Many people know that there is a sand cushion for the foundation, but not everyone can say exactly why it is needed and how it is created. As a result, newbies in the construction business often pour sand into the trench without any understanding and end up only harming the entire structure.

The cushion under the base of the foundation can perform three functions:

• Leveling. If the soil is not heaving and not mobile, then the only task of the sand is to level the bottom of the trench or pit for uniform placement of the solution or proper distribution of the load from the FBS.

Compensating. Heaving soils under the support of a house in winter can greatly influence the distribution of loads, leading in difficult cases to the destruction of the concrete strip or slab.

In this case, the task of the sand is to compensate for the deformations and reduce them to a level acceptable for the given foundation.

Replacement If there is organomineral or organic soil under the house (for example, peat), then you have to put up with the continuing processes of decomposition.

In this case, the soil will necessarily be mobile, heaving and characterized by low bearing capacity. It has to be taken out to a great depth, until the end of the organic layer, and the trench must be covered with sand.

How thick a foundation cushion is needed depends on what function it performs in this particular case.

Pillow device

The easiest way is to create a bedding that plays a leveling role. As a rule, its thickness in this case does not exceed 15-20 cm. It is enough to pour sand once, carefully level it, spill it with a small amount of water, moisten it and then compact it.

But such a minimum can be done either on non-heaving soils, or in the case of a deep foundation, below the freezing level and supported by non-deformable soil layers. In other cases, you have to lay a compensating cushion. Its dimensions depend on the width of the foundation base. Exact data can be calculated from the table.

50-70	2.4*b	1.2*b
70-100	2*b	1.15*b
100-120	1.8*b	1.1*b

For example, if a foundation is laid with a base width of 60 cm, then the width of the pillow will be 60 * 2.4 = 144 cm, and the height 60 * 1.2 = 72 cm. Strip foundation with a belt width of over 120 cm there is no need for a compensating cushion.

A compensating sand cushion is laid as follows:

Sand is considered a non-heaving material; also, due to its structure, it prevents the capillary rise of moisture from the underlying layers to the concrete. But all this is typical only for sand not filled with water.

If a lot of moisture gets under the foundation, it can radically change the properties of the pillow.

Therefore, in areas with high level groundwater or where there is a possibility of sedimentary water getting under the concrete, it is imperative to provide a moisture removal system - drainage.

The process of laying a replacement cushion under the foundation is not fundamentally different from the compensating one. The role of geotextiles and water drainage systems is only increasing. In any case, the important point is proper compaction. It is worth considering in more detail.

Watch our video collection on the topic:

How to seal correctly?

Pure sand practically does not shrink, but only after proper compaction. If this procedure is neglected and performed in bad faith, there is a high risk of subsidence with subsequent destruction of the foundation.

For everything to work out properly, you should adhere to the following rules:

Compaction work is carried out more conveniently and quickly using a vibrating plate or a special construction vibrator.

In some cases, road construction equipment can be used, and sometimes compacting by hand works well.

Which method to choose depends on the characteristics of the site and capabilities.

Sand selection

Few people think about what sand to choose for a foundation cushion. They take the one they bring. However, the properties of this material affect the properties of the bedding no less than the correctness of its laying.

Washed quarry or river material is best suited for foundation cushions.

The ideal choice is gravel. Do not forget that it is also possible to use other materials that meet the presented requirements.

However, it is difficult to correctly determine the loads and properties of a particular soil at home, so the easiest way is to take the material that is guaranteed to fulfill its task.

Watch our video compilation on how to create sand cushion:

Proffu » Posts » Materials and tools » Sand bedding under the foundation

Before starting construction work, many people pre-calculate required amount material. This the right approach to such a serious matter. But at this stage, many 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. The modern market offers a huge range of sand, both natural and artificial. The article will tell you how to make a choice so that the foundation does not suffer from it.

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. This material is not suitable for construction work, so the sand must be sifted and cleared of foreign debris.

However, simple pouring is not enough 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 permissible clay content in sand is no more than five percent of 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 types of sand there are.

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 of the reliability and strength of quarry sand is 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 its low quality due to the large amount of impurities of clay and other substances. Nevertheless, this raw material 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, paving slabs, concrete, brick and reinforced 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 to prepare a mass 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 rarely contains organic compounds and impurities. Therefore, river sand is considered clean 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. The following types of bulk river material are also distinguished.

