Which sand for concrete is better, river or quarry sand? Which sand is best to use to create concrete? Which sand is better for concrete?

Before the beginning construction work many pre-calculate required amount material. This the right approach to such a serious matter. But on at this stage This is exactly where a lot of questions arise. One of them: what kind of sand is needed for the foundation?

The choice of such material should be given Special attention, since it is an important component, one of the main components used in the manufacture of concrete. The durability of the foundation - the future foundation of the house - will depend on the quality of the resulting mixture. Modern market offers huge assortment sand, both natural and artificial. The article will tell you how to make a choice so that the foundation does not suffer from it.

Sand Selection Basics

Even a person ignorant of construction issues can guess that only clean sand is suitable for the foundation. Initially, it may contain various organic elements: small twigs, grass, etc. Such material is not suitable for construction work, so there must be sifted sand, cleared of foreign debris.

However, simple pouring will not do if we're talking about about impurities such as lime or clay. Cleaning such sand is much more difficult, so when purchasing building materials you should immediately pay attention to this. The clay content in sand should not exceed five percent of the total mass, especially if a solution is being made for the foundation. Otherwise, after some time the structure will shrink, crack and will not be particularly reliable.

Checking the cleanliness of the sand

Before choosing what kind of sand you need for your foundation, you should check its cleanliness. A simple method is usually used for this. You will need any empty transparent bottle (glass or plastic). One third of it is filled with sand and half filled with water. Then shake the bottle vigorously so that the components are thoroughly mixed with each other. After that, they place it and wait for five to ten minutes. If the water in the bottle has become cloudy and dirty, then such sand is not suitable for the foundation. If a foreign substance appears on the surface, the layer of which exceeds half a centimeter, then such material cannot be taken either.

Now let's look at what exist

Types of sand for embankment under the foundation

To ensure the reliability of the structure under construction, according to SNiP standards, it is necessary to use bulk mixtures. The market sells sedimentary rocks in three types, depending on where they are mined. This is sand:

• career;
• river;
• nautical.

To answer the question of which of them is most suitable for a foundation pillow, it is worth familiarizing yourself with the characteristics and nuances of using each type.

Quarry sand

These raw materials are extracted in quarries by breaking down rocks. An important indicator The reliability and strength of quarry sand is determined by its moisture content. An acceptable ratio is from one to five percent. Suitable humidity can be determined visually. It will not be possible to form a dense lump from sand - it will simply crumble.

The cheapest material is considered to be quarry construction sand. The price for it ranges from three hundred to seven hundred rubles per cubic meter. This is due to his low quality due to the large amount of impurities of clay and other substances. Nevertheless, it is in considerable demand.

Types of quarry sand

Depending on the type of processing, quartz raw materials are classified as follows.

1. Sandy soil. This is an unrefined mixture with various impurities. As a rule, it is leveled summer cottages and fill up the trenches.

2. Washed sand. It is extracted from flooded deposits using hydromechanical equipment. The technology allows you to assemble the mixture without any impurities or unnecessary components. This material is used in the production of roads, bricks and iron. concrete products.

3. Seeded sand. It is cleaned using a technical and mechanical method to remove large particles and stones. Typically, such raw materials are used for the preparation of plaster, masonry mortars and in the casting of stone products.

river sand

These raw materials are mined from the very bottom of freshwater rivers. It is rarely found organic compounds and impurities. That's why river sand considered pure and natural product, which is designed for multi-purpose use. This is an ideal material for laying foundations, creating drainages and diluting solutions necessary for interior decoration Houses. Due to natural polishing, river sand has a perfectly smooth shape and a fine fraction within two millimeters.

Thanks to all the listed advantages, this material becomes a universal and desirable, but rather expensive raw material for the foundation. Thus, the price of construction sand extracted from the river can vary from seven hundred to one thousand rubles per cubic meter.

Classification of river sand

Raw materials from the river bottom can differ greatly from each other. Therefore, you should understand the variety of grains of sand. They can be of several fractions: from 0.7 to 5 millimeters. The filling of small grains of sand shrinks and compacts strongly, so it is only suitable for lightweight buildings. Also distinguish the following types loose river material.

