How to properly reinforce a slab foundation? Do-it-yourself reinforcement of a floor slab Reinforcement of a 150 mm slab.

Reliable reinforcement monolithic foundation

Using exclusively one, even high-quality concrete, cannot ensure the reliability and durability of the structure. In a slab monolithic foundation, concrete is only a building material, and its optimal strength and ability to neutralize external influences from loads is possible only thanks to the reinforcing belt.

Therefore, reliable and durable monolithic foundations, on which high-rise concrete buildings are often erected, have powerful reinforcement, and in this case can often use several at once various types reinforcement depending on permissible loads, soil structure and slab dimensions.

What reinforcement is used for a monolithic slab?

This is what a drawing of the reinforcement of a monolithic slab looks like. But in reality, the scheme is significantly different - it is more detailed, since it is necessary to provide for many factors and parameters.

Considering the size and weight of the iron concrete slab, for reinforcement it is better to use:

For vertical belts, rods with an outer diameter of up to 10 mm.
For horizontal belts – up to 14 mm.
8 mm is also suitable for jumpers.

If composite reinforcement is used, then the diameter of the load-bearing elements may be smaller, but the number of rods must be increased. In most cases, the layout of the reinforcement involves the use of rods with a diameter of up to 5% of the thickness of the slab itself. Then maximum design efficiency will be achieved with minimal financial costs.

Unlike strip foundations, a monolithic slab is reinforced unevenly. In areas with minimal load, the frame will be weakened, but at the corners of the building, at the intersections of load-bearing walls, the reinforcement will be much stronger, since these are zones of punching - maximum pressure, where deformation shifts occur.

Reinforcement along the width of the slab

The standard square slab size is accepted, where the pitch reinforcement cage will be the same in all directions. For concrete buildings, reinforcement is done at intervals of 200−400 mm, for brick buildings 200 mm is enough, the drawing will resemble a chessboard.

For the lungs frame buildings the step will be even smaller, because the load on the foundation is much less, but here a lot also depends on the type of soil and its bearing capacity. But, in accordance with the joint venture “Concrete and reinforced concrete structures", the maximum distance between the rods should not be 1.5 times the thickness of the slab as a whole.

What are punching zones and their effect on reinforcement

In places where the foundation is affected by the main load from the supporting structures of the building, additional stress occurs. It affects not only the distribution of concrete, but also the degree of depreciation. To neutralize the influence of the mass of load-bearing structures, a continuous series of reinforcement is used at the junction of the load-bearing walls and the foundation.

If the reinforcement in the center of the slab has a pitch of 200 mm, then in the punching zone the pitch will be already 100 mm or even less. The calculations and future slab reinforcement scheme will indicate the maximum permissible distance between vertical reinforcement links.

The optimal solution in such cases would be:

Development of a detailed design of a reinforcement frame with specified distances between chords.
Execution of the working reinforcement scheme.
Removing vertical rods above the base to connect the load-bearing walls and foundation with a reinforcement belt, rather than leaving only a concrete connection.

At the moment, in accordance with GOST 5781-82, there are the following types of steel reinforcement:

A240 (AI). These are smooth rods, mostly used for vertical reinforcement; they are not used in monolithic bases.
A300 (AІІ). Rods with a working diameter of 10-12 mm have an external periodic profile with ring notches.
A400 (АІІІ). It has a crescent-shaped profile, a large working diameter and is optimal for a monolithic slab.

The choice of reinforcement for a monolithic foundation depends on many factors.

How to tie reinforcement cage

Some drawings already provide a connection method if the permissible load on the base has been calculated. But most builders use the welding or bonding method. Welding is rarely used now, because due to prolonged local heating, the metal changes its structure and is slightly deformed. But binding provides sufficient flexibility. For tying, it is recommended to use a soft, durable steel wire with a diameter of 3−4 mm, as well as pliers or clamps.

The principle of reinforcement of a monolithic slab:

First you need to make formwork, install roll waterproofing on the inside 5 cm from the edge.
Then install a horizontal reinforcing belt at a distance of up to 5 cm from the sand and gravel cushion, strengthen it with pegs or compactors. The reinforcement should not come into contact with the cushion and side walls of the formwork.
Vertical rods are installed at intervals of 200–400 mm and connected to a horizontal belt at the lower edge. In order to increase the strength of the building, reinforcement is installed more often in the corners, and additionally reinforced with longitudinal rods.
Horizontal belts are installed at intervals of 15 cm, but take into account the thickness of the slab. In some cases, the distance can be reduced, but not increased. The verticals are sequentially connected to the horizontal belt.
A vertical layer of reinforcement is placed above the upper edge of the foundation. It will then connect to the bottom edge of the load-bearing walls.

After reinforcement is completed, the entire structure is filled with concrete.

A typical example of calculating a reinforcement frame for a monolithic foundation

For the calculation, a monolithic slab with overall dimensions 6x6 meters, slab thickness for a private house 20 cm. In the example, the calculation of the reinforcement belt in the interface zone will be used:

Foundation area: 1.2 sq. meters.
Minimum reinforcement area 1.2*0.3% = 36 sq. cm.
The reinforcement area for one horizontal belt, taking into account the interval between the belts of 100 mm, will be 36/2 = 18 sq. cm.

