STP1095: Geotechnical Aspects of Leaching of Carbonates from Loessial Soils

    Lamb, RO
    Senior Geotechnical Engineer, Trinity Engineering Testing Corp., Austin, TX

    Pages: 15    Published: Jan 1990


    Abstract

    A study was made of the changes that occur in the geotechnical properties of loessial soils as a result of leaching of carbonates from the soil matrix. Profiles of particle-size distribution, carbonate content, preconsolidation pressure, undrained shear strength, and soil index properties are reported for loess deposits from a study area in the midcontinental United States. The study revealed that abrupt changes in clay content, carbonate content, and soil unit weight mark the boundary between leached and unleached portions of the deposits. The leached soils are soft, low-to-medium sensitivity clayey silts having undrained shear strengths as low as 8 kPa (1.2 psi). Leaching of carbonates was found to have increased the soil compression index by a factor of approximately 1.5 and reduced the undrained shear strength to less than one-half of the unleached soil. The mechanism of leaching and its effects on soil behavior are discussed.

    Keywords:

    soil, leaching, carbonates, loess, consolidation, shear strength


    Paper ID: STP23545S

    Committee/Subcommittee: D18.05

    DOI: 10.1520/STP23545S


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