Soil is the oldest most material on which different engineering as well as non-engineering structure depends.
It also can be defined as the complex material formed by the weathering of solid rocks.
There are two types of weathering:
Cohesionless soil are formed by physical weathering. E.g.Gravel,sand ,etc. It is due to the Temperature change, effects of plants and animals etc.
Cohesive soil is formed due to Chemical weathering. E.g. silt,clay,etc. It is due to chemical reaction or chemical change between minerals.
1.2.IMPORTANCE OF SOIL
1. As a Construction Material
Some of the use of soil as a construction material are:
a. As a mud mortar for stone or brick masonry.
b. As a mud mortar for plastering adobe masonry wall.
c. In the construction of earthern wares(Vessels).
d. In the construction of dams,pavements,etc.
e. As a filling or soling material.
2. As a foundation bed for structure.
Most of the structure like buildings , pavements , dams , bridges , etc are founded on the earth. Hence, the soil act as a foundation bed for structure by taking the load from foundation and distributing in lager area.
fig: soil with different layers