Sand is a sedimentary rock, as well as an artificial material consisting of rock grains. Very often it consists of almost pure quartz mineral (the substance is silicon dioxide).
Natural sand is a loose mixture of grains with a particle size of 0.10-5 mm, formed as a result of the destruction of hard rocks.
Natural sands, depending on their genesis, can be alluvial, deluvial, marine, lacustrine, or aeolian. Sands resulting from the activity of reservoirs and watercourses have a more rounded, rounded shape.
Heavy artificial sand is a loose mixture of grains obtained by crushing hard and dense rocks. The shape of the grains of crushed sand is acute-angled, and the surface is rough.
TYPES OF SAND
In trade, sand is classified according to its place of origin and processing:
River sand is construction sand extracted from river beds, characterized by a high degree of purification and the absence of foreign inclusions, clay impurities and pebbles.
Quarry washed sand is sand that is extracted from a quarry by washing with large amounts of water, as a result of which clay and dust particles are washed out of it.
Quarry sifted sand is sifted sand extracted from a quarry, cleared of stones and large fractions. Quarry seeded sand is widely used in the production of mortar for masonry, plastering and foundation work. And also in the preparation of asphalt concrete mixtures.
Construction sand -
According to GOST 8736-93, construction sand is an inorganic bulk material with a grain size of up to 5 mm, formed as a result of the natural destruction of rocks and obtained during the development of sand and sand-gravel deposits without or using special processing equipment.
APPLICATION
Widely used as part of building materials, for the reclamation of construction sites, for sandblasting, in the construction of roads, embankments, in residential construction for backfilling, in the improvement of courtyard areas, in the production of mortar for masonry, plastering and foundation work, used for concrete production. In the production of reinforced concrete products, high-strength concrete, as well as in the production paving slabs, curbs, well rings use coarse sand (Fineness modulus 2.2-2.5). Fine construction sand is used to prepare covering mortars. In addition, sand is the main component in the manufacture of glass.
Construction river sand is quite widely used in various decorative (mixed with various dyes to obtain special structural coatings) and finishing works of the finished premises. It also acts as a component of asphalt concrete mixtures, which are used in the construction and laying of roads (including for the construction of airfields), as well as in water filtration and purification processes.
Quartz sand is used for the manufacture of welding materials for special and general purposes.
Sand (psammit) is a loose clastic rock. It consists of small grains of angular or rounded shape, the size of which ranges from 0.05 mm to the size of a pea. The most common type of sand is quartz. Sand is varied in color, composition and impurities. Its deposits are formed due to the disintegration of rocks under the influence of running water or the atmosphere.
Another type of sand is magnetic sand. It is called so because its grains consist of magnetic titanium iron ore. Any sand, as a rule, contains a mixture of minerals. In magnetic sand, the main admixture is quartz grains and mica.
Magnetic sand can be found on the shores of bodies of water - seas, rivers, and some lakes. For example, thick deposits of magnetic sand are found in New Zealand, in its northern part. Deposits of quartz sand are found in coastal and shallow waters, in dunes and in geological systems, that is, where quartz rocks are destroyed, crushed and transported by water or the atmosphere. Gradually, loose sand, under the influence of natural phenomena, is compacted, cemented and transformed into solid solid rock - sandstone.
Quartz sand is most often white or yellow. It is used in the production of glass, porcelain, cement, and asphalt mixtures. Pure quartz sand is sprinkled on paths in gardens and sidewalks. It is used to clean dishes. Sands that contain precious metals or minerals are called placers.
Depending on the location and location, sand can be river, mountain, gully and burial. Of all the types (types) of sand, the cleanest sand by location is river sand. It is found on the banks or bottom of rivers and has rounded grains polished by water.
Mountain and ravine sand has uneven and angular grains mixed with particles of earth or silt. Such sand is found at the foot of mountains or in ravines.
Under a layer of earth, clay and other rocks, at a certain depth, lies burial sand. It has sharp angular grains, the surface of which is rough. Of all types of sand, burial sand is the best building material.
Sand is divided according to grain size:
- fine-grained (small) – 0.05 mm – 0.25 mm;
- medium sand – 0.25 – 0.5 mm;
- coarse-grained (large) – up to 3 mm.
With the help of special sieves (screen), it is sorted by grain size (lines in diameter):
- large grains of sand - 3/4 - 1;
- medium – 3/4 – 1/2;
- small – less than 1/2.
Pea-sized grains of sand are called gravel (cartilage). It is also divided into small, medium and large with the size of the lines in diameter:
- fine gravel - up to two lines,
- medium gravel – from 2 to 5 lines,
- coarse gravel - from 5 to 8 lines.
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 usually divided into the following brands:
- 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 the material 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 for making 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 we evaluate this material using a traditional five-point scale, its cost, practicality and appearance you can assign a solid “A”. The only thing that raises doubts is the environmental friendliness of this species, since the radioactivity level of the sands is artificial origin much higher than natural.
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 from which it is removed during 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 you to use this building material in all areas of construction production: from zero cycle to finishing 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.
