Sand gravel backfill. How to make a bedding under the foundation. Road foundation device

The set of rules for foundations and earthworks SP 45.13330 regulates the backfilling of the foundation. The technical norms TR 73-98 contain the rules for sealing the materials used. The general principle is to apply inert materials outside, any inside.

The question of how to fill the foundation inside is relevant, both for floors on logs and for floors on the ground. The choice of material and sealing technology depends on the following factors:

type of operation - in buildings permanent residence heating is year-round, the soil under the sole of the house does not freeze, so you can even sprinkle it with clay, which cannot swell in the absence of moisture and freezing;
ceiling / floor construction - if the project includes a ceiling on beams, it is cheapest to fill the inside with clay, for subconcrete of a floating floor on the ground, sand is needed to level the base at least at the top level (10 cm minimum layer);
the height of the basement - for large volumes, it is more rational to use the soil from the building spot, taken out of the trenches, to fill the footing, the very top must be covered with sand;
GWL level - at high groundwater it is preferable to fill with crushed stone, if the aquifer (“perch water”) is 1 m away from the base of the foundation, sand must be used to save the construction budget.

Attention: Clay castles are prohibited outside, although the technology was described in the old SNiP. Clay does not let moisture through, but intensively absorbs, which is dangerous due to uneven swelling, not only when freezing, but also when swelling.

When backfilling, a layer-by-layer (20 cm) compaction of the soil is required.

Do not neglect the filling of the internal space of the cells of the strip foundation in the manufacture of floors along the logs:

the underground is too low for normal operation;
fumes are inevitably emitted from the soil, harmful to the power structures of the building;
ventilation products are required, heat losses through the floor of the lower floor increase;
harmful radon is often emitted from the pits, from which the dwelling will have to be protected with foil materials.

Backfilling before overlapping will solve all problems in a comprehensive manner and improve the quality of operation.

materials

Almost any soil is allowed in the internal backfill, however, large stones (more than 25 cm) must be excluded from them, if necessary, longitudinal drains should be laid, including them in the general contour located around the perimeter of the house (only with a high groundwater level). Depending on the heating mode, GWL, freezing depth, the width of the shell of non-metallic material around concrete structures is:

heating is permanent - no restrictions, with proper compaction, backfilling with clay is allowed;
heating is periodic - 20 cm of a layer of sand or ASG is enough for internal walls foundation;
freezing 1 m, no regular heating - sinuses 20 cm filled with inert material;
freezing 1.5 m, without heating - 30 cm layer of non-metallic material near the tape;
freezing 2.5 m - sinus width 50 cm minimum.

The depth of backfilling of the sinuses is considered from the planning mark (usually the blind area), it is ¾ of the depth of the sole of the strip foundation.

Technologies

Compaction of clay, sand, sandy loam and other materials is not required inside the foundation tape in the only case - when making floors along the logs. If it is planned to pour a screed, any of the indicated materials must be compacted to a density of 0.95 units. To do this, you need to use manual rammers or vibrating plates.

You can determine the quality of the rammer visually - as soon as the traces are no longer imprinted on the soil, you can pour a 5-10 cm screed "concrete". It is not recommended to shed sands, sandy loams, loams with water, so as not to saturate the underlying horizons. Instead, the backfill material is moistened to values:

15 - 23% heavy soils (including dusty), waterlogging is not more than 1%;
12 - 16% - light loams, waterlogging coefficient Kp 1.15%;
9 - 14% - light sandy loam, Kp 1.25%;
7 - 12% - coarse sandy loam, Kp 1.35%.

You can pour the screed after the soil has completely dried. When filling any monolithic foundation footing is used. This structural element allows:

reduce the height of the protective layer;
prevent leakage of cement laitance into the lower layer with high drainage characteristics;
protect the waterproofing layer of the foundation sole.

