How sand is made in nature. What is construction sand

/ Rock Sand

Sand is a fine-grained, loose sedimentary rock consisting of grains of destroyed minerals 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.

But what usually ends up happening is that the blame ultimately falls on the public authority and the community, which, in addition to suffering the consequences of environmental damage, must also indirectly pay for the costs incurred government agencies for restoring degraded areas through this type of profitable activity.

Before suction of material begins, probing should be carried out using tipped steel rods positioned on the sand pack to better understand the potential of the deposit. This avoids unnecessary shuffling of the watercourse bottom.

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).

This and other measures are aimed at minimizing negative consequences related to sand mining. The lack of clear legislation is seen as one of the major obstacles to mining operations, as many do not have adequate laws in place without knowing in advance how much they will have to invest in rehabilitating the area that will be exploited.

Another difficulty noted by the owners mining operations, is that environmental requirements are imposed by several government bodies, from three levels of government, whereas if this responsibility were covered by the level, it would be easier. However, this difficulty cannot be used by anyone who mines sand, since a license from the town hall is enough to operate it.

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.

The following measures are considered to be predominant for the viability of extractive enterprises within the framework of an ethic of environmental sustainability. Protecting areas permanent preservation. When such sites become degraded, a revegetation project should be identified, giving preference to native species. It can also stimulate the restoration of local fauna.

To restore the vegetation, therefore, to restore the fauna, it is recommended to install nursery seedlings, native preferences, to be used in the restoration of slopes and in the area degraded by this activity. Fauna management. Capturing, treating and reintroducing specimens of local fauna allows for more rapid restoration of degraded areas.

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 facades of buildings and various products, in residential construction for backfilling, in the improvement of courtyard areas and in everyday life (filling paths, installing children's sandboxes, litter boxes for cats, 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. 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 binders 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- valuable raw material for the glass industry.

Soil storage The layers of soil removed to create conditions for sand extraction must be placed in such a way that they are protected from the erosive agent and outside permanent zones conservation for subsequent use during the reconstruction of the degraded area.

When cutting, leave a layer of approximately 20 cm fertile soil to facilitate revegetation. Before reuse soil scarification is recommended to minimize soil compaction due to the circulation of equipment and trucks required for the extraction process and the transportation of the extracted material.

Sand in construction

IN modern construction most often used river sand and quarry sand.
river sand- This 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 all types of construction work, since its composition 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.

Slope stability Preventative measures are aimed at maintaining slope stability. In the case of sand removal, suction must take place in the middle of the waterway to avoid destruction and therefore siltation and destruction of vegetation.

Proper packaging and handling of oils and lubricants prevent contamination waterways and soil. The sides of dredgers must be protected on their sides to prevent oil and grease from leaking onto the riverbed. It is necessary to periodically maintain the equipment to prevent leakage of oil, grease and fuel, and when washing water, water should not be thrown into a layer of water or into the ground without letting it pass. appropriate treatment.

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 a large number 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.

Adequate removal solid waste. The deviations, if any, should be deposited at such a place as to cause landslides. Solid residues associated with human activities and the packaging of oils, greases and other substances will be sent to municipal services or sold for recycling or disposal in a location that cannot contaminate soil and groundwater. Never play directly on land or in waterways.

Faced with the wrath of thousands of opponents of the exploitation of shellfish sand in the Gulf of Lannion, which was demonstrated on Sunday, the Armorican Shipping Society, on Tuesday, September 13, decided to suspend its collections until November, she just quit. The victory, however, is temporary. And indeed it is, a camouflage for two associations and thirteen municipalities that have been bitterly defending a fragile coastal ecosystem for more than five years. In fact, the sandblasting vessels, known as "marissalopes" because of their work, were considered "dirty" - an underwater dune located less than ten kilometers from the coast and about forty meters deep.

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.

Problem: This accumulation of shell debris is the area of reproduction and birth of young fish and sand eels, well known to fishermen. Hence their concern: once the mining project begins, all organisms living on the dunes are doomed to be crushed. This breeding ground also feeds colonies of monk gannets and puffins nearby national reserve Saint-Iles.

The reform of the mining code will contribute to

And the damage is likely to be much wider! For the dredger's elding - its giant suction arm - a cloud appears fine particles, which, like an atmospheric cloud, will drift with currents and tides, darkening the water and settling on surrounding marine vegetation, with deadly effects. This is an area of research for which we do not yet have mathematical formula, and therefore modeling is not possible. The Gulf of Lannion is just the latest theater of operations for French exploitation, which already produces more than 7 million tons of sand from the coast each year.

Mineral stores

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What kind of sand is there and where is it used?
In trade, sand is classified according to the processing performed and, of course, by place of origin.

Sand is a material widely used in construction, consisting of grains up to 6 mm in size. Sand is mined in all regions of the country and is used both for the production of building materials and for laying the foundations of structures - roads, foundations, etc.

And the government is pushing for further expansion of coastal development. The current mining code reform should contribute to this by simplifying procedures and reducing the time required to obtain mining titles. “Sand is ubiquitous in our everyday life" writes Christian Boucher, director of the Center for Research and Research of the Sea at the Catholic Institute of Paris in his Black Book of the Sea. Today there is a rush to sand, which has nothing to envy to gold.

In fact, worldwide, sand is the third most consumed resource after air and water: over 15 billion tons per year, with a trade value of $70 billion. However, it is still mainly used in the construction and public works, in particular for reinforced concrete consisting of two-thirds sand. In France, to meet construction needs, it consumes seven tons per year and per capita. But most of them does not work, being deeply buried in the oceans or under other sediments.

