1. SOIL CLASSIFICATION
-Ms Ikmalzatul

2. TWO KINDS of Soil...
Two kinds of soil in this world…
COARSE
FINE

3. Fine-Grained vs. Coarse-Grained Soils
U.S. Standard Sieve - No. 200
inches
0.074 mm

4. Sieve Analysis (Mechanical Analysis)
This procedure is suitable for coarse grained soils
e.g. No.10 sieve …. has 10 apertures per linear inch

5. Hydrometer Analysis
Also called Sedimentation Analysis
Stoke’s Law

6. Grain Size Distribution Curves

7. Soil Plasticity
Plasticity is a property that enables a soil to undergo deformation without breaking.
Clays for instance are moulded into earthen pots when its plastic state.
This property is characteristic on fined grained soils only, in the presence of water.
When water is replaced by some other liquid , say kerosene, the clay will behave as a granular mass.

8. Plasticity is due to clay minerals in the soils and is exhibited only over a specific range of moisture content.
Excessive water turns the soil into a suspension (liquid state).
With gradual decrease in the water content, the soil passes into a plastic state, then into a semi-solid (or semi-plastic) state and finally into a solid state.

9. Plastic state Semi-solid state VOLUME MOISTURE CONTENT SOLID STATEWA T ER
CONT
ENT
DECREAS
ING
Liquid limit
Plastic limit
Shrinkage limit
Solid
SOLID STATE
MOISTURE CONTENT
SOLID
STATE
SEMI
PLASTIC
LIQUID
VOLUME
Plastic state
Semi-solid state

10. The water content at which these changes of state occur called limits or indices.
Albert Atterberg, Swedish Soil Scientist ( )…..series of tests for evaluating soil plasticity. He defined these limits as follows: the liquid limit (LL) is the water content at which a soil passes from liquid to plastic state; the plastic limit (PL) is the water content at which a soil passes from plastic to semi-solid state; and the shrinkage limit (SL) is the water content at which a soil passes from semi solid state.

11. Further classification within fine-grained soils (i. e
Further classification within fine-grained soils (i.e. soil that passes #200 sieve) is done based on soil plasticity.
Arthur Casagrande adopted these tests for geotechnical engineering purposes

12. Atterberg Limits
Consistency of fine-grained soil varies in proportion to the water content
Shrinkage limit
Plastic limit
Liquid limit
solid
semi-solid
plastic
liquid
Plasticity
Index
(cheese)
(pea soup)
(pea nut butter)
(hard candy)

13. Liquid Limit (LL or wL) Empirical Definition
The moisture content at which a 2 mm-wide groove in a soil pat will close for a distance of 0.5 in when dropped 25 times in a standard brass cup falling 1 cm each time at a rate of 2 drops/sec in a standard liquid limit device

14. Engineering Characterization of Soils
Soil Properties that Control its Engineering Behavior
Particle Size
coarse-grained
fine-grained
Particle/Grain Size Distribution
Particle Shape
Soil Plasticity

15. Clay Morphology Scanning Electron Microscope (SEM)
Shows that clay particles consist of stacks of plate-like layers

16. Soil Consistency Limits
Albert Atterberg ( ) Swedish Soil Scientist
….. Developed series of tests for evaluating consistency limits of soil (1911)
Arthur Casagrande ( )
……Adopted these tests for geotechnical engineering purposes

17. Arthur Casagrande ( )
Joined Karl Terzaghi at MIT in 1926 as his graduate student
Research project funded by Bureau of Public Roads
After completion of Ph.D at MIT Casagrande initiated Geotechnical Engineering Program at Harvard
Soil Plasticity and Soil Classification (1932)

18. Casagrande Apparatus

19. Casagrande Apparatus

20. Casagrande Apparatus

21. Liquid Limit Determination

22. Plastic Limit (PL, wP)
The moisture content at which a thread of soil just begins to crack and crumble when rolled to a diameter of 1/8 inches

23. Plastic Limit (PL, wP)

24. Plasticity Index ( PI, IP )
PI = LL – PL
or IP=wL-wP
Note: These are water contents, but the percentage sign is not typically shown.

25. Plasticity Chart

26. USCS Classification Chart

27. USCS Classification Chart

28. Plasticity Chart

29. THE END