Sand contains a mineral. Varieties of sand

/ Rock Sand

Sand is a fine-grained, loose sedimentary rock consisting of grains of minerals from destroyed rocks. Natural sand is a loose mixture of grains 0.14-5 mm in size, formed as a result of the destruction of hard rocks. It consists mainly of grains of minerals (quartz, feldspar, mica, etc.), small fragments of rocks, and sometimes particles of skeletons of fossil organisms (corals, etc.).
The grain sizes in sands usually range from 0.1 to 2.0 mm.

Sands are classified according to grain size:

coarse-grained (2.0-1.0 mm.),
coarse-grained (1.0-0.5 mm.),
medium grain (0.5-0.25 mm.),
fine-grained (0.25-0.01 mm.).

The shape of the grains can be rounded, semi-rounded, angular and acute-angled - depending on the origin and duration of grain transfer.

By origin, sand can be river, lake, sea and bottom, and by composition - quartz, glauconite-quartz, arkose, magnetite, nepheline, mica, polymict, etc. Most often, quartz and polymict sands are found with a greater or lesser admixture of other mineral components (clay, mica, chlorite, iron oxides, feldspar, glauconite, carbonates).

Often sands are monomineral quartz, and then consist of almost pure quartz.
Depending on the conditions of occurrence, natural sands can be river, sea, mountain, or ravine. River and sea sands have rounded grains, mountain sands contain acute-angled grains. Mountain sands are usually more contaminated with harmful impurities than river and sea sands.

As a result of natural cementation of sands, sandstones are formed.
The term sands in geomorphology is used to designate flat areas covered with a more or less thick sandy cover.

Practical use

Sand is widely used in building materials, for washing construction sites, for sandblasting building facades and various products, in housing construction for backfilling, in landscaping courtyard areas and in everyday life (filling paths, installing children's sandboxes, cat toilets, soil in greenhouses, etc.), in the production of mortar for masonry, plastering and foundation work. Widely used in concrete production; in the production of reinforced concrete products, high-strength concrete. An important material in the construction of roads, embankments, as well as in the production of paving slabs, curbs, well rings (in these cases, coarse sand Mk 2.2 - 2.5 is used). Fine construction sand is used to prepare covering mortars. River construction sand is widely used in various decorative (mixed with binding components and dyes to obtain special structural coatings) and finishing works. Construction river sand is a component of asphalt concrete mixtures that are used in the construction and laying of roads. Quartz sands are a valuable raw material for the glass industry.

Sand in construction

In modern construction they are most often used river sand and quarry sand.
river sand is a natural material extracted from the bottom of rivers. This type of sand contains practically no clay particles, as well as stones and pebbles. The moduli of river sand coarseness are mostly average. River sand particles are small (up to 2 mm), medium (2.0 to 2.8 mm) and large (from 2.9 to 5 mm). The color of river sand can be gray or yellow. River sand is considered a universal material and is used for any type of construction work, since it does not contain various impurities. River sand has become the main component needed for the production of concrete. River sand is also widely used for various finishing works. River sand is used as a component for asphalt concrete mixtures in road construction; it is also necessary during road laying. The main disadvantage of river sand is its high cost, which will significantly reduce the possible scope of its use.

Quarry sand. Unlike river sand, quarry sand usually contains various impurities, in particular clay and dust. In this regard, it is problematic to use quarry sand for preparing solutions. However, with the help of simple equipment, quarry sand is washed in hangars or embankments with large quantities of water. After leaching treatment, quarry sand can be used as a filler for concrete. Coarse quarry sand is used to construct foundations and surfaces for roads and airfields.

Artificial sand

Artificial sand is obtained by crushing rocks such as granite, marble, limestone, as well as man-made substances - slag, etc. Artificial sand is usually used to prepare decorative mortar and for the textured layer of external building panels.