GOST 5781-82 contains the entire permissible range of reinforcing bars with their cross-section and permissible length. Therefore, for this example it is advisable to use 12 rods with a diameter of 14 mm each. Then you need to make a drawing of the future frame in order to calculate the required amount of reinforcement. For a side 6 meters long, it is advisable to take a horizontal belt pitch of 300 mm, and for a vertical belt - 300 mm using reinforcement with a diameter of 8 mm.

If we summarize all the data in tables, taking into account the use of U-shaped connecting reinforcing clamps, then to reinforce a monolithic slab with an area of 36 sq. m will have to buy and invest 515.2 m of reinforcement with a diameter of 12 mm and 56 m with a diameter of 8 mm.

Private and multi-storey construction is not complete without floor slabs, which can be divided into the following types: beam, precast reinforced concrete and monolithic.

Most often, standard welded mesh made of rods with a diameter of more than 6 mm (mostly from 8 to 14 mm) is used for reinforcement. The distance between such rods should not be more than 60 cm.

The most common practice is to use the procedure of self-reinforcement of floor slabs. Due to the fixed tandem of “concrete and reinforcement”, they provide a decent level of strength. Moreover, in this way, many different flights of stairs, arched and reinforced lintels are created.

Characteristic features of reinforced floor slabs

Since the width of the foundation strip is usually no more than 400 mm, the width of the reinforcement frame will also be 300 mm. The space between the frame and the formwork at the top, bottom and on both sides should be 50 mm.

Process of creation monolithic design must necessarily include the use of reinforcement, which represents binder material in reinforced concrete structures: staircases, arched and reinforced lintels, reinforced slabs.

Reinforcement of monolithic floor slabs is carried out using reinforcement with a cross-section of 8 - 14 mm. An important condition for this slab is its thickness, which should be a maximum of 150 mm. However, the thickness may vary depending on the type of product. Reinforced floor slabs make it possible to truly solve the construction concept warm houses . They are actively used in industrial, commercial and housing construction

for building a roof and horizontal floors between floors. Floor and covering slabs make it possible to ultimately obtain warm ones and guarantee adequate protection of attics and attics in the winter, as well as the absence of cold bridges.

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Marking of reinforced floor slabs

Reinforced concrete floor slabs, like regular concrete, include specialized markings that must be taken into account when selecting slabs. Reinforced concrete is marked using marks consisting of numbers and letters. Accordingly, the meaning of these letters determines the type of slab. For example, PC - floor slabs, NV - internal flooring, PNO - lightweight flooring slabs. The numbers following the letters determine the length and width of the supporting structure in decimeters.

When choosing a concrete slab, you must keep in mind that these buildings differ not so much in the size of their markings, but in their structure. Depending on the type of section, reinforced concrete slabs can be divided into 3 types: ribbed, hollow and solid. The best-selling and most relevant of the three groups are hollow core slabs, which have many advantages.

The reinforcement is tied into a mesh using binding wire. Cell size 150x150 or 200x200mm. The reinforcement in the mesh must be solid, without breaks.

These floor slabs have a relatively small weight, which greatly simplifies the process of their transportation and installation. In addition, such slabs have a high percentage of resistance to deformation and have excellent sound and heat insulating qualities. It is worth noting that the hollow type of reinforced slabs can have a variety of shapes: vertical, round or oval.

Because of these variations, reinforcement slabs can be selected for specific situations depending on natural features and characteristics of the climate zone where you want to build a house. When purchasing reinforced concrete, be sure to keep in mind that if floor slabs are used as a concrete floor or ceiling, it is necessary to practice ribbed reinforcement of such structures (in this case, the ribs must be present on only one side).

Advantages of reinforced floor slabs

The reinforcement of the floor in places where it rests on columns is very different from conventional reinforcement; in these places additional volumetric reinforcements are required: 1 - main mesh; 2 — additional reinforcement of the main grid; 3 - “U” shaped reinforcements of the edges of the slab; 4 - “L” shaped reinforcement of the corners of the slab; 5 - load-bearing walls.

Absolutely all types of reinforced floor slabs are recommended for use in coverings of public and residential buildings that contain walls made of cellular concrete blocks, large blocks and bricks. The slabs are also suitable for buildings with a maximum air humidity of up to 60% and for structures that have vapor barrier features in the inner plane of the walls with a maximum air humidity of up to 75%. In this case, the depth of the platform support should not be less than 80 mm.

Reinforced slabs make it possible not only to achieve effective insulation of buildings, but also to speed up the overall construction process and increase the percentage of sound insulation. The small mass of reinforcement slabs and concrete lintels reduces the load on the base and walls. Among other things, this also brings with it economic benefit when building a house. The procedure for reinforcing hollow-core floor platforms itself does not require the use of huge construction equipment (for example, a crane), which undoubtedly simplifies construction and is a big advantage.

The insignificant weight of reinforced slabs and concrete lintels reduces the load on the walls and foundation, allowing for additional economic benefits when building a house.

As a result, using these floor platforms, the overall structure will have sufficiently high strength and can easily withstand enormous stresses and external factors, such as fire, long time. To compare these irons concrete structures with other materials, it is worth saying that wood can withstand direct exposure to fire for no more than 25 minutes, while monolithic platforms can withstand more than one hour.

The construction of monolithic structures using large blocks and floor platforms makes it possible to build houses of any size and complexity. In the process of creating floor platforms, it is possible to cover a room with incorrect wall geometry. Accordingly, it is possible to create even the most outlandish ceilings in terms of their dimensions. In this case, the support for such a reinforced floor is not so much the walls as the columns, thanks to which general layout the building will have a freer appearance.