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

2. Coarse sand. Has an unobtrusive neutral color, mined in dry rivers. Ideal for finishing and decorating a room.

3. Washed river sand. These are medium-sized grains. Have gray or yellow, since they contain iron and silicon oxides.

Positive aspects of river sand

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

For the construction of multi-storey buildings, only the large-fraction type is used, and for capital buildings, the medium-sized type is suitable. River sand is also 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. Due to this, 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, consumption increases cement mixture.
• 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 levels and the amount of 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.

When laying the foundation, it is important to choose building materials correctly and competently. 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. Foreign objects may include branches, leaves, and 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 discover 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 are also a 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.

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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. Its 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.

To correctly determine the humidity parameter, you can use 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.

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river sand

River sand is ideal for laying foundations, and is also used when diluting mortars for interior decoration 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 organic impurities (shells, algae) and foreign objects.

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Sand fractions

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

• Very thin contains grains of sand the size up to 0.7 mm, but due to the low fraction it is unsuitable for foundations. The foundation based on it will be as fragile as possible.
• Thin contains grains of sand the size from 0.7 to 1 mm. This sand is not dense, so it is also not suitable for foundation mortar. Typically, fine sand is used to pour concrete.
• Very small contains grains of sand the size up to one and a half mm, but still again not suitable for pouring a foundation, since the strength will still not be optimal.
• Small contains grains of sand the size from one and a half to 2 mm. And again, it is not suitable for pouring a foundation due to the high cost of cement for it.
• Average contains grains of sand the size from 2 to 2.5 mm and is ideal for pouring foundations due to its strength and high performance properties.
• Large contains grains of sand the size up to 3 mm and is intended for the production of high-quality and expensive grades of concrete. This sand is very expensive.
• Sand increased size contains grains of sand the size up to 3.5 mm and is used to make sand cushions designed to increase the strength of the base and distribute the load evenly across all corners.

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

You must take care of your purchase building materials for preparing concrete. It is recommended to pay special attention to sand. After all, how durable the mortar for laying the foundation of a home will largely depend on its quality and origin. The best sand for foundations is discussed below.

Sand, in top layer which contains large foreign substances larger than 5 mm, is not suitable for foundation mortar.

Material quality

Sand is a bulk building material that belongs to a type of sedimentary rock. At the same time, it is also obtained artificially - by crushing stone and crushed stone. But no matter what type of sand you decide to purchase, first of all it must be of high quality, that is, clean. The presence of various organic matter in it - branches, grass, leaves and other things - is unacceptable. Of course, you can always clean contaminated building material by sieving it, but it will take a lot of effort and time to do this. In addition, do not forget that in addition to organic contaminants, sand can contain various impurities: lime, clay, and so on. Their presence in bulk building materials is extremely difficult to determine accurately. Moreover, clean the sand from them. It is worth remembering that it is allowed to contain impurities only in an amount of 5% of the total mass. If the amount of clay or lime in the sand is higher, this will lead to a deterioration in the strength of the concrete, which, in turn, will negatively affect the durability of the finished foundation.

To determine what kind of sand the manufacturer offers you, ideally you need to go to a laboratory for examination. Only then will it be possible to find out exact amount impurity content. However, not everyone has the opportunity to do it, because it is expensive. Therefore, here it is proposed to take a different route and check what kind of sand the manufacturer offers you in the field. Many builders use a method that involves placing a clear plastic or glass bottle pour 1/3 of the sand and fill up to half the volume with water. After which the container is thoroughly shaken so that the bulk building material is moistened as much as possible. Then leave it for 5-7 minutes and then see what the water has become. If it is dirty, then you cannot make a foundation from such sand. If there are third-party substances on the top layer, the thickness of which is more than 5 mm, then such a building material is also not suitable for constructing the foundation of a house. If the water remains clear and there are less than 5 mm of foreign substances in it or they are completely absent, then you can make a foundation from such sand.

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Material moisture

Quarry sand is extracted by breaking down rocks, and the quality of such material is very low.

