Precast concrete floor slabs. Reinforced concrete floor panels

Overlappings consist of a bearing part, which transfers the load to the walls or individual supports, and an enclosing part, which includes floors and ceilings. According to the material of the bearing part, they distinguish reinforced concrete ceilings, on wooden and iron supports, also armosilicate and clay. The price of ceilings and floors in the total price of the house achieves 20% of its total price.

The main material for floor devices in modern construction is an reinforced concrete. Reinforced concrete floors divide by prefabricated and whole, concreted in formwork. AT last years used in the main prefabricated and solid ceilings.
Overlappings must meet the requirements of strength, rigidity, fire resistance, durability, sound and thermal insulation, if they separate heated rooms from unheated rooms or from the external environment. Overlappings in rooms with wet processes must be waterproof, and in rooms with the release of gases - gas-tight.

AT suburban homes with brick walls use reinforced concrete floor panels with round voids, the length of which varies from 4800 mm to 6980 mm, width from 1000 to 2400 mm, height 220 mm, also with flat voids - length 2700-4200 mm with a gradation of 300 mm, width 1200, 1500 mm, width 120 and 160 mm . Panels they are laid (Fig. 1) on a layer of freshly laid masonry mortar 10 mm wide with embedding on supports more than 120 mm. Through one panel(step 2400-3000 mm) are connected to the walls with anchors with a diameter of 8-10 mm, which are strengthened to the hinges and led into the masonry 250 mm from the end of the panel, ending with a bend at an angle of 90 ° horizontally by 380 mm.

Seams between panels fill with cement substance composition 1: 4 (by volume). Panel installation produced using cranes. Reinforced concrete floors

Such floors possess a number of valuable properties, the main of which are great strength, durability and fire resistance. When designing parts prefabricated concrete floors it is necessary to strive to enlarge them to reduce the number of assembly operations and butt mates.

Precast concrete floors

Precast concrete floors subdivided into three main groups: in the form of flooring (slabs), large-panel and beam. Overlappings in the form of floorings consist of flat or ribbed parts of the same type, laid tightly; connect them by filling the gaps with cement. Such floors consist of a bearing reinforced concrete part (usually textured from below), a sound or thermal insulation layer and a floor structure. The supports for the flooring are walls and girders. More common hollow flooring 160 mm high with gaps up to 4 m and 220 mm - with gaps over 4 m. The decks have longitudinal voids of circular cross section (Fig. 2, a).

In the manufacture of floorings with vertical voids, the consumption of concrete is reduced by up to 15% compared to round-hollow ones. Vertical round voids are formed using pipe liners (the liners are welded to the channels). decking, which can cover entire rooms, are called large panels. No connections in floor panels within the boundaries of the room increases their sound insulation and provides a higher quality ceiling finish.
To ensure standard soundproofing parameters from airborne noise, single-layer structures interfloor panel ceilings, made of heavy concrete, must have a mass exceeding 300 kgf / sq.m.

At flooring device separate type, in which the soundproofing ability of the air gap between the upper and lower floor panels of the connection is used, also when installing layered floors, it is possible to ensure the normative soundproofing ability with a floor mass of at least 300 kgf / sq.m.
By design interfloor large-panel reinforced concrete floors can be with a layered floor, separate type (with a separate floor, ceiling or from 2 separate load-bearing panels) and with a layered floor and a separate ceiling (Fig. 3). All these floor structures have a relatively small mass (less than 300 kgf / sq.m.); normative noise insulation is provided by a layered floor structure or the presence of a continuous air gap in the thickness floors.
floor panels produce solid, hollow (with round voids) and tented. The bearing single-layer panel (Fig. 4, a) is reinforced concrete slab unchanged section with a bottom surface ready for coloring, and a flat top.

solid single layer reinforced concrete panels 140 mm wide cover gaps up to 3.6 m. To cover huge spans (6-6.6 m), they mainly use solid single-layer for previously stressed reinforced concrete panels 14-16 cm wide or expanded clay-reinforced concrete 18 cm wide.

hipped panel(Fig. 4, b) has the form of a slab framed along the contour with ribs facing downwards in the form of a cornice. satisfied interfloor floors and from flat reinforced concrete panels 14-16 cm wide.

Ceilings on reinforced concrete supports

Prefabricated reinforced concrete floors(Fig. 5) beam type consist of T-beams and filling between them. The filler here is a roll of gypsum concrete or lightweight concrete slabs 80 wide and 395 mm long, reinforced with wooden slatted or bar frames, and in attic floors - easily concrete plates 90 wide and 395 mm long, reinforced with welded iron meshes. The seams between the supports and slabs are filled with cement and rubbed. Attic and basement floors certainly insulate, interfloor soundproof. To do this, use expanded clay or sand bedding, layered coatings with elastic gaskets. With all this, it is better that heat and sound insulation be carried out not due to an increase in the weight of the building structures.
Because the elements beam floors have a relatively small weight, they are used on buildings equipped with low-capacity cranes (up to 1 ton).
At installation of reinforced concrete floors and in sanitary facilities, a waterproofing layer is included in the floor structure. To do this, over decking or panels are usually glued to bituminous mastic 1-2 layers of roofing material.

