Liquid Limit Determination of Soil

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Liquid Limit Determination of Soil
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 )
Solid
Water Content
w%=0
Brittle
Plastic
Liquid
Plasticity Index
Wpl
Plastic Limit
wll
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)

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