6. Physical Properties of Soils

   1. Plasticity: The soil can undergo deformation without cracking. Soil contains clay. Soil contains clay and when it is wet, it can be moulded into various shapes in its plastic stage. If the soil contains non-plastic materials like quartz and rock floor, it would not become plastic.

   2. Cohesion: The cohesion of soil can be defined as the tendency for particles of the soil to stick together. Thus the soil can resist shear stresses. When the water percentage of very fine-grained saturated soil is decreased by consolidation, the volume of voids occupied by water decreases. However, the volume occupied by the absorbed substances remains the same. 

   3. Consolidation: Consolidation is defined as the gradual process of reduction in volume under sustained static loading./Consolidation is the process of reducing the volume of saturated soil due to removing water from the soil.

   4. Compaction: Compaction is the artificial process of packing the soil particles together by mechanical means to reduce the void ratio of the soil and increase the dry density of soil. The soil need to be compacted, such as in the laying of highways, formation of railway lines, formation of earthen bunds etc. Cohesive soils need to be compacted by rulers and cohesionless soils by vibration.
      Objects of compaction:

• To decrease the permeability and water absorption of soil.

• To reduce the settlement of soil under loading.

• To increase my density of soil to increase shear strength.

5. Permeability: It is defined as the property of the soil, which allows the flow of water through it. Soil is a porous material with many interstices and they are interconnected. Permeability varies with size, cross-section, and orientation of interstices for different soils.

6. Compressibility: When the compressive load is applied on soil mass by moving or vibratory roads or expulsion of air from voids leads to a decrease in volume under stress is known as compressibility.

When in the soil mass, voids are filled with air, compression of soil occurs rapidly because air is compressible and when the voids are filled with incompressible water decrease in volume takes place when water is expelled out of voids.