When purchasing this building material, you need to take into account its moisture content. She may have different meanings. In this case, humidity is considered optimal from 1 to 5%. This is exactly what you need to buy sand with. To find out this parameter, you can use the following method: take a metal pan, weigh it (in kg), then measure 1 kg of sand on a scale and place it in the container, then put it on the stove and heat it over low heat for 30 minutes, stirring mixture from time to time. When this process is completed, immediately place the pan on the scale and look at the total mass, and then subtract the weight of the container from it and divide the result by 100. The final figure will be an indicator of humidity as a percentage.

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What type of sand should I choose?

When purchasing sand, you need to know exactly which type is best suited for building the foundation for a house. This means that you need to become more familiar with each of its varieties. They are as follows:

River sand, due to its fraction sizes from 1.6 to 2.2 mm, is used for concrete solutions for foundations, for interior decoration, and for creating drainage systems.

1. River. It is obtained from the bottom of rivers. Its builders consider it universal. The sizes of its fractions vary within the following limits: from 1.6 to 2.2 millimeters. Therefore, it can be used not only for preparing concrete for the foundation, but also for finishing rooms, creating drainage systems, and so on. It is important that there are practically no clay impurities in such building material. Therefore, as a rule, there is no need to check it for their presence. In addition, no organic compounds are found in it. Accordingly, such sand can be called clean. Therefore, this building material is ideal for preparing concrete. Experts recommend making a foundation based on it. But it should be taken into account that river bulk building material has a relatively high price. This means that you will need to allocate a substantial budget for its purchase. If it is not provided, then you will need to make a choice in favor of another type.
2. Nautical. This type building materials are mined from the bottom of the seas. It comes with particles of shells and various impurities. But before delivering it to customers, manufacturers clean it. Therefore, it can be used to build a foundation, after making sure that the manufacturer has conscientiously filtered it from impurities and organic substances.
3. Career. This type is inferior in quality to the first two. Its extraction occurs by destroying rocks. The purchase of such building material is always very economical, since the price for it is set extremely low. And if you allocated very little for the construction of the foundation Money, then the purchase of quarry sand will be great solution. But you will need to pay special attention to its quality, since in most cases it leaves much to be desired.

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Which sand fraction should I choose?

A building material such as sand is divided into several types according to fractions. The gradation looks like this:

1. Very thin - sand grain fractions do not exceed 0.7 mm. Such building material is unsuitable for constructing a foundation, since it will have minimal strength.
2. Thin – fractions from 0.7 to 1 mm. Builders do not recommend using this material for preparing concrete. It will not have good density.
3. Very fine – fraction size up to 1.5 mm. It can be used to create a foundation, but you need to take into account that it will not have very high performance characteristics.
4. Fine – fraction size from 1.5 to 2 mm. Not well suited for the preparation of concrete, since it requires a large amount of cement to create it, which leads to increased costs for building the foundation.
5. Medium – the fraction size is from 2 to 2.5 mm. Ideal for building foundations. This is what construction experts recommend using. Therefore, you should opt for such sand.
6. Large – fractions up to 3 mm. This material is used exclusively for the preparation of high-quality concrete. Making a regular solution out of it is unprofitable.
7. Increased size – fractions up to 3.5 mm. With its help, they create foundations on sand, that is, they make cushions necessary to increase the strength of the building’s foundation and evenly distribute the load.

When choosing sand, you need to pay attention to its edges. They must be sharp, since material with this shape increases astringent qualities concrete mortar.

Sand is an important component for a concrete mix, so its selection should not be taken lightly. To build a foundation, for every kg of cement you will need approximately 3 kg of sand. Like any component, it has special requirements. When mixing concrete yourself using sand, you should be guided by GOST 8736-93 “Sand for construction work. Specifications"(hereinafter GOST).

There are many varieties, each of which differs in:

• chemical composition;
• physical properties;
• origin;
• extraction method.

In addition to differences in the listed characteristics, GOST distinguishes sands depending on their fraction. The class to which the material of a given fraction may belong, depending on quality indicators, is indicated in brackets. The first class has more stringent requirements for the percentage of grains with a particle size of less than 1 cm.