1. These are pebbles about five millimeters in size. They are obtained by splitting rocks using special crushing and grinding equipment.

2. Coarse sand. It has an unobtrusive neutral color and is mined from dry rivers. Ideal for finishing and decorating a room.

3. Washed river sand. These are medium-sized grains. They are gray or yellow in color because they contain iron and silicon oxides.

Positive aspects of river sand

Fluvial sedimentary rocks have several positive qualities who have great importance for foundation construction. They meet technical and aesthetic requirements, do not rot and are not exposed to aggressive environments. River sand is characterized by high moisture resistance and excellent sound insulation. It is also a safe and environmentally friendly material.

For construction multi-storey buildings Only the coarse-grained type is used, and for capital houses the medium crumb is suitable. Also, river sand is ideal for landscaping areas, playgrounds, landscape work and decorating rooms.

Sea sand

Sea chips are also exactly the material needed for the foundation. Sand is initially no better than river sand, and sometimes even worse. This is due to the presence of organic impurities (algae, shells) and foreign objects. But sea sand must be cleared of foreign substances and washed, so it is considered clean and of high quality. Thereby this material is the most expensive, and not everyone is willing to pay for it. It is more appropriate to use sea crumbs for construction where they are sold nearby and are cheaper.

Sand fractions

Any sand can be classified by its size. Experts distinguish the following types of fractions.

• Very thin. These are grains of sand about 0.7 millimeters in size. They are suitable for arranging playgrounds and are not suitable for construction.
• Thin. The grains range in size from 0.7 to 1.0 millimeters. This is not a dense material. This kind of sand cannot be used for construction, but it will be good for making lean concrete.
• Small fraction. It is grains measuring 1.5-2.0 millimeters. When using it, the consumption of cement mixture increases.
• Average. Grains (2.0-2.5 millimeters) can be used to create standard concrete.

• Large. Sand particles reach three millimeters in size. This fraction is ideal for breeding high-quality concrete mixture, which will be used in large-scale construction.
• Very large. The particles are more than three millimeters in diameter. They are added to the foundation cushion and used to distribute the mass of the structure.

Choosing sand for the foundation

So what kind of sand is needed, river or quarry? Experts agree that the first option is most suitable for building foundations. It will create a layer that will increase the strength and stability of the building, and prevent “walking” and the formation of cracks.

However, river sand will not be affordable for everyone. In this case, it is allowed to use quarry crumbs, but they must be washed. Also suitable Sand and gravel, which improves the quality of the composition for laying under the pillow.

Required amount of sand

Usually take one part cement to five parts sand. But this calculation is suitable if the solution is made only from these two components. The ratio of sand, crushed stone and cement for the foundation will be completely different. As a rule, they are taken in following proportions: four parts sand, two parts crushed stone and one part cement.

As can be seen from the calculations, it is always necessary to take more sand than other components. The sheer amount of materials directly depends on the height of the pillow and the building itself. It is better to buy sand with a small reserve so that you do not have to buy more at the wrong time. The remains can be used to prepare solutions for finishing walls or laying them.

Summarizing

Answering the question what kind of sand is needed for the foundation, it should be noted that ideal option river grains of the middle fraction are considered. This material has excellent properties for construction purposes. It allows you to build the strongest possible foundation, which will last for a long time and will be an excellent basis for construction.

It is necessary to purchase sand from reliable manufacturers so as not to stumble upon low-quality raw materials. It is recommended to check the material before purchasing for moisture level and quantity. foreign impurities. It is also worth paying attention to the size of the purchase. As a rule, in cubic meter there should be about one and a half tons of sand.

Every developer knows what building materials are used to build a house or bathhouse. At the same time, it would be useful to ask what kind of sand is needed for the foundation? And who wondered why this ingredient is better than another?

Sand as fine aggregate

Everyone knows the components of concrete, where sand is one of the components. What is its peculiarity? Is it better to replace it or do without it?