Expanded clay sand (fine expanded clay) is a building material that is not sand in the strict sense of the word, but since such a term has taken root, it should also be mentioned. Expanded clay sand is a loose sand-like material obtained artificially by firing clay fines. The firing process takes place in special rotary and shaft kilns. Expanded clay sand can also be obtained by crushing expanded clay gravel. Typically, the particle size of such sand is from 0.14 to 5 mm. The main purpose of expanded clay sand is to fill lightweight concrete. There are several ways to produce expanded clay sand, but the most effective today is fluidized bed firing. This technology is the least expensive, which ultimately ensures a lower cost of expanded clay sand; the volume of sand obtained is always less than the volume of gravel.

Sand mining

Sand is mined by open-pit and alluvial methods. Various equipment is used for this. One method or another is selected based on the conditions in which the material is mined. Convenient access must be provided to the mining site. This is important to do for the rational use of funds.

There are sand deposits all over the world.

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Rock Sand

English name: Sand

Minerals in the rock Sand: Quartz

Sedimentary rock consisting of grains of rock fossils is called “sand.” Most often, sand consists of practically purified quartz mineral; it can be of both unnatural and natural origin. The grain size of natural material is 0.16-5 millimeters.

Types of material

Sand comes in the following types.

Bottom mined - material that is mined from river beds.
Sifted - sieved extracted from a quarry, cleared of large particles and stones.
Washed sand is a rock that is extracted from a quarry by washing with a huge volume of water. This washing allows you to remove dust particles and clay.
Construction is a loose rock, the grains of which have a particle size of up to 5 millimeters.
Heavy artificial - a material that is mined by crushing rocks.

History of the breed

The grains of sand appeared as a result of crushing the stone. Due to various external natural factors, rock weathering occurred. Sand existed even when life on Earth was just beginning.

Today sand is one of the indispensable materials. This is a universal rock, as it differs in technical characteristics.

What does sand look like?

The material has a dull yellow color. It can be very different in shade. Much depends on the deposit. Sand grains can be round or angular in shape.

Sand mining

There are sand deposits all over the world. The largest sand deposits of them are located in Russia - in St. Petersburg and the Leningrad region.

Features of use

In the production of various building materials, including reinforced concrete products and building mixtures, including concrete of various grades, sand is indispensable. It is also suitable for creating construction sites, for constructing embankments and roads, and landscaping adjacent areas. Sand is also used in foundation, plastering, a variety of finishing and decorative works, and in sandblasting. Sand is the most important ingredient for making glass. This breed is also suitable for purifying and filtering water.

Rock Properties

Rock type: sedimentary rock
Color: yellow
Color 2: Yellow

And an artificial material that contains fractions of rocks. Quite often it consists of the mineral quartz, which is a substance called silicon dioxide. If we are talking about natural sand, then it is a loose mixture, the grain fraction of which reaches 5 mm.

Classification by rock destruction

This material is formed during the destruction of hard rocks. Depending on the accumulation conditions, sands can be:

alluvial;
sea;
deluvial;
aeolian;
lake

When a material arises during the activity of reservoirs and watercourses, its elements will have a rounded round shape.

Main types of sand and features of their extraction

Today, almost all types of sand are used by humans in various fields of activity and industry. River sand is a building mixture that is extracted from river beds. This material has a fairly high degree of purification, which is why the structure does not contain small stones, clay impurities and foreign inclusions.

Quarry sand is extracted by washing with water in a huge volume, as a result it is possible to get rid of dusty clay particles. Considering the types of sand, you can find quarry sand, which is cleared of large fractions of stones during the mining process. This material is quite widespread in the production of mortars that are used for laying foundations and carrying out plastering work. You can also find quarry seeded sand in asphalt concrete mixtures.

Construction sand must comply with GOST 8736-2014, according to which the material is a loose inorganic mixture of coarse grains, the size of which reaches 5 mm. equal to 1300 kg/m3. Construction sand is formed during the natural destruction of rocks; it is mined by methods of developing sand-gravel and sand deposits without and with the use of processing equipment.

