Importance of soil as construction material?

Answer 1

In construction, soil is a significant part of the building process. If performed improperly, settlement of the soil could occur and result in unnecessary maintenance costs or structure failure. Almost all types of building sites and construction projects utilize mechanical compaction techniques. There are five principle reasons to compact soil:

- Increases load-bearing capacity

- Prevents soil settlement and frost damage

- Provides stability

- Reduces water seepage, swelling and contraction

- Reduces settling of soil

There are five basic types of soil (gravel, sand, silt, clay, and organic), and the dirt in a given location is generally some combination of all or most of these types. The soil from a new building site is tested to determine its suitability. Organic material must be removed from the soil and, if necessary, a different type of soil can be trucked in and mixed with the existing dirt to create a blend that will work. Cement may be added to the soil to increase both its strength and its resistance to moisture-usually at about one-fourth the ratio that would be used to make concrete. A variety of tests are conducted to determine the suitability of the local soil for construction material. For example, a particle determination test reveals the relative proportions of sand and silt in the sample. A compaction test is performed by forming a ball of mud and dropping it from a height of 3 ft (1 m); the degree to which the ball disintegrates on impact reveals its usefulness for building. Other, more precise, tests can be performed at a geotechnical laboratory. If the native soil is unsuitable or inadequate for building, it can be blended with or replaced by soil from another source.

The ability of soils and rocks to hold and transmit water varies, and the depth to groundwater varies in different geological settings. Physical properties of soils and rocks, such as degree of consolidation, cementation, and hardness, determine drilling methods and the potential for groundwater production. When drilling, consolidated rock is harder to penetrate but is more stable than unconsolidated rock. Well drillers usually use a down-hole air hammer on consolidated rock with no well casing for support. Drillers must support holes in unconsolidated rock to avoid cave-ins. Wells in unconsolidated rock frequently yield more water at a shallower depth than wells in consolidated rock.