1. very large (l, ll);
2. increased size (l, ll);
3. large (l, ll);
4. middle(l, ll);
5. small (l, ll);
6. very small (ll);
7. thin (ll);
8. very thin (ll).

To determine which sand is better for the foundation, you also need to give a classification by origin:

• natural (river, quarry, sea);
• of artificial origin.

Natural origin

The most common type of material. Possibility of use depends on the location of the mining sites. There may be several types.

Quarry sand. Mined open method. Contains a large amount of impurities (clay and dust), sometimes stones are found. For use in building structures requires pre-processing:

• Washing quarry sand involves washing with a large volume of water;
• sifting allows you to achieve high quality quarry sand; this material is even used for preparing plaster mixtures.

Extraction of quarry sand.

But sometimes there is quite clean sand in quarries, it all depends on the deposit.

The second origin option is river sand. Its advantages include:

• usually less contamination;
• no cleaning required.

Extraction of river sand.

The disadvantages of river sand include the high cost of extraction and, accordingly, the high cost of the material. As part of a cement mixture, it accelerates its settlement, which leads to the need for constant mixing.

Sea sand is similar in characteristics to river sand. He has high quality and purity, but is characterized by high cost. Sea and river materials are more often used in the production of finishing mixtures than for building structures, because usually finer than quarry sands.

Extraction of sea sand.

Artificial origin

Sands of this group are produced according to special technology, which makes it possible to provide bulk materials to areas located at a great distance from the sites of extraction of natural raw materials. It is better to resort to materials of this manufacturing method if there are no other options. Depending on the feedstock, sands are divided into:

• crushed (from basalt, marble, diabase, metallurgical slag);
• porous (from tuff, pumice, agricultural and wood waste, volcanic slag);
• sedimentary (from shell rock and hard tuff);
• expanded clay;
• agloporite (from slag or fuel ash, raw materials containing clay);
• porous (from slag).

Cleanliness check

To use river or quarry material, you need sand cleared of:

• organic inclusions (grass, branches, plant seeds and others);
• large inclusions (stones);
• impurities (clay, lime).

It is better to get rid of the first two types of impurities by sifting. The presence of organic inclusions is determined using the method described in paragraph 6 of GOST.

The latter may be difficult. First you need to determine the percentage of clay and dust particles. Which method to use for this, and how exactly, is described in GOST, paragraph 5.

There are several methods:

• elutriation;
• pipette;
• wet sifting;
• photoelectric.

All these methods are suitable for research in the laboratory, but which method is best used for self-construction foundation? In “field conditions” the following procedure is needed:

1. take a transparent one sealed container(you can use a plastic or glass bottle);
2. add sand to a third of the volume, add up to half the volume of water;
3. shake the contents well;
4. wait 5 minutes at rest and analyze the result.

It is better to avoid using the material in the manufacture of concrete mixture for the foundation when following results experience:

1. the liquid did not become transparent again, suspended particles remained in the water;
2. a sediment more than 5 mm thick has formed on the surface of the sand.

Which sand to choose

To understand which raw material is best to choose for concrete, it is recommended that you familiarize yourself with the table.

Sand type according to GOST	Particle size (fraction)	Recommendations for use
Increased size	3-3.5 mm	Good for foundation pads
Large	2.5-3 mm	Used for high-grade concrete mixtures, provides increased reliability and strength, also used for cushions under foundations
Average	2-2.5 mm	Ideal for mixing concrete mixture
Small	1.5-2 mm	Use allowed
Very small	1-1.5 mm	Not recommended for use
Thin	0.7-1 mm
Very thin	less than 0.7 mm	Use prohibited

Important! When laying the foundation, the question of the material for the sand cushion also arises. The use of the last four fractions in this case is unacceptable, since the pillow will shrink more.

It is recommended to use compounds of natural origin, since artificial ones can be radioactive and dangerous to humans. Be sure to comply with the requirements for fraction and purity. If the particles are of the appropriate size and there are no foreign inclusions in the composition, inexpensive quarry or river sand can be used. It is recommended to choose raw materials belonging to the first class. River sand is often finer than quarry sand, so you need to look at its characteristics before using it.

To summarize, we can say that the origin of sand has no of great importance, the main thing is its characteristics - fraction and purity class. Proper selection of each component of the concrete mixture will ensure its quality and reliability of the finished structure.