In order to efficiently perform the reinforcement of the floor slab and calculate all the necessary aspects at the preparation stage, it is necessary to use the following tools:

electric gun for tying reinforcement;
hook for tying reinforcement;
knitting wire for reinforcement;
manual screwdriver for reinforcement;
welded mesh of indirect reinforcement.

Floor platform reinforcement diagram

The reinforcement scheme for the monolithic floor must be carried out. It provides additional reinforcement in some places: the middle of the slab, places of contact with supports, places of accumulation of loads and places of contact with holes.

On at this stage development, it is necessary to take into account all the components of the slab that are organized together. In general, the reinforcement scheme for the floor platform will have next view: working rods in the lower and upper parts of the slab, reinforcement that redistributes the load and wire rod supports. The construction drawings used may also vary. However, it is important to correctly calculate the planned load and the required concrete thickness. The calculation of the latter is carried out according to the proportion 1:30. Accordingly, in order to find out the required concrete thickness, you need to divide the span length by 30.

If the platform thickness is over 150 mm, the reinforcement is made in two layers, which are placed on top of each other and connected with wire. The cell size in this case should not exceed the proportion of 200:200 mm, but at the same time should not be less than 150:150 mm. For example, if the width between the load-bearing walls is 6 meters, then the thickness of the reinforced platform should be 0.2 m.

If you deliberately reduce the concrete thickness, then the consumption of rolled metal will increase significantly. Moreover, if the thickness increases, then the overall costs of concrete will also increase. In order to achieve high structural strength, it is best to use reinforcement of a similar cross-section. Auxiliary reinforcement can be carried out using rods having a length of 400-1500 mm.

The connection of individual reinforcement rods is carried out using knitting wire and a special crochet hook. It is allowed to weld only fittings that have the letter “C” in their marking, for example A500C.

The bulk of the loads fall on the lower reinforcement, and the upper one receives a compressive load. Concrete does this wonderfully. Please also take into account that the reinforcement of a monolithic floor platform must be carried out along the entire plane of the product, if possible using formwork, which is one of the most important stages of slab installation. It is also acceptable to use this tree ( regular boards 50:50 millimeters) or cheap fittings.

An important point is to securely and firmly fasten the formwork posts, since the mass of concrete used during this construction operation can reach 300 kg per square meter. m of flooring. The only thing that is difficult to do without at the stage of installing the reinforcement slab is the telescopic type racks, which can withstand about two tons of weight. Comparing them with boards, which may include knots or microcracks, many advise making their choice in favor of racks.

Correct calculation of reinforcement

In order to correctly analyze the soil, you need to calculate the reinforcement itself and the construction of the foundation for any type of house (wooden, brick). Once you determine the composition of the soil on the premises of the building, performing the calculation will not be difficult, and it can be done quite accurately. The calculation is performed immediately based on deformations for several reinforcement solutions.

Among other things, you need to calculate the layout of the axes for filling strip foundation under the building of a house. This can be done using a theodolite. If the latter is absent, then it is permissible to use a shovel and work manually or perform all the work automatically using special equipment.

Rules for reinforcement of floor slabs

View of formwork prepared for concreting with prestressed reinforcement.

Reinforcement of the floor platform should be carried out only in accordance with the specific requirements of the technological plan:

A tension mesh, which consists of high-strength ropes, must be used to reinforce slabs spanning spans and those that are over 8 m in length.
In particular, for reinforcement, conventional meshes of a welding sample made of rods with a diameter of over 6 mm are used. The distance between such rods should not exceed more than 60 cm.
The thickness of the platform will depend on the width of the overlap. Reinforcement with rods is carried out if this ratio is less (this can be determined by performing the appropriate calculation).
A platform thickness of less than 15 cm makes it possible to use only single-layer reinforcement. If the thickness is large, then it is necessary to create two layers (one at the bottom, the other at the top).
For pouring reinforcement, it is best to use liquid concrete grade M200. Otherwise, the materials will not provide adequate strength.
In addition, the calculation of the reinforcement of the floor slab is carried out, providing for additional reinforcement in certain areas. Accordingly, places of contact with supports, accumulation of loads, contact with holes and the middle of the slab are subject to this reinforcement.
Auxiliary reinforcement is mainly used only for holes, while the main reinforcement is fully implemented. However, the calculation of the formwork must be carried out along the entire length of the structure.

The improvement and development of the field of individual construction leads to the emergence of new materials and ways of using them on construction sites. One of these innovations is self-reinforcement and pouring for the roof of the house.

The floor slab is one of the most common reinforced concrete products in construction.

Reinforcement of a monolithic slab must be carried out strictly according to technology. Since the bottom layer of reinforcement bears the main load, the slab will not withstand it if the reinforcement is incorrect.

The working load on the finished monolithic floor slab is directed from top to bottom. From the point of application it is distributed evenly throughout the entire slab. Without proper reinforcement, such a slab will not withstand loads. The main load falls on the lower layer of reinforcement. It works in tension, so it must have special strength. The upper part of the slab experiences compression, which concrete tolerates well even without reinforcement.

Monolithic concrete floors, their reinforcement can be done with your own hands if you really want to. But it will require high costs time and effort. Before starting work, it is necessary to make an accurate calculation of the production of a monolithic floor. Experts do this calculation on a computer using special software.

