Which sand is best for pouring a foundation? What sand should be used for the foundation. General requirements for selection

Before starting construction, many people wonder what kind of sand is needed for the foundation. The sand mixture is the main component of the concrete mixture and the strength of the foundation and the entire future building depends on its choice. Let's look at the main questions that will help you make your choice.

Let's talk frankly

Even a person ignorant of construction understands one thing: a high-quality foundation cannot be made from dirty sand. And therefore, first of all, its composition should not contain various impurities. These include:

• Grass or branches. Such debris can be easily dealt with by simply sifting sand for the foundation.
• Clay. Here things are more complicated; in the sand mass, no more than 5% clay of the total mass is allowed, otherwise the strength of the concrete will be lower.
• Gravel. In principle, you can turn a blind eye to this component, but only if its component share is no more than 0.5–0.7%, and the fractions are no more than 10 mm in size.

Of course, you can save on the purity of the material and, having purchased low-quality sand, sift it before work. But think: do you need this, because such work will take quite a long time and take a lot of your energy.

High-quality material – a strong foundation

To independently check the sand for cleanliness, you will need a transparent bottle. You need to pour 1/3 of the sand into it, chosen for the foundation, and after pouring water, shake it well. Then leave the bottle for 5-7 minutes and check the purity of the water. If it is dirty, then the quality of the sand is not at the best level.

You also need to pay attention to the size of the sand mixture fractions. And not all sand is suitable for mixing concrete for the foundation. Sand looks like this:

• Very small. The fraction size is in the range of 1.0-1.7.
• Small. The particles of such sand are 1.5-2.2.

• Medium size. Granules 2.0-2.6 are the best option for preparing concrete for the foundation.
• Large. The particles of this material are 3.5, such sand is well suited for a pillow.
• Thin and very thin. This sand is not recommended for use for preparing concrete for foundations.

So, the trench is ready, we have sorted out the purity and size of the sand mixture, all that remains is to talk about the types. Sand is conventionally divided into four types and each of them is better suited for one or another job.

Lake sand

It is extracted from the bottom of large lakes and is in first place in terms of the amount of organic impurities. In this regard, before mixing concrete under the foundation, it must be washed.

In principle, a good option, but the fact that it needs to be washed before use leaves the consumer with another choice.

This option is cleaner because it is washed naturally. Its composition is homogeneous and balanced, and the relatively small size of the fractions indicates the advisability of its use for preparing the foundation.

Sea sand

This material is mined from the bottom of the sea, and therefore its price is relatively high. But in terms of composition and purity, this is the best option.

Quarry sand

This is the cheapest material; it is mined in quarries naturally or by crushing. This is not the best option for a foundation, because before work, like a lake foundation, it requires preliminary cleaning. Its main advantage is its low cost.

Based on the above qualities of the materials, we can say that the river type of sand mixture is the best option for preparing a concrete mixture for the foundation.

If you have any additions to this article, then you can leave them below and help readers with the choice of material.

In modern construction, sand is used very actively and almost everywhere. At the same time, there are about 10 different varieties of this material, but in the practice of Russian builders, two types are most common: quarry and river. Naturally, each type has those properties that determine its advantages and disadvantages as a building or finishing material. Therefore, non-professionals who decide to build some kind of structure on their own often find themselves faced with a choice:

Quarry sand - advantages and disadvantages

Quarry sand is sand mined in quarries from huge layers located at a certain depth underground. The qualities of such sand are largely determined by its origin. The fact is that such underground sand is formed as a result of the weathering of rocks. This process goes on for centuries; decay products are deposited underground, eventually turning into compacted masses of sand.

The formation of sand deposits is caused by the weathering of rocks such as mica, quartz, feldspar and partially limestone. The composition and characteristics of sand depend on which rocks predominate in a particular area.

What must be taken into account when deciding which sand is better, quarry or river sand, is the possible presence of impurities in the total mass of natural material. Clay contamination is common in quarry sands and only the concentration of foreign matter varies depending on the deposit.

Another important characteristic is the heterogeneity of fractions. The mass of quarry sand contains both very small and very large particles; it often contains fragments that, in terms of size, can be classified as fine gravel. However, in the case of using sand for construction purposes, this property cannot be called a minus. The fact is that the heterogeneity of sand fractions and the presence of various impurities in it determines the higher astringent characteristics of sand.

