desiccation

In the dewatering of a bottom which is formed by sedimentation in the water, there occurs a change in volume, which is referred to as shrinkage. Particularly striking is the shrinkage in clay soils, Muddenböden and occasionally in silt soils through the formation of dry or shrinkage cracks.

The shrinkage of a soil particle is independent of its material properties, caused by the force of surface tension of the water. At room temperature (20 ° C) is this force of 72.75 mN / m, which is relatively high. The drying of a base resulting in a strong tendency to the reduction of water to air interface which leads to a pressure difference at the interface and thus to a capillary rise of water. They form menisci, whose deflection is proportional to the pressure difference; the soil particles are drawn together.

The difference in pressure at the meniscus, and thus the force for shrinking, thereby the greater, the smaller the capillary is (→ soil moisture tension ). Therefore, the shrinkage processes are in fine-grained soils, especially in fine-pore texture particularly strong, it caused dry cracks.

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