The main types of sand also include artificial heavy sand, which has the form of a loose mixture obtained by mechanical crushing of rocks, among the latter we should highlight:

slags;
granites;
limestone;
marble;
pumice;

Features of artificial sand

They can have different origins and densities. If we compare the grains of this sand with grains of natural origin, the former are distinguished by their acute angular shape and rough surface. Artificial sands are commonly used as fillers in the preparation of plasters and decorative mortars. As a result, it is possible to achieve a noticeable texture of the top layer on the outer surfaces.

This material can become part of any layer of plaster, because the fractionation of grains can be different, which depends on the type of solution. Typically, the grain size is assumed to be equal to the size of natural sand. When making artificial sand, burnt coal, rocks, and unburned particles with a low sulfur content are processed.

The characteristics of the material will depend on the quality of the covering layer. When making decorative plaster from such sand, in order to save money, crushed stone, powder of this rock or crumbs can be additionally added; the quality of the texture even benefits from this quality.

Applications and characteristics of sea sand

Sea sand can be used in the production of building mixtures, the manufacture of aggregates, plastering work, laying road bases, building fences and fences, as a filler for construction grouts and dyes. The production of such sand is regulated by GOST 8736-93.

Fractions can vary from 2.5 to 3.5 Mk, which determines the particle size modulus. The grain density is equal to the limit from 2 to 2.8 g/cm 3 . Sea sand should be completely free of foreign impurities, but in some fractions you can find a low content of clay and dust particles. Sea sand is characterized by labor-intensive production, which makes its cost higher than quarry

Characteristics and price of quarry sand

The main feature of quarry sand is the absence of impurities and frequency. Alluvial quarry material has the following characteristics: fraction ranging from 1.5 to 5 mm, density equal to 1.60 g/cm 3, as well as low content of clay, dust and other impurities. The latter should not contain more than 0.03%.

Quarry sand, the price of which per cubic meter is 2,200 rubles, is used not only in construction, but also in decoration, as well as in the national economy. The use of such sand is especially cost-effective in the production of concrete and bricks, as well as in road and housing construction.

Quarry sand, the price of which will be 2300 rubles, can be presented in the form of a material with a fraction ranging from 2.5 to 2.7 mm. In the production of high-strength concrete and reinforced concrete structures, alluvial quarry fractions are usually used. The quarry material is used for masonry and the production of paving slabs.

Technical characteristics of river alluvial sand and features of its extraction

Alluvial river sand has a density of 1.5 kg/m3. If we are talking about density in a state of natural humidity, then this figure will be reduced to 1.45. The composition may contain dust particles, silt and clay elements, but not more than 0.7% by weight. The moisture content of the material is 4%, while the specific gravity is 2.6 g/cm 3 . These types of sand are extracted using a dredger that is fixed to a barge. Such equipment is complemented by hydromechanical installations, powerful pumps, networks and tanks for dividing the material by composition. The extraction of sand from dry river beds is similar to the extraction of quarry sand.

Conclusion

Almost all types of sand can be classified as class 1 in radioactivity. The only exception is crushed sand. If we talk about other varieties, then they are radiation safe and can be used in all construction work without restrictions.

The use of sand is quite common today. For example, its quartz variety is used for the manufacture of welding materials for general and special purposes. As for the construction variety, it is used to obtain structural coatings by mixing with dyes. Sands are also used when carrying out finishing work, as well as when renovating premises. The material is also a component that is used in road laying and construction.

The term “sand” is commonly understood as a bulk material of non-metallic origin used at various stages of construction. The group of sands includes crumbly substrates of various types, differing in the production method, fraction sizes and amount of impurities.

Construction sand can be of natural or artificial origin. The first variety is formed as a result of the destruction of rocks of the rock type, which occurs naturally, and is mined by developing sand and sand-gravel deposits.