The fact is that in concrete the binder is cement, which, in interaction with water, sets and hardens. In this case, volume deformation occurs - shrinkage, accompanied by internal tension and the occurrence of cracks. To avoid these phenomena, fillers are added to cement - sand, crushed stone and others, which neutralize internal deformations, reduce shrinkage, and increase the strength of concrete. The flowability and density of sand allows it to fill voids and hold together crushed stone, which is the basis of concrete.

Classification of fine aggregates

1. natural sand;
2. sand from crushing screenings.

They are used as fine aggregate for the production of concrete, mortars, production of dry mixtures, etc. And if the first does not need explanation, then the second type is the same bulk material, but it is obtained during the development of rocks, from enrichment waste iron ore and other ores.

All technical and quality indicators of fine aggregate are regulated by GOST 8736-93. It applies to sand with a grain density from 2000 to 2800 kg/cub.m.

In terms of quality, this bulk material is divided into classes I and II and its criteria are:

• grain composition;
• content of dust and clay particles;
• mineralogical and petrographic composition;
• radiation-hygienic characteristics.

According to the grain size, sand is divided into groups from “very coarse” (over 3.5) to “very fine” (up to 0.7). When calibrating, sieves of different cell sizes are used.

The mineralogical and petrographic composition is established during geological exploration of the deposit and is indicated by the sand manufacturer in the quality certificate, as well as all other indicators.

Depending on the radionuclide contamination, the use of sand is limited to:

• for housing and civil construction;
• construction of industrial buildings and roads within the city;
• For road construction outside populated areas.

Types of sand

Natural sand, depending on its origin, can be quarry, river or sea.

Career

Mining takes place in open-pit mines. In addition to organic ones, it contains many other impurities and inclusions. Washing and sifting are always required. The grains are quite large. The cheapest price.

River

This material originates from the river bed mainly by hydromechanical means. It is much cleaner than quarry and without impurities, but sifting is carried out, and sometimes washing. The grain composition is finer.

Nautical

It is mined from the seabed and the grain composition is similar to river sand. To be cleaned. In view of high costs This extraction method is the most expensive of the sands.

When choosing sand, you need to pay attention to the grain composition and purity from impurities.

Requirements for fine aggregate

There remains one more thing to figure out which sand is best for the foundation. This will allow you to know the requirements for fine aggregate in the production of concrete, which are contained in GOST 26633-91. In the video you will see how to choose the right sand for construction.

According to clause 1.6.11 of this GOST, the choice of fine aggregate is made according to technical and quality indicators (discussed above in GOST 8736-93). Specific figures are given in clause 1.6.12, where the lower limit of sand coarseness is indicated - 1.5 and the upper limit - 3.25. Now we can confidently say that the following groups of sands are used for the production of concrete:

• small 1.5–2.0 mm;
• average 2.0–2.5 mm;
• large 2.5–3.0 mm.

Moreover, if the grain composition does not correspond to the specified parameters, then a coarsening additive is used for fine and very fine sands - coarse sand and, vice versa: for coarse sand - an additive that reduces the coarseness.

In concrete grades M50, M100, the use of very fine sands is allowed.

The conclusion is simple. Sand is a consumer product, a building material that meets certain standards and is subject to control. Its use in construction is irreplaceable.

If we talk about residential and industrial housing construction, then the origin of the sand does not matter for the construction of the foundation.

And that's why:

1. Concrete compaction occurs using vibrators.
2. Chemical additives are used to improve the properties of concrete, and special aggregates are used to reduce cement consumption.
3. The workability of concrete mixtures is regulated by the addition of plasticizers.

Although even without this, the quality of the foundation will not suffer.

Which is better: quarry or river

Concerning individual construction, then the load on the foundation is disproportionately lower here. The use of a group of fine sands is not capable of compromising the integrity of the foundation. Consequences are possible if the soils are inappropriate, the technology is violated, or the proportions are not observed. In the video you will see how to properly mix the mortar using cement and sand.

And yet there is one nuance in the answer to the question: quarry or river sand is better for the foundation. The trick is that the grains of river sand have a rounded shape, while the grains of quarry sand have a rough, faceted shape. Rounded grains fill the voids in crushed stone faster and more densely, so concrete mixed with river sand settles immediately and shrinks less than with quarry sand.

