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The shrink–swell capacity of soils refers to the extent certain clay minerals will expand when wet and retract when dry. Soil with a high shrink–swell capacity is problematic and is known as shrink–swell soil, or expansive soil . [ 1 ]
The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid and plastic limits (PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay.
In 1907, Edgar Buckingham created the first water retention curve. [2] It was measured and made for six soils varying in texture from sand to clay. The data came from experiments made on soil columns 48 inch tall, where a constant water level maintained about 2 inches above the bottom through periodic addition of water from a side tube.
In the dry season, evaporation moves water from the deep horizon toward the soil surface through capillary action. The water removal results in shrinkage of clay, and the soil becomes dry and hard. In the wet season, high precipitation leads to a swell of clay to absorb water. The high moisture content results in wet and sticky clay texture.
Clay soils also resist wind and water erosion better than silty and sandy soils, as the particles bond tightly to each other, [14] and that with a strong mitigation effect of organic matter. [ 15 ] Sand is the most stable of the mineral components of soil; it consists of rock fragments, primarily quartz particles, ranging in size from 2.0 to 0. ...
Expansive clay, also called expansive soil, is a clay soil prone to large volume changes (swelling and shrinking) directly related to changes in water content. [1] Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called vertisols .
For optimal plasticity, the water requirement for plasters should fall within the liquid and plastic limits of the soil. Opting for a water-clay content close to the liquid boundary can enhance ease of application and mitigate surface cracking. The recommended approach is to maintain an initial water content between 30% and 40% of the clay's ...
When stress is applied that causes densification due to water (or other liquid) being displaced from between the soil grains, then consolidation, not compaction, has occurred. Normally, compaction is the result of heavy machinery compressing the soil , but it can also occur due to the passage of, for example, animal feet.