In the second case, granite, marble, tuff, as well as limestone rocks are used as the starting material for its creation, which are crushed to obtain the required structure. This type of sand is used to create textured solutions.

The strength of sand is determined based on the stability of the rock that serves as the basis for its production.

Depending on the degree of strength, various types are usually divided into the following grades:

grade 800, corresponding to igneous rocks;
grade 400, denoting rocks of a metamorphic nature;
grade 300, belonging to sedimentary rocks.

These designations are used to mark construction sands intended for external and internal work related to the finishing of concrete and reinforced concrete structures.

The most important indicator characterizing the quality of this material and the possibility of its use in various areas of production is the group of sand, determined by the level of its coarseness, as well as its grain composition, which is divided into the following fractions:

large, the particle size of which ranges from 2.0 to 5.0 mm.
medium, having grains ranging from 0.5 to 2.0 mm.
small, with grain sizes up to 0.5 mm.

The grain size of construction sand is a fundamental factor that directly influences the further use of this material. In accordance with this parameter, all construction sands are divided into two main classes: first and second.

In the composition of various solutions, sand of fine and medium fractions is often used, and coarse sand is one of the main components of concrete and is used in the construction of foundations of buildings under construction.

Classification of sands by type and their characteristics

The main technical parameters characterizing the quality and composition of this material include the following.

Size module

This indicator reflects the size of sand fractions and includes the following varieties:

dusty. This type of sand has a very fine structure, resembling dust in appearance. The grain size of this material ranges from 0.05 to 0.14 mm. In turn, silty sands are usually divided into several subtypes: unimportant, wet and saturated with water.
fine sand, the grain size of which is from 1.5 to 2.0 mm.
medium-sized, which includes fractions from 2 to 2.5 mm.
large, having grains of 2.5 - 3.0 mm.
increased fineness - from 3.0 to 3.5 mm.
very large, having grains measuring 3.5 mm or more.

This is what quartz sand with a fraction of 1-2 mm looks like:

Filtration coefficient

Another important characteristic describing the physical and technical properties of the material is the filtration coefficient. This parameter demonstrates how much water is needed to pass a cubic meter of sand per unit of time (hour). The porosity of the material directly influences the value of this indicator.

Bulk density

The value of this indicator for a material of natural origin is about 1300 -1500 kg/m?. When humidity changes, its volume changes, which directly affects the bulk density. Moreover, regardless of the origin and production method, construction sand must comply with the requirements of GOST 8736-93.

The characteristics of construction sands also include:

radioactivity class;
the amount of dust, clay and silt impurities present.

To ensure the quality of the material and the possibility of its subsequent use as a binder in mortars, there are quite strict requirements regarding the amount of impurities it contains.

In particular, in the total mass of medium, coarse, and high-size sand, the presence of no more than 3% of dust, clay and silty impurities is allowed. For fine and very fine sands this figure is 5%.

Artificial origin

Unlike natural varieties, artificial sands are produced using specialized equipment through mechanical action on rocks. In turn, artificial sands are divided into subtypes of sedimentary and volcanic origin.

These include:

thermosite or porous sands from slag melts, obtained from materials with a porous structure, for example, slag pumice. They are considered one of the most economical types, since the basis for their production is industrial waste.
perlite sands. They are produced through heat treatment from crushed glasses of volcanic origin, called perlites and obsidians. They have a white or light gray color and a minimum bulk density of 75-250 kg/m?. Used in the manufacture of insulation elements.
quartz. Sands of this type are also commonly called “white” because of their characteristic milky white hue. However, the more common varieties of quartz sand are yellowish quartz, which contains a certain amount of clay impurities. Due to its versatility and high quality, sand of this type is widely used in various industries, including water treatment systems, glass, porcelain production, etc.
expanded clay. P obtained by crushing expanded clay gravel, mainly in roller crushers, followed by firingin a fluidized bed orin a rotating kiln.
marble. It is one of the rarest species. Used to make ceramic tiles, mosaics, and tiles.

