Sand (38 photos): types and fractions, fine and coarse natural sand, its classification according to GOST, the chemical composition of the rock

Definitions

There are several types of sand, for a qualitative understanding of the essence of the issue, you need to familiarize yourself with the main differences:

natural sand. A material that has a free-flowing state, while it is inorganic. The grains reach a size of 5 mm. Sand is produced by the natural crushing of rocks. It is obtained by mining from sandy deposits or mixed with gravel;

Natural

special enrichment equipment can be used;
crushed. The grain size does not differ and is less than 5 mm. It is made by man using special equipment of crushing and grinding type. Received by crushing rocks;

Crushed

fractional. This is a homogeneous sand that has been previously divided into 2 or more fractions. For this, special equipment for sifting is used;

Fractional

screenings from crushing. Product of inorganic origin, grain size up to 5 mm. It is obtained by sifting out the destroyed rocks of the mountains. It is a minor product in the production of crushed stone and some types of metals. Also obtained from some non-metallic minerals.

Grades and fractions

The grain size of the sand is distinguished by the following grain sizes:

up to 0.5 mm - fine fraction;
from 0.5 to 2 mm - middle fraction;
from 2 to 5 mm - large.

It is not uncommon for construction sites and production to use sand screening. The size of the grains in it is about 5 mm. It is not a natural sedimentary rock, but a derivative that appears in the process of crushing stones in industrial quarries. Professionals call it "0-5 fraction rubble".

After the stones are crushed, sorting work is carried out at the quarry using specialized units, the so-called "screens". Large pieces of stone are sent to a conveyor belt along moving metal grates installed at an angle, while small pieces fall into open cells and are collected in heaps. Everything that appears in the cells of 5x5 mm is considered screening.

The brand is one of the important characteristics that determine the purpose of the sand:

800 - rocks of the igneous type are taken as the source material;
400 - sand from metamorphic raw materials;
300 - means a product of sedimentary rocks.

An important factor that determines the likelihood of using sand in specific construction or household tasks is the size of the grains, which is called the coarseness modulus.

Dusty. Very fine sand with particles no more than 0.14 mm. There are 3 types of such abrasives, depending on the level of moisture: low-moisture, wet and water-saturated.
Fine-grained. Means that the grain size is 1.5-2.0 mm.
The average size. The grain is about 2.5 mm.
Large. Granularity approximately 2.5-3.0 mm.
Increased size. Sizes range from 3 to 3.5 mm.
Very large. The grain size exceeds 3.5 mm.

The filtration coefficient is taken into account, showing the speed with which water passes through the sand under the conditions established by GOST 25584. This characteristic is influenced by the porosity of the material. The design resistance also differs in type and brand. To determine it, you need to use special tables with calculations. Calculations must be made before starting construction work.

Materials of natural origin have a bulk density of about 1300-1500 kg / m3. This indicator increases with increasing humidity. The quality of the sand is determined, among other things, by the class of radioactivity and the proportion of additives (in percentage terms). In the smallest and moderately fine sandy masses, up to 5% of additives are allowed, and in other types - no more than 3%.

Types of sand

Sand is a type of inert material, which is a loose mixture of yellow or brown color. The size of sand can vary from 0.16 - 5 mm, and all types of sand, without exception, are classified primarily by location.

River sand, as the name implies, is mined in rivers. The size of river sand can be from 0.3 to 0.5 mm. Sand of this type is widely used for construction purposes, as well as at treatment facilities when arranging purification filters.

For plaster, river sand is poorly suited due to its rapid settling. Therefore, for plastering it is best to use sand extracted from quarries, but only without admixture of clay.

Quarry sand - is extracted from artificial quarries. Its fraction is not so large, from 0.6 - 3.2 mm. Sand extracted from quarries often contains impurities of dust particles and stones.

Most often, this type of sand is used as a sand cushion under the foundation, in the manufacture of monolithic products, etc. For finishing work in the form of plaster, quarry sand can also be used, especially since many sand manufacturers today wash and sift their products before selling.

Well, you can read about how to wash the sand at home in another article in this construction magazine.

Separate types of sand include sea sand and artificial sand. The first is mined from the bottom of the seas and practically does not contain any impurities in its composition. This material is very much in demand in the construction industry, but due to its rather difficult method of extraction, there is a certain shortage in it.

