Expansive soil refers to a type of soil or clay, that demonstrates a tendency to expand or contract in response to changes in water content. Expansive soil will expand when there is a significant water influx and contract when the water evaporates. This expansion and contraction are attributed to the change in the volume of the soil which offers challenges to the engineering for the construction. Black cotton soil is one type of expansive soil which exhibit the same characteristic of expansion and contraction on the absorption of water and loss the water through evaporation respectively.
Types of Expansive Soil are:
- Montmorillonite: This type of expansive clay is highly prone to swelling and shrinking due to changes in moisture content. It has a high cation exchange capacity and exhibits significant volume changes.
- Bentonite: Bentonite is another type of expansive clay known for its swelling properties. It forms as a result of weathering volcanic ash and contains a high proportion of montmorillonite.
- Kaolinite: While kaolinite is not as prone to expansive behaviour as montmorillonite or bentonite, it can still exhibit some degree of swelling and shrink in response to moisture fluctuations. Kaolinite is a common clay mineral found in many soils.
- Smectite: Smectite is a group of clay minerals that includes montmorillonite. These minerals have a unique layered structure that allows for high water absorption and significant swelling behaviour.
- Beidellite:
- Vertisols: These are clay-rich soils with a high content of expansive clay minerals. They are known for their pronounced shrink-swell behaviour, forming deep cracks when dry and becoming sticky and plastic when wet.
Tshering Dorji Changed status to publish 06/19/2023