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Atterberg Limits of Soil. Prepared by: Marcia C. Belcher Construction Engineering Technology University of Akron. Atterberg . Albert Atterberg was a Swedish chemist and agricultural scientist. Conducted studies to identify the specific minerals that give a clayey soil its plastic nature
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Atterberg Limits of Soil Prepared by: Marcia C. Belcher Construction Engineering Technology University of Akron
Atterberg • Albert Atterberg was a Swedish chemist and agricultural scientist. • Conducted studies to identify the specific minerals that give a clayey soil its plastic nature • Stated that depending on the water content, soil may appear in four states: • Solid (no water) • semi-solid (brittle, some water) • plastic (moldable) • liquid (fluid) • In each state the consistency and behavior of a soil is different and thus so are its engineering properties. • The boundary between each state can be defined based on a change in the soil's behavior.
Atterberg Limits (Non-Plastic ) Plasticity Index Solid Brittle Plastic Liquid Water Content w%=0 wll Wpl Plastic Limit Liquid Limit
Plastic limit • The plastic limit (PL) is the water content (w%) where soil starts to exhibit plastic behavior.
Liquid limit • The liquid limit (LL) is the water content where a soil changes from liquid to plastic behavior • Determined using a Casagrande cup (lab) or cone penetrometer (field)
Shrinkage limit • The shrinkage limit (SL) is the water content where further loss of moisture will not result in any more volume reduction • The shrinkage limit is much less commonly used than the liquid limit and the plastic limit.
Use of Plasticity Index • The PI is the difference between the liquid limit and the plastic limit (PI = LL-PL). • The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. • Meaning: • High PI tend to be clay • Low PI tend to be silt • PI of 0 tend to have little or no silt or clay.
Use of Liquid & Plastic Limits • Used internationally for soil identification and soil classification (AASHTO)