What kind of sand is better for a pillow under a river or quarry foundation? What sand to use: types and characteristics of building sand Quarry sand for foundation

Before starting the construction of the foundation, take care to purchase suitable materials from which high-quality concrete can be prepared.

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

Sand is a loose material belonging to the category of sedimentary rocks. It can be mined from quarries or created artificially by crushing rubble 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 impurities of organic and inorganic materials, pebbles, leaves, grass.

If you bought a low-grade building material, you will need to clean by screening, which requires additional labor and time. Cleaning will not rid the sand of fine litter - particles of clay and lime.

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

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

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

If the water remains dirty or the top layer is clogged with third-party 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 third-party particles, feel free to mix concrete from this sand.

Suitable humidity

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

To find out if your raw materials have normal humidity, you can do this:

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

Selecting the type of sand

According to the extraction 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 you to create drainage systems. An important plus is the absence of clay impurities and organic substances. 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 thoroughly clean such sand before delivering it to customers. It is recommended to analyze a certain amount in the laboratory before purchasing a large lot.

Career. The quality is lower than that of the sea and river. It is mined through the destruction of rocks. Often clay and other impurities are 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 choose which sand is best for your area.

You have to pay for quality. If you do not have a large budget, it is better to save up more money and wait with the construction. After all, the foundation is too important part of the house to save on it.

What is the best grain size

There are several types of sand according to fractions:

Very thin (less than 0.7 mm). It cannot be used in the foundation, 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 can't make concrete out of it. This fraction does not allow to achieve the required level of density.

Small (up to 0.15 cm). It is used for the foundation 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 the foundation, so experts recommend using it.

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

Extra large. The size of the fraction is less than 0.35 cm. Suitable, which increases the strength of the building and helps to evenly distribute the loads. Varieties are suitable for the construction of skyscrapers.

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

How much sand is required

Suitable is 5 parts of sand to 1 share of cement. 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 proven over decades of practice.

The quality of the cement is also important. Some grades 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. Here there is a risk to pay both with money and with your own safety.

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

To paraphrase the famous phrase about water, in relation to construction, we can say - "sand, sand, sand all around" - and this exactly describes the process that occurs during the construction of the foundation of your country residence. A lot of this building material is used on the construction site - sand for the foundation, for the pillow, in interior and exterior decoration, in bonding mixtures - you need a lot of it, and all of it must be of proper quality.

Construction of the foundation of the cottage occurs with the direct use of huge volumes of sand, which is selected and calculated at the design stage by InnovaStroy specialists. This process is approached responsibly, since such parameters as stability of the structure, durability, shrinkage, drainage, adhesion of components to each other, environmental friendliness, and strength directly depend on the quality of the material. In order to choose the right volumes and types of sand, you need to understand the differences that the variants of this sedimentary fossil material offered on the construction market have.

Sand for the foundation: what does it look like?

If we consider it from the point of view of geology, then sand is a sedimentary rock of a very small type, represented by fragments of various minerals, mined in an open way or produced by industrial enterprises. At their core, these are very small pebbles of various shapes and sizes - resulting from natural or artificial processes. There are several varieties of sand on the market, each of which has its own unique properties and is suitable for various building processes:

Career - the most common and cheapest option. It is mined by an open method in workings, contains a lot of impurities from clay, lime and earth, which must be taken into account when choosing this type of sand;
River - a cleaner option, mined from the bottom of the rivers - is most suitable for the construction of foundations and use in branded monolithic concrete. By the way, Dubai's famous skyscrapers are built using river sand from Europe;
Mineral - obtained by processing various rocks - that is, these are finely ground remains of granite, crushed stone, limestone, marble and other varieties. It is almost never used in concrete mixtures, as it has certain limitations on adhesion and strength - but it is suitable for finishing;
Marine - they extract it from the bottom of the seas and further purify it. Such sand is considered the highest quality and most expensive, it is used in branded concrete and has increased strength characteristics, since it does not contain organic matter or harmful clay inclusions.

