Effects of Test Duration and Specimen Length on Diffusion Testing of Unconfined Specimens

    Volume 21, Issue 2 (June 1998)

    ISSN: 0149-6115

    CODEN: GTJOAD

    Page Count: 16


    Cotten, TE
    Geoenvironmental engineer, Portland, OR

    Davis, MM
    Geotechnical engineer, Shepherd Miller, Inc., Fort Collins, CO

    Shackelford, CD
    Associate professor, Colorado State University, Fort Collins, CO

    Abstract

    Effective diffusion coefficients, D*, of chloride and zinc diffusing in saturated, unconfined specimens of a compacted sandclay mixture are measured for three specimen lengths, L (2.91, 5.83, and 11.60 cm) and three test durations (7, 14, and 21 days). For a specimen length of 2.91 cm, both the chloride and zinc D* values tend to decrease with increasing test duration, possibly due to the measurement of concentration-dependent D* values. For a 14-day test duration, no consistent trend in D* with specimen length is observed, but the overall effect of specimen length on D* is minor relative to the range of measured D* values. A 21-day test duration provides the best correlation between the D* values based on reservoir concentrations, D*Res, and the D* values based on soil concentrations, D*Soil, for chloride for a given test regardless of the specimen length. The effect of test duration on the correlation between D*Res and D*Soil for zinc is minor based on the relatively narrow range of measured zinc D* values. The observed effects of specimen length on the correlation between D*Res and D*Soil for a given test are consistent with the more uniform final porosity distributions in the shorter specimens and the contrasting effects of the non-linear distributions in porosity and dry density that become less significant as the specimen length increases.


    Paper ID: GTJ10746J

    DOI: 10.1520/GTJ10746J

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    Author
    Title Effects of Test Duration and Specimen Length on Diffusion Testing of Unconfined Specimens
    Symposium , 0000-00-00
    Committee D18