Overlap calculation

Correct and its reinforcement has a number of advantages:

a monolithic slab ceiling will have a high bearing capacity;
an accurate calculation will give best option selection of reinforcement, slab thickness, grade and amount of concrete. All this together allows you to save money and time;
professional calculation makes it possible to use not only walls, but also columns located indoors as a support for a monolithic floor;
the calculation will show all the necessary volumes of work and their cost;
can be of non-standard geometric shape;
The service life of a floor constructed in strict accordance with reinforcement calculations is practically unlimited.

General rules

Reinforcement must be done in two layers. To connect the rods into a mesh, you will need 1.5 mm binding wire.

Not everyone is capable of performing professional mathematical calculations. But there are general rules buildings and According to these rules, the thickness of the slab should be equal to 1/30 of the length of the overlapped span. For example: with a span length of 600 cm, the thickness of the finished monolithic floor will be 20 cm. Increasing the thickness will only lead to excess consumption of expensive concrete. If the length of the overlapped openings does not exceed 7 meters, then you can resort to the standard calculation option. According to this calculation, a monolithic slab should be reinforced with two layers of reinforcement. Both layers are made from A-500C reinforcing bars. They have a diameter of 10 mm. The rods are laid in increments of approximately 150-200 mm. The connection of the rods into a mesh with a square side of 150-200 mm is carried out using soft knitting wire with a diameter of about 1.2 - 3.0 mm. The slab can be reinforced using commercially available welded mesh.

When determining the dimensions of a monolithic structure, the size of the grip should be taken into account. This is the part of the slab that will rest on the wall. If the walls are brick, then the grip size should be 15 cm or a little more. For walls made of aerated concrete, this value is 25 centimeters or more. Reinforcing bars are cut so that their ends are filled with a layer of concrete at least 25 mm thick.

After tying the reinforcing mesh, it is necessary to correctly space them in height. With a monolithic floor slab thickness of 180 to 200 mm, the length of the overlapped span can reach 6 meters. In such slabs, the distance between the upper and lower reinforcement mesh is from 105 to 125 mm. To maintain this distance, original clamps are made from scraps of reinforcement 10 mm thick. The upper and lower horizontal parts of the clamps are made about 350 mm long. The height of the vertical elements is 105-125 mm. These clamps can be bent using homemade device. Ready-made clamps are installed between the upper and lower reinforcing mesh in increments of about a meter. In the area where the slab is supported on the wall, this distance is reduced to 400 mm.

To space the reinforcement mesh in height, clamps are used, which are installed in a checkerboard pattern in 1m increments.

The simplest calculation shows that with proper reinforcement per square meter. m of monolithic concrete floor 20 cm thick requires approximately 1 cubic meter. m and above (preferably M350), 36 kg of reinforcement grade A-500C, having a diameter of 10 mm.

Under the bottom mesh for reinforcing the monolithic structure there should be a layer of concrete of about 25-30 mm or a little more. The top reinforcing mesh is covered with the same layer. To maintain this size, plastic clamps are placed at the intersections of the lower reinforcing bars in increments of about 1 meter. These fasteners are sold in stores building materials. They can be replaced with wooden blocks nailed or screwed to the formwork. If they are not secured in this way, they may float when the formwork is filled with concrete. These are general rules. But only a professional can make an accurate calculation.

Construction of formwork

To make a monolithic slab, you need to install formwork. It is made from wood. Special telescopic stands on durable tripods are installed under the formwork. The racks should be securely fastened. Their number should be such that the formwork does not sag under the weight of concrete. Its weight reaches 300-500 kg per square meter. m with a layer thickness of 200 mm. The racks are usually located every 120-150 cm. In the absence of special racks, they can be replaced with racks made of timber with a cross-section of 100x100 mm or round timber of the same diameter.

The formwork must be positioned strictly horizontally and have no gaps between the boards.

The bottom of the formwork is a layer of sheet laminated material. Laminated plywood is suitable for this. Mathematical calculation recommends using sheets with a thickness of 18-20 millimeters or more. Concrete does not stick to the laminated surface. You can also use plain thick plywood, painted oil paint. Concrete doesn't stick to it either. This material allows you to obtain a completely smooth and even lower surface of the floor slab. In the simplest version, ordinary treated boards can be used. Their thickness should be 50 mm. Plywood or boards are attached to the racks with screws.

It is important to check the absolute horizontalness of the formwork using a level or other available means. There should be no gaps between the plywood panels or boards. You can lay the formwork on top plastic film so that liquid concrete does not seep down. The film will also prevent moisture from the concrete mass from being absorbed into the wood of the formwork. Loss of moisture reduces the strength of concrete. Carelessly installed formwork will lead to unevenness bottom surface monolithic slab and additional difficulties during final finishing work.

The bottom of the future slab consists of a layer of concrete to insulate the reinforcement, about 20 mm thick. Reinforcing mesh is laid on it through the supports. The entire structure is poured with concrete grade M200 or higher.

When the width of the overlapped spans is more than 8 meters, the overlap is reinforced with high-strength ropes. If the monolithic slab rests on columns, then additional reinforcement is installed at the support points. The formwork is made along the entire length of the slab.

To prevent concrete from cracking when hardening, it must be moistened with water during the first week.

Concrete is laid over the entire floor area at once. It is better to use industrially prepared concrete mixture, which is delivered by special mixer machines in the required quantity. This type of concrete is better than homemade concrete. It undergoes quality control and contains special additives to improve its properties.

