Sand for pouring the foundation: how to fill

Determination of the presence of impurities

Impurities that can be observed in the sand

In addition to the size, it is necessary to take into account the presence of organic matter and impurities. The presence of organic components, such as plant residues, etc., is unacceptable. You can get rid of these contaminants using conventional sieving.

It is more difficult to get rid of the presence of clay, which should be no more than 5% if the sand is to be used for the foundation. Otherwise, the mortar will not meet the standards and reduce its strength.

You can check the sand for suitability in the "old-fashioned" way. Pour some sand into a glass container, add a small amount of water, shake and leave for a while.

The next type of impurities is gravel. Its presence is acceptable if particles 10 - 12 mm in size do not exceed 5% of the mass. If these particles are smaller, then their presence is permissible, but not more than 10% of the total mass.

Purpose and requirements for the blind area

As for the blind area for the screw foundation, it is already necessary to make it at the stage of arranging the basement, there are several reasons for this, namely:

Exclusion of the penetration of rain moisture, other atmospheric precipitation underground, including weeds.
The need for reliable thermal insulation of the foundation of the entire lower part of the house.
Giving an aesthetic look when using decorative finishes.
The presence of a sidewalk around the perimeter of the building.

The design of the blind area for the pile foundation is simple, easy to manufacture and can be easily equipped with your own hands. You just need to remember her characteristics, which she must answer - these are:

The obligatory slope is about 5 ° С, i.e. that part of the blind area that is adjacent to the house should be 3-5 cm higher than its outer part.
The width of the blind area should be 20-30 cm wider than the cornice hanging over it, so that rainwater from the roof falls onto the protective part.
The thickness of the gravel, sand or clay pad is about 30 cm.
The height of the decorative top layer depends on the selected material, if it is concrete, then 13-15 cm, in the case of tiles or natural stone - 4-5 cm, if asphalt is laid, then 3 cm is enough.

Isolation of the blind area from the basement

The blind area around the house in the case of a pile-screw foundation excludes a rigid connection with the latter. Otherwise, even with minor ground movements (and this type of foundations is quite common in such areas), the decor of the basement of the house and the protective strip along the perimeter of the building will inevitably be destroyed.

This will be avoided only by very high-quality insulation of the blind area from the basement part, the so-called expansion joint. The latter type is performed with the help of DSP, penoplex, roofing material or boards impregnated with a bitumen composition. The thickness of such a seam is about 3 cm. Having made a blind area around the house, you can protect the foundation for many years.

It must also be remembered that the basement space must be ventilated, for which, along the perimeter of the basement at a level of 50 cm from the blind area, it is necessary to make a number of holes of about 100 mm in diameter and close them with decorative ventilation grilles to prevent rodents from entering the underground space.

What is the need for an embankment?

The residential structure must be built on a solid capital basis. A monolithic structure located on a special bulk support has good strength indicators. After preparing the territory (cleaning from debris, marking), determining the depth, digging out the pit, a sand cushion is lined. When is it better to build it? Sprinkling is recommended in the following cases:

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

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

Manufacturing technique

So, when the proportions are clear, you can go directly to practice. You can cook it with your own hands in two well-known ways - manual and mechanized. The first method is a simple mixing of the starting components with a shovel in a suitable container.

The method is quite laborious and requires great physical strength. The second is using a portable stirrer. This method is less labor-intensive, but requires additional financial investments - to buy a mixer.

Manual way

It is better to prepare the material using this method when the total volume of the foundation is small. For example, it can be a columnar base for a porch, terrace, barn or a small extension to the house, as well as a shallow, narrow tape of several meters around the perimeter.

After all the theoretical calculations have been carried out and it has become clear which ones are necessary in a particular case - in accordance with the type of structure, terrain conditions and load - you can proceed to the manufacturing process, which consists of the following stages:

Preparation. It is necessary to prepare in advance not only all the necessary material (cement, sand, crushed stone, water source), but also a container suitable for mixing the components (this can be a low trough or a bath with a volume of about 100 liters) and a tool. The latter can be played by an ordinary bayonet shovel. You will also need a shovel to load the finished material into the formwork.

Mixing of components. All measured components must be poured into a container. Then mix them with a shovel until as homogeneous as possible using the manual method.
Adding water. In order not to get an excessive amount of it in the finished mixture during the addition of water, and not to disturb the consistency by this (simply speaking, not to spoil it with water), you need to add water in small portions during stirring until the desired consistency is reached.

