1. Atterberg Limits of Soil
Prepared by:
Asso.Prof.Dr.Eng.I.A.Malik
Department Of Grology
University Of Elneelain

2. 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.

3. Atterberg Limits
(Non-Plastic )
Plasticity Index
Wpl wll
Plastic Limit Liquid Limit
Water Content
w%=0
Solid LiquidPlasticBrittle

4. Plastic limit
The plastic limit (PL) is the water content
(w%) where soil starts to exhibit plastic
behavior.

5. 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)

6. 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.

7. 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.

8. Use of Liquid & Plastic Limits
Used internationally for soil identification
and soil classification (AASHTO)