The laid concrete should vibrate well. A deep construction vibrator will best cope with this task. You can get it from the rental department of a building materials store. The vibrator compacts the concrete mass, expels air and excess water from it. After all the concrete has been completely laid, the surface of the future slab is smoothed with a special trowel with a long handle. You can sprinkle the surface with a thin layer of dry cement.

Diagram of reinforcement elements: support reinforcement; concrete; crown; rods.

The ambient air temperature when laying concrete should not fall below +5 degrees Celsius. At lower temperatures, moisture inside the concrete mass may crystallize. This will cause the concrete to crack and lose its strength. There are additives that allow concrete to be poured at low temperatures, but the resulting product will be of lower quality.

The monolithic slab will reach its design strength under the recommended temperature conditions in four full weeks. For the first 2-3 days, in order to avoid the appearance of cracks on the surface of the slab, it must be periodically moistened with water. Only in this way can the required strength of the monolith be achieved. It is not necessary to stop construction at the site. You can continue building walls or performing other work.

AND last tip: if it was not done at the construction design stage, it is better to turn to professionals. You should not save on this; as a result of such savings, you may end up a big loser.

Monolithic concrete floors, made according to the calculations of specialists, will be guaranteed to be of high quality. They will have great load-bearing capacity. A professionally performed calculation will allow you to purchase required quantity

reinforcement and concrete. If there are columns in the room, the calculation will allow you to correctly reinforce the places where the floor slab rests on these columns. It is impossible to do this by eye.

Didn't find the answer in the article? More information Any building is constructed using concrete. Used for amplification wire mesh or reinforcement cage. Monolithic floors are common, the formation of which involves pouring concrete mortar into the formwork installed between the load-bearing supports. To increase the load capacity, it is necessary to strengthen the concrete slab. To do this, perform additional slabs

floors, which must meet the requirements of the project. It is important to perform calculations taking into account the distance between the walls, select the quantity and diameter of the reinforcement.

What is monolithic slab reinforcement? A common element of residential and industrial buildings is, to enhance which is used large diameter

. To connect elements of a reinforcement grid or spatial frame, it is not recommended to use welding, which weakens the structure. The joints of the rods must be tied with annealed wire. The part of the monolith reinforced with reinforcement is capable of bearing significant loads. Floor reinforcement is a set of measures to strengthen a concrete structure.

The most used floor covering in the construction of individual low-rise buildings is reinforced concrete products

The sequence of actions is as follows:
First, a project is developed and reinforcement calculations are performed, taking into account the dimensions of the floor and the magnitude of the acting forces. Based on the calculations, an amplification circuit is developed.
After preparing the panels, the formwork is installed between the main walls. When installing a formwork structure, support elements are installed that increase the load-bearing capacity of the formwork.
Next, the blanks are cut, the frame is tied together and installed in the panel formwork. The manufacture and assembly of metal structures is carried out in accordance with pre-developed design documentation.

When developing a reinforcement scheme for a concrete slab, it is planned to install additional steel rods in problem areas:

in areas of contact between a monolithic slab and supporting columns, main walls and arched structures;
in areas of concentrated effort associated with the installation of heating appliances, heavy furniture or massive equipment;
along the contour of exit openings to the upper floors, as well as around openings for ventilation lines and smoke exhaust pipes;
in the central part of the concrete slab, which is one of the most weakened areas of the floor.

To prevent corrosion processes, the reinforcing grid is located on special supports inside the concrete mass, not reaching the surface 30-40 mm. Taking this factor into account, the rod lengths are selected and the immobility of the load-bearing structure during concreting is ensured. Using reinforcement technology, it is easy to ensure increased strength properties of a concrete floor, as well as its long service life.

Calculation of the thickness of the floor reinforcement depends on its length

How to reinforce correctly - requirements for strengthening a concrete slab

Reinforcement of a monolithic floor slab is a responsible process, the implementation of which is subject to a set of requirements.

When performing work on the formation of a reinforced reinforced concrete floor structure, follow the following recommendations:

Use tying wire with a diameter of 1.2-1.6 mm to connect steel bars. The use of electric welding is unacceptable due to the disruption of the metal structure at the joints;
ensure the required thickness of the concrete floor mass in relation to the distance between the main walls. The thickness of the reinforced concrete structure is 30 times less than the distance between the supports. In this case, the minimum thickness of the slab is at least 15 cm;
arrange the elements metal frame taking into account the vertical dimensions of the ceiling. With a minimum slab thickness, the reinforcement is laid in one layer. For thicknesses greater than 15 cm, perform reinforced reinforcement in two layers;
Use a concrete mixture marked M200 or higher to fill the formwork. Concrete of these brands has good performance characteristics, able to withstand significant loads and has an affordable price;
use for making steel grating reinforcing bars with a diameter of 0.8-1.2 cm. When performing reinforcement in two layers, use an increased cross-sectional size of the metal profile in the bottom row. It is possible to use a purchased mesh;
construct a formwork structure from planed boards or moisture-proof plywood. Carefully seal the joint areas. To strengthen the formwork, use wooden posts with a diameter of up to 20 cm or metal racks telescopic type.

Compliance with these requirements when performing reinforcement measures will ensure strength characteristics the ceiling being constructed.

The reinforced platform, made taking into account technological subtleties, will last for decades

Additional reinforcement of floors - advantages and disadvantages

Need for reinforcement concrete floors related to the characteristics of concrete. The concrete mass is capable of withstanding increased compressive loads, but is susceptible to tensile forces and the influence of bending moments. Concrete is not capable of damping loads on its own and requires additional reinforcement. To compensate for tensile forces and maintain the integrity of reinforced concrete structures, additional reinforcement of floor slabs is performed.