Natural sand for most is something natural and not attracting attention. These are small particles that arose in the process of destruction and transformation of the earth's surface over millions of years. The main element of the substance is silicon dioxide molecules. Iron, sulfur, calcium, gold, magnesium are also included, but in minimal quantities. The main areas of use are construction and industry, for which sand is ideal if it consists predominantly of quartz. But pure composition is rare in the natural environment. More often, sand is filled with crushed feldspars, mica, skeletal remains, silt, gypsum, clay and other elements. There are also types of sand whose particles do not contain quartz at all, for example, coral or gypsum. The childishly simple and primitive question: “who created sand?” has completely logical answers - the sun, wind and water. As well as all the processes occurring on the planet, including volcanic eruptions.
Sand under a microscope
Sand of different characteristics is available in trade. The main type of sand, the most popular and irreplaceable, is construction sand, which has an additional classification. It is worth highlighting that, despite the rapid progress in the production of building materials, this inexpensive and widespread substance today has no full-fledged analogues. For example, natural stone is quite successfully replaced by brick, concrete products, and blocks; iron and wood are giving way to more advanced alloys and plastics. And sand is a unique and unsurpassed species natural materials. Moreover, the amount available on the planet more than sufficiently satisfies the needs of industry and construction.
Main types and types of sand
The appearance of sand depends on the conditions under which it occurs. The general characteristic of sand is that it is a loose granular mass consisting of round or angular particles ranging in size from 0.1 mm to 5 mm. Color and properties vary depending on the conditions of origin. The most common color on earth is yellow.
Red coloring (for example, volcanic sands with corresponding colored rocks) or green (including peridot, chlorite-glauconite) is rarely found. There are black sands containing the minerals magnetite or hematite, as well as purple, orange and multi-colored sands. The photo shows multi-colored sand; the view from above shows a landscape unusual for Russian nature.
Based on the method of formation, bulk material is divided into natural and artificial. In turn, depending on the genesis natural sand may represent:
- – marine and lake species;
- – aeolian (associated with wind activity);
- – alluvial (brought by permanent and temporary water streams) and colluvial species (deposits on the slopes and foothills of mountains).
Artificial type is obtained due to mechanical action on rocks or certain production wastes:
- – expanded clay is produced by crushing expanded clay gravel;
- – pure is formed by crushing the original mineral (in nature, pure crushed mineral is extremely rare);
- – perlite sand occurs when volcanic glass is crushed;
- – sand slags or thermosites are a representative of waste-free production in industry;
- – marble grains of sand are formed when marble is crushed.
If we compare a natural substance and an artificial one, then, of course, the latter wins in terms of purity of properties. In the natural environment, all kinds of processes continuously occur that introduce changes and additions to the structure of the granular substance.
Types of sand used for construction
Construction materials are mined from deposits. The conditions of receipt and the method of processing determine the name of the product: reservoir, mountain (quarry or ravine) and artificial. The main documents defining standards of use in construction are GOST 8736-2014 and GOST 8736-93. The most popular types are, and, their use has few restrictions due to their excellent characteristics.
- – Alluvial (washed) - best choice for many construction processes. Concrete mortar, reinforced concrete products, road construction, preparation of building mixtures and compositions. To obtain this type of sand it is used large number water and drying devices. Clay, dust, and debris are washed away by pressure. Thanks to mechanical action, the lumps are broken up. After drying and sifting, a free-flowing mass is formed, characterized by purity and uniformity. Strength artificial stone or bonding solution depends on the quality of the components used. Impurities disrupt construction technology and lead to destruction. Therefore, washed quarry material is one of the most expensive and sought-after goods.
- - Seeded. This is an accessible and inexpensive building material. The only thing cheaper is sand for backfilling, which is delivered to the site without preparatory stages for sale. Sifting removes small and large debris in the form of stones, branches, plant elements, and also breaks up lumps. The process takes place at the extraction site using mechanical devices. For consumers, the cost increases by the amount of effort expended by the development company.
Features of mountain sand are angularity, variety of sizes, and the presence of impurities. The main determining factors in the use of crushed rock are: a large number of sand quarries in our area, and on the planet as a whole; easy extraction, fast transportation, and as a result, reasonable cost. On the structural side, the quarry formation has the best angularity (adhesion) and cuboidality of all types. This form contributes to the creation of high-strength products, and is a fundamental criterion for selecting sand for concrete compositions.
Types of river construction sand and its application
The method of processing the material involves lifting it from the bottom of the river and drying it. The product is distinguished by its purity and uniformity of composition. Prolonged exposure to water smooths out corners, reduces shape and washes out clay impurities between grains of sand. Therefore, goods of river origin have a lighter, lighter and more uniform composition than those of quarry origin. Like washed mountain sand, it is an ideal type for concrete. The differences lie in size and flakiness. The river one is more crushed and rounded, therefore it practically does not shrink, unlike the angular, cube-shaped quarry one. In addition to concreting, uniformity serves as the basis for obtaining a smooth surface in the production of plaster and masonry mixtures, the production of filler for paints and grouts.