Advice! If you need contractors, there is a very convenient service for selecting them. Just submit in the form below detailed description work that needs to be done and you will receive offers by email with prices from construction crews and companies. You can see reviews about each of them and photographs with examples of work. It's FREE and there's no obligation.

Looking at a pile of sand brought to a site, two builders will behave differently.

The newcomer will cast an indifferent glance at her and take up the shovel.

An experienced builder will first take a handful of sand, look at it carefully and rub it in his palms. After that, he will give a verdict: it’s suitable for concrete, but not suitable for plaster and masonry.

What is the secret? construction sand, requiring such careful evaluation? We will examine this issue in more detail.

Physical and mechanical characteristics

Volume weight

It shows the mass of 1 m3 of sand in its natural state (wet, with all impurities). On average, the volumetric weight of this material ranges from 1500 to 1800 kg.

The composition of construction sand is assessed according to the following parameters:

1. Granulometric;
2. Mineral;
3. Chemical.

Granulometric shows the percentage of grains of different sizes. To determine it, sand is sifted through calibrated sieves (from 0.16 mm to 10 mm).

A sieve with aperture sizes of 5 and 10 mm reveals gravel granules. GOST allows the presence of grains measuring 1 cm. However, their quantity should be no more than 0.5% of the total mass of sand.

Granules larger than 5 mm are normalized as follows:

1. Maximum content - up to 10% in natural;
2. up to 15% in crushed;
3. up to 5% in enriched sand.

Mineral composition

Chemical composition

It plays an important role in determining the suitability of bulk material in various fields of construction. Red, yellow, and orange shades indicate the presence of oxidized metals. Green and blue colors are characteristic of river sand, which contains aluminum salts.

Types of construction sand

The classic definition is that sand is a mixture of mineral particles (quartz, mica, limestone) formed as a result of natural or artificial destruction of rocks.

GOST 8736-93 lays out the most important properties of sand “on the shelves”. According to this standard, sand is divided into two classes:

• Class I - very coarse, then comes sand of increased coarseness, coarse, medium and fine;
• Class II - very large, extra large, large, medium, small, very small, thin and very thin.

The main difference between these classes is that lower quality sand (second class) includes three additional fractions. Small dust particles are an undesirable component mortars. They impair the bond between the large sand granules that the cement binds.

In real production there is no such fine gradation.

Here the extracted sand is conventionally divided into three fractions:

• 0.5-1 mm – small;
• 1.5-2 mm – average;
• 2.5-3.5 mm – large.

Sands with a particle size modulus of 2-2.5 mm are used for the production of concrete and reinforced concrete structures. Bulk material 1.5-2 mm in size is used for making bricks. The finest sand is used for preparing dry construction mixtures.

Having taken note of the GOST classification, let’s move on to the practical aspects of the origin and use of construction sand.

Based on the type of production, they are distinguished:

• Career;
• River;
• Nautical;
• Quartz (artificial) sand.

Career

The name clearly indicates the origin of the sand. It contains clay and stones, so quarry material is used to a limited extent: for site planning, backfilling concrete screeds or foundations.

To improve its properties, quarry sand is washed with water right at the mining site, freeing it from dust particles and clay. This is how alluvial (washed) sand is obtained. It is suitable for plastering and masonry mortars. In addition, sifting through sieves can be used to remove clay.

Important practical conclusion: If you are offered to buy quarry (gully) sand, do not forget to check whether it has been cleaned (washed, sifted) or not.

Areas of application of washed (sifted) quarry sand:

• cement screed, masonry and plaster mortars;
• Finishing work;
• brick production;
• foundation installation;
• preparation of concrete.

river sand

This building material is extracted by a dredger from the river bottom. IN river sand no clay particles and very few rocks. This allows you to use it for concrete work without restrictions.

It is very valuable that medium-sized river sand (1.8-2.2 mm) practically does not shrink. This makes it ideal for masonry and plastering.

Quarry sand is more difficult to use in this capacity. In the solution it settles to the bottom and has to be stirred periodically.

Areas of application of river sand:

• concrete production;
• brick production;
• masonry work and cement screed;
• preparation of asphalt concrete;
• drainage device;
• filler for paints and grouts.

