Geoscience Reference
In-Depth Information
2.11 Soil plasticity
•
Typically a good assessment can be made of soil plasticity in the field.
•
Some classification systems uses the Intermediate (I) symbol instead of the L/H.
The latter is an economy of symbols.
Table 2.11
Soil plasticity.
Term
Symbol
Field assessment
Non plastic
-
Falls apart in hand
Low plasticity
L
Cannot be rolled into (3 mm) threads when moist
Medium plasticity
L/H
Can be rolled into threads
Shows some shrinkage on drying
High plasticity
H
when moist.
Considerable shrinkage on drying.
Greasy to touch. Cracks in dry material
Figure 2.2
Consistency limits.
2.12 Atterberg limits
•
Laboratory Testing for the Atterberg confirms the soil plasticity descriptors
provided in the field.
•
These tests are performed on the % passing the 425 micron sieve. This % should
be reported. There are examples of “rock'' sites having a high PI, when 90% of
the sample has been discarded in the test.
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