Sand for making concrete. What sand is better for a pillow under a river or quarry foundation? What sand is better than river sand

Before starting construction work, many pre-calculate the required amount of material. This is 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 a 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 mixture obtained. The modern market offers a huge range of sand, both natural and artificial. How to make a choice so that the foundation does not suffer from it, the article will tell.

Sand selection basics

Even a person who is ignorant of construction issues will be able to guess that exceptionally clean sand is suitable for the foundation. Initially, various organic elements may be present in it: small twigs, grass, etc. Such material is not suitable for construction work, therefore, there must be sown sand, cleaned of foreign debris.

However, simple pouring is not enough when it comes to impurities such as lime or clay. It is much more difficult to clean such sand, so when buying building materials, you need to immediately pay attention to this. The content of clay in the sand is not more than five percent of the total mass, especially if a solution is being made for the foundation. Otherwise, the structure after some time will shrink, crack and will not be particularly reliable.

Checking the purity of the sand

Before choosing what kind of sand is needed for the foundation, you should check its purity. For this, a simple method is usually used. Any empty clear bottle (glass or plastic) will be needed. Sand is poured into it by one third and half filled with water. Then shake the bottle vigorously so that the components mix well with each other. After that, they put it up and wait for five to ten minutes. If the water in the bottle has become cloudy and dirty, then this 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 consider what exist

Types of sand for embankment under the base

To ensure the reliability of the structure under construction, in accordance with 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 one is most suitable for a foundation pillow, it is worth familiarizing yourself with the characteristics and nuances of using each type.

Quarry sand

This raw material is mined in quarries, breaking rocks. An important indicator of the reliability and strength of quarry sand is its moisture content. A ratio of one to five percent is considered acceptable. Suitable humidity can be determined visually. It will not work out of the sand to form a dense lump - it will simply crumble.

The cheapest material is considered to be quarry building 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, it is in great demand.

Types of quarry sand

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

1. Sandy soil. It is a crude mixture with various impurities. As a rule, dacha plots are leveled with it and trenches are filled up.

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

3. Seeded sand. It is cleaned by a technical and mechanical method from large particles and stones. Typically, such raw materials are used to prepare a mass of plaster, masonry solutions and in the casting of stone products.

River sand

This raw material is mined from the very bottom of freshwater rivers. It rarely contains organic compounds and impurities. Therefore, river sand is considered a pure and natural product that is designed for multipurpose use. It is an ideal material for laying foundations, creating drains and diluting the mortars needed for interior decoration of the house. Due to natural grinding, river sand has an ideally smooth shape and a fine fraction within two millimeters.

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

River sand classification

Raw materials from the bottom of the river can be very different from each other. Therefore, you should deal with 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 compresses strongly, therefore it is suitable only for lightweight buildings. The following types of bulk river material are also distinguished.

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 obtained from dry rivers. Ideal for finishing and decorating a room.

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

Positive sides of river sand

River sedimentary rocks have several positive qualities that are important 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 the construction of multi-storey buildings, only the coarse-fraction type is used, and for capital houses, an average crumb is already suitable. Also, river sand is ideal for landscaping sites, playgrounds, landscaping and decorating rooms.

Sea sand

Sea chips are also exactly the material that is needed for the foundation. The 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 cleaned of strangers 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 chips for construction where it is sold nearby and is cheaper.

Sand fractions

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

• 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. Grains in size reach from 0.7 to 1.0 millimeters. This is a loose material. You cannot use such sand for construction, but it will be good for making lean concrete.
• Small fraction. It is a grains of 1.5-2.0 millimeters in size. When using it, the consumption of the cement mixture increases.
• Average. Nibbles (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 diluting high-quality concrete mix that 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 the construction of foundations. It will create a layer that will increase the strength, stability of the building, 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 crumb, but it must be washed. A sand and gravel mixture is also suitable, which improves the quality of the bedding compound.

Required amount of sand

Usually, one part of cement is taken for five parts of sand. But this calculation is suitable if the solution is made from only 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 the following proportions: four parts of sand, two parts of crushed stone and one part of cement.