Kneading with a mixer

The ratio of raw materials for the preparation of concrete is the same for both manual and mechanical methods. Preparation of a solution using a mixer is relevant when the volume of the base reaches several tens of cubes, or in all other cases when health, time or any other circumstances do not allow a private builder to interfere with the material manually.

Mixer production

The use of such a unit makes it possible to produce material faster, with better quality and in much larger volumes.

In this case, the cooking process is reduced to the following stages:

The equipment is installed in working position. At the same time, it is necessary to take into account not so much the convenience of its loading as its unhindered unloading.

To do this, it is installed either at a special chute, through which the concrete will be delivered directly to the formwork, or directly at the formwork itself - in the case when it itself can be moved along the perimeter of the poured structure.

A mixture of initial components is loaded, taking into account the calculated ratios. Rotation of the drum is turned on in order to mix the components in dry form.
Water is added.The amount of water required to prepare a certain amount of concrete is best determined empirically, since sand and crushed stone may already contain a certain amount of water in their mass.

Unloading from the mixer

Proportions for the foundation from ASG

So, before starting construction, you need to correctly calculate the ratio of concrete components for the base. Then you need to determine what brand of material is required, based on the type of structure, soil characteristics and terrain.

After that, it is necessary to choose a convenient method for preparing the concrete mixture - by hand or by means of a suitable concrete mixer. The photos and videos in this article clearly show how to correctly calculate and prepare concrete for the foundation with your own hands.

Sandy soil is different

We think there is no need to explain what a sandy soil is. In a dry state, it is free-flowing, but moisture does not make it plastic. At the same time, depending on the size of sand particles and their percentage, five types of sandy soils are distinguished:

dusty. Of all sandy, silty sand is the most unsuccessful type of foundation for a foundation. its load-bearing capacity is largely determined by moisture content. When moistened, its properties begin to resemble clay. The content of particles larger than 0.1 mm does not exceed 75%;
small. With an increase in humidity, the bearing capacity also decreases, but not to the same extent as for silty sands. When pouring the foundation, it must be borne in mind that such soil does not retain moisture, therefore, the foundation pit (trenches) should be waterproofed with plastic wrap. The content of particles larger than 0.1 exceeds 75%;
medium size and coarse sandy soil contain more than half of the particles larger than 0.25 mm and 0.5 mm, respectively. They are distinguished by high indicators of bearing capacity and serve as an excellent foundation for a home;
gravelly sandy soil contains more than a quarter of particles, the size of which exceeds 2 mm. At the same time, a foundation made of such soil is ideal for the construction of any type of foundation.

About the foundation and the bearing capacity of sand

An important characteristic of sandy soil for construction is its bearing capacity, which largely depends on its moisture content and compaction of layers. The denser the soil, the greater the load it can carry without significant settlement

At the same time, an increase in water content in it negatively affects the bearing capacity (this statement does not apply to gravelly soil and coarse sand). Sand with larger particles for building a foundation on such a basis is better suited than fine or dusty sand. As with any other soil, with an increase in the depth of the rock, its resistance to compression also increases: the deeper the base of the foundation, the less the house will subsequently settle. A set of measures to protect the base of the house from moisture deserves special attention. Even though sand does not retain water, foundation waterproofing is indispensable.

Foundation options

In most cases, sandy soils can be considered non-porous, because they practically do not retain moisture and do not increase in volume during freezing. For this simple reason, almost any type of foundation can be built on them. And even if the groundwater level at the site is high, the drainage device and insulation of the perimeter of the base of the house will easily solve the problem.

Some nuances

It is necessary to understand that sandy soil can differ in a heterogeneous structure: first, there is a layer of the middle fraction, and deeper - silty sands or sand with clay. Accordingly, the calculated resistance of such soil will differ at different depths.Therefore, before construction, we recommend digging pits to a depth of at least 2 m and assessing the nature of the soil in your area.

Finally

In most cases, the presence of sandy soil at the construction site can significantly save on the construction of the foundation. As a rule, the water table is low, and you do not need to worry about the change in the bearing capacity of the foundation over time. Equally, freezing of the soil does not pose a particular threat, because normal sand does not belong to the category of heaving soils.

How to fill the foundation inside: the choice of material

The owners of the plots at the beginning of construction are interested in the issue of arranging the foundation. Do I need to fill it up from the inside, what materials are the work performed and what affects the choice of bulk materials.

When performing work on a pile foundation, it is necessary to take into account minor features.

To finally decide on the selection of material and the thickness of the dump, you should find out at what level the groundwater is located, how much the soil and the financial condition of the owner can sink.