Artificial sand is produced by crushing various types of stone, such as marble or granite. Quartz sand, which also belongs to artificial types of sand, is the most in demand today.

It is widely used in sandblasting, as well as for the manufacture of various decorative materials, in the production of concrete mixtures and much more. You can read about sandblasting sand by clicking on the highlighted link.

Sand classification by size

All types of sand are classified according to the so-called coarseness modulus (GOST), depending on the grain size

And since it is important to use only suitable sand to perform certain types of construction work, it is advisable to understand this issue

Dusty sand has a very fine dust-like structure. The size of grains of dusty sand is not more than 0.14 mm. A slightly larger grain size is observed in sand of fine modulus, up to two millimeters. Sand of medium size, has a grain size of 2.5 - 3 mm. Well, everything above 3 mm is sand of increased coarseness.

It should always be remembered that the smaller the sand is, the more liquid will have to be used to prepare a construction mixture from it. As a rule, the finest types of sand are used in the manufacture of various solutions, and medium-sized sand is most in demand for concrete solutions.

Size matters

The greater the granularity of the sand, the larger the grains of sand, the stronger the building mixture will be with them in the composition. But at the same time, it will be less plastic.

That's why:

Coarse grains are good for the production of high-grade concrete from B35 (M450). In private construction, it is used for paving slabs, curbs, well rings. It is also an excellent solution for a drainage device, because the more grains of sand, the better they absorb water.
Sand of medium grain size is a universal solution for the production of bricks and commonly used grades of concrete B15 (M200). Such concrete is used for foundations, staircases, retaining walls; plots on plots, paths, etc. are poured with it.
Fine-grained sand is a part of building mixtures, which have special requirements for leveling and finishing properties. We are talking about plaster, bulk field - wherever the fineness of application, evenness, smoothness are very important.

So when you purchase sand for the preparation of building mixtures, be guided by the manufacturer's recommendations for use.

What kind of sand you pour into a concrete mixer, you will get such a mixture

Can you determine the graininess by eye?

In general, yes. Large grains of sand in front of you or small ones can be seen with the naked eye. But it is better to measure, even if you decide to dig the sand yourself and will not use it in a responsible facility.

Place a small amount of sand in front of the ruler, and then check the grit values above. The main thing is that all the material is homogeneous, otherwise measure some fractions, and dig deeper, you will dig up grains of sand of a completely different size.

Also focus on color:

yellow (towards beige) or beige;
medium - brighter, more yellow;
small - pale yellow, white, with a grayish tint.

Why not try to determine the grain size of the sand yourself?

Applications

The main area of use of sand is construction and industry. In addition, the material is widely used in everyday life, for example, to increase soil fertility. Not all gardeners know which specific species are best suited for the beds. Clay (quarry) sand extracted from the depths of sandstones is considered infertile. He weakly permeates water and practically does not "breathe". Some summer residents use standard construction sand for the garden, not realizing that this only worsens the quality of the soil.

River sand extracted from river beds will help to increase soil fertility on the site. It helps to retain moisture, planted cuttings quickly take root in it, roots grow safely, which are not damaged during transplantation. Soil mixtures based on river sand are considered the best options for seedlings and grown plants. A combination of 40% river sand with 60% high quality peat is considered optimal.

It is best to mix solutions from dry components with washed sand. It is also the most successful material for creating reinforced concrete building blocks. And in road construction, coarse-grained sand shows itself perfectly. Washed fine sand is often added to the finishing putty, decorative mixes and grouts. For self-mixing of mixtures under self-leveling floors, you need to buy high-quality fine-grained sand.

Sifted quartz sand is used for the base of the flexible stone mix. And screening is in demand in the production of asphalt concrete, as a component of building mortars, therefore it is widely used in landscape design in adjoining plots. It can be used for the manufacture of paving slabs and certain grades of concrete. But more often, ordinary sand is used for this purpose.

Rules for the reception of quartz, river and alluvial sand

Quartz, river, alluvial sand and screenings during crushing must be assessed before shipment to the consumer and additional samples are taken upon delivery of the cargo. For this, special tests are carried out, the technical control service is responsible for the reception.

