Sand: formula, characteristics. Sand for construction

Sand, the formula of which is as follows: SiO2, is a mountain sedimentary rock and an artificial material that has elements of rocks in the composition. 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. First of all, this should include private and industrial construction. Sand becomes part of various solutions for the formation of foundations and plastering surfaces.

Description of sand

Natural sand is a loose mixture of grains, the fraction of which varies from 0.16 to 5 mm. The material is formed when solid rock is destroyed. Depending on how the accumulation took place, the sand can be:

• Deluvial;
• Alluvial;
• Lake;
• Marine;
• Aeolian.

As a result of the activity of watercourses and reservoirs, sands appear that have a rounded and rounded shape.

Main characteristics of building sand

The 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 sands consists not only of quartz, but also feldspars. In the role of impurities there are clay minerals and silicates.

On the surface of the earth the sands are quite common, both in the seas and on land. The porosity in the friable state is approximately 47%, while in the dense state it is 37%. Density is estimated by the coefficient of porosity. For fine-grained sands, this value is 0.75.

Sand, the formula of which can be useful to professionals, has an open porosity, which ensures the quality of water permeability. If the sand is densely packed, then it is capable of absorbing loads and distributing stress under the foundations. The modulus of deformation of fine-grained sands varies from 30 to 50 MPa.

Specific gravity of different types of sand

Sand, the formula of which is not so often required by builders, has a certain specific weight, depending on the variety of materials. In the case of construction sand, this value is 1.5 t / m ³ , while the cubic meter of dry loose construction sand will weigh 1.44 t. In a compacted form this value increases to 1.68 t / m ³ .

In the wet form, construction sand weighs 1.92 t / m ³ , and in the compacted wet form the specific gravity is 2.54 t / m ³ . The mass of sand will vary with 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.

In addition to the density

Considering the properties of sand, it should be noted that in one of its important qualities is density. If we are talking about a quartz variety of material, then this characteristic is determined by two approaches. Thus, the density can be bulk and true. Bulk is determined by the method of the ratio of mass to volume in the free-flowing state. This value means not only grains, but also airspace. This value can vary from humidity.

Sand construction can also be characterized by true density, this value is constant and is determined by the ratio of matter to volume in a dense state. At the same humidity does not matter. Density changes with a change in chemical composition or molecular structure.

The true density is greater than the bulk density. Hardness, crushing and abrasion of sand are indirect indicators of strength. To determine these parameters, tests are performed on a rotating and abrasive wheel. The seeds are then clamped mechanically.

GOST and basic parameters of building sand

Sand construction is divided into quarry and river. This material is manufactured in accordance with GOST 8736-93. Depending on the purpose, quality and standardized parameters 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. The first class includes coarse-grained sand, which is obtained by crushing screening. The second class of sand assumes not only very large sand, but also fine, medium, and also thin material.

The sand, the GOST of which was in the above mentioned, can also be an alluvial. This material is obtained by washing career sand. Used in this case, the liquid in a large volume, which allows you to rid the material of clay and dust particles. Injected sand can assume the presence of fine fractions, the dimensions of which are 0.6 mm. This kind of sand is used for plaster works, where the presence of clay is undesirable.

The size of the river sand

The chemical formula of sand can help a specialist, but this is rarely paid attention to by private craftsmen. A more important parameter for them is the grain composition, which is determined by a set of sieves with cell sizes ranging from 0.16 to 5 mm. Dry sand passes a sieve, which allows you to determine the partial and complete residue. The size of the complete residues and will determine the grain composition.

For mortars , use a sieve with a size modulus of 1.2. If we are talking about concretes, then this value should be equal to two. In this case, the grain composition for concrete is regulated by GOST 10268-80. The river sand is used in construction taking into account factionalism. 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.

Dependence of bulk density on humidity

Natural river sand can have a bulk density in the range from 1300 to 1500 kg / m ³ . The material will change its volume and bulk density if the 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. After all, each grain of sand will be covered with a thin layer of liquid, and the volume of material will increase. If the humidity increases, the water will enter the voids between the grains, displacing the air. The bulk density will then increase again, which should be taken into account 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, extracted from the river bed, it is characterized by a high degree of purification and the absence of stones, clay impurities and foreign inclusions. The washed quarry sand is mined in the quarry by the washing method, as a result of which dust and clay particles are removed from it.

Seed quarry sand is mined in a quarry, cleared of stones and large inclusions. It is widely used in the manufacture of solutions for foundation work, masonry and preparation of plaster. Career soybean sand quite often becomes the basis of asphalt mixes.

Construction sand is an inorganic bulk material, which is formed by the method of natural destruction of rock. Artificial heavy sand is a loose mixture, which is obtained by the method of crushing rocks as follows:

• Limestones;
• Granite;
• Marble;
• Slags.

The shape of the grains turns out to be acute, and the surface is rough. This material is used as a filler and when carrying out the plaster works, when it is necessary to achieve the effect of a tangible texture of the covering layer.

Artificial sands can become a part of any layer of plaster, the fractionality can be different, depending on the solution and the requirements of the project.

Artificial sand is made from coal slag, and charred coal is used for processing. As a result, a low sulfur content is obtained in the material, on which the quality of the coating layer depends. When performing decorative plaster using artificial sand, rubble, powder and crumb of this rock can be used for saving with it.

Conclusion

The cost of sand depends on its characteristics and is related to the remoteness of the quarry from the areas of consumption. The cheapest is the natural quarry sand that has not been processed. It contains clots of clay and a large amount of clayey mud particles. After finishing the treatment, the price of sand increases. Seed sand can cost 2 times more expensive than its predecessor.