Classify - Period#6 Soil Classification Systems and Usage A Fundamental Idea • Collect soil samples from the field • Perform easy and

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Unformatted text preview: Period #6: Soil Classification Systems and Usage A. Fundamental Idea: • Collect soil samples from the field. • Perform easy and inexpensive tests on the soil samples (typically GSD tests and Atterberg Limit tests) • Based on the results from these tests, classify the soil(s) in question • Based on the classifications of the soil(s), determine whether or not the might be appropriate for the intended usage. • If yes, perform more extensive lab tests on the soil(s) (shear strength, consolidation, compaction, etc.) as needed. MAJOR SOIL CLASSIFICATION SYSTEMS USED IN THE U.S. USDA Textural Class ification : Used primarily in agriculture, but not much by civil or geotechnical engineers. AASHTO Classificati on System : Used quite extensively by civil engineers in selecting soils for usage in roads and highways. Unified Classificat ion System (UCS) : Used by geotechnical engineers for selecting appropriate soils in non-highway projects. 1 53:030 Class Notes;C.C. Swan, University of Iowa 2 B. USDA Textural Classification This system is based entirely on the GSD of a given soil sample. Soil Type Diameter Range Cobbles & Boulders d > 75mm Gravels 2mm ≤ d ≤ 75mm Sands 0.05mm ≤ d < 2mm Silts 0.002mm ≤ d < 0.05mm Clays d ≤ 0.002mm The classification in this system is based on the relative % sand, % silt, and % clay. % with 0.05mm ≤ d ≤ 2mm relative % sand = -------------------------- 100% - % with d ≥ 2mm % with 0.002mm ≤ d ≤ 0.05mm relative % silt = -------------------------- 100% - % with d ≥ 2mm % with d ≤ 0.002mm relative % clay = --------------------------...
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This note was uploaded on 11/10/2010 for the course CIVIL 53:30 taught by Professor Swan during the Fall '09 term at University of Iowa.

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Classify - Period#6 Soil Classification Systems and Usage A Fundamental Idea • Collect soil samples from the field • Perform easy and

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