important, properties, soils
The size of the grains of a soil is one of the factors on which depend some of the physical properties important for engineers, such the cohesion and the permeability of a soil. Permeability is the property of a soil which allows the flow of water through it. If the grains of a soil are small, the openings between them will also be small, so water will have more difficulty to flow through such a soil than through a soil with larger grains and larger openings between them. Smaller grains and openings in a soil may cause a greater cohesion between the soil particles as a result of larger total surfaces of contact between the greater quantity of small grains. The know ledge of the grain size is not sufficient for the definition of such properties as permeability and cohesion. Other data are required, which give indications how closely the grains are packed, that is, the data about the density of the soil. The dense soils are better for carrying the weight of the foundation than the loose ones. So some-times it is necessary to increase the density of a natural soil artificially.