Sea sand has similar properties to river sand. It is also highly valued in construction for its high purity and uniformity of particle size distribution.

Quartz sand

This material is obtained by mechanical crushing of quartz-containing rocks. It is homogeneous in structure, chemically inert and pure.

The main area of ​​application of this type of sand is the construction materials industry. He goes dry building mixtures, sand-lime brick, blocks and concrete, used for preparing grinding compounds. Landscape design, expensive interior and facade plasters also cannot do without quartz sand.

It is impossible to unequivocally answer the question which sand is better., since each material is intended for certain types of work.

Still, the main conclusions are already obvious:

• for brick and large-block masonry, it is better to take river sand. If you mix it with a small amount of unwashed quarry sand, the solution will become more plastic (due to clay particles);
• for concrete, coarse or medium river sand is better suited (you can add a little fine washed quarry sand to it);
• for plaster would be better suited washed quarry sand with or without a small addition of river sand.

Approximate prices

Obviously, the cost of sand is higher, the more manipulations had to be done with it during extraction and cleaning.

The cheapest is quarry unwashed and unsown. Its price per cube ranges from 300 to 400 rubles. Quarry sand purified by water or sifting for construction work will cost from 550 to 700 rubles per 1 m3 with delivery.

River sand is significantly more expensive than quarry sand. Its price starts at 750 rubles and ends at 950 rubles/m3.

Fractionated quartz sand is the most expensive. When purchasing from 10 tons (1 KAMAZ), its price with delivery is from 4,500 rubles per cubic meter.

Before you start construction works, many first calculate everything and prepare the material. This is correct and commendable. But at this stage, various questions arise, one of them is what kind of sand is needed for the foundation. The choice of sand should be given special attention, since it is one of the main and important components used in mixing concrete. And your future foundation, foundation, depends on the quality of the concrete mixture. Considering that the market provides big choice of various sands, both natural and artificially produced, it is important to choose the most suitable one for performing these works. In this article we will tell you how to make your choice.

Purely theoretically

Any person who is not knowledgeable about the construction business and its nuances can guess that it is necessary to choose clean sand for the foundation. The sand may initially contain various organic elements, such as grass, branches, etc. Such sand is not suitable for work, but it can be easily cleaned. Perhaps you have seen more than once how workers sift sand, clearing it of unwanted elements.

But if we talk about impurities such as clay, lime and other similar ones, then simple sifting is not enough. It is more difficult to clean such sand, so you need to immediately pay attention to this when purchasing. The presence of clay in sand should not exceed 5% of the total mass, especially when it comes to foundation mortar. Otherwise, the future structure will not be reliable, it will shrink, and this will lead to cracks. It is important to check how clean the sand is before purchasing. You can use a simple method to check.

You will need a clear bottle, either glass or plastic. You need to fill it 1/3 with sand and fill it with water up to half. Next, shake the bottle vigorously so that the sand is mixed with water and completely wet. After that, put it down and wait 5-10 minutes. If the water has become dirty, this sand will not be suitable for the foundation. If a foreign substance has formed on the surface in a layer of more than 5 mm, such sand cannot be taken. Let's look at what types of sand there are, how they differ and what type of sand is best to purchase for the foundation.

Varieties of sand

Sand is divided into several types, depending on the place of its extraction:

1. River.

The very name of river sand suggests that it is mined from the river bottom. This universal material, since it contains fractions different sizes– from 1.6 mm to 2.2 mm. Due to this, it is used not only for pouring the foundation, but also for various construction purposes. The main advantage of river sand is its natural purity and uniformity. There is very little clay, vegetation particles and other impurities in it. This sand is ideal for foundations. Only its price is quite high.

Sea sand is mined from the bottom of the sea, after which it is cleaned of shell rock and other impurities. The difference between this sand is its grain size, which is approximately 1 mm. This size of granules allows it to be used for the construction of reinforced concrete structures. It can be called quite pure, since before sale it is cleaned, screened and washed. But you have to pay for quality, which is why sea sand is the most expensive.