Sands, depending on the type, can be sea, lake, river, quarry, or artificial. Sand mined in reservoirs, as a rule, has fewer impurities and is considered to be of higher quality.

Types of sand

For construction purposes, sand is classified according to its place of origin and processing:

river sand

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.

Stolen beach without any opposition

A future with a global fleet of thousands of excavator ships, each capable of sucking 000 to 000 cubic meters sand per day in water depths from 0 to 200 meters. The example of Dubai is symbolic. This is several hundred million tons of sand. The contractor stopped working and the islets gradually collapsed into the sea. As shortages increase and prices rise illegal traffic growing. This is especially true for West Africa, Cambodia, Indonesia, Mexico and India, where the "sand mafia" is extremely effective: forcibly borrowing local population, it manages to illegally extract about 500 million tons of rivers and coastlines.

Quarry washed sand

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 seeded sand

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.

However, the ocean represents the account of these nonsense. Everywhere coastlines recede, the sand no longer exists to cushion the effects of storms. In Indonesia, 25 islands have already disappeared to supply sand to Singapore. According to Robert Deconto of the University of Massachusetts and David Pollard of State University Pennsylvania, ocean waters should rise more than a meter at the horizon. Stunned human actions, tens of thousands of other islands will be removed from the map. General indifference?

Sand: Why can't we get it out of the desert? Why did Dubai choose sea sand for its devouring construction needs, and the city is at the gates of the desert and countless light dunes? Because the desert sand was created by the wind, which for a long time rolled its quartz grains into round and smooth beads. As a result, they do not unite with each other and move inexorably towards the sea. To raise an island - or any other structure - by backfilling, you need to use angular and coarse grains that cling together.

Construction sand

According to GOST 8736-93, construction sand is inorganic bulk material with grain size up to 5 mm, resulting from natural destruction rocks and obtained during the development of sand and sand-gravel deposits without or with the use of special processing equipment.

Thus, all countries with deserts are forced to import sea sand. That is, aggregates with ideal roughness and adhesive properties. How many times have you had to explain to those around you that you are not going to be only in the dunes on your next trek in the Sahara. Moreover, the animals that accompany us in the desert do not like, but then not the dunes at all. Or a small, round, easy cross.

All this suggests that the Sahara is not just sand. But let’s return to what interests us, sand and, in particular, Ergs. And yet, the imaginary Sahara consists only of sand. The largest sugar eras are well known to tourists. But where does this sand come from?

Alluvial sand

Alluvial sand is extracted from riverbeds former rivers. The peculiarity of alluvial sand is that it has high degree cleaning: it does not contain particles of clay and many other foreign elements and impurities. Sand is extracted without additional costs or processing. Alluvial sand is divided into fine, medium and coarse, and has gray, light gray and light yellow colors. Characteristics of alluvial sand:

We need to wrap our necks around another very popular idea that the sand will come from the sea. The Sahara sand is essentially the result of the erosion of large mountain ranges that are composed of grasses, sedimentary rocks that are the result of the accumulation of "sediments" carried by streams to the seas and oceans from which they build the lower part. This grenade comes from the erosion of pre-existing continental rocks.

With plate tectonics and continental continuity, this submarine sandstone occurs on outdoors and is located at the beginning of Tassilis.

Complies with GOST 8736-93.
Size module from 1.6 mm to 2.2 mm.
Content of dust, clay, silt particles, incl. in lumps 0.3%.
Filtration coefficient from 5.0 to 11.0 m/day.
Class I radioactivity.
A eff. 47 BC/kg.
The density of the water-filled soil is 1.65 g/cm3.

Sand cost

The price of sand depends primarily on the characteristics of the sand, and is also directly related to the distance sand quarry from areas where sand is consumed or from large construction projects.

Sahara sand is the result of erosion of these sandstone plateaus. This is impossible without the influence of water and vegetation, which degrade the rock with its acidity. There is little wind in this process. Water is the main factor in this breakdown. Sand is formed by alteration of rock during long wet periods and is moved by wind during dry phases.

Thus, the sandstone disintegrates, then the sand is transported by large wadiyas. The wind then enters the lists and the sand is then sorted, organized and moved. Why so many different colors? From the purest white to the darkest red through all the pastel colors, from yellow to orange, there is a wide range of what is seen when trekking in the Sahara.

The cheapest sand is quarry natural sand, i.e. sand extracted from a quarry and not subject to further processing. This sand usually contains lumps of clay, as well as large number dusty and clay particles.

After processing, the cost of sand increases significantly. For example, sieved sand, which is obtained by sifting quarry natural sand(small stones, lumps of clay and other foreign objects are removed from it), can cost 1.5-2 times more than its predecessor. Washed sand, obtained by washing quarry natural sand in water, costs about 1.5 times more than seeded sand and about 2-3 times more expensive than natural sand.

The location of a sand quarry also affects the cost of the sand mined from it. Thus, the average cost of sand mined in the Moscow region is significantly higher than the average cost of sand mined in Kaluga region. And the price of sand mined 50 km from Moscow exceeds the cost of similar sand mined in a quarry located 100 km from the capital. he also goes to the beach

Application

Widely used in 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 of reinforced concrete products, coarse sand (fineness modulus 2.2-2.5) is used. 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.

Radioactivity of sand

Almost all sands belong to the 1st class of radioactivity according to GOST 30108-94 (the specific effective activity of natural radionuclides in them does not exceed 370 Becquerel/kg, the only exceptions can be crushed sands), that is, they are radiation safe and suitable for all types of construction without restrictions.