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    Volume 42, Issue 6 (November 2019)

    The Flow Index of Clays and Its Relationship with Some Basic Geotechnical Properties

    (Received 7 April 2018; accepted 4 October 2018)

    Published Online: 21 December 2018


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    The flow index (FI), which is the slope of the water content versus log10 of the blows number plot for the Casagrande cup method, is the measure of the rate at which soil mass loses its shear strength with increased water content. FI was plotted against the plasticity index (PI) of 59 clays; each clay had a different mineralogy and origin, and together they accounted for a wide range of plasticity values. A linear relationship with R2 = 0.91 was observed. However, if FI is plotted against the liquid limit (LL) and the plastic limit (PL) separately, although a good correlation with LL is observed, FI poorly correlates with PL. FI was also correlated with the activity of soil, cation exchange capacity, specific surface area, and water uptake. Predicted equations from PI and activity were established on 13 independent samples confirming that a good correlation against measured values and estimated values (from FI) exists. From the literature review, FI was also used to indirectly estimate PL. Results show a trend, albeit the results are scattered (R2 = 0.66 for the Casagrande cup method and R2 = 0.76 for the cone penetrometer method), thus indicating that PL cannot be directly obtained from FI.

    Author Information:

    Spagnoli, Giovanni
    BASF Construction Solutions GmbH, Trostberg,

    Feinendegen, Martin
    Chair of Geotechnical Engineering and Institute of Foundation Engineering, Soil Mechanics, Rock Mechanics and Waterways Construction, RWTH Aachen University, Aachen,

    Di Matteo, Lucio
    Department of Physics and Geology, University of Perugia, Perugia,

    Rubinos, David A.
    Sustainable Minerals Institute, Centro Internacional de ExcelenciaFreelance Researcher and Consultant, ApoquindoA Coruña,

    Stock #: GTJ20180110


    DOI: 10.1520/GTJ20180110

    Title The Flow Index of Clays and Its Relationship with Some Basic Geotechnical Properties
    Symposium ,
    Committee D18