The main advantage of artificial sand compared to its natural counterpart is the minimum amount of foreign impurities and the uniformity of the composition, due to which a higher quality of the final product produced on its basis is achieved.

If you evaluate this material using a traditional five-point scale, its cost, practicality and appearance can be assigned solid “fives”. The only thing that raises doubts is the environmental friendliness of this species, since the radioactivity level of sands of artificial origin is much higher than natural ones.

Types of construction sand

Natural views

Based on the extraction method and origin, natural construction sands are usually divided into several main groups. These include:

river sand. This variety is considered the “cleanest” and is used in the manufacture of many mortars. The main advantage of this type is its homogeneous structure and small particle sizes, on average ranging from 1.5 to 2.2 mm. At the same time, individual grains of sand, due to “polishing” with water for a long time, have a “correct” oval shape. However, at the same time, river sand is considered one of the most expensive types of this building material, which is why, in order to save money, it is often replaced with cheaper quarry sand.
nautical. This type of sand also has minimal contamination caused by the accumulation of salts present in seawater, most of which are removed through a two-stage cleaning system. Having a sufficiently high quality, sea sand is also suitable for cleaning industrial equipment using sandblasting machines, creating screeds, etc.
ravine or mountain. These types are characterized by the presence of clay, which somewhat reduces the strength of the solutions, and therefore are used less frequently.
career It also has a fairly large volume of clay and dust, but is one of the most commonly used types due to its low cost. For example, quarry sand is widely used in “zero cycle” work, as well as in housing and road construction, for preparing construction sites and backfilling.

Characteristics of river sand

Specifications	Indicators
Density of dry river sand	1.5kg/m3
Density of river sand in a state of natural humidity	1.45 g/cm3
Humidity of river sand	4,00%
Content of dust, clay and silt particles in river sand	0.7% by weight
Specific gravity of river sand	2.65 g/cm3
The presence of lumps of clay in river sand, loam and other clogging impurities	0,05%
More than 10 mm of gravel particles in river sand in ballast	0%
Modulus of river sand fineness	1,68

In addition to this gradation, quarry sand is divided into the following subgroups:

Alluvial (washed)

It is extracted in quarries using a special technology using a large amount of water and a device called a decanter, in which the sand mass settles and the waste liquid is removed from the sediment. Thus, it is cleaned from clay and dust particles present in the bulk of the material. Sand of this type is characterized by the presence of very fine fractions, with an average size of about 0.6 mm. Used in the manufacture of mortars and concrete, in road construction, etc.

Seeded

This species is also mined in quarries, and, after reaching the surface, it is subjected to mechanical processing, as a result of which foreign substances present in it, such as dust particles and clay, are eliminated.

The main advantage of sand can be called its versatility, which allows the use of this building material in all areas of construction production: from the zero cycle to the finishing of erected structures.

Using the five-point scale already mentioned above to evaluate this material, you can give it “fives” for low cost, practicality and ease of use, as well as for accessibility and excellent environmental characteristics.

Here you will get acquainted with minerals that are widespread in nature. One of the first places among them is occupied by such stone building materials as sand, clay, limestone and other rocks. It is these rocks that make up the thickness of the earth’s crust and in some places extend directly onto its surface.

Sand and gravel

Sand is a common and well-known rock. However, look closely at a handful of sand, compare river sand with sand taken from a ravine or pit, and you will see that they differ greatly from each other in color, grain size and impurities. Impurities are sometimes visible to the “naked” eye, as they say, but sometimes, on the contrary, they are difficult to distinguish even under a magnifying glass. Impurities greatly change the properties of sand and limit its use.

The mineral composition of sand is not always homogeneous. Its bulk consists of quartz grains. The presence of pinkish, grayish and other colored grains indicates the presence of another mineral in the sand - feldspar.