Concrete slab, the strength of which is increased due to additional reinforcement, - reliable design, characterized by a number of advantages. Main advantages:

long service life. Thanks to the increased safety margin, the service life of a reinforced concrete structure is calculated in decades;
absence of butt seams, as well as smooth surface of ceilings and floors. There is no need to perform expensive and labor-intensive finishing work;
reduced weight of the monolithic floor structure compared to purchased ones reinforced concrete panels. This significantly reduces the load on the foundation;
increased strength characteristics. The combination of the properties of steel reinforcement and concrete makes it possible to increase the strength of the base and ensure its integrity under increased loads;
increased reliability of reinforced concrete structures. Resistance to loads acting in different directions is achieved through reinforcement. Reinforced floors are capable of supporting from 0.5 to 0.8 tons per square meter of surface;
Fire safety. The use of non-combustible building materials ensures the fire resistance of the structure. The slab is capable of maintaining its integrity for a long time under the influence of elevated temperature and open fire;

This design weighs noticeably less compared to ready-made reinforced concrete slabs, however, this factor does not affect its strength

reduced costs compared to using standard panels to form floors. The costs of constructing a monolithic floor are significantly lower compared to a similar prefabricated structure;
no need to use special lifting equipment and rigging equipment. A crane is not required to form a monolithic slab;
uniform transfer of forces from the monolithic slab to the load-bearing walls of the building or support columns. As a result of load equalization, the likelihood of crack formation is reduced.

Among other advantages, it should be noted the possibility of pouring a non-standard configuration of the ceiling. This allows the construction of buildings of varying levels of complexity with non-standard layouts. A serious advantage is the ability to create interfloor openings and communication openings at the concreting stage.

Along with the advantages, there are also weaknesses:

increased labor intensity of carrying out activities for assembling the reinforcement frame;
increased duration of the process of cement hydration and, accordingly, the gain of operational strength by concrete.

Professional builders often give preference to monolithic floors, which, along with these advantages, are resistant to high humidity and reliably soundproof the room.

What material is used for the manufacture of reinforced floor elements

To form reinforced floors, the following building materials are required:

concrete mixture made from M300 cement, fine sand and medium-fraction crushed stone;
steel bars with a corrugated surface, made from A4 class reinforcing steel.

The platform is used for covering long-span and heavily loaded structures

You will also need following materials, tools and equipment:

annealed wire for connecting reinforcing bars;
special device for tying reinforcement;
moisture-resistant plywood or boards for making formwork;
equipment for bending reinforcement blanks;
grinder or special nippers for cutting rods.

Do not forget to prepare a tape measure with which you can take the necessary measurements.

We calculate a monolithic slab for increased load

The calculation of a solid reinforced concrete slab is carried out on the basis of a previously developed diagram, taking into account the requirements of building codes and regulations.

Based on the calculation results, the following characteristics are determined:

thickness of reinforced concrete floor;
range of reinforcement and number of rows of reinforcement.

Let us dwell separately on each type of calculation.

How is the thickness of a concrete slab calculated?

Determine the thickness of the formed reinforced concrete floor structure using the following algorithm:

Measure the distance between the load-bearing walls.
Divide the resulting value by 30.
Multiply the result by a safety factor of 1.2.

For example, for a building with a distance of 600 cm between the main walls, the thickness of the slab will be: 600:30x1.2=24 cm. When designing loaded structures, it is advisable to entrust the calculations to specialists who will take into account all the nuances.

The monolithic slab does not support combustion and can withstand exposure to open flame for a long time

Counting the number of rows of reinforcing bars

The number of reinforcement levels is determined depending on the thickness of the floor:

single-tier reinforcement is allowed with a minimum thickness of the reinforced concrete structure equal to 150 mm;
a two-level reinforcement frame is constructed when the thickness of the floor increases above the specified value.

The diameter of the upper and lower reinforcement is 8-12 mm. When connecting the rods, a lattice with cells in the form of a square with a side of 200-400 mm is formed.

Design and drawing of the upper floor

Structurally monolithic ceiling It is a prefabricated structure made of branded concrete, inside of which a power grid is located. The reinforcement scheme for a monolithic floor slab is developed at the design stage.

It contains the following information:

dimensions of the reinforcing grid;
sizes and sections of reinforcing bars;
profile of the rods used;
reinforcement connection method;
spacing between reinforcing bars;
design features of the reinforcement belt.

Based on the diagram, the amount of building materials is calculated and the sequence of construction activities is planned.

Additional reinforcement of floor slabs - preparatory activities

When planning how to reinforce a monolithic slab, you should carefully prepare for the work:

Perform strength calculations.
Develop an amplification circuit.
Determine the need for building materials.
Prepare materials and tools.
Cut reinforcement blanks.
Prepare panels for assembling the formwork.

Attention should be paid to preparing the concrete solution in the required volume.

An example of reinforcement of a monolithic floor slab

Let's look at how to properly reinforce a monolithic slab using the example of a floor for a building with dimensions of 6x6 m with a reinforced concrete platform thickness of 0.24 m.

Procedure:

Assemble the panel formwork.
Seal the cracks.
Cut the reinforcement.
Tie a two-tier lattice with a 20x20 cm cell.
Install the grate in the formwork on special stands.