It's also a good idea to think about what is more profitable in terms of finance:

dumping under the foundation when using bulk materials;
arranged basement with ventilation and high-quality thermal insulation of the flooring.

Materials used for internal backfill

An excavator is most often used to dig a hole for the foundation. The construction project is the main document. Therefore, when digging a recess, a reconciliation with it is necessary. It has calculations based on the amount of excavated land.

The pit should first be sprinkled with sand, the thickness of which should be no more than fifteen centimeters. The sandy coating is well leveled and compacted.

In order not to make a mistake in choosing the best way to fill up the internal foundation, special attention should be paid to the type of soil. Construction soils are divided into the following types:

black soil, which is not used for backfilling inside the foundation;
loam;
rocky soil;
clay;
crushed stone.

Clay and loam have the most benefits. They are characterized by excellent waterproofing properties and can resist impact loads. It is not recommended to use clay with other impurities. Because it loses its waterproofing properties.

The inside of the foundation is sprinkled with it no more than thirty centimeters. Do not forget about the intensive compaction, which must be done when backfilling. This helps to exclude sinuses. Mixed gravel and sand are not used for the pile foundation.

Good raw materials for backfilling the foundation are sand and crushed stone. Coming in contact with water, their qualities do not change. The sand is well compacted with periodic watering. After that, backfilling is performed, which balances the pressure on the foundation.

It is produced evenly throughout the entire part of the future home.

Internal filling under the screed

Very often the basement cannot be used. Owners whose plots are located on swampy soils fall into this category. Then backfill is made inside under the screed. The materials for work are the same. Clay is one of the best ways to base under a screed.

It fits and tamped down to a thickness of thirty centimeters. The clay mound provides complete protection from groundwater. The next ball is covered with sand, which must be tamped and soaked well with water. After that, it is necessary to waterproof with roofing material.

From above, to form a heat-insulating layer, foam is laid or sand is poured in order to make a concrete screed.

In addition to these actions, other work is carried out to provide additional waterproofing. In particular, drainage is being set up, the basement is waterproofed, a blind area is made throughout the entire territory of the house.

External backfill of the foundation

The outer foundation can quickly give in to swelling due to the fact that its edges are not protected from the cold. The soil freezes and begins to pull out concrete structures. To avoid this, it is also necessary to sprinkle the foundation from the outside. This problem is solved using the following methods:

the sinuses of the foundation during backfilling are filled with non-metallic materials: a sandy or crushed stone shell of at least twenty centimeters;
the blind area is insulated;
thermal insulation is performed using expanded polystyrene, polyethylene film, PSB sheets.

The main layer of thermal insulation does not get damaged due to the soft polystyrene. In the spring, the structural elements return to their original state, after the soil decreases in volume. Of the materials for sprinkling the outer part, sand and crushed stone are used.

Normal operation requires a certain density of the shell, therefore backfilling is performed in layers and must be rammed. The sand does not need to be watered, so that there is no danger of erosion of the lower layers. It is moisturized before styling.

In the case of a high groundwater table, it is recommended to use crushed stone.

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.

Calculation of sand for a pillow under the house

The amount of sand required to create a foundation cushion depends on the area of the base and the thickness of the cushion. We examined this issue in more detail in the article on the topic: building a foundation on sandy soil.

You can determine the area of the base yourself, just know its parameters.

As for the thickness of the sand cushion, the following factors are taken into account:

Groundwater location.
The depth of soil freezing.
The total load on the foundation.

Based on these factors, you can choose the optimal height of the sand cushion. However, the recommended parameters should be taken into account: the minimum height of the sand layer should be 10 cm, the maximum value can be 20 cm.

The final volume of sand to create the pillow is calculated by multiplying area of the foot of the foundation to the height of the sand layer.

Types of sand for pouring the foundation

There are several types of sand extraction.

