Consistency Atterberg Limits
- Liquid Limit (WL)
- Plastic Limit (Wp)
- Shrinkage Limit (Ws)
- It is defined as the minimum water content at which soil is in the plastic stage of consistency or behaves like a plastic material.
- At the plastic limit, soil passes a plastic state of consistency to a semi-solid state of consistency & visa-versa.
NOTE: -Plasticity in the property of soil which allows it to be deformed rapidly, without elastic rebound, without volume change, without rupture.
- This plasticity of fine-grained soil is due to the presence charge over the surface of particles & bipolar nature of water.
- Fine-grained does not become plastic when a nonpolarizing liquid like kerosene, Naphthalene is added to it.
Plastic Limit Determination
- From a determination point of view, the plastic limit is defined as the minimum water content at which soil just begins to crumble or crack when rolled in a thread of 3 mm diameter.
- 15 Gm air dried sample soil passing through 425μ sieve is mixed with a sufficient amount of water so as make it plastic.
- A ball is formed with about 8 gm of this plastic soil & is rolled between fingers & a glass plate into a thread of 3 mm diameter.
- The soil is remolded again into a ball & rolled again into the thread of 3 mm diameter up to an extent it begins to crumble.
- The crumble thread is tested for its water content & termed as Plastic Limit (Wp).
- An average of three tests is considered as the final result.
|Unit||Soil Formation & Properties of Soil|
|Topic||Plastic Limits- Consistency Atterberg Limits|
|Next Topic||Shrinkage Limits- Consistency Atterberg Limits|
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