Based on the above, what kind of sand is needed for the foundation should be determined at the design and development stage of the construction process. Professional specialists of our company will offer several options that will be optimally correlated in terms of quality and cost. Although country cottages are built for long-term use, it is not always rational to use very expensive materials, since on such small volumes the qualities of different types of sand are almost identical. Especially if the project includes the use of ready-made concrete mixes from the manufacturer, who himself monitors the quality of the sand used in monolithic concrete.

What sand is needed for the foundation: technical parameters

When talking about the properties of the described sedimentary material, many begin to wonder - why all this, and isn't it easier to just take and buy sand in the nearest quarry so as not to bother? The answer is obvious and simple - not easier! After all, sand remains one of the important components of the structure, designed to improve and ensure the reliability of the structure, its durability and stability.

In the construction practice of InnovaStroy, a variety of sand grades are used, each of which has its own technical parameters. Below we will describe only those that allow you to choose the right sand for the foundation, so that the foundation of the house is as reliable as possible. The selection is made according to different criteria, in accordance with the accepted standards of GOST and SNiPa:

By variety

Depending on the method of extraction and purification, each option has its own clear direction of use. Quarry sand, due to the special faceted structure of the fractions, is most suitable for building a building base cushion, as it allows you to create a dense damping layer - it softens the impact of the soil and does not lead to strong shrinkage of the building. Purified quarry sand is also used for bonding mixtures, as it has a very high adhesiveness - the ability to bond the components of the solution together. River sand is most used in monolithic concretes and in the construction of drainage layers - due to its more uniform particle size, which is larger than that of a quarry counterpart. Sea sand is used in high-quality concrete and reinforced concrete structures, it has the lowest content of foreign impurities. The mineral version is best used for finishing, as it contains many very small fractions, almost dust, which are completely unsuitable for concrete.

According to the size of the granules

It is well known that size matters when creating concrete mixtures, mortars, foundation cushions and drainage. The larger the fraction of sand, the better its properties in the construction and arrangement of the foundations of cottages. For example, to pour a monolithic foundation, price InnovaStroy does not take into account the creation of a sand cushion, which should be located throughout the development area and reach a significant thickness. In construction, such subclasses of sand are used, for tape, for the pile foundation of the house:

Small- the size of the pebbles varies from 1.5 to 2.0 mm - it can be used in lightweight bases that are not deep;
Average- fractions in the range of 2.0-2.5 mm - the most ideal option when pouring any type of foundation for a private house. Also suitable for backfilling free space, if carried out pile foundation, price which is significantly lower than other analogues;
Large- sizes of pebbles from 2.5 to 3.0 millimeters - suitable for concrete mixtures with a high grade index, as the only one capable of providing its strength and the necessary technical parameters. Such sand is used by manufacturers of concrete mixtures throughout the country;
Extra large- with fractions from 3.0 to 3.5 mm - ideal for creating a foundation cushion, drainage layers under the base of the building, in the blind area, when arranging garden paths.

Composition

Naturally, it is quite difficult to calculate sand for the foundation, since it is impossible to predict its overrun. The specialists of our company use modern computer modeling and many years of experience in order to determine with maximum accuracy the amount of sand needed to build a cottage. This allows you to keep installed on strip foundation prices in the Moscow region and Moscow at an affordable and acceptable level. Most often, one type of sand is purchased in order to optimize financial costs. The medium-fraction building material is perfect for both pillows and concrete mixtures when construction is carried out in a temperate climate zone.

The main thing that is required from the supplier is to provide clean and dry building material, since all its technical characteristics depend on this. In construction, sand is used only with the following indicators:

Density - not less than 1.5 tons / m3. If this indicator is lower, then there is too much moisture in the sand, and if it is higher, then there are foreign impurities;
Composition - without organic inclusions, which are completely unacceptable for building material. The amount of impurities of clay, lime and earth cannot exceed 5% of the total mass;
The shape of the fractions - it is believed that faceted pebbles of quarry sand hold solutions much better, and smooth river and sea analogues do not allow achieving the desired strength. Such maxims can be confirmed or refuted only by laboratory methods, and this does not affect the quality of the construction of the foundation of the cottage;
Availability - the cheaper and faster the logistics, the easier it will be for both builders and customers. When wondering what kind of sand to choose for the foundation, our specialists always study the market in your region to understand how expensive it will be to bring quarry or river sand.

