What is Shrinkage and Swelling


The terms shrinkage and swelling refer mostly to clay soil. In the previous lesson on capillary water, we introduced the term capillary tension, which you should associate with shrinkage for a better understanding.

This strain is the primary cause of shrinking. See the shrinking process diagram.

Figure (a) shows a soil mass saturated to full level a-a due to capillary water or any other reason.

Assume that the temperature rises and some water evaporates; as a result of this evaporation, water is lost (b-b)

Because of this small amount of tension in the soil particle,

We’ve already talked about capillary water tension.

When the water level is low, water adheres to the surface of the soil particle, and tension is formed in the water. or clearly soli particle compression,

Water, in essence, compresses the soil particle due to the tension it creates. For a clear understanding, attempt to imagine.

The more water evaporates, the more soil particle compression occurs. which causes significant shrinking of soil mass

However, if the water loss scenario destroys water tension because there is insufficient water present, no further compression is formed in between particles, we accomplish maximum shrinkage in the prior case.

That is due to shrinking.

Soil swelling is caused by a variety of factors such as increased water content, adsorbed layer, entrapped air, and clay minerals, but we only address the increase in water content.
When we reverse the shrinkage cycle from maximum shrinkage to no shrinkage by adding water, we see expansion of soil particles and slight swelling.
Effects of Shrinkage and Swelling

  1. The structure is stressed because it is resting on soil, which has shrinkage and swelling properties.
  2. Swelling causes light structure lifting, which is not beneficial for any structure.
  3. The problem on roadways is caused by shrinkage and swell soil.

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