So samples are taken from each production line, then it is confirmed whether the sand is suitable for construction or whether the sand is suitable for sandblasting or there are any deviations from the norm.

During the control, it is revealed:

the composition of the grains;
the presence of clay and its amount in pieces;
the amount of dusty residues and clay components;
lack of third-party impurities and debris.

Periodic monitoring is carried out in order to determine changes in rocks over a certain period of time:

once every 3 months - the density of the embankment is determined, if necessary, a test is possible under certain humidity conditions. The presence of harmful, organic additives and their quantity are revealed;
once a year or with a changing composition of the rock, it is necessary to check the density of the grains, the amount of minerals contained, mainly harmful. The strength grade and efficiency of radionuclides are determined.

Research on radionuclides cannot be carried out within the enterprise, so the samples are taken to specialized research institutions. They must be accredited by supervisors.

If geological analysis data are not available, then an assessment of the radioactivity can be carried out immediately after extraction. An expressive version is used, based on the alluvium map. Sample preparation for examination is carried out on the basis of GOST 8735.

When delivered by rail or sea, the consignment is the simultaneous quantity of the shipped cargo. Upon delivery, all material brought in a day is taken into account.

Why do you need a passport for sand GOST 8736 93

The consumer may require a passport for sand GOST 8736 93 issued to the enterprise and technical documentation for the batch. To obtain information about the quality of the goods, samples should be taken, their quantity depends on the order:

for a batch up to 350 m3, the number of samples is 10;
orders of 350 - 700 m3 can be sampled 15 times;
over 700 m3 should be sampled from 20 different locations.

The price per m3 of sand GOST 8736 93 is approximately 500 rubles, but the cost varies greatly in accordance with the quality of the product, the distance of the quarry and the manufacturer's or intermediary's premium. So river sand GOST 8736 93 is somewhat more expensive than screening after crushing.

Also, coarse sand is somewhat cheaper than the fine fraction and not every manufacturer divides the fraction.

Properties

Natural material is formed due to the combination of minerals, rocks. The particles are of different sizes, do not stick together. Coarse sand can be found in quarries or at the bottom of water bodies. There is also an artificial method of extracting natural material by crushing rocks, for example, quartz. Therefore, the following types of material are distinguished, which have a name.

Career. The grains of sand have an uneven surface. Such material is much more common.
River. The grains of sand have a smoother surface, are heavy and therefore quickly settle to the bottom. Such material is less common and more expensive.
Quartz. The grains of sand have a flat surface and are of the same size. The substance has reliable performance characteristics. The quality characteristics of a coarse-grained substance are determined by the presence of various impurities, for example, clay, pebbles, dust, crushed stone. The cleaner the sand, the higher the quality, and the more expensive it is.

The sizes of grain fractions are measured in size modules.

Coarse material, where the modulus is from 2.5 to 3.
Material of increased size, where the indicator exceeds 3.

There are two classes of sand, which differ in the indicator of the presence of grains of different sizes and impurities. The density of a substance depends on the size of the internal cavities between solid particles. There are the following types of density.

Real. This indicator is applied in practice. It is taken into account when using sand in various fields. The density index is influenced by the type of sand, the size of the fractions, and the presence of impurities. Determining the exact indicators is quite difficult. The fact is that the specific gravity is influenced by the moisture content of the substance. The higher the humidity, the higher the density.

Conditional. This indicator is determined in laboratory conditions using complex methods. The figures obtained differ in a larger way from the real density. The physical parameters of sand include the following.
- The ability to maintain its properties at low temperatures.
- Roughness, which ensures reliable adhesion in mortars.
- The ability to expand in volume.
- Low radioactivity allows the material to be used in any area.

How is it checked?

As mentioned above, the building material must meet a number of stringent requirements. The conformity of the material to certain properties and characteristics is checked during specially designed tests. All of them are regulated by official documents and GOSTs.

