Some observations considering undrained shear strength, liquidity index, and fluid/solid ratio of mono-mineralic clays with water-ethanol mixtures

Spagnoli, Giovanni and Stanjek, Helge and Sridharan, Asuri (2018) Some observations considering undrained shear strength, liquidity index, and fluid/solid ratio of mono-mineralic clays with water-ethanol mixtures. In: CANADIAN GEOTECHNICAL JOURNAL, 55 (7). pp. 1048-1053.

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Abstract

The mechanical properties of clays are influenced by the characteristics of the fluid in the pore space. The liquid limit reacts differently to the permittivity, epsilon, of the fluid: for smectites the slopes are positive, for kaolinite and illite they are negative and smaller. This dissimilarity can be explained by the structural differences between swelling smectites with solvated interlayer cations and nonswelling clay minerals such as kaolinite and illite. Undrained shear strengths, c(u) of Ca-smectite, but not Na-smectite, correlate with the actual fluid ratio. Regressing c(u) against the liquidity index, I-L, yields two different regression lines for Na-smectite and Ca-smectite. For the first time it is shown that normalizing c(u) to the epsilon of the pore fluid results in a single regression line for both smectitic clay types. As kaolinites and illites possess significantly less exchangeable cations than smectites, this yields significantly smaller ranges for Atterberg limits and reduces the impact of e on almost pure particleparticle interactions. In addition, the much larger particle sizes of the kaolinite and illite may dominate the undrained shear strengths, as normalization of c(u )to epsilon did not change the relationship to either the actual water content or the liquidity index.

Item Type:	Journal Article
Publication:	CANADIAN GEOTECHNICAL JOURNAL
Publisher:	CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS, 65 AURIGA DR, SUITE 203, OTTAWA, ON K2E 7W6, CANADA
Additional Information:	Copyright of this article belong to CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS, 65 AURIGA DR, SUITE 203, OTTAWA, ON K2E 7W6, CANADA
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	19 Jul 2018 14:54
Last Modified:	17 Dec 2018 17:02
URI:	http://eprints.iisc.ac.in/id/eprint/60236

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