STP1308: Laboratory Hydraulic Conductivity Testing of GCLs in Flexible-Wall Permeameters

    Daniel, DE
    Professor, University of Texas, Austin, TX

    Bowders, JJ
    Research Scientist, University of Texas, Austin, TX

    Gilbert, RB
    Assistant Professor, University of Texas, Austin, TX

    Pages: 22    Published: Jan 1997


    Abstract

    One of the important properties of geosynthetic clay liners (GCLs) is hydraulic conductivity. In the laboratory, hydraulic conductivity of GCLs is typically measured in flexible-wall permeameters. The most important variables in hydraulic conductivity testing of GCLs are addressed, including (i) trimming the GCL specimen; (ii) determining the thickness of the specimen; (iii) selecting the effective stress; (iv) selecting the hydraulic gradient; and (v) selecting the first wetting liquid and permeant liquid. A round-robin testing program was conducted in which 18 laboratories independently measured the hydraulic conductivity of a GCL that was permeated with water. The test specimens all came from the same GCL sample. The coefficient of variation, accounting for all sources of variability, was 42%. For experienced laboratories, this value reduced to 35%, which was identical to the variation in quality control tests performed over a 7-month period by the manufacturer on a variety of GCL samples. The round-robin test results are encouraging; there was less variability than might be expected, considering the difficulty in accurately measuring the hydraulic conductivity of relatively impermeable materials such as GCLs.

    Keywords:

    hydraulic conductivity, permeability, bentonite, geosynthetic clay liner, GCL, flexible-wall permeameter, precision, bias, variability


    Paper ID: STP11804S

    Committee/Subcommittee: D35.04

    DOI: 10.1520/STP11804S


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