Therefore, a small layer of sand on top of loam, sandy loam, crushed stone or clay will further level the base and reduce concrete consumption.

backfill outside

Unlike the inner perimeter, which cannot freeze (with a heated building), the soil adjacent to the outer edges of the foundation is not protected from the cold. It swells unevenly and tends to pull out the concrete structure with tangential forces. The problem is solved by the following methods:

backfilling of the sinuses of the foundation with non-metallic material (minimum 20 cm sand, gravel shell);
blind area insulation - 60 - 1.2 m tape around the building pushes the freezing zone;
sliding and crushing thermal insulation - rigid fixation of extruded polystyrene foam high density EPPS to the outer walls of the foundation, covering with two layers of a polyethylene film fixed at the base level, installing sheets of PSB 25 (minimum density of polystyrene) vertically close to the film without fastening (held by sand powder).

When heaving forces occur, soft polystyrene is crushed, rises up along a perfectly smooth film, without harming the underlying layer of thermal insulation. In the spring, structural elements return to their original form after the soil is reduced in volume.

materials

The possibility of freezing of the soil adjacent to the foundation from the outside is always present. Therefore, despite the insulation of the blind area, the sinuses of the trenches are filled from the outside with sand, ASG or crushed stone, depending on the groundwater level. For normal operation of concrete structures, a shell density of 0.95 units is required, therefore, non-metallic materials are poured in layers of 10–20 cm, compacted with a vibrating plate, hand tool. Spilling sand is not recommended, because. there is a danger of erosion of the lower layers (relevant for silty soils).

Therefore, when backfilling with sand, it is necessary to moisten the material abundantly before laying it in the sinuses. Natural shrinkage takes time, so it is better to rent or make your own vibrating plate, reducing ramming time to a minimum.

With a high GWL or the possibility of its seasonal rise, crushed stone should be used. Gravel material is inferior to this non-metallic product in terms of its main characteristic - flakiness. Therefore, shrinkage during operation is possible, leading to deformation of the blind area.

Technologies

Backfilling the sinuses from the outside with sand or gravel allows you to completely eliminate swelling of the layer adjacent to the foundation. However, all non-metallic materials have excellent drainage properties. Therefore, ring drains at the level of the base of the foundation are a prerequisite for normal operation.

Scheme of ring drainage around the base of the foundation.

When filling the sinuses, it is necessary to ensure that there is no shrinkage during operation. This is possible only by compacting materials with vibrating plates, manual rammers. The maximum effect is observed when preventing the mutual penetration of inert materials and neighboring soils. The technology looks like:

laying geotextile or dornite on the walls of the sinus;
backfilling outside with sand or gravel 10 - 20 cm layer;
compaction with a rammer or vibrating plate.

If a deep foundation tape is being filled up, at a distance of 30 - 40 cm from the surface, horizontal thermal insulation should be laid (5 cm sheets of high-density extruded polystyrene foam), after which work should be continued.

In MZLF tapes, the depth of occurrence usually does not exceed the specified level, therefore, thermal insulation is laid outside along the bottom of the trench by default. Backfilling is done on top of it.

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The ISO Altair company offers to buy a sand and gravel mixture that meets the requirements of GOST 23735-2014. We deliver with our own fleet, 7 days a week, without holidays and weekends. We supply up to 2000 cubic meters of sand and gravel mixture per day.

Under the order we will make the necessary ratio of sand and gravel.
The price of PGS according to your parameters is discussed individually. Call!

Price for sand and gravel mix

The table below shows ISO Altair's base prices for sand and gravel.

Photo	Name	3 m3	10 m3	15 m3	20 m3	100 m3
	PGS enriched	3350	1050	1000	950	900
	PGS natural	3250	1000	950	900	850

The Altair company has entered into dealer relations with quarries where sand and gravel is mined, and therefore has set the lowest possible prices for this non-metallic material. The cost of a cubic meter of sand and gravel mix depends on the volume of purchase. The more PGS the client orders, the more profitable the price is. The numbers are shown in the table.

ISO "Altair" is equipped with a car park. Therefore, the truck with the load is sent from the warehouse immediately after the payment of the order. The transport department and the order department work around the clock. The client receives the sand and gravel mixture at the specified address within a few hours after placing the order. Each batch of PGS is certified.