Conclusion! The best choice for the foundation it is washed river sand.

Before you start building a foundation, take care of purchasing suitable materials, from which high-quality concrete can be prepared.

The greatest attention should be paid to sand, since the strength of the solution depends on it.

Sand is a bulk material belonging to the category of sedimentary rocks. It can be extracted from quarries or created artificial method by crushing crushed stone and stone.

Regardless of how the selected variety is made, main criterion what he must possess is purity. It is important that there are no impurities of organic and inorganic materials, pebbles, leaves, grass.

If you bought low-grade building material, you will need to clean it by sifting, which requires additional labor and time. Cleaning will not rid the sand of small debris - particles of clay and lime.

According to technical standards up to 5% impurities are allowed. When the number of particles is higher than this value, produce the maximum durable concrete impossible. And a foundation built from low-quality raw materials is short-lived.

To understand how good a raw material is, it is best to submit it for expert laboratory analysis. This is the only way to accurately know all the characteristics. True, you will have to pay money for the procedure. But there is economical way independently analyze the raw materials. You will need:

• Pour sand into a transparent container up to a third of the volume;
• To fill with water;
• Shake the container thoroughly so that the contents are saturated with moisture as much as possible;
• Do not touch the bottle for 10 minutes so that all the small grains of sand settle.

If the water remains dirty or upper layer clogged with foreign substances with a thickness of 5 mm or more, such material cannot be used for the foundation.

If the water “cap” remains transparent and there are no third-party particles, feel free to mix concrete from this sand.

Suitable humidity

The moisture content of the building material is of great importance. The best indicator is 1-5%.

You can find out whether the humidity of your raw materials is normal like this:

• Take a metal pan, weigh it;
• Pour exactly 1 kilogram of sand there;
• Using kitchen stove, heat the pan for half an hour, stirring the contents from time to time;
• Then measure the weight of the container. Subtract the mass of the pan from the existing value. Divide the result by one hundred;
• The resulting number is the percentage of humidity.

Selecting sand type

Based on the extraction method, the following types of this building material are distinguished:

River. As the name suggests, it is mined from the bottom of rivers. It is considered universal. Ideal for foundations and interior decoration. Allows you to create drainage systems. An important plus is the absence of clay impurities and organic matter. But it's expensive.

Nautical. Since it is mined from the bottom of the seas, fragments of shells and other objects may come across. Manufacturers usually carefully clean this sand before delivering it to customers. It is recommended that a certain quantity be analyzed in the laboratory before purchasing a large batch.

Career. The quality is lower than that of sea and river. It is mined through the destruction of rocks. Clay and other impurities are often found in quarry sand. This economical option, but the quality is usually not high enough to build a solid foundation.

Expertise will help you choose which sand would be better suited for your area.

You have to pay for quality. If you don't have a big budget, it's better to save up more money and hold off on construction. After all, the foundation is too important a part of the house to skimp on it.

Which sand grain size is best?

There are several types of sand by fraction:

Very thin (less than 0.7 mm). Cannot be used in foundations, even when building a small cottage. Such sand does not allow to obtain sufficiently strong concrete.

Thin (thinner than 1 mm). Concrete cannot be made from it. This faction does not allow achieving required level density.

Small (up to 0.15 cm). It is used for foundations when it is necessary to build a small building (up to 1-2 floors).

Medium (0.2 - 0.25 cm). This fraction is suitable for pouring foundations, so experts recommend using it.

With grains of sand up to 0.3 centimeters thick. These varieties are too expensive. High-quality concrete is made from them, and it is not practical to use it in domestic construction. Suitable for the foundation of high-rise buildings.

Extra large. The size of the fraction is less than 0.35 cm. Suitable for increasing the strength of the building and helping to evenly distribute loads. The varieties are suitable for the construction of skyscrapers.

Don't forget to examine the edges of the grains of sand through a magnifying glass. The sharper they are, the better binding properties the concrete will have.