High-quality concrete foundation: proportions of sand

One of the criteria that will allow you to more or less approximately know the amount of sand needed for construction is the generally accepted proportions and ratios of it in mixtures. As a rule, a ratio of 1: 4 is applied - that is, four parts of sand fall on one part of cement. And even when crushed stone is used in solutions, the percentage does not change - all the same, sand is needed 4 times more than cement. This is provided that the concrete is kneaded on the spot and a constant continuous supply of it to the formwork is required.

If the matter is limited only to the creation of a pillow and drainage under the foundation, the proportions of sand will differ dramatically, as they are calculated in cubic meters, based on the thickness of the required layer. In any case, there is never too much sand, as it is used in any construction process - from laying foundation walls, to grouting joints and exterior finishes. InnovaStroy specialists will calculate the required amount of material for a high-quality construction of the building foundation. Even if there is some sand left, then you can safely arrange a playground near the house - both children will be happy and the sand will not disappear.

What sand to choose for the foundation: results

Based on the data described above, it is necessary to select the type of sedimentary building material based on the characteristics of the cottage, its characteristics, soil properties and ongoing construction work. In Russian practice, quarry and river sand of various fractions are equally often used, which does not differ much in cost and quality characteristics.

It is best to contact our architects and designers who have been building country cottages for more than seven years - they will be able to suggest the most optimal and profitable option. Of course, no one excludes the elite construction, when the country palace itself simply requires the use of only high-quality sea sand, and not simple and common analogues.

When laying the foundation, it is important to correctly and correctly choose building materials. Especially carefully it is necessary to choose sand, since it is precisely the strength of the solution for the foundation depends on it, and hence the strength of the entire foundation. To the question of which sand is better to choose for the foundation, we will answer in this article.

Sand selection

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

If you can find foreign objects larger than half a centimeter in it, it is not suitable for laying the foundation. Foreign objects may include branches, leaves, organic debris.

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

Better immediately choose high-quality sand and get to work. Remember that high-quality sand suitable for making mortar should not contain more than 5% impurities. In addition, a large number of additives will degrade 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 mortar for pouring the foundation.

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

Pour sand into a transparent bottle by a third, and then fill up to half with clean water and shake. Then let the mixture stand for 5 minutes and look at the transparency of the water. If it has become cloudy and dirty, then the sand contains a lot of impurities. Floating foreign matter is also a bad sign, and such sand is unsuitable for construction. If the water is clear and without impurities, then the sand is ideal for laying the foundation.

Origin of sand

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

Quarry sand

Quarry sand is mined in a quarry, destroying rocks. It is of lower quality than river, but there are exceptions. When choosing quarry sand an important factor in its reliability and strength is the moisture parameter. Its percentage should be from 1 to 5%. Humidity of 5% is determined by eye by the fact that it is impossible to make a dense ball or snowball out of sand - it crumbles.

To correctly determine the moisture parameter, you can resort to the following method. To determine the moisture content of quarry sand, take a container and weigh it. Then, weigh 1 kg of sand in it and hold it at a 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 than river sand, since its extraction method is less expensive.

river sand

River sand is ideal for laying foundations, and is also used in diluting mortars for interior decoration of a house or creating drainages. Therefore, such sand versatile and multifunctional. Its fine fraction of 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 emit nautical, but in modern construction it is used where it can be quickly brought from, otherwise it the price exceeds even the river. In terms of quality, it is no better than river water, and sometimes even worse due to organic impurities (shells, algae) and foreign objects.

Sand fractions

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

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

The choice of sand for the foundation pad

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

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

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

Podsypka under the foundation - another name for the pillow, is made on the basis of sand or gravel.

The foundation, translated from Latin, means “foundation”, the fate of the entire structure depends on its strength and reliability. That is why it is so important to select high-quality materials for this part of the building. The strength of the concrete base is affected not only by the brand of binder, but also by aggregates - sand and crushed stone.

