Foundation, Concrete and Earthquake Engineering

Field Identification of Silt from Clay Soil by Shaking Test

Dear reader we have discussed about many methods to differentiate one type of soil from other and some methods are still to come. We have, mainly, so far, discussed about filed identification of soils. Here in this post we will discuss about some simple tests to differentiate silt from clay soils.

We can place soil particles under microscope only in laboratory which is a time consuming and also costly and difficult task. So for rough estimation about project involved soil (say for tender purpose) to have rough idea about cost and time of construction (as an example related to consolidation) and sometimes for determining way of examination and testing program, we depend on index properties of soil. The test like shaking test is easier but rough than even index properties, but useful in some cases.

Shaking test:

Here a portion material is placed in the palm and shaken-

If silt-

Bright shiny appearance of silt soil

A shiny appearance is observed as water comes out to surface.

When kneaded, the shiny appearance disappeared as moisture in surface is re-entered into soil.

If clay-

The moisture cannot move out easily which doesn’t provide shinny look, remaining soil dark as in previous state.

But if there have some soil in clay, the shine appears relative slow rate which gives a rough estimation of amount of silt in soil particles.

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