How much sand is required

5 parts sand to 1 part cement is considered suitable. If you want to use crushed stone, then the ratio will be as follows: 4 parts sand, 2 parts crushed stone and 1 part cement. There's no point in trying to find another perfect recipe. The proportions have been tested over decades of practice.

The quality of the cement is also important. Some brands have such characteristics that you need to add a little less or more of them, but on a small scale this difference is not significant.

In no case should you experiment in order to save money. There is a risk of paying both with money and with your own safety.

If you buy a lot of cheap sand and mix it into concrete, then over time the building will sag and collapse.

When laying the foundation, it is important to choose correctly and competently Construction Materials. It is necessary to select sand especially carefully, since it is the strength of the foundation mortar depends on it, and therefore the strength of the entire foundation. The question of which sand is best to choose for the foundation will be answered in this article.

Sand selection

Foundation sand is a bulk material obtained from sedimentary rocks or artificial creation . The quality of sand does not depend on its production method; it is important to consider only its purity.

If foreign objects larger than half a centimeter can be found in it, it is not suitable for laying a foundation. TO foreign objects may include branches, leaves, organic debris.

Of course, you can try to clean the sand yourself by taking a sieve and sifting it, but just imagine how much time and effort this process will take you. By sifting the sand, you will only remove large impurities, but what about the content of elements that are undesirable in the sand for building the foundation of a house, such as lime or clay.

Better immediately select high-quality sand and get to work. Remember that high-quality sand suitable for making a solution should not contain more than 5% impurities. Besides a large number of additives will deteriorate the strength of the sand, which will affect the foundation and the house or building itself. Content gravel in sand should not exceed 10%, since gravel is an integral element of the solution for pouring the foundation.

Of course, you can only find ideal sand by conducting a special examination of its compliance with all standards in the laboratory, finding out the percentage composition of impurities in the total mass and other indicators. But such an examination is a costly and lengthy process, so You can determine the quality of sand using improvised methods.

Pour sand into a transparent bottle, a third of the way, and then fill it halfway clean water and shake. After this, give the mixture stand for 5 minutes and look at the clarity of the water. If it becomes cloudy and dirty, then the sand contains many impurities. Floating foreign substances, too bad sign, and such sand is unsuitable for construction. If the water is clear and without impurities, then sand is ideal for laying the foundation.

Origin of sand

Which sand is better - quarry or river, we will talk in this part.

Quarry sand

Quarry sand is extracted from a quarry by breaking down rocks. It is of lower quality than river water, but there are exceptions. When choosing quarry sand An important factor in its reliability and strength is the humidity parameter. Her percentage should be from 1 to 5%. Humidity 5% is determined by eye because it is impossible to mold sand into a dense ball or snowball - it crumbles.

For correct definition humidity parameter, you can resort to the following method. To determine the moisture content of quarry sand, take a container and weigh it. Then, weigh 1 kg of sand in it and hold it at low heating temperature for about half an hour, and then weigh only the sand. Humidity will be calculated using the formula: the mass of sand after heating minus the mass of the container divided by 100.

Quarry sand is cheaper in price than river sand, since its extraction method is less expensive.

river sand

River sand is ideal for laying foundations, and is also used when diluting mortars for interior finishing of a house or creating drainages. That's why this sand versatile and multifunctional. Its fine fraction from one and a half to two millimeters and the absence of impurities make it desirable, but expensive building material.

In addition to river sand, they also distinguish nautical, but in modern construction it is used where it can be quickly brought from, otherwise it the price exceeds even the river one. In terms of quality, it is no better than river water, and sometimes even worse due to impurities of organic matter (shells, algae) and foreign objects.

Sand fractions

Depending on the size of the grains of sand, the following types of fractions are distinguished:

Pouring the foundation assumes that the edges of the medium sand you choose should be sharp. It is the sharp edges of grains of sand that increase operational properties solution and make it as durable as possible.

Choosing sand for foundation cushion

The sand foundation cushion is a special layer that needed to provide increased durability and stability of the building, increased strength and uniform load. The sand cushion prevents the building from “walking” in the spring due to higher level groundwater and prevents the formation of cracks in it. This pillow is essential facilitates construction on soils with high humidity.