Let's consider the main properties, advantages and disadvantages of the most common building sands - river and quarry, compare them and try to answer the question which one is more suitable for building a foundation.

construction sand

Natural sand is a loose loose rock of sedimentary origin, has a crystalline structure with a grain size of up to 5 mm and consists of destroyed mineral residues, most often quartz with a small amount of other inclusions.

Requirements for it as a building material, according to GOST 8736-93, include such parameters as grain size, its bulk and true density, the permissible limit for the content of dust and clay particles, harmful impurities, radionuclides.

river sand

River sand is mined in riverbeds. It is characterized by a uniform consistency, good fluidity, and an average granule size in the range of 1.5–2.5 mm. Due to long-term natural washing, it is clean, the grains have the correct rounded shape.

It is believed that this is the highest quality aggregate for concrete mortar, the strength of which is especially important in the construction of load-bearing structures. The advantages of the material, as a rule, include the following features.

It does not contain clay and silt particles, which are unacceptable in cement-sand mortars and degrade their quality.
Oval-shaped crystals do not compact during the preparation of the concrete mixture, the cement milk evenly envelops them, and the finished concrete practically does not shrink.

river sand

He also has shortcomings.

Mixing with this type of aggregate requires more cement and more thorough mixing.
It is the most expensive of building sands.

Quarry sand

The most common and affordable concrete filler. Careers with its development are everywhere, manufacturers saturate the market with an abundance of inexpensive and sought-after products.

In contrast to the river counterpart, quarry sand has a wider range of fractions, its granules are irregular in shape, angular. It contains a fairly large percentage of impurities, including dust, organics, clay, rock fragments.

There are several ways to enrich it.

The washed (alluvial) product is obtained by the technology of a special directed hydraulic action on the rock mass with its subsequent settling. As a result, foreign substances are removed, primarily clay deposits.

The second way of enrichment is sifting through a system of sieves that trap large fragments of stones, clods of clay, etc.

Sand pit development

Despite the fact that quarry sand is inferior in quality to river sand, it is in demand in the construction industry and has a number of advantages.

Much more common.
Less cement is used to prepare concrete - this is due to the property of irregularly shaped crystals to be more compacted.
It has an attractive price.
The enriched product meets the highest standards.

Among the shortcomings, experienced builders note the following.

Quarry sand contains a higher percentage of organic clay and silt particles - up to 7% versus 0.05% in the river analogue.
Due to the structural composition, it settles, compacts at the time of concrete setting and solidification. The finished structure shrinks up to 1 mm per 1 cm.

Criterias of choice

Most builders on the issue of choosing sand for the foundation agree on one thing - the fraction, the minimum percentage of foreign matter and density are much more important than the origin or place of extraction.

Quality sand aggregate should meet the following criteria.

The most acceptable grain size modulus is from 1.5 to 3 mm.
The limiting content of organic and clay impurities is 3-5%.
It should not contain harmful components that can enter into a chemical reaction with cement alkalis - silicon dioxide, sulfur, chlorine, etc.
Have in the composition of active radionuclides no more than 370 Bq/kg, which corresponds to class I radioactivity.

An important point that allows you to control the quality of the delivered products is its bulk weight. The average for clean dry sand is 1500 kg/m3. A smaller weight indicates the presence of impurities, a larger one indicates high humidity.

In its natural form, these criteria are more consistent with river sand. Seeded or alluvial quarry is in no way inferior to him. But if the requirements for future development are low, and the foundation will not be subject to heavy loads, then an inexpensive filler from a nearby quarry is quite suitable.

The amount of sand under the house

Many are wondering how to correctly calculate the volumes of the components of the concrete mixture needed to build the foundation of the house.

To fill the foundation, concrete is needed not lower than M300. It takes about 650 kg of sand to prepare 1 m3. Calculate the volumetric indicators of your foundation (multiply height by width and depth) and calculate the tonnage of sand, then convert it to volume at the rate of 1.5 t / m3.

