Liquid and plastic limits characterise clay behaviour.
Liquid limit (LL), plastic limit (PL) and shrinkage limit mark water contents where soil behaves as liquid, plastic or solid. Plasticity index PI=LL-PL; liquidity index and activity assess behaviour. Casagrande chart classifies fine soils as CL, CH, ML, MH.
Clay with PI=35 is highly plastic and difficult to compact.
Atterberg limits describe how a clay changes with water content, which tells engineers how it behaves and how it will shrink or swell.
Liquid and plastic limits characterise clay behaviour.
Atterberg limits describe how a clay changes with water content, which tells engineers how it behaves and how it will shrink or swell.
The liquid limit, plastic limit and shrinkage limit, which mark the water contents where the soil changes between states.
The difference between the liquid limit and the plastic limit, which indicates how much water the soil can hold while remaining plastic.
Typical applications include deciding whether a clay is suitable as an embankment fill, predicting the shrink-swell risk of a clay below a house and classifying a fine-grained soil for a road subgrade.
Study "Soil phase relationships" first (topic 27 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
Cone penetrometer or Casagrande cup. High PI means swelling potential. Consistency.
Clay with PI=35 is highly plastic and difficult to compact.
The next topic is "Compaction", which builds directly on this one.
It is classed as Beginner in Civil & Structural (topic 28 of 112). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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