Choosing sand for a foundation cushion is quite simple: use sand with the size of sand grains from 0.25 to 2 mm, better than river sand or, if you cannot afford river sand because of its high cost, washed quarry sand. Sand or a sand-gravel mixture also works great for a pillow.

The sand-gravel mixture, as the name suggests, contains gravel, which only improves the mixture for laying under the pillow. The most popular height of the foundation cushion is height up to 15 centimeters, but not less than 10, otherwise the meaning of the pillow will be lost. If the building is built on soils with high level groundwater, sand can also be used to create drainage, and only then a cushion and foundation. This will make the foundation even more reliable and durable.

Foundation bedding is another name for a pillow; it is made on the basis of sand or crushed stone.

A reliable foundation for a building is the key to its strength and durability. Laying is based not only on choice quality concrete and proper tying of reinforcement, but also proper filling of the pit cushion. When choosing sand for the foundation, it is necessary to take into account the varieties, species and nuances of using the material.

Functions of a sand cushion

Quartzite fractions are used to create a foundation and organize bedding during construction. In the latter case, sand copes with several tasks:

• levels dense soils, evenly distributing the load of the building;
• compensates for the increase in the volume of frozen water on heaving soils. The material eliminates deformation and reduces the risk of cracks;
• eliminates damage to organic rocks - peat bogs, increases bearing capacity substrates.

A well-equipped layer will act as a barrier in conditions where groundwater is close and will absorb the weight of a multi-story building.

What is the need for an embankment?

A residential building must be built on a solid capital foundation. Has good strength properties monolithic design, located on a special bulk support. After preparing the area (clearing debris, marking), determining the depth, and digging a pit, a cushion of sand is lined. When is the best time to build it? Sprinkling is recommended in the following cases:

• when constructing a dwelling on heaving soils. The sand layer prevents destruction and deformation of the structure during freezing and thawing;
• in the presence of uneven soil. The embankment provides distribution and leveling of the construction site;
• with increased dampness from passing groundwater. The layer acts as a barrier;
• with possible settlement of the building. The cushion resists compressive forces in the soil;
• when constructing a building of several floors. The topping is laid to cushion the structure.

Sand under the foundation is laid in even layers, to a depth of no more than 20 cm, followed by compacting and watering each layer.

What type of material is poured under the base?

Correct arrangement of the bottom of the pit in accordance with the norms and regulations of SNiP 3.02.01 - 87 “Earth structures, foundations and foundations” requires the use of a bulk mixture to ensure the reliability of the structure. It is worth choosing what kind of sand is needed for the foundation - river or quarry, focusing on the product range of modern manufacturers.
The construction materials market sells sedimentary rock for foundation construction in 2 types: quarry and river. Which one is better to use for a pillow? In answering this question, you should decide on the nuances of using each.

Quarry sand: characteristics, application features

The raw materials are extracted from a quarry formed through the destruction of rocks. It is of low quality due to large volumes of impurities from clay and other substances. It is used for constructing pits, but not in natural form. Before use for the construction base, it is washed, dried and sieved to remove impurities. The popularity is due to the low cost of raw materials.
A quarry fill cushion must have an important factor determining reliability and strength future design– humidity. Its percentage in raw materials should be 1-5%.

Types of material

According to the type of processing, quartz raw materials are divided into:

• washed. It is extracted using hydromechanical equipment from flooded deposits. The technology makes it possible to obtain a composition without impurities and various components. The alluvial type is used in the production of bricks, concrete, reinforced concrete products, paving slabs and roads;
• seeded Obtained as a result of technical and mechanical sifting from stones and large particles. It is used in casting stone products, preparing masonry mortars and for forming a mass of plaster;
• sandy soil. It is an unrefined mixture with many impurities. As a rule, they are used to fill trenches and level the topography of summer cottages.