After completing these operations, pour the concrete.

How to reinforce a floor slab - step-by-step instructions

Reinforcement of a slab is a critical operation performed according to the following algorithm:

Cut the reinforcement blanks to the required sizes.
Tie the power grid of the lower tier.
Place it with a gap of 30-40 mm to the surface of the formwork.
Securely fasten the vertical bars.
Tie the upper level reinforcement to them.

To ensure rigid fixation of the elements, use a knitting device. After ensuring the immobility of the reinforcement frame, proceed to concreting.

Let's sum it up

Knowing how to reinforce a floor slab, it’s easy to do the work yourself and save money. cash. It is important to make the calculations correctly and follow the technology.

Reinforcement of a monolithic foundation slab is a mandatory stage of work before pouring such a foundation with concrete. Any without reinforcement concrete foundation will be extremely vulnerable to the effects...

Monolithic slab foundations are installed on soils with poor load-bearing characteristics, and are also suitable for areas with high levels groundwater. Reinforcement of the foundation slab is a mandatory stage of work, performed immediately before pouring the base with concrete. Reinforcement ensures the creation of a reliable support that can withstand multidirectional loads - if pure concrete can withstand compression well, then the reinforcement helps it cope with tensile and torsional forces. Required amount The material can be approximately determined using a reinforcement calculator for a monolithic slab, but the final calculations must be made by specialists.

Pouring a reinforced slab foundation with concrete

Why is reinforcement made?

The foundation is based on concrete, which can withstand compression, but has low bending and tensile strength. When constructing a building on a concrete foundation, the load on it will be distributed unevenly - this contributes to the occurrence of bending moments. This feature very dangerous for concrete structures, therefore the installation of reinforcement or reinforcing mesh is designed to neutralize Negative influence these forces. The combination of concrete, which takes on compressive loads, with reinforcement that takes bending, will ensure the reliability of the structure.

On a note! To strengthen the structure, you will need steel reinforcement, which must be combined into a rigid frame. Reinforcing a concrete wall in this way will increase the strength characteristics of the base and increase the operational life of the building.

Foundation construction technology

The reliability of a monolithic foundation depends on the quality concrete mixture and well-executed reinforcement. Reinforcement of a slab foundation is a very responsible and complex process that is performed immediately before pouring the foundation. Completely all manufacturing work concrete base produced in the following steps:

The site is cleared and markings are made.

Dig a pit of the required size.

Form a drainage system.

Fill and compact the base with sand and gravel.

Foundation cushion made of sand and crushed stone

Lay waterproofing.

Assemble and fix the formwork.

The reinforcement cage is installed and the base is reinforced.

The structure is filled with concrete.

Current standards regulate piping schemes for monolithic foundations, which are used for the construction of various buildings. Reinforced concrete base with steel rods is a guarantee of reliability future construction. Laying reinforcement will improve the following characteristics of the foundation:

enhances the strength of the monolithic base, gives the ability to perceive increased loads;

prevents the risks of shrinkage of the building, which are associated with insufficient strength of the base;

does not allow deformation of the monolithic concrete base under the influence of negative factors high level groundwater.

Reinforcement scheme

When reinforcing a slab foundation is carried out, the layout of the reinforcement must be drawn up strictly according to the technology. In addition, reinforcement schemes for a monolithic foundation slab, if necessary, require an uneven order of placement of rods. Areas where it is planned to erect load-bearing partitions and columns are further reinforced. Such places are called squeeze zones. The reinforcement is laid in one layer with a reinforced concrete slab thickness of 15 cm or less. If the plan of a monolithic foundation assumes a layer size greater than 15 cm, it is recommended to reinforce it with frames. For a slab-pile foundation, calculations must be made separately - depending on the location and material of the piles. In any case, in order to correctly reinforce the foundation slab, the drawing must be drawn up based on careful preliminary calculations.

Basic parameters of the plate

Let's look at the main components of the structure using an example. The diagram shows a grid with constant cell sizes. The distance between the rods must be the same. When calculating the loads, the steps of the rods are made every 20-40 cm. For brick buildings, 20 cm is suitable, and for light frame houses It is allowed to lay reinforcement less frequently. In any case, according to the building rules from the paragraph about “concrete and reinforced concrete structures” it is stated that the distance between the rods should not exceed the thickness of the base by 1.5 times.

A common laying method is in two rows. Their combined action will be ensured by the installation of vertical rods. The spaces between such rods should be equal to the steps of the main steel structure twice the distance is also allowed. According to the rules, the slab at the ends should be reinforced with U-shaped clamps, the length of which should be equal to two thicknesses of the base or more. The rod binding should cover the top and bottom rows. This technique ensures reliable perception of torques at the edge of the foundation and will allow anchoring the ends of longitudinal rods.

Reinforcement at the edges and laying in two rows

It is important! The entire reinforcement structure should be buried in concrete mortar approximately 2-3 cm on all sides - bottom, top, sides. Otherwise it happens accelerated process corrosion of reinforcement, which will subsequently lead to structural damage.

Punching zones

In places where load-bearing vertical structures will rest on the foundation, the layout should be done by reducing the reinforcement steps. In the case when the reinforcement is laid every 20 cm along the main width of the slab, it means that under the partitions it is necessary to move to a distance of 10 cm. This method allows you to prevent the occurrence of punching and the formation of cracks.

If the interface zone coincides with a monolithic basement wall, the laying depth will be made in accordance with the height of the planned room. In this option, work is carried out with the base tied to the walls.

