Sand, the formula of which is as follows: SiO2, is a rock sedimentary rock and an artificial material containing rock elements. Quite often, it consists of pure mineral and quartz, which is silicon dioxide.
Today, sand has found its wide distribution in many areas of human activity. This primarily includes private and industrial construction. Sand becomes part of different solutions for the formation of foundations and plastering surfaces.
Sand description
Natural sand is a loose mixture of grains, the fraction of which varies from 0.16 to 5 mm. Material is formed during the destruction of hard rocks. Depending on how the accumulation occurred, sand may be:
- deluvial;
- alluvial;
- lakeside;
- sea;
- aeolian.
As a result of the activities of watercourses and ponds, sands arise that have a rounded and rounded shape.
Main characteristics of building sand
Sand, the formula of which was mentioned above, is a loose non-metallic material that can be used in almost any construction work. The bulk of such sand consists not only of quartz, but also of feldspars. Clay minerals and silicates are present as impurities.
Sands are quite common on the surface of the earth, both in the seas and on land. The porosity in the loose state is approximately 47%, while in the dense state it reaches 37%. Density is estimated by the coefficient of porosity. For fine sands, this value is 0.75.
Sand, the formula of which can be useful to professionals, has open porosity, which ensures water permeability. If the sand is tightly laid, then it is able to absorb loads and distribute stress under the foundations. The deformation modulus of fine-grained sands varies from 30 to 50 MPa.
The proportion of different types of sand
Sand, the formula of which is not so often required by builders, has a certain specific gravity, depending on the type of materials. If we are talking about building sand, then this value is equal to 1.5 t / m 3 , while a cubic meter of dry loose building sand will weigh 1.44 t. In a compacted form, this value increases to 1.68 t / m 3 .
In the wet state, construction sand weighs 1.92 t / m 3 , and in a wet compacted state, the specific gravity is 2.54 t / m 3 . The mass of sand will vary in river, quartz, marine and quarry varieties. The specific gravity of these sands will be as follows: 1.6; 1.6; 1.62; 1.5 t / m 3, respectively.
More about density
Considering the properties of sand, it should be noted that density is one of its important qualities. If we are talking about a quartz variety of material, then this characteristic is determined by two approaches. Thus, density can be bulk and true. Bulk is determined by the ratio of mass to volume in a loose state. This value means not only grains, but also airspace. This value may vary due to humidity.
Building sand can also be characterized by true density, this value is constant and is determined by the ratio of substance to volume in a dense state. The humidity does not matter. Density changes with a change in chemical composition or molecular structure.
True density is greater than bulk density. Hardness, crushability and abrasion of sand are indirect indicators of strength. To determine these parameters, tests are carried out on a rotating and abrasive wheel. Grains are clamped mechanically.
GOST and basic parameters of building sand
Building sand is divided into quarry and river. This material is manufactured in accordance with GOST 8736-93. Depending on the purpose, quality and standardized indicators that determine the content of clay and dust particles, the material can be divided into two classes, each of which has its own grain composition.
The chemical formula of sand was mentioned above, however, it is not the only thing that professionals are interested in. Depending on the grain composition, the material can be classified by size. Coarse sand, which is obtained by crushing screenings, belongs to the first class. The second class of sand involves not only very coarse sand, but also fine, medium, and also thin material.
Sand, GOST which was in the above, can also be alluvial. This material is obtained by washing quarry sand. In this case, a large volume of liquid is used, which allows you to rid the material of clay and dust particles. Washed sand may suggest the presence of fine fractions, the dimensions of which are 0.6 mm. This type of sand is used for plastering, where the presence of clay is undesirable.
River sand fineness modulus
The chemical formula of sand can help a specialist, but this is rarely done by private craftsmen. A more important parameter for them is the grain composition, which is determined by a set of sieves with mesh sizes ranging from 0.16 to 5 mm. Dry sand passes a sieve, which allows you to identify private and complete residues. The size of the total residues and will determine the grain composition.
For mortars , sieves with a particle size of 1.2 should be used. If we are talking about concrete, then this value should be equal to two. At the same time, the grain composition for concrete is regulated by GOST 10268-80. River sand is used in construction, taking into account fractionality. Quite often, it is divided into large and small. In the first case, the particle sizes can vary from 1.25 to 5, in the second - from 0.16 to 1.25 mm.
Bulk density versus humidity
Natural river sand may have a bulk density ranging from 1300 to 1500 kg / m 3 . The material will change its volume and bulk density if humidity changes from 0 to 20%. If the humidity varies from 3 to 10%, then the density will decrease compared to that of dry sand. Indeed, at the same time, each grain of sand will be covered with a thin layer of liquid, and the volume of material will increase. If humidity increases, water will enter the voids between the grains, displacing the air. The bulk density will increase again, which should be considered when dosing the material by volume.
Features of the main varieties of sand
Sand, GOST of which was mentioned in the article, is classified according to the processing and origin. For example, river sand is extracted from the riverbed, it is characterized by a high degree of purification and the absence of stones, clay impurities and foreign inclusions. Washed quarry sand is mined in the quarry by washing, as a result of which dusty and clay particles are removed from it.
The seeded quarry sand is mined in the quarry, cleaned of stones and large inclusions. It is widely used in the manufacture of mortars for foundation work, masonry and preparation of plaster. Career seeded sand quite often becomes the basis of asphalt mixtures.
Building sand is an inorganic bulk material that is formed by the natural destruction of rocks. Artificial heavy sand is a loose mixture, which is obtained by crushing rocks of the type:
- limestone;
- granite;
- marble;
- toxins.
The shape of the grains is acute-angled, and the surface is rough. This material is used as a filler and during plastering, when there is a need to achieve the effect of a tangible texture of the coating layer.
Artificial sands can become part of any layer of plaster, while the fractionation can be different, which depends on the solution and the requirements of the project.
Artificial sand is made from coal slag, and charred coal is recycled. As a result, a low sulfur content is obtained in the material, on which the quality of the coating layer depends. In the implementation of decorative plastering using artificial sand, gravel, powder and crumbs of this breed can be used together with it to save.
Conclusion
The cost of sand depends on its characteristics and is associated with the remoteness of the quarry from the areas of consumption. The cheapest is natural quarry sand that has not undergone further processing. It contains lumps of clay and a high content of clay silty particles. After processing, the price of sand rises. Sown sand can cost 2 times more expensive than its predecessor.