So, let's summarize. Quarry sand is characterized by increased surface roughness of the particles, as well as the angularity of their shape. This makes it excellent for use as an element that provides additional adhesion for binder additives in building mixtures. There are also construction areas in which it is recommended to use quarry sand. It makes an excellent cushion for a recessed strip foundation. From this point of view, no other variety can compare with quarry sand.

River sand - pros and cons

Now let’s look at the main characteristics and properties of river sand so that, through comparison, we can try to answer the question of which sand is better: quarry or river sand. River sand, as its name suggests, is mined from river beds. This circumstance is due extremely low content of various impurities in it, especially clayey rocks and loams. They are simply washed away by the current, which provides natural cleaning of the sand.

Also, the constant exposure to water to which river sand is exposed leads to the fact that it the particles are approximately the same size and have an almost perfect round shape. Due to this, this material is actively used in landscape design to create the desired decorative effect.

One of the advantages of the material is the fact that to arrange children's sandboxes or volleyball courts, it is imperative to use river sand.

If we talk about construction, then the main properties of river sand, in addition to shape and size, should be recognized as low ability to absorb and retain moisture, as well as environmental cleanliness and safety.

Taking all this into account, river sand is used mainly to obtain decorative finishing materials. For example, if you plan to install a cement screed on the floor of the house, then river sand is better suited for these purposes. It will not accumulate moisture, and will also help to obtain a more even and smooth coating surface.

For the same reasons, river sand is the preferred material for making paving slabs. In Krasnoyarsk it is also used in the construction of drainage and filter systems.

In fact, the only, but very significant disadvantage of river sand as a building material is high price. The process of its extraction involves the use of complex, expensive equipment; special barges and powerful hydraulic pumps are required to lift rock layers from the bottom of the riverbed and subsequently wash it. As a result, the cost of the final product is very high.

It is precisely because of the significant cost that when deciding which sand is better, quarry or river sand, builders often give preference to the former. The issue of price becomes especially relevant when carrying out rough construction work, for example, laying out a foundation, creating open areas for cars, etc. And here for finishing work, especially internal, it is recommended not to save money and choose river sand, the use of which provides better results.

Our company is engaged in retail and wholesale supplies of river and quarry sand in Krasnoyarsk. For more information and to order delivery, call the phone number indicated on the “” page.

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Before starting construction work, many people 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 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.

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. 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 when it comes to 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. It is permissible to contain clay in sand no more than 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 one 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, 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 used to level summer cottages and fill 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 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 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 rarely contains organic compounds and impurities. Therefore, river sand is considered a pure and natural product, which is designed for multi-purpose use. This is an ideal material for laying the foundation, creating drainages and diluting mortars necessary for the interior decoration of the house. 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.

River sand classification

Raw materials from the bottom of the river can vary 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. 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

River sedimentary rocks have several positive qualities that are of 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 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 a loose 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 diluting high-quality concrete mixtures 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 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. A sand-gravel mixture is also suitable, 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 the 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

When 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 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, there should be about one and a half tons of sand per cubic meter.

It is imperative to take care of purchasing 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 the top layer of which there are 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 the exact amount of impurities. 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 consists of pouring 1/3 sand into a transparent plastic or glass bottle and filling 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 foreign 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. It can 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 put 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 of building material is 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 have allocated very little money for the construction of the foundation, then purchasing quarry sand will be an excellent 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 by 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 its creation requires a large amount of cement, which leads to increased costs for the construction of 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 a material with this shape increases the astringent qualities of the concrete mortar.

The composition of concrete includes sand, cement, crushed stone and water. All these components are important for both the creation and subsequent use of a concrete structure. Sand in concrete serves to fill the voids formed between crushed stone particles. It ensures uniform distribution of internal stresses during concrete hardening and reduces the cost of the solution by reducing the amount of cement introduced into the mixture.

In the process of preparing the solution, it is important to take into account all the requirements and select the most suitable components in the correct proportions.

Particle size

Based on particle size, bulk material can be divided into two classes - I and II. In the higher quality first class, there are no small, fine and very fine fractions, which are undesirable in mortars. Their presence leads to a deterioration in the connection between larger fractions. It is the first class sand that is desirable to use in the manufacture of cement mortars.

A more detailed division by particle size modulus (from very fine to very coarse), provided for by GOST 8736-93, is not used in real practice. Sand is usually divided into fine, medium and coarse. Coarse sand, the particle size of which is 2-2.5 mm, is best suited for a durable, high-quality solution. If you use smaller particle sizes, the quality of the solution will decrease, and its cost, on the contrary, will increase.

