Soil properties

Foundations for home. Short article on soil types and their classification

At a glance amateur all the soils are the same. Yellow or gray, when wet - dirty, when dry - dusty. Despite the similarity of the properties of the soil is very different. They depend not only on the composition, humidity and density of the soil. Soil properties also depend on the topography of the site, the presence or absence of groundwater, their seasonal variations, and climatic conditions.

The most preferred soils are homogeneous, as they usually have a uniform draft. It should be noted that a small draft of the foundation, about 1-3 cm, is not dangerous for the building. Coarse sand, for example, is an excellent uniform base.

Non-uniform soils are a significant hazard. Such soils include both bulk and fertile (vegetable) soil layer. Bulk soils have a low density and various inclusions, such as remnants of debris consisting of a mixture of planks, fragments of concrete and brick, mixed with paper and sand. Even to a non-specialist it is clear that in the presence of such inclusions under the base of the foundation, the foundation can give an uneven draft. Not suitable for the device bases also vegetable soil - humus. Uneven sediment base is often the cause of the destruction of the basement. Evidence of uneven precipitation - the appearance of cracks on the walls of the house.

If you are “lucky” and your site is on top of a solid rock, then you can do without the foundation. You can put the walls of the house directly on the stone surface. It is not necessary to go below ground level. However, in the overwhelming majority of cases, the top layer of soil consists of not durable and loose vegetable soil. Often below is a denser layer, such as loam or sand. In this case, the base of the foundation should be installed on a more dense layer of soil.

Ubiquitous heaving soils are widespread. These are clay soils such as sandy loam, clay and loam. They perfectly retain moisture, and when freezing increase in volume. The reason for this is the formation of ice crystals in the soil body. The owners of the sites located on clay soils should take into account that in clay soils only layers located below the depth of frost penetration can serve as the foundation of the foundation.

For example, in the Kiev region the freezing depth is about 1 m, in the Odessa region - 80 cm, in the Kharkov region - 1.2 m.

Quite often there are ground subsidence. Such soils, when moistened, decrease in volume. In the dry state, subsidence soils have an increased porosity. However, they are instantly compacted when soaking. Lossy and loesslike loams are referred to the subsidence.

I draw your attention to the fact that in dry condition loess is extremely dense. They are almost impossible to “gnaw” with a shovel. Personal experience - I used a jackhammer when I was digging a basement in loess runes. But do not be fooled by this. A little bit of moisture and forest instantly turns into liquid mud.

It may happen that the upper layer consists of a dense soil, under which there is a settling layer. In such soils it may be necessary to apply pile foundations or monolithic reinforced concrete slab.

There are swims - soils saturated with water, consisting of fine-grained silty sand with silt and clay impurities. At autopsy, they set in motion like a thick kissel. With the ingress of moisture, the quicksies turn into a liquid state. It is clear that it is impossible to build a foundation on water, therefore, the quicksand is unsuitable as natural bases. In such soils, it is likely that pile foundations will have to be applied. Piles must go through a layer of quicksand and reach a solid base.

Determine the properties of soils that are under the spot of your house, the depth of the foundation (that is, the depth at which the soil can serve as the foundation for the foundation), make a technical decision on which foundations are optimal for this type of soil only based on the results of geological surveys.