As can be seen from the calculations, it is always necessary to take more sand than other components. The amount of materials itself directly depends on the height of the pillow and the building itself. It is better to buy sand with a small margin so that you do not have to buy it at the wrong time. Residues can be adapted for the preparation of mortars for wall decoration or masonry.

Summarizing

Answering the question of what kind of sand is needed for the foundation, it should be noted that river grains of the middle fraction are considered the ideal option. This material has excellent properties for construction purposes. It allows you to build the most durable foundation that will stand for a long time and will be an excellent foundation 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 matter. It is also worth paying attention to the consistency of the purchase size. As a rule, there should be about one and a half tons of sand in a cubic meter.

Sand is a loose mixture of fine particles of various minerals and rocks. It is formed in the course of their long-term erosion and destruction. In the composition of sand, silicon dioxide (quartz) and calcium carbonate are most often found. The size of the sand grains is 0.06 - 2 mm. By origin, all sands are divided into: sea, aeolian, lacustrine, alluvial and deluvial. If the reason for the appearance of sand was the activity of water, then its particles have a smoother and more rounded shape.

The sands are divided into categories by such characteristics as: composition, density, origin, type, shape of grains, strength, content of dust and clay, presence or absence of harmful impurities, as well as physical properties.

The origin of the sand is river, sea and quarry. The river is mined in the river beds. Usually it is more pure, there are few impurities in it, including clay. It is more uniform, and the grains of sand are smoother and more rounded. The downside of its extraction is that it disrupts river ecosystems, which can lead to adverse consequences. River sand is quite heavy and can precipitate, therefore frequent mixing is required when preparing the mortar.

In many ways, sea sand is similar to river sand. But it has a drawback: the presence of larger particles - pebbles (sometimes) and fragments of shellfish shells. In general, it is a high-quality building material, but at the same time the most expensive one.

Sea sand

Quarry sand is obtained directly from sedimentary rocks - in sand quarries. It contains an admixture of clay and stones and requires cleaning. Its advantage is its low price.

The sand can also be of artificial origin. It is obtained by crushing hard rocks, for which special devices are used. The raw material is quartz rock. This sand contains almost no impurities, since it is cleaned immediately after crushing. For this, rinsing and sieving is used. Washing provides a greater degree of purification from impurities, but such sand is also more expensive. Artificial sand is fairly uniform in color and composition.

In terms of particle size, sand can be fine, medium and coarse. A more precise classification assumes the division into 8 categories according to the size of the fractions. The finest falls into the "very thin" category with a grain size of less than 0.7 mm. The coarsest grains are classified as "very coarse" with a particle size of more than 3.5 mm.

General requirements for concrete sand

Concrete sand plays an important role in the composition of the concrete mix. The strength and durability of future buildings depends on it. There are certain standards established by GOST, which the sand used for concrete must comply with. In accordance with them, the dust fraction (particle size less than 0.14 mm) should be less than 10% of the total mass of sand, dust and clay - less than 3%. Control over the content of clay is especially important, since its presence negatively affects the strength of the concrete and its resistance to frost. Also, in accordance with GOST, the content of particles with a size of 0.5 - 1 cm should be no more than 5 percent of the total mass, and even larger particles are not allowed. Also, the presence of organic impurities is not allowed.

River sand for concrete is best

To determine the particle size, the sand is passed alternately through sieves with different mesh sizes.

For concrete, it is better to use sand with a lower specific gravity (optimally 1.5 t / cubic meter). One cubic meter of wet sand weighs in the range of 1300 - 1800 kg.

The moisture content of the sand also matters. In raw sand, it is 5-10%, and in dried sand, it drops to 1%. The amount of water that needs to be added to the solution depends on the humidity. To determine it, one kilogram of wet sand is dried under the influence of high temperature. The difference in the weight of the sand before and after drying shows the mass of the evaporated water. Directly on the construction site, the saturation of the sand with moisture can be approximately determined by squeezing it in a fist. If after that it still crumbles, then it means that it is dry enough. If not, then its moisture content is over 5 percent.

What sand to choose for making concrete?

It is better to add quarry sand in limited quantities.