Career babe offered at construction markets, has exceptional quality according to GOST 8736-93. Materials extracted from quarries are inexpensive. To check the quality, i.e. humidity, it is recommended to weigh the wet sand and keep it in the sun for about 30 minutes, and then re-weigh it. Humidity is calculated as the mass of the raw material after heating, from which the mass of the container is subtracted, dividing it by 100. The optimal humidity indicator is from 1 to 5%.

River sediment is a versatile material

A universal type of quartzite raw material is mined from the bottom of freshwater rivers. The composition is considered a natural, pure product, designed for multi-purpose use in accordance with GOST - 8736-93. It rarely contains impurities and other organic compounds. Thanks to natural polishing, river rock fractions have perfect shape. Experts note the fact that it is better to use it for building foundations.
The fine-grained product is relevant for internal and exterior finishing, For brickwork and plastering walls, as well as to create a drainage system.

Breed gradation

Raw materials extracted from the river bottom are characterized by heterogeneity. Choosing right size pebbles for the base, it is worth understanding the factional diversity.
There are the following types of river bulk material:

1. Washed - represents medium-sized grains of sand, gray or yellow color. They contain silicon and iron oxides.
2. Coarse-grained - mined in the beds of dry rivers. It has an unobtrusive neutral color. It is used for decoration and finishing of premises.
3. Large – pebbles reach sizes up to 5 mm. It is obtained using specialized crushing and grinding equipment by splitting rock.

River bulk material comes in several fractions. Sizes range from 0.7 mm to 3.5 mm. The cushion, equipped with a mound of small grains of sand, is intended only for lightweight buildings. The fine-grained filling is strongly compacted and shrinks.

Positive characteristics of river sand

For residential capital buildings, it is better to use medium and large-sized chips - 2-3 mm, and for multi-storey buildings, only the coarse-grained type is used.
River sedimentary rock has a number of positive qualities:

• meets aesthetic and technical requirements;
• has increased moisture resistance;
• is not exposed to aggressive environments and does not rot;
• characterized by excellent sound insulation qualities;
• environmentally friendly and safe.

It is popular not only construction sites. Bulk rock is used for arranging children's playgrounds, for the manufacture of concrete products, landscaping, in decorating rooms and in landscape work.

Sand material fractions

Quarry and river varieties are classified according to the size of the elements. Experts distinguish several fractions of quartz rock:

• very thin. Sand grains measuring 0.7 mm are unsuitable for foundation construction. They can be used in arranging children's play areas;
• thin. The grain sizes reach 0.7-1 mm. Loose sand is not suitable as a base component, but is not bad for creating lean concrete;
• very small. The elements are 1.5 mm, but it is not enough to fill the foundation;
• small. Characterized by the presence of fractions of 1.5 – 2 mm. Usage of this type material increases the consumption of cement mixture;
• average. Grains of 2 to 2.5 mm in diameter are suitable as a component of standard concrete;
• large. Sand grains up to 3 mm in size are ideal for making high-quality concrete mixtures intended for large-scale construction;
• a composition of increased coarseness with grains of sand up to 3.5 mm is needed to cushion the foundation and distribute the mass of the structure over it.

For pouring, only particles with sharp edges are needed, which increase the adhesion of the concrete dough to the surface.

Features of the construction of a sand cushion

To build a reliable foundation, you must properly make an embankment and level the surface of the pit. The arrangement of the embankment implies the following indicators:

1. The pillow is constructed 1/3 of the width of the foundation. The depth of the embankment layer should not exceed 20 cm.
2. Before the flooring, geotextile sheets are laid on the bottom of the pit. It will provide additional drainage and protect the embankment from mixing with the soil.
3. The embankment is laid in parts. After laying each layer of bulk material, it must be well moistened and compacted. It is better to compact sand using a vibrating plate.
4. Compaction of sand under the foundation is carried out until then. Until there are no footprints left on the surface.
5. Upon completion of filling, the surface level should be checked. It should be smooth. The correctness of the subsequent construction of the building depends on this indicator.

After filling the bottom, reinforcement is installed, formwork is laid and concrete is poured.
To build a good and reliable foundation, you must first take care of the arrangement of the sand cushion. It plays an important role in the construction of the foundation, especially on heaving soils.