Quartz sand is the purest material produced artificially.
Mechanical crushing of quartz-bearing rocks provides a clean and homogeneous substance. The production price stands out significantly among similar natural products. A distinctive feature is its high angularity and flakiness, which does not have the best effect on strength, but gives the necessary effect in grinding processes. The main scope of application is industry and the production of building materials (facade compositions, sand for plaster, landscape design).
Indicators that determine the type of sand required for construction
The purpose and use of bulk material is determined by the coefficients and indicators of gradation of characteristics.
Environmental safety- the most important factor for the construction of houses and premises in which people exist. Almost all varieties belong ToI - class of radioactivity(GOST 30108-94). Difficulties can only arise with artificially created material. Thus, a type of quartz sand is suitable for plaster, while another type of artificial raw material can exceed the permissible background radiation level. Therefore, it will only be used in the construction of railway tracks. Main role plays the original mineral or substance that has been crushed.
Types of sand fractions (fineness modulus) affect the density of sand. According to the size, sand grains are divided into large (2–5 mm), medium (0.5–2 mm) and dusty (up to 0.5 mm). The coarser the sand, the greater the bulk and compacted density, which is important to consider when determining the quantity for construction and purchase. The particle size modulus also influences the scope of application. For grinding work, fine material is purchased; for internal plastering work, coarse quarry sand with clay impurities is suitable. Clean coarse sand is used to build the foundation.
Strength is expressed in marks, which rely on the properties of the constituent minerals. Grade 300 refers to sedimentary rocks that cannot withstand significant loads; 400th - metamorphic rocks with average values. 800 grade is the strongest and most expensive, this bulk substance comes from igneous rocks that have been tested by extreme temperatures and conditions.
According to hygroscopicity, sand d Spreads on a wet composition, saturated with water and low in moisture. For construction, only dry material is needed, all proportions are based on it. A wet composition disrupts the calculation of density indicators taken into account, significantly increases in weight, and becomes plastic and viscous. The average volumetric bulk density of sand is 1300 -1500 kg/m2. If the humidity of the crushed substance increases slightly, then the density and weight decrease - each grain of sand is enveloped in moisture and creates voids around itself. And if the crushed rock becomes wet, then the weight and density exceed the average.
Filtration coefficient depends on porosity and size. The more pores, the slower the water passes, and the more thoroughly it is cleaned, which is important for the operation of filters. Large grains of sand (3–5 mm) facilitate the rapid passage of water; this fact is used when designing a drainage system.
Indicator of the maximum permissible amount of impurities. In the river composition, the standard dose determined by the standards is 0.7%. Washed quarry sand has a small content, while seeded sand has a significant content. Additives can have a positive or negative effect on the technological process. Thus, clay is a plasticizer in plaster, but destroys the adhesive strength of the foundation.
If the buyer is not a builder and does not know how to choose, then difficulties arise. Companies specializing in building materials provide qualified advice. The leading seller of quality building materials in Moscow and the region is MSK-Region.
Quite often we can see children examining particles of sand under a magnifying glass or with the naked eye, trying to answer the question of what it consists of. But even adults cannot always answer this question. We will explain to you what sand is made of.
Looking at grains of sand, you can determine that they consist of different rocks, and therefore have different colors.
Sand is a rock sedimentary rock, which is a loose mixture of particles of various minerals (quartz, calcite, mica, feldspar, etc.) with a diameter of 0.14 - 5 mm, and formed as a result of weathering of rocks. There are few deposits that contain almost only quartz sand. But the main part of the sand consists of a mixture of quartz with feldspar, magnetite, mica, garnet, which allows you to give the sand a variety of shades. There are also several deposits on our planet where you can find sand that does not contain quartz. For example, there are white gypsum sands or red coral sands.
Sands can be either natural or artificial.
Natural sands are usually divided into sea, river and mountain (gully) sands, this depends on the conditions of occurrence. River and sea sand have rounded particles, while mountain sands consist of acute-angled particles. Mountain sand is often contaminated with harmful impurities, unlike river and sea sand. Natural sand is a product of weathering (or wind erosion). The weathering process contributes to the destruction of the source material into particles of various diameters, including sand. Wind and water can transport sand hundreds and thousands of kilometers. In connection with this, over time, sand deposits may form in the lowlands or at higher elevations. The texture of such sand greatly depends on the way in which small grains of sand were delivered to the deposits. Water is capable of moving particles of different sizes at the same time. Therefore, very often we can see how deposits with an incredibly variegated pattern and texture are formed next to some obstacle of natural origin. At the same time, the wind performs the function of filtering particles. The wind carries different grains of sand with different strengths and at different distances. In this way, deposits are formed that consist of grains of sand that are approximately the same size.
Where does sand come from in deserts? Most of the sand is carried by the wind into deserts. But there are also cases when desert grains are formed by the destruction of mountains. Some deserts were originally seabed, but many millennia ago the water left and receded.
Sand is also made artificially. This occurs by grinding hard materials such as stone or slag.
Sand is useful and required material. It is used to make glass, concrete, water purification filters, and sandpaper.
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