For the manufacture of concrete, it is advisable to take medium- or coarse-grained river sand. A small amount of refined sand from a quarry can be mixed with it. Particles of quarry sand have a rougher surface than river sand, and, ideally, this is a plus, since such grains of sand create a stronger bond with the concrete components. But in such sand, even if it is cleaned, there may still be an admixture of clay, which degrades the quality of the solution. That is why it is recommended to put more river sand in the solution than quarry sand.

Harmful impurities

In addition to clay, other components that can be part of the sand are also unwanted impurities. Iron oxides can cause brown stains on the surface of the concrete, as well as make it less reliable in use. Mica plates weaken the adhesion of concrete components, which can lead to corrosion in the future. Sulfur compounds can cause cracking in concrete. Such properties are possessed by gypsum and pyrite, which are able to interact with water.

Concrete preparation

In order to obtain high-quality and durable concrete, it is required to maintain the required proportion of its constituent components. The ratio of the number of buckets of cement, sand and crushed stone should be 1: 3: 5. If there are more buckets, then all terms of this ratio should be multiplied by the same coefficient. The sand that is optimal for the preparation of concrete should consist of granules with a size of 1.5 - 3.5 mm. Coarse sand is used to obtain concrete grade M350 and higher. For the preparation of concrete grade M200, finer sand is used. This concrete can also be used to fill the foundation.

Before starting construction work, many first calculate everything and procure the material. This is correct and commendable. But at this stage, different 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 when mixing concrete. And your future foundation, foundation depends on the quality of the concrete mix. Taking into account the fact that a large selection of various sands, both natural and artificially obtained, is provided on the market, it is important to choose the most suitable one for performing these works. In this article we will tell you how to make the right choice.

Purely theoretical

Anyone who is not versed in the construction business and its nuances can guess that it is necessary to choose clean sand for the foundation. Initially, the sand may 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 the sand, cleaning it of unwanted elements.

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

You will need a clear bottle, be it glass or plastic. It is necessary to fill it with sand by 1/3 and fill it with water to half. Then shake the bottle vigorously so that the sand mixes with the water and gets completely wet. Then put it on and wait 5-10 minutes. If the water becomes dirty, this sand will not work for the foundation. If a foreign substance has formed on the surface, with 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 kind 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. It is a versatile material, as it contains fractions of different sizes - from 1.6 mm to 2.2 mm. Thanks to this, it is used not only for pouring the foundation, but also for various construction purposes. The main advantage of river sand can be called its natural purity and uniformity. There is very little clay, particles of vegetation 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 such sand is its grain size, which is approximately 1 mm. This granule size allows it to be used for the construction of reinforced concrete structures. It can be called quite clean, since it is cleaned, sifted and washed before being sold. But you have to pay for quality, so sea sand is the most expensive.

Open pit sand is extracted from the open pit. If you compare it with river and sea sand, this is the worst option. And it is not surprising, since it contains a lot of impurities - clay, vegetation and gravel. Because of this, the price for such sand is the lowest and it is suitable for rough work at the initial stage of construction.

In order to unambiguously determine which sand is best for concrete, it is important to consider other features. Some craftsmen advise buying quarry sand, which is cheaper, referring to the fact that this will not affect the quality of the foundation of the house. 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 save. Be that as it may, you need to consider other features and criteria that will help you make your choice.

Specifications

As mentioned above, the sand must be clean. If there are vegetation or branches in it, this is not scary, they can be weeded out. But clay, silt, gravel and other particles can degrade the quality of the concrete slurry. 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 the gravel ranges from 5 mm to 10 mm, then a higher percentage is allowed - up to 10% of the total mass.

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

• very fine sand, the size of the granules of which is not more than 0.7 mm. For the manufacture of concrete, such sand will be unsuitable;
• fine sand, the size of the granules of which is from 0.7 mm to 1 mm. This type is also not used for making concrete;
• very fine sand, the grain size of which is in the range from 1 mm to 1.5 mm. You don't need to choose it for concrete either;
• fine sand, the size of the granules of which is from 1.5 mm to 2 mm. Not suitable for preparing high-quality concrete mix;
• sand of medium size, the size of the granules of which is from 2 mm to 2.5 mm. It is sand of this size that is ideal for preparing a concrete mixture for a foundation;
• coarse sand, the size of the granules of which ranges from 2.5 mm to 3 mm. It is used for the manufacture of high quality quality concrete;
• sand of increased coarseness, the size of granules 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 the building.