River sand. This is the most common type of mixture as it is easy to obtain. Professionals advise using river sand for the construction of the foundation. It is also perfect for the construction of brick and masonry, for the construction of drainage systems. By its nature, this type of sand rarely contains impurities and additives that are difficult to get rid of. It does not require additional testing to make sure it is clean. The only negative is the high price for excellent quality.
Sea sand. Unlike river sand, you can find all kinds of additives and organic debris in sea sand. Manufacturers are required to clean it before selling it, but not everyone is responsible for cleaning it. For this reason, you should be especially careful when buying sea sand. The price for this type of mixture is very high, primarily due to the complexity of its extraction, and secondly, due to additional sand cleaning. It is used only for laying the foundation, but if there is such an opportunity, then it is better not to use it at all.
Sand from the lake. By its structure, it has rather large grains of sand. It is almost twice as dirty as other types of sand. In addition to debris, particles of silt are present in the sand due to the lack of flow in the stagnant water of the lake. Such sand should be thoroughly washed, and only then subjected to additional cleaning. It is not recommended to use it for solid walls and foundations. Its standard use is wall decoration.
Quarry sand. Such mixtures are mined in quarries using special equipment. In terms of its quality, this type of sand is worse than all of the above varieties. The reason for this is the large amount of clay impurities present in the earth. Therefore, if you have chosen this type of sand, then before using it, you should thoroughly rinse and clean the mixture, preferably several times. It is better not to use it for the foundation, but it is quite suitable for finishing work. The main advantage of such sand is its price - it is the cheapest type of sand.
Crushed sand. Artificial sand is a ground crushed crumb that is obtained from crushed stone. The resulting grains of sand are varied in shape and size, which is why such sand is used only for filling cement mortars. This filling method makes the fill stronger and stronger. Thus, less cement is required during construction, and less time is required during pouring. This type of sand has only recently become available to a wide range of consumers, which is why few people know about it yet.

Purpose and thickness of the pillow under the foundation

The structure of the foundation is always exposed to the harmful effects of the environment, which is why it can become less durable. Only the owner who has taken care of arranging the correct pillow under the foundation is able to avoid weakening the base of the house. It is she who makes the surface below the base stable and even.

The pillow is located at the very bottom of the created "pie"

In order for this pillow to perform its task without fail, it must be covered with a thick layer. Layer thickness depends on:

type of foundation;
dimensions and weight of the structure;
the types of soil on which the building is planned to be erected;
the depth of freezing of the earth;
the proximity of groundwater to the topsoil.

Also, the density of the pillow is affected by the material from which it will be constructed. These raw materials can be sand, crushed stone and gravel mixed with sand.

Sand under the base of the house

A sand pillow is popular because it protects the foundation well from deformation. And the sandy bedding blocks access to the base of the house for groundwater.

Most often, sand is poured under the foundation.

In order for the foundation pillow to serve properly, it must be covered with a thick layer of material. The optimum thickness of each layer of sand is 20 cm.

The sand cushion is located above the ground and below the concrete foundation, reinforced with reinforcement

The raw materials used should be medium to coarse. When going to lay the next layer of such sand, the previous layer of material is supposed to be pressed and sprayed with water.

Video: when and how to make a sand pillow

Crushed stone under the foundation

A crushed stone pad is chosen when you want to provide the foundation with the best protection against destruction. Crushed stone is stronger than sand and therefore is actively used as a bedding under the base of a building, the walls of which are erected from heavy material.

A crushed stone cushion is popular because it is significantly denser than a sand cushion.

Under the foundation, it is customary to fill in crushed stone with a size of 2 to 4 cm. Such a diameter of stones is considered average and allows you to achieve the desired qualities from the pillow: density, evenness and adhesion ability.

A crushed stone pillow, laid on top of the sand, is poured in a layer of 10 cm.But if the building is heavy, then it is recommended to increase the thickness of the layer of stones to 20 cm.The layer of stones is well compacted, thereby improving the quality of the backfill, which should not sag under the pressure of the foundation.

It is recommended to lay the crushed stone cushion from stones with a grain size of 30-50 mm

Special requirements are imposed not only on the thickness, but also on the width of the pillow. A layer of rubble will flawlessly fulfill its task of ensuring the stability of the structure if it is 30 cm wider than the base of the house.

In order for the foundation to be built on a crushed stone cushion without problems, the layer of stones should be laid perfectly evenly. Therefore, in the ground with the help of a peg, they measure the zero level and, when filling the hole with rubble, they are guided by it.

Video: an example of creating a pillow for a crushed stone foundation

A mixture of sand and gravel under the base of the building

They resort to creating a pillow, which consists of sand and gravel, wishing to make the pillow durable and at the same time save on the purchase of construction materials.

The sand and gravel cushion is laid in layers of different thickness. The main thing is that this parameter should be at least 5 cm.As a result of filling the hole with several layers of sand and gravel, a pillow 25 cm thick should be obtained.

The thickness of the sand and gravel cushion is usually 30 cm

Usually, the first layer of sand and gravel cushion is created from fragments of limestone, which enhances the strength of the embankment. The second layer, as a rule, consists of coarse river sand, which is rammed and watered. After it, 15–20 cm of gravel pressed by a vibrating plate is poured into the pit.