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Procedure and Equipment Factors Affecting Permeability Testing of a Bentonite-Sand Liner Material

出版	ASTM International, 1985
URL	http://books.google.com.hk/books?id=gxt9zgEACAAJ&hl=&source=gbs_api

註釋This paper presents the findings of an investigation regarding the effects of procedural and equipmental factors on the laboratory measurement of permeability of a bentonite-sand liner. In the experimental program, permeability tests were performed on compacted specimens of a bentonite-sand mixture to study the effect of (1) permeameter type (rigid- versus flexible-wall permeameters), (2) back pressure application, and (3) hydraulic gradient magnitude on the measured permeabilities. The liner material used in the tests was a mixture of 90% P20-R30 Ottawa sand and 10% bentonite clay. Water was used to prepare the specimens and as the permeant. Specimens were prepared by compaction at moisture contents exceeding optimum using the standard proctor method. A pressure of 380 kPa was used in the tests involving back pressure. The low and high hydraulic gradients used were nominally 29 and 290, respectively. Prior to the termination of a test, a red indicator was passed through the permeameters under the high gradient. The specimens were dissected and inspected after the test for the identification of flow areas and channels.