Very coarse sand, larger than 3.5 mm, can also be used for cushioning the foundation.

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

If you purchased sand, you need to take care of its protection 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 the sand? Use a saucepan or iron bucket. Take a container and place it on weights. Having learned 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, put it on a stove with low heat and "cook", stirring occasionally, for 30 minutes. After the time has passed, everything must be weighed again. Subtract the weight of the bowl or bucket from the weighing result and multiply the result by 100. As a result, you should get a number in percentage that indicates moisture. For clarity: a bucket or bowl has a weight of 0.2 kg. After drying 1 kg of sand, the total weight is 0.9 kg. It turns out:

0.9 - 0.2 x 100 = 70

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

Let's summarize

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

• clean sand, in the composition of which clay and gravel do not exceed 5% of the total mass;
• sand with a medium size, the size of the granules of which ranges from 2 mm to 2.5 mm;
• sand, the moisture content of which does not exceed 5%.

When buying such a building material for a foundation, you must definitely pay attention to these indicators. The best option in terms of price and quality is washed and screened quarry sand, the size of granules of which is 2–2.5 mm. Better to buy it directly at the place of production. If you have money and want your foundation to be strong and stand for a very long time, stop on river sand of the same faction. Then your concrete for the foundation will have the necessary qualities.

When buying sand, you should control the weighing process of a loaded and empty dump truck, as there are unscrupulous suppliers who do not weigh the sand, profiting from you.

We hope this article helped you figure out what kind of sand to choose for the foundation.

Before starting the construction of the foundation, take care of purchasing suitable materials from which you can prepare high-quality concrete.

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

Sand is a free-flowing material belonging to the category of sedimentary rocks. It can be mined from quarries or created by an artificial method by crushing crushed stone and stone.

Regardless of how the selected variety is made, the main criterion that it must have is purity. It is important that there are no admixtures of organic and inorganic materials, stones, leaves, grass.

If you bought a low-grade building material, you will need to clean it by sieving, which is labor intensive and time-consuming. Cleaning will not rid the sand of fine litter - particles of clay and lime.

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

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

• Pour sand up to a third of the volume into a transparent container;
• 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 fine grains of sand settle.

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

If the water "cap" remains transparent, and there are no foreign 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 considered to be 1-5%.

You can find out if your raw materials have normal moisture content like this:

• Take a metal pan, weigh it;
• Fill in exactly 1 kilogram of sand there;
• Using a stove, heat the pot for half an hour, stirring occasionally;
• Then measure the weight of the container. Subtract the weight of the pan from the available value. Divide the result by one hundred;
• The final number is the percentage of moisture.

Choosing the type of sand

According to the mining method, the following types of this building material are distinguished:

River. As the name implies, it is mined from the bottom of the rivers. It is considered universal. Ideal for foundations and interior decoration. Allows 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 clean this sand thoroughly before delivering it to customers. It is recommended to analyze a certain amount in the laboratory before purchasing a large batch.

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

Expertise will help you decide which sand is best for your area.

Quality comes at a price. If you do not have a large budget, it is better to save up more money and postpone construction. After all, the foundation is too important a part of the house to save on it.

What size of grains of sand is better

There are several types of sand by fractions:

Very thin (less than 0.7 mm). Cannot be used in foundations, even when a small one-story house is being built. Such sand does not allow to obtain sufficiently strong concrete.

Thin (thinner than 1 mm). You cannot make concrete from it. This fraction does not allow achieving the required level of density.

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

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

With grains of sand up to 0.3 centimeters thick. These varieties are too expensive. High-quality concrete is made of them, and it is impractical to use it in household 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 the loads. The varieties are suitable for the construction of skyscrapers.

Do not forget to examine the edges of the grains of sand with a magnifying glass. The sharper they are, the better the binding properties of the concrete.

How much sand is required

5 parts of sand to 1 part of cement is considered suitable. If you want to use crushed stone, then the ratio will be as follows: 4 shares of sand, 2 - crushed stone and 1 part of cement. There is 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 they need to be added a little less or more, 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 off 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.