Sand should always be bought with a small margin (15–20%) of the calculated figure - this material tends to compact, part of it will disperse over the area during transportation, something will come in handy for backfilling.

taxi-pesok.ru

What kind of sand is needed for the foundation

Before starting construction work, 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, as it is one of the main and important components used in concrete mixing. And your future foundation, foundation depends on the quality of the concrete mix. Given that the market provides a large selection of various sands, both natural and artificially obtained, it is important to choose the most suitable for these jobs. In this article we will tell you how to make a choice.

Purely theoretically

The main criterion is cleanliness

Any person who is not versed in 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, and so on. Such sand is not suitable for work, but it can be easily cleaned. Maybe you have seen more than once how workers sift sand, clearing it of unwanted elements.

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

You will need a clear bottle, be it glass or plastic. It needs to be filled with sand by 1/3 and filled with water to half. Then shake the bottle vigorously so that the sand is mixed with water and completely wet. After that, put it on and wait 5-10 minutes. If the water has become 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 are, how they differ and what type of sand is better to buy for the foundation.

Varieties of sand

river sand

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

River.
Nautical.
Career.

The very name of river sand suggests that it is mined from the river bottom. This is a universal material, as it contains fractions of 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 can be its natural purity and uniformity. There is very little clay, particles of vegetation and other impurities in it. This sand is ideal for the foundation. Only here its price is high enough.

Nautical

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 granularity, which is approximately 1 mm. This size of the granules allows it to be used for the construction of reinforced concrete structures. It can be called fairly pure, as it is cleaned, screened and washed before being sold. But you have to pay for quality, so sea sand is the most expensive.

Career

Quarry sand is mined in an open pit from a quarry. If we compare it with river and sea sands, this is the worst option. And it is not surprising, since it contains a lot of impurities - clay, vegetation and rubble. Because of this, the price of such sand is the lowest and it is suitable for rough work at the initial stage of construction.

To unambiguously determine which sand is best suited 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, which cannot be saved on. Be that as it may, you need to consider other features and criteria that will help you make a choice.

Characteristics

It is better to use coarse sand

As mentioned above, the sand must be clean. If it has vegetation or branches - it's not scary, they can be weeded out. But clay, silt, gravel and other particles can lead to a decrease in 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 exceed 5%, and the particle size should not exceed 10–12 mm. If the size of the gravel ranges from 5 mm to 10 mm, then a larger 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 grain size of which is not more than 0.7 mm. For the manufacture of concrete, such sand will be unsuitable;
fine sand, the grain size of which is from 0.7 mm to 1 mm. This species is also not used for the manufacture of concrete;
very fine sand, the grain size of which is in the range from 1 mm to 1.5 mm. It is also not necessary to choose it for concrete;
fine sand, the size of the granules of which is from 1.5 mm to 2 mm. Not suitable for the preparation of 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 the foundation;
coarse sand, the grain size of which is from 2.5 mm to 3 mm. It is used for making high quality concrete;
sand of increased size, the size of the granules of which is from 3 mm to 3.5 mm. Sand of this fraction is best used to cushion the foundation under the base of the building.

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

Sand must be dry

Another important point when choosing sand for the foundation is humidity. The water content in the sand plays an important role, since its amount must be taken into account when the solution is mixed 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. If sand has fallen under precipitation, then its moisture content can reach up to 10%.

If you purchased sand, you need to take care of its protection from precipitation. To do this, it needs to be covered with something or unloaded 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 a container and put it on the 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, for 30 minutes. After the 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 number as a percentage that indicates humidity. For clarity: a bucket or bowl has a weight of 0.2 kg. After you have dried 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 humidity. It is enough just to use a special device that will show the exact figure.

Summing up

It is better to buy sand at the place of extraction

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

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

When buying such building material for the foundation, you must definitely pay attention to these indicators. The most optimal 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 extraction. If you have money and want your foundation to be strong and last a very long time, stop at the river sand of the same faction. Then your concrete under 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 underweight the sand, profiting from you.

We hope this article has helped you figure out which sand to choose for your foundation.

Video

Sand selection tips below:

kakpravilnosdelat.ru

How to choose the right sand for the foundation

When laying the foundation, it is important to correctly and correctly choose building materials. Especially carefully it is necessary to choose sand, since the strength of the mortar for the foundation, and hence the strength of the entire foundation, depends on it. To the question of which sand is better to choose for the foundation, we will answer in this article.