When reinforcing foundations, it is recommended to jointly tie the frames monolithic walls and slabs. When pouring the foundation, you need to leave parts of the vertical rods that will serve as connecting links. These ends are inserted into the base, the edges are bent to approximately two parts of the height of the slab, and then they are tied to the main part of the frame.

After pouring and hardening of concrete, vertical rods are used to “tie” the walls to the base

To make a competent calculation of building materials and reinforcement of a slab foundation, you will need a diagram and drawing. Data on the steps between the rows of reinforcement and its diameter must be entered.

On our website you can find contacts of construction companies that offer the service. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Which fittings are best to choose?

Steel reinforcement is manufactured in accordance with GOST 5781-82, with various types of profiles. For reinforced concrete monolithic slabs, class A400 rods are used. The rods have visual distinctive features, namely:

A 240 – a product with a smooth surface;

A 300 - has a periodic profile with a ring pattern on the surface;

And 400 - there is a crescent-shaped pattern on the herringbone profile.

Important! It is not permissible to use fittings of low categories.

Method of manufacturing reinforcing mesh and frame

There are two options for connecting rods to each other - tying and welding. When using the binding method, wire with a diameter of 2-3 mm is used. Winding occurs manually or using special equipment, which helps to make a winding around the rods. This option is labor-intensive, but will ensure reliable connections.

Video description

How to manually knit a reinforcement cage, see the video:

Ready-made welded meshes are quicker and easier to install than using the tying method. The only negative is the difficulty that arises when selecting the required size.

The welding method is used in rare cases, since the main disadvantage of this option is the rigid and immovable connection. This has a bad effect on the quality of the monolithic foundation. When welding metal elements melt, after which the strength of the reinforcing elements decreases.

Work on laying reinforcement

When laying the reinforcing structure into the formwork, everything should be calculated so that all the rods after pouring are covered with a protective concrete layer 2-3 cm. To maintain the required distance, special plastic fixing elements, metal “frogs” or “chairs” are used.

In the case where the length of the rod is shorter than the entire width of the foundation, an overlap of at least 40 diameters of the working rods is made. For example, for a rod 1.2 cm, the recommended overlap is 48 cm.

Reinforcement of a monolithic foundation in a pre-prepared pit will reduce the duration of work and will help to carry out installation directly on site without any difficulties.

The disadvantage of this installation is the risk of damage to the laid compacted cushion and waterproofing material. It is best to lay the frame in this order:

The assembled lower belt is placed on supports.

Install cross bars.

The upper part of the structure is assembled, and the racks and the upper chord are connected using wire binding.

How to calculate the diameter of reinforcement

When reinforcing a slab foundation, even using the diagrams you can make approximate calculations of the material. Total area reinforcement sections for a monolithic foundation in one direction take no less than 0.3% of the general indicators of the foundation section. If the side length of the slab is less than 3 m, a rod diameter of 1 cm is suitable, for a longer length - 1.2 cm. Vertical rods must be at least 6 cm. Maximum dimensions products 4 cm, in practical application use 1.2, 1.4, 1.6 cm.

Calculation example

The initial data indicates a reinforced concrete surface of 8x8 m. The recommended step size for private houses is 20 cm. This example does not consider strengthening the areas where load-bearing walls will be located. To determine the diameters, it should be taken into account that laying will be done in two rows. Because the thickness of the structure exceeds 15 cm.

Calculation required area metal rods are produced in the following sequence:

area calculation cross section foundation base: 8 m * 0.2 m = 1.6 m 2;

calculations of the minimum area of all reinforcing material: 1.6 m2 * 0.3% = 0.0048 m2 (36cm2);

indicators of the minimum reinforcement area, one direction, one row: 48 cm 2 /2 = 24 cm 2.

the thickness of the concrete layer intended for protection is 2-3 cm on both sides;

permissible overlap;

vertical reinforcement;

number of rods for U-shaped clamps.

Video description

You can also calculate the foundation using an online calculator. You just need to take into account that it is unknown what tolerances and formulas are hidden behind the program interface. Therefore, the reinforcement calculator for a monolithic slab can only be used for approximate calculations.

Errors when installing reinforcing structures

Even minor defects can lead to the destruction of the foundation or complicate the concreting process. Common mistakes when creating a frame and how to avoid them:

rods connected end-to-end will lead to loss of strength of the frame structure;

When installing a reinforcing frame, the rods are located in close proximity to the ground or stuck into it. When the soil moves, the reinforcement will crash into the ground and with this interaction, metal corrosion will form, and this in turn will reduce the strength of the entire foundation;

Reinforcement clamp, which is installed between the meshes

if the ends of the rods do not have a protective coating, corrosion of the products will form under the influence of moisture from the concrete mixture;

Special attention should be given correct reinforcement in the corners of the building and in areas under load-bearing wall;

the frame was installed on wooden blocks or other inappropriate elements - this is a gross mistake. Only special fasteners should be used. Otherwise, moisture will penetrate to the metal parts, which in turn will lead to a violation of the integrity of the concrete base.

Video description

For a clear overview of the production of formwork and reinforcement of a slab foundation, watch the video:

Conclusion

From correct execution The reinforcement of a slab foundation determines the strength and service life of the entire foundation of your home. Therefore, all calculations, preparatory and installation work must be carried out by professionals who will not only do everything quickly and efficiently, but also give a guarantee for their work.