they can be applied in the evaluation of the microstructural strength of clayey and sandy soils and allows for inferences regarding inter-particle shear strength. However, the test is not applicable to very dry soil samples and sample preparations can affect the results. We suggest a number of approaches to find solutions for these difficulties/problems.
publisher Escola Superior de Agricultura "Luiz de Queiroz"
publishDate 2018
url http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162018000200154
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AT gubianipauloivonir microstructuralstrengthoffoursubtropicalsoilsevaluatedbyrheometrypropertiesdifficultiesandopportunities
AT reichertjosemiguel microstructuralstrengthoffoursubtropicalsoilsevaluatedbyrheometrypropertiesdifficultiesandopportunities
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