Sand selection

Sand for the foundation is a bulk material obtained from sedimentary rocks or an artificial creation. The quality of sand does not depend on its method of obtaining, it is important to consider only its purity.

If you can find foreign objects larger than half a centimeter in it, it is not suitable for laying the foundation. Foreign objects may include branches, leaves, organic debris.

It is better to immediately choose high-quality sand and get to work. Remember that high-quality sand suitable for making mortar should not contain more than 5% impurities. In addition, a large number of additives will degrade the strength of the sand, which will affect the foundation and the house or building itself. The content of gravel in sand should not exceed 10%, since gravel is an integral element of the mortar for pouring the foundation.

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

Pour sand into a transparent bottle by a third, and then fill up to half with clean water and shake. After that, let the mixture stand for 5 minutes and look at the transparency of the water. If it has become cloudy and dirty, then the sand contains a lot of impurities. Floating foreign matter is also a bad sign, and such sand is unsuitable for construction. If the water is clear and without impurities, then the sand is ideal for laying the foundation.

Sand is a loose mixture of small particles of various minerals and rocks. It is formed in the process of their long-term erosion and destruction. Silicon dioxide (quartz) and calcium carbonate are most often found in sand. The size of sand grains is 0.06 - 2 mm. By origin, all sands are divided into: marine, eolian, 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 on such grounds as: composition, density, origin, type, shape of grains, strength, dust and clay content, the presence or absence of harmful impurities, as well as physical properties.

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

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

Sea sand

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

Sand can also be artificial. 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, as it is cleaned immediately after crushing. For this, washing and sifting are used. Rinsing gives a greater degree of purification from impurities, but such sand also costs more. Artificial sand is quite uniform in color and composition.

The particle size of the sand can be fine, medium and coarse. A more precise classification involves the division into 8 categories according to the size of the fractions. The smallest one falls into the “very fine” category, with grains less than 0.7 mm in size. The coarsest is classified as "very coarse" with a particle size of more than 3.5 mm.

General Sand Requirements for Concrete

Sand for concrete plays an important role in the composition of the concrete mix. The strength and durability of future buildings depend on it. There are certain standards established by GOST, which the sand used for concrete must comply with. In accordance with them, the dusty 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%. It is especially important to control the content of clay, since its presence negatively affects the strength of 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 - best

To determine the size of the particles, the sand is passed in turn through sieves with different hole sizes.

For concrete, it is better to use sand with a lower specific gravity (optimally 1.5 t / m3). 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 will need to be added to the solution depends on the humidity. To determine it, one kilogram of wet sand is dried under high temperature. The difference in the weight of sand before and after drying shows the mass of evaporated water. Directly on the construction site, the saturation of sand with moisture can be approximately determined by compressing it in a fist. If it still crumbles after that, then it is dry enough. If not, then its humidity is more than 5 percent.

What sand to choose for the preparation of concrete?

Quarry sand is best added in limited quantities.

For the manufacture of concrete, it is desirable to take medium or coarse-grained river sand. A small amount of cleaned sand from the quarry can be mixed with it. Quarry sand particles have a rougher surface than river sand, and ideally this is a plus, as such sand grains 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 into the solution than quarry sand.

Harmful impurities

In addition to clay, other components that may be part of the sand are also undesirable impurities. Iron oxides can cause brown spots on the surface of the concrete, as well as make it less reliable in service. Mica plates weaken the adhesion of the concrete components, which can lead to its corrosion in the future. Sulfur compounds can cause cracks 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 necessary to maintain the necessary proportion of its constituent components. The ratio of the number of buckets of cement, sand and gravel should be 1:3:5. If there are more buckets, then all members of this ratio must be multiplied by the same factor. The optimal sand for the preparation of concrete should consist of granules, 1.5 - 3.5 mm in size. Coarse-grained sand is used to produce concrete grade M350 and above. For the preparation of concrete grade M200, finer sand is used. Such concrete can also be used for pouring the foundation.