This material is a mixture of gravel and sand. The fractionation of the sand-gravel mixture is heterogeneous: the diameter of the grains of sand and pebbles is not the same here.
Sand and gravel mixture is an environmentally friendly natural material. It is mined in open pits using excavators. This building mix is coarse and its use is limited. ISO "Altair" among the non-metallic building materials sells in Moscow and the region and sand-gravel mixture.

Characteristics of PGS

The ratio of sand and gravel in the sand-gravel mixture is not the same.

Natural ASG is a coarse material with impurities. No additional processing of the mass after its extraction is done. Such a mixture is subdivided, depending on the place of extraction, into mountain-ravine, lake-river or sea. Natural ASG is used in land reclamation and in road construction for backfilling the drainage layer. The company delivers the natural mixture to customers in the form in which the raw material was mined in the quarry. The size of the pebbles in this mixture exceeds 5 mm in diameter, and their number in the total mass is no more than 10%.
Enriched sand-gravel mixture is artificial material consisting of sand and granite chips given size. The quality of the material depends on this. The grades of the mixture differ in the ratio of sand and gravel and the size of the pebbles. The demanded brand of PGS is the one in which the content of granite chips is 70%, and sand - 30%.

Enriched PGM is divided into 5 types:

group 1 - from 15 to 25% gravel;
group 2 - from 25 to 35% gravel;
group 3 - from 35 to 50% gravel;
group 4 - from 50 to 65% gravel;
Group 5 - from 65 to 75% gravel.

Application of PGS

Sand and gravel mixture is used for laying communication lines, for foundation works, for backfilling pits, as well as in construction and road laying. It is purchased for backfilling roads, laying drainage collectors, and even sometimes for preparing mortars. True, the latter are made only using enriched PGS.
The Moscow region is very rich in deposits of this natural material. Its extraction here is well established, and therefore the cost of natural ASG is low. It is difficult to find prices for ASG in the region cheaper than in Altair.

5 reasons to buy PGS at ISO Altair

ASG is delivered to the customer on the day of payment, since a sufficient number of dump trucks and handling equipment are provided for this. In addition, a stock of this material is available at the transshipment bases.
The company sells only certified PGS.
On a permanent basis there is a system of discounts for regular and wholesale customers.
The departments of the company work around the clock and seven days a week.
ISO "Altair" offers the cheapest price in the region for PGS and accepts payment in a convenient way for the buyer.

PGS is a high-quality, purified mixture of sand and gravel. Thus, the sand-gravel mixture refers to non-metallic materials used in the construction of residential and industrial facilities, the creation of high-quality road surfaces, in railway construction, when laying drainage layers, for leveling areas in landscape design, for making iron concrete products used for the construction of panel buildings. Also adding ASG necessary to create a cushion for the construction of the foundation, equipment sites for the operation of special equipment and in the construction of roads, for backfilling trenches and pits.

Can be natural and enriched. It is mined in quarries or from the bottom of reservoirs. Natural ASG contains at least fifteen percent of gravel, and in an enriched mixture, the content of gravel can significantly exceed this figure. The enriched ASG differs in the content of gravel into five groups: 15-25%, 25-35%, 35-50%, 50-65%, 65-75%. The more gravel the mixture contains, the harder it is, respectively. Gravel is introduced into the mixture artificially in production. The price of enriched ASG depends on the amount of gravel in it and its size. Both types of PGS are characterized by durability and resistance to physical influences, which contributes to their widespread use. If you need such high-quality materials, then the construction company offers to buy and deliver all the necessary building non-metallic materials: sand, crushed stone, gravel, bedding, PGS other.