Determination of the composition of grains. In order to correctly assess the composition of the sand (to determine the properties of its fractions), the material is sieved through a sieve specially designed for this purpose. After all the sand has been sifted, but especially large particles remain in the sieve, they are measured and weighed. In this way, the average grain size is determined.
Determination of the presence or absence of impurities. In order to assess the level of purity of the sand, experts select the viscous particles of the material from its total volume.
Calculation of the amount of clay and dust. To make such calculations, the method of varying the weight after soaking the fractions is traditionally used. In some cases, so-called pipette and photoelectric methods can also be used.
Determination of the presence of organic matter. The composition of building sand quite often includes various substances of a humic nature. In order to understand how many of these components are present in the composition of the material, experts began to carry out a comparative analysis. To do this, the sand itself is painted with ethanol, and then the resulting mixture is compared with the coloring of an alkaline solution.
In relation to the sand that is mined by processing various rocks, the method of analyzing the amount of minerals in the composition is used. For these purposes, devices such as a binocular loupe or a microscope are used.
For a clear determination of the density index, a pycnometric method is used.
An important step in assessing the quality of sand is determining the presence or absence of voids between grains, as well as calculating an indicator such as bulk density. For these purposes, use specific measuring glassware.
In order to analyze the moisture content of the sand, compare the material in its natural state, as well as the sand in the state of the material dried in a special cabinet.

Choosing sand for concrete

The difference between quarry and river sand is so noticeable that it is customary to use material of river origin in construction practice. At the same time, it is worthwhile to carefully study the analysis data - the minimum amount of contamination and the uniformity of the fraction significantly increase the predictability of the properties of the concrete solution and the final concrete monolith.

If we rely on the opinion of professionals, then the question of which sand is better for preparing concrete, then the primacy will remain with the river - medium and large fraction, with minimal sedimentary impurities. For the creation of drainages, river material with a throughput (filtration coefficient) of 12 m per day is suitable, which is three times higher than the indicator of quarry sand.

The homogeneity, smoothness and purity of the mass extracted from the bottom of a river or a dried-up bed allows you to pack and sell sand in 40 kg bags, as a material with predictable properties and a guaranteed level of quality. The properties of quarry and river sand are so different that in the field of professional construction and work with concrete, these are practically different materials with their own specific areas of application. It is possible to save on the use of alluvial sand from a pit in a concrete solution - provided that the monolith does not bear a heavy load and its strength does not become critically low for the integrity of the entire structure.

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Scope of application

Possessing unique characteristics, quartz sand has found wide application in human life and is used in the following areas:

used in construction for the manufacture of various types of decorative plasters, dry mixes, as well as for the creation of self-leveling floors;
for injection heat-resistant forms in the metallurgical industry;
for the pool as a filter material;
for football fields as a covering;
in the production of glass, fiberglass;
in the production of building materials - for the manufacture of sand-lime bricks, paving stones, refractory concrete;
in the agro-industrial sphere as an additive in animal feed;
in the manufacture of electrical fuses, since quartz is a dielectric material;
for creativity and drawing, in landscape design;
when composing mixtures for the production of reinforced concrete with increased strength.

Quartz sand is a part of modern road surfaces, since silicon dioxide is strong and resistant to abrasion, which allows the asphalt road to be durable and reliable, despite the huge weight load and high cross-country traffic. Most of the tableware on the shelves is made using quartz sand. A mineral additive from fine-grained quartz allows it to be added to porcelain, earthenware and ordinary glass, which gives these materials increased strength and shine. Quartz is also added in the manufacture of technical glasses, as well as window, automobile varieties, with its use, laboratory glassware that is resistant to heat and chemical environments is produced, and is also added to the composition of the mass intended for the production of ceramic finishing tiles.

But that's not all. Quartz sand is an integral component used in the production of optical lenses, making these products smooth, transparent and durable in use. Due to its ability to retain heat, quartz sand is used for industrial and domestic needs. With his participation, electric heating devices are made - quartz is included with an incandescent spiral system, which heats up quickly and maintains the required temperature for a long time.

Engraving and grinding surfaces, as well as processing stone, metal or durable polymers, are not complete without the use of quartz sand, which is used in sandblasting materials. The essence of the process lies in the fact that acute-angled rock particles, mixing with the air flow, are supplied under a certain pressure to the surface to be treated, which is polished and becomes perfectly clean and smooth.

The well-known ability of quartz sand to absorb various substances is used to filter water in hydraulic structures of various types and purposes. In addition, the adsorbing properties are used in the food industry, as well as in the production of filter technology.

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