Quarry sand is extracted by open pit mining. If you compare it with river and sea sand, this is the worst option. And it’s not surprising, since it contains a lot of impurities - clay, vegetation and crushed stone. Because of this, the price of such sand is the lowest and it is suitable for rough work on initial stage construction.

To clearly determine which sand is best for concrete, it is important to consider other features. Some craftsmen advise buying quarry sand, which is cheaper, citing the fact that this will not affect the quality of the house’s foundation. Others say that quality is higher than price, so you need to choose expensive sand, which will ensure the reliability of the foundation, on which you cannot skimp. Be that as it may, you need to consider other features and criteria that will help you make your choice.

Characteristics

As mentioned above, the sand must be clean. If there is vegetation or branches in it, it’s not a big deal, they can be weeded out. But clay, silt, gravel and other particles can reduce the quality of the concrete solution. The presence of clay should not exceed 5%. The presence of gravel as a percentage of the total mass should not be more than 5%, and the particle size should not be more than 10–12 mm. If the size of gravel ranges from 5 mm to 10 mm, then a higher percentage is allowed - up to 10% of the total mass.

Quite a lot important point when choosing a material - its granulometric composition, that is, the size of the granules. Based on the size of sand granules, it is divided into:

• very fine sand, the granule size of which is no more than 0.7 mm. Such sand will not be suitable for making concrete;
• fine sand, the granule size of which is from 0.7 mm to 1 mm. This type is also not used for making concrete;
• very fine sand, the granule size of which ranges from 1 mm to 1.5 mm. There is no need to choose it for concrete either;
• fine sand, the granule size of which is from 1.5 mm to 2 mm. Not suitable for preparing high-quality concrete mixture;
• medium-sized sand, the granule size of which is from 2 mm to 2.5 mm. It is sand of this coarseness that is ideal for preparing a concrete mixture for the foundation;
• coarse sand, the granule size of which is from 2.5 mm to 3 mm. It is used for the production of high-quality quality concrete;
• sand of increased coarseness, the granule size of which ranges from 3 mm to 3.5 mm. Sand of this fraction is best used to cushion the foundation for the base of a building.

Very coarse sand, larger than 3.5 mm in size, can also be used to cushion the foundation.

Another important point when choosing sand for the foundation is humidity. The water content in sand plays an important role, since its quantity must be taken into account when mixing a solution with the addition of water. The recommended moisture content of sand for the foundation should be no more than 5%. Dried rock may have 1% moisture content. If the sand is exposed to precipitation, then its humidity can reach up to 10%.

If you purchased sand, you need to take care to protect it from precipitation. To do this, you need to cover it with something or unload it under a canopy. Then it will not absorb excess water.

But how to determine the moisture content of sand? Use a saucepan or iron bucket. Take the container and place it on the weights. Having found out the weight of the container, take 1 kg of sand and fill the container with it. Now you need to dry the sand. To do this, place it on the stove over low heat and “cook”, stirring, for 30 minutes. After time has passed, everything needs to be weighed again. From the weighing result, subtract the weight of the bowl or bucket and multiply the result by 100. As a result, you should get a percentage number that indicates the humidity. For clarity: a bucket or bowl weighs 0.2 kg. After you have dried 1 kg of sand, total weight it turned out to be 0.9 kg. It turns out:

0.9 - 0.2 x 100 = 70

The humidity of your sand is 7%. There is another method for determining humidity. It is enough just to use a special device that will show the exact number.

Let's sum it up

So, having all the data, you need to analyze it and make a choice. You learned that the ideal sand for foundations is:

• clean sand, in which clay and gravel do not exceed 5% of the total mass;
• medium-sized sand, the granule size of which ranges from 2 mm to 2.5 mm;
• sand, the humidity of which does not exceed 5%.

When buying such building material for the foundation, you should definitely pay attention to these indicators. Most the best option in terms of price and quality is washed and screened quarry sand, the granule size of which is 2–2.5 mm. It is better to buy it directly at the place of production. If you have money and want your foundation to be strong and last for a very long time, choose river sand of the same fraction. Then your concrete for the foundation will have the necessary qualities.

When buying sand, you should control the process of weighing a loaded and empty dump truck, as there are unscrupulous suppliers who underweigh the sand, profiting from you.

We hope that this article helped you figure out which sand to choose for the foundation.