The backfill, as a rule, is made of non-porous soil, and instead of the ASG, building soil is also used as a backfill no smaller than medium-grained. The size of the bedding is determined by a special temperature calculation, and it is necessary to provide for ventilation and thermal insulation in it so that it is not too large. PGS filling is used for arranging a monolithic foundation one- or two-story house. The installation of such a foundation begins with the development of a pit, tamping and creating a pillow, using ASG bedding, sand and gravel. A waterproofing material is laid on top of it and poured with a small layer of concrete, then reinforcement is laid, and the foundation pit is poured with a special concrete solution. The result is a solid monolithic slab used for the basement floor.

The technology of erecting various structures on initial stage construction also almost always involves the arrangement of a site for work (this requires backfilling). Backfilling of sites and roads is a crucial stage of any construction. Thus, depending on the type of structure, climatic and geographical conditions, the filtration properties of the material, the quality and operational life of the buildings largely depend on the quality and operational life of the buildings, therefore, for arranging the cushion of the canvas, the foundation device is used adding ASG, crushed stone, sand - high quality. The technology consists of several stages:

First, with the help of a bulldozer or excavator, the top layer of soil is removed to hard rocks, this is necessary to insulate the base of the future structure.
Then soil rollers strengthen the soil and form a platform for subsequent work.
The pillow itself and compaction are carried out using the addition of ASG, crushed stone, sand.
Additional bedding of hard rocks of crushed stone and its compaction are possible.

The foundation is not only the basis of any building, but also the guarantor of the durability and strength of the building. Exactly right choice and compliance with a strict sequence of work, as well as the competent selection of materials used in the construction of the foundation, guarantee its reliability and compliance with the required quality standards. The main purpose of this part of the house is to provide the future building with a stable and strong platform. A properly prepared and laid sand and gravel cushion under the foundation is able to provide it with a lesser degree of settlement. Thus, a reliable pillow helps to significantly improve its quality.

In the event that the construction of the foundation is carried out without observing the necessary building codes and contrary to the existing and time-tested rules, the constructed building in a very short time can become completely uninhabitable. Cracks appear on the surface of the walls, window frames warped, the doors no longer close tightly. All this leads to the appearance of mold, dampness, drafts.

The renovation and decoration of the premises is losing its attractiveness. The owners of such unsuccessful buildings have to invest additional funds, time and money in unforeseen repairs.

Compliance with all requirements for the construction of the foundation will help to avoid disappointment. And its correctness depends on how exactly the sand and gravel cushion under the foundation was made. It is rightfully considered the key to a strong and solid foundation. The pillow ensures the complete absence of contact between building materials and building objects with the foundation itself, which, in turn, eliminates the appearance of various deformations. Due to the presence of a well-chosen and prepared pillow, the building (at its very bottom) rises high in relation to groundwater.

A mixture of sand and gravel is one of the most popular and commonly used building materials. Both of these components, mixed in strict accordance with the recommended proportions, are very often used for the construction of residential buildings, shops and other buildings. This seemingly simple composition belongs to one of the most the best options basics. It guarantees the strength of the mixture of mortar from concrete or cement.

Why do you need a pillow under the foundation?

Those who are thinking about making the foundation for the construction themselves should pay attention to clearly defined building rules regarding this issue. First of all, it is important to comply with all the requirements for such a stage of work as the installation of a sand and gravel cushion. In addition to a pillow made from a combination of sand and gravel, pillows for a foundation made of concrete and gravel are common. As a rule, a concrete cushion is required only when a reinforced belt is made under the FBS blocks or when the foundation walls are further expanded.

The sand and gravel pillow is made on construction sites with weakly bearing soil. It is important to remember that in no case should sand dust or fine-grained sand be used to form it. The ready-to-use mixture must consist of gravel and sand, which have an average particle size. After the pillow from this composition is laid, it will give a minimum shrinkage, for which it is necessary to make careful tamping. Such a base for the foundation will perfectly withstand the load of not only a medium-sized house built from frame building materials, timber or logs, but also a large structure, for example, with an attic or a second or third floor.