Sand mining site

The composition of sand and its properties are largely influenced by the place where it is mined. There are quarry, river, sea and quartz sands. All of them are mined by open pit mining:

• Quarry sand may contain impurities in the form of clay and stones, so it is mostly used as bedding for concrete screeds or foundations. To use quarry sand for making concrete, it is washed at the mining sites, after which the sand gets rid of clay and dust impurities.
• River sand initially does not contain clay, and there is a minimal amount of stones in it. This sand is most often used in construction work, since it makes it possible to obtain better quality cement mortar. This sand tends to precipitate, so it is necessary to prepare the solution by constantly stirring it. River sand is more expensive than quarry sand. When choosing a specific type of sand, it is necessary to analyze whether it is better to choose a concrete structure that is cheaper or more durable.
• Sea sand is similar in properties to river sand; it is clean and uniform in grain size. This sand may contain shells, which requires additional cleaning.
• Quartz sand is produced artificially by crushing quartz rocks. This sand is characterized by homogeneity, purity and chemical inertness.

According to the processing method, sand is divided into alluvial and sifted sand, obtained by sifting to remove large particles and debris.

Characteristics of sand

Indicators characterizing the properties of sand used for preparing concrete mixtures are established by regulatory documents. Some of these characteristics are tested only in laboratory conditions; there are also indicators that can be monitored directly on the construction site:

• Volumetric weight, or the mass of one cubic meter in its natural state. Typically this mass is 1500-1800 kg. If there is a choice, it is preferable to use sand with a lower volumetric density.
• The granulometric composition shows the percentage of grains of different sizes in the sand.
• Mineral composition according to which the sand can be dolomite, quartz, limestone or feldspathic.
• The chemical composition on which, that is, on the elements present in its composition, the possible scope of use of sand may depend.
• Humidity, usually 5%. In dried sand, the humidity drops to 1%, and if the sand is exposed to rain, its humidity can reach 10%. The humidity indicator is important for normalizing the water added to the solution. To determine the moisture content, you can calcinate a kilogram of the mixture by weighing it before and after drying. You can quickly check this indicator right at the construction site by squeezing sand into a ball and seeing if it crumbles. If the sand does not crumble, its moisture content exceeds 5%. But in laboratory conditions it is possible to more accurately study this indicator.
• The porosity coefficient is the ability of sand, and, therefore, of future concrete, to pass moisture through itself. This indicator can only be determined in the laboratory.
• The average bulk density can range from 1.3 to 1.9 t/cubic meter. meter. The optimal value is 1.5 t/cubic meter. m. With a lower value, we can talk about undesirable impurities contained in the sand, and with a higher value, we can talk about excessive moisture in the sand. This parameter must be written down in the accompanying documents for sand.

Preference for different types of work

When choosing the most suitable sand for creating concrete of a certain grade, it is necessary to consider for what specific work the resulting mixture will be used:

• For brick and large block masonry, it is best to use river sand. The plasticity of the resulting solution can be further increased by adding a certain amount of unwashed quarry sand to it, which will also reduce costs.
• For the production of concrete, it is best to use river sand of medium or coarse fraction with a small addition of washed quarry sand. Sand grains of quarry sand, unlike sea and river sand, have a rough surface and irregular shape. The aqueous environment polishes the surfaces of the particles, impairing their ability to adhere to other components of the solution. But washing quarry sand does not make it possible to completely remove clay impurities. Therefore, for concreting, it is best to use river sand, which itself has already been washed, the particles are of the same size and do not contain clay, which impairs the strength of the cement mortar.

So, when choosing sand, you need to take into account its type, type and cost (quarry sand is cheaper).

Ratio of cement and sand for concrete

To obtain high-quality concrete, it is necessary to maintain the correct ratio between the components of the mixture, primarily between sand and cement. There is an exact recipe for the components, but on average the proportion is taken as follows: for one part of cement, three parts of sand and five parts of crushed stone are taken. The brand of concrete produced is also important. For grades below M300, it is better to take sand with grain sizes less than 2.5 mm. This concrete is used for unloaded foundations of garages, outbuildings, and one-story houses. For multi-storey buildings, concrete grade M350 and higher is used, which requires sand with grains of 3 mm or more.