Rocks forming the surface layer of the lithosphere are commonly called soils. Soils were formed naturally due to the destruction of the main continental plates. And this process was provoked by a variety of processes, for example, air and water erosion, displacement of lithospheric plates, anthropogenic activity, as well as the vital activity of the plant and animal world. If we talk about the origin, here scientists distinguish 2 groups of soils: organic and mineral. In turn, according to the nature of the connection between the particles, as well as the mechanical strength and size, it is customary to distinguish rocky, semi-rocky, bound, loose and coarse rocks.
Soil characteristics
Each group of soils has its own specific qualities, which are currently well-studied and successfully used in the construction industry. Half-breed rocks are distinguished by their composition, which is cemented and has the possibility of further compaction. It is customary to distinguish water-resistant and non-water-resistant compounds, marls and gypsum, respectively.
Rocky rocks, on the other hand, are water resistant and almost never compressible. This should include, first of all, granites and sandstones. Sand groups of soils, which are also called loose, are the result of erosion and weathering. The incoherent particles are quite small in size, the total mass of which is not plastic, but can perfectly fill any cavities.
Cohesive rocks, which are called clayey rocks, are also considered the result of the destruction of primary rocks. But unlike sandy soils, particles in size do not exceed more than 0.005 millimeters, due to which the total mass of the substance is quite plastic. This allows you to successfully apply the composition not only in the construction industry, but also in other types of human life.
Coarse soil groups are particles whose size is about 2 mm or more. They do not communicate with each other in any way. Nevertheless, their popularity is explained by a high rate of strength.
Evaluation criteria and soil properties
During construction, clay and sand rocks, as well as their mixtures, coarse and semi-rock compositions, are most often used. The costs of the development and effectiveness of the technology of the production process, as well as the complexity are the main indicators, they are used to evaluate this or that soil.
The properties that are needed for various construction works are very diverse:
- lumpiness;
- humidity;
- strength;
- erosion and others.
For example, humidity can determine how much water is saturated with soil, as well as the ratio of the mass of liquid to the mass of the total composition. Loosening can be characterized by an indicator of an increase in soil volume during its development. It is customary to distinguish the coefficient of residual and primary loosening. An important indicator of soil is the angle of repose. It can be determined by the physical parameters of a particular composition that the rock possesses in a state of critical equilibrium. Depending on different criteria, this value is found in different ways.
Classification of soils into groups
Soils are usually divided into three main categories:
Rocky
Rocky types of soil are metamorphic, igneous, volcanogenic-sedimentary, sedimentary, technogenic and alluvial rocks, which have rigid cementation and crystallization structural bonds.
Dispersion
Dispersion types of soil include volcanic-sedimentary, sedimentary, man-made and alluvial rocks, which differ in mechanical and water-colloidal structural bonds. These types of soil are divided into disconnected and cohesive. And this development soil group is divided into mineral, organomineral and organic groups.
Frozen
Frozen varieties of soil are the same dispersive cryogenic types, but in addition they have the so-called cryogenic bonds. Soils where only cryogenic bonds are found are commonly called icy.
Particle size classification
The table of the group of soils by particle size is as follows.
| Particles | Fractions | Size mm |
| Large debris |
| Blocks | large | > 800 |
| medium size | 400-800 |
| small | 200-400 |
| Crushed stone | large | 100-200 |
| medium size | 60-100 |
| small | 10-60 |
| Gravel, Dresva | large | 4-10 |
| small | 2-4 |
| Little debris |
| Sand | very big | 1-2 |
| large | 0.5-1 |
| medium size | 0.25-0.5 |
| small | 0.1-0.25 |
| very small | 0.05-0.1 |
| Suspension |
| Dust (silt) | large | 0.01-0.05 |
| small | 0.002-0.01 |
| Colloids |
| Clay | | <0.002 |
Determination of the type of soil at the construction site
Even a person who is not familiar with geology will be able to see the difference between sand and clay, as well as between other groups of soil. And not everyone can already determine the estimate of the share of clay and sand in the mixture. It will be quite difficult to understand externally what percentage of the net length, for example, is contained in the soil. First of all, it is necessary to examine nearby residential areas. The experience of organizing the foundation of neighbors can provide very valuable information. If the fences are slanted, the foundations are deformed when they are not deeply laid, and there are cracks in the walls of the house, then all this may indicate too rough ground.
After this, you need to take a small amount of soil for sampling from your site. It is advisable to do this closer to the place where the future house will be built. Some experts are advised to make a small hole. However, the narrow trench cannot be dug too deep. Therefore, construction can begin with a deep hole under the septic tank. Thus, a well is obtained, the depth of which should be at least 3 m, and the width should be at least 1 m. Such a well will have many advantages:
- the space where it will be possible to take soil samples from various depths;
- external inspection of the soil in cross section;
- the ability to check the soil, without removing it, for its strength, including the side walls.
However, it is worth paying attention to the fact that concrete rings must be installed in the well so that it does not crumble on the sides from precipitation. Also, during construction, it is worth taking into account the table of the soil group, which was presented above.