When building a sand and gravel support, you can use the following work option:

dig a trench of the required width and depth up to the level of dense layers of soil;
in the ditch, which thus turns out, it is necessary to fill up the river sand of a coarse-grained brand;
sand should be covered in layers and in small portions. Each layer should be 15 cm thick;
after laying each new layer, it must be spilled with water;
all layers are compacted using special tamping equipment;
the finished support should have a width of 10 mm greater than the planned width of the future building.

The need for a sand and gravel cushion in the construction of not only low-rise, but also larger ones is determined by its relatively affordable cost, a high degree of durability and the ability to carry out work on their own, without the help of professional builders. However, it should be noted that such trifles as cleaning the trench after an excavator, backfilling sand and gravel with buckets or a wheelbarrow, manually watering all layers with water will require serious physical effort from workers. An attempt to involve family members or friends in the process may well be justified.

Do-it-yourself sand and gravel pillow

Every experienced master builder knows what a sand and gravel cushion is for. Such a foundation under the foundation is able to ensure the subsequently built building full functioning without defects and damage. It must be remembered that the layers of the sand-gravel mixture are laid in layers, but in different thickness each such layer. The fact is that this question is fundamental for each individual type of soil. In no case should a layer of sand and gravel be less than 5 cm thick. Many builders do not welcome a pillow thickness of more than 25 cm.

It is desirable to equip the pillow under the entire area of the building. It is this method of laying that provides the most uniform draft of the structure. The width of such a pillow should be wider than the width of the foundation base by at least 30 cm. Thus, the structure is supported over its entire surface area. When laying a sand and gravel cushion, it should be compacted so intensively that it acquires a density equal to 1.6 g / cm3 of the density of the soil layers.

Doing such work yourself, monitor the quality of the building materials used. So, for example, the presence of even a small amount of clay impurities in sand can lead to serious unpleasant consequences. If water gets into such a pillow, it will begin to swell. Therefore, control the composition and condition of the materials used, and also, be sure to follow the recommendations and step by step instructions at all stages of work.

Many novice builders think about when and how to make a sand and gravel pillow with their own hands. The solution to this problem is quite accessible to master everyone. And since laying the foundation is the first step in the construction of any building, its implementation requires a serious and responsible approach. The depth of the foundation is primarily determined by the level of water flow in the soil. With a large depth of laying the foundation, it is not complete without a sand and gravel cushion.

Having decided what a sand and gravel cushion is, you can proceed with its installation, which basically boils down to the following:

it resembles a kind of “pie” with layers of sand and gravel (you can use crushed stone);
the first layer in a dug trench (pit) is a rubble, which will provide additional strength;
the second layer is coarse river sand, which, after being distributed over the entire surface, must be leveled, watered and compacted;
the third layer, at least 20 cm thick, is gravel. After laying, it is rammed with a vibrating plate;
ready-made layers are covered with a layer of sand equal to 20 cm. After it is watered, it precipitates on gravel.

This technology must be followed layer by layer until the wet sand has nowhere to settle. After completing the work on the manufacture of the pillow, you can begin to build the foundation.

The subtleties of building a shallow foundation

The shallow foundation is a monolithic tape, mainly made of reinforced concrete. The height of such a tape is from 40 to 60 cm, and its width is 35 - 50 cm. These indicators depend on the thickness of the walls and the materials from which they are built. Laying such a foundation under the building is carried out under all external and internal load-bearing walls.

Very important point the construction of such a foundation can be called an installation the right pillow, in which only components that are not subject to heaving should be used. Ideal components for it will be sand and gravel. In this case, the ratio of these components can be approximately as follows:

river sand of large fractions - 60%;

gravel - 40%.

Such a mixture replaces the soil and is laid on the bottom of the prepared trench. Most often, the depth of the trench is about 50 cm. All laid materials are subjected to ramming. This bedding significantly reduces the impact on the foundation of heaving forces during frosts. The sand and gravel mixture neutralizes and springs the impact coming to the base of the structure from below.

The advantages of a shallow foundation include its low cost and the absence of high labor intensity. However, with this choice, the size of the future building is limited, for example, the walls should not exceed 7 m. As for the construction of basements, they are not provided for with this type of foundation.