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Title: EFFECTS OF WATER ADSORPTION ON KAOLIN CLAY DURING SHEAR
Accession Number: 00193796
Record Type: Component
Availability: Find a library where document is available Abstract: Stress-controlled direct shear tests were made on laboratory-desiccated specimens of kaolin clay (W sub D approximately - 1.5 percent). The standard apparatus was modified to permit progressive adsorption of water through the bottom porous plate. Various levels of constant shearing stress pi and a vertical stress of 24 kPa (3.5 lbf/sq in.) were applied, and shearing deformation measurements to failure were taken. When the deformation rate accelerated markedly, failure was defined for that particular pi and water content w. Failure surface w determinations were confirmed by an independent study of time versus wetting rate. Deceleration in wetting rate with increasing water content indicated decreasing negative pore pressure or soil water suction. Suction increases shearing resistance by its "reinforcement" of effective normal stress between soil solids; it is greater at lower w and reduces most at w greater than 23 percent--the point of contraflexure in the wetting rate versus w curve--which is followed by swelling. Higher constant stress levsls produced initial deformations at lower w and at higher deformation rates. The approximately linear relation between applied pi and w at initial deformation indicates that increases in w account for decreases in interparticle shearing resistance and corresponding losses of strength. This is confirmed by qualitative analysis of test results in relation to the Coulomb equation and the principle of effective stress. Because the maximum strength of specimens at W sub D was greater than maximum strengths between 1.5 and 23 percent, stress-controlled tests were replaced by strain-controlled tests; therefore, peak and residual strengths were obtained on desiccated specimens rewet to w in this range and held constant during stress application. These tests were extended to W sub E (equilibrium W approximately 35 percent) for comparison with stress-controlled test results. /Author/
Supplemental Notes: This paper appeared in TRB Record 675, Moisture and Frost-Related Soil Properties.
Publication of this paper sponsored by Committee on Physico-chemical Phenomena in Soils. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
Monograph Title: Monograph Accession #: 01411514
Authors: Glenn, G RPagination: pp 20-23
Publication Date: 1978
Serial: Media Type: Digital/other
Features: Figures
(7)
; References
(3)
TRT Terms: Subject Areas: Geotechnology; Highways
Files: TRIS, TRB
Created Date: May 11 1979 12:00AM
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