Now a little about impurities. The most common admixture to sand is clay particles, otherwise known as fine earth. Depending on the amount of clay, sands are divided into three groups: loose or loose, clayey and sandy loam. Quick sand is easy to distinguish from other sands we have noted: they do not generate dust when you stream sand from a handful, well dried in the sun or in an oven. When viewed under a magnifying glass, the grains of sand are transparent and almost not shrouded in dusty deposits (fine soil). For this reason, a teaspoon of such sand will not produce noticeable turbidity in a glass of water.

Clay sands are a little dusty when dry, but when wet they show some cohesion. Under a magnifying glass, an admixture of fine earth is clearly visible in them.

When dry, sandy loam generates a lot of dust; when wet, it slightly sticks to your fingers (you can even roll it into a ball).

If you look at sandy loam under a magnifying glass, you can see that the grains of sand are shrouded in fine earth.

Other impurities are also found in sand. You can find sand in which “golden grains” clearly burn. There are a lot of them. It even seems to you that they make up the bulk of the sand. But take a pinch of this “golden sand”, throw it into a glass of water, and you will see that real sand will quickly settle to the bottom, and heavy “gold”, contrary to the laws of physics, will float...

This is “cat gold” - small flakes of golden mica. Mica comes in a different color - light, silver-white (“silver sand”), and there is also mica in darker shades. Such sands are called mica sands. In the sand you can also find small rounded grains of bluish-green and dark green color; sometimes there are so many of them that the sand appears green. Such sands are called glauconite sands after the mineral glauconite (in Greek “glaukos” - bluish). Glauconite grains can be easily crushed with a fingernail into a green powder.

A harmful impurity for sand, especially when used as an additive to cement, is pyrite, otherwise known as iron or sulfur. The presence of pyrite is indicated by small golden grains and cubes, clearly visible in the total mass of sand. We will take a closer look at pyrite as a valuable ore for sulfur mining later.

The presence of lime in sand is also a harmful impurity. This impurity is easy to detect if you drop 10% hydrochloric acid or vinegar, since rocks containing lime boil when exposed to acid.

The accumulation of lime is also clearly visible in the form of individual white grains and pebbles, which also boil violently under the influence of acid. Iron compounds color the sand in yellowish-reddish tones. The admixture of organic substances gives the sand a dark color.

Based on grain size, sands are divided into the following groups:

Fine-grained - very fine, powdery sand;
Medium-grained - individual grains of sand are smaller than a pinhead;
Coarse - grains of sand approximately the size of a pinhead;
Coarse-grained - grains of sand smaller than a match head.

If you have a magnifying glass, you can do some interesting research. Examining various sands on a glass plate, you are convinced that the shape of the grains in some sands is round (river and sea sands), while in others it is angular (mountain sand).

For concrete and gray sand-lime brick, sand with angular grains is used. Thanks to this shape, the products retain greater strength. Sands used in foundry have a rounded grain shape. It creates porosity in the sand in which the casting is made. And the result is better heat and gas transfer.

Sands are widespread in nature, but they do not always meet certain technical requirements. Sand added to cement should contain no more than 2 percent of impurities, especially clayey and organic substances, and should not contain pyrite at all. For building bricks, you need sand without admixtures of limestone pieces, since after firing the brick, the limestone turns into quicklime; as it absorbs moisture from the air, the lime “quenches”, increases its volume and tears the brick. Clay sands are unsuitable for road construction - they generate dust. The iron content makes the sand unsuitable for the glass industry, as it produces brown and green glass.

(in French, gravel means coarse sand).

With a grain size from 2 millimeters to 1 centimeter, the rock is called gravel if the grains are rounded; if the grains are angular, the rock is called gruss, or crushed stone.

Gravel is a very valuable material for concrete production; necessary for the construction of railways and highways.

Significant accumulations of gravel occur among glacial sediments, as well as ancient and modern river sediments.