Solid ceilings

Solid ceilings make according to the established formwork. Transferring loads from the floor to load-bearing walls, solid ceilings serve as an additional rigid frame of the structure. Their device requires a certain professional skill and should be done according to the project under the guidance of a specialist builder. fabrication floors locally has its own merits. With all this, special transport and lifting equipment are not required. Small-scale mechanization is sufficient for lifting and moving concrete. To base solid floors laid down Monier plate, in which the reinforcement is located in places of tension, in other words, at the bottom of the slab. This is justified by the fact that steel has 15 times greater tensile strength than concrete. The reinforcing frame of the slab should be placed at a distance of more than 3-5 cm from the formwork walls so that concrete can fill this place. The length of the gap covered solid slabs, should not exceed 3 m. For plumbing pipelines, special iron or vinyl sleeves with an inner diameter larger than the pipeline being laid are installed in the ceiling. The gap between the sleeve and the pipeline is minted with tarred tow.

To the shortcomings solid floors we can attribute the need to install wood formwork virtually throughout the entire area of ​​​​the house. But, this does not mean that the formwork must be exposed all at once. overlap can be made in separate gaps, transferring the formwork as the concrete sets.
Load bearing capacity solid floors provided with reinforcement, the diameter of which must be at least 8-12 mm. With all this, intermediate connections of the rods along the entire length of the floor are undesirable. A small layer of concrete on the outer side of the ceiling should be more than 2 cm. It is necessary to concrete the gap in one working cycle.

Catalog of articles "Building walls" >>

Design characteristics

Ceilings consist of a bearing part, which transfers the load to individual supports or walls, and an enclosing part, which includes ceilings and floors. According to the material of the bearing part, it is possible to distinguish reinforced concrete (reinforced concrete) floors, for steel and wooden beams, ceramic and armosilicate. The cost of floors and ceilings will reach 20% of the total cost of the house. The consumption of reinforced concrete for the ceiling will be up to 60% of the total consumption.

It should be understood that the cost of overlapping should be minimal.

In modern construction, the main material for the construction of floors is reinforced concrete. from reinforced concrete (reinforced concrete) can be divided into monolithic and prefabricated, concreted in the formwork. Recently, only monolithic reinforced concrete floors and prefabricated ones have been used for the first floor. Prefabricated allow you to block the span up to 12 m. Speaking about which one is needed, you should know that the consumption of this mortar per 1 m² will be 0.223 m³, and steel - 6.5 kg. This cost is approximate and may vary slightly.

It is worth knowing that floors must necessarily meet the requirements of rigidity, strength, fire resistance, durability, sound and heat insulation, if they separate heated rooms from the outside environment or from unheated rooms. Ceilings in rooms in which wet processes will take place must be waterproof, and in rooms in which gases are released, gas-tight.

AT country houses with brick walls, most often people prefer precast concrete floors with round voids. Their length is from 4800 to 6980 mm, width - from 1000 to 2400 mm, and height - 220 mm. Structures with flat voids 2700-4200 mm long with a gradation of 300 mm, 1200-1500 mm wide, 120 and 160 mm thick are also used.

Panels for the ground floor should be laid on a layer of freshly laid masonry mortar 10 mm thick, embedded on the support at least 120 mm. With a step of 2400-3000 mm, they are connected through one panel with anchors with a diameter of 8-10 mm. The anchors are attached to the hinges and driven into the masonry 250 mm from the end of the panel. It is necessary to finish with a bend at an angle of 90 degrees horizontally by 380 mm.

Seams between panels are filled cement mortar. Speaking about what composition should be, it is worth knowing that it is 1: 4 by volume. Installation of panels is carried out with the help of truck cranes.

Reinforced concrete floor installation

Similar designs for the first floor have some valuable qualities. The main ones are durability, high strength and fire resistance. To reduce the number of butt mates and assembly operations, when designing the structures of elements of prefabricated reinforced concrete (reinforced concrete) floors, it will be necessary to strive to enlarge them.

Next, we will talk about precast concrete floors. It is divided into 3 main groups: beam, large-panel and in the form of flooring (slabs). The structures in the form of decks will consist of flat or ribbed elements of the same type, which are stacked closely. Speaking about which connection method to use here, it is worth knowing that you need to fill the gaps with cement mortar.

Similar structures for the ground floor consist of a reinforced concrete bearing part, a thermal and sound insulation layer and a floor structure. The walls and girders will serve as supports for the decks. The most common are hollow flooring, having a height of 160 mm if there is a span of up to 4 m, and 220 mm if there is a span of more than 4 m.

In the process of manufacturing floorings with vertical voids, the consumption of concrete will be 15% less than with round-hollow floorings. Round vertical voids are formed using pipe liners (the liners are welded to the channels). Floorings that can cover entire rooms are called large panels. In this case, the cost will be less. The absence of joints in the panels within the rooms will increase their sound insulation and provide a higher quality ceiling finish.

In order to provide standard soundproofing properties from airborne noise, single-layer structures of panel ceilings on the first floor, which are made of heavy concrete, must necessarily have a mass that exceeds 300 kgf per 1 m².

During the installation of separate type ceilings, in which the soundproofing ability of the air gap between the lower and upper panels of the precast concrete floor is used, and when installing layered ceilings, it will be possible to ensure the soundproofing normative ability with a floor weight of less than 300 kgf per 1 m².

Interfloor large-panel reinforced concrete (reinforced concrete) ceilings by design can be with a layered floor, with a layered floor and a separate ceiling, of a separate type (from two separate load-bearing panels, with a separate ceiling or with a separate floor). All of the above floor structures have a relatively small mass (less than 300 kgf per 1 m²). Normative sound insulation can be provided by a layered floor structure or by the presence of a continuous air layer in the thickness.

Floor panels for the first floor are made solid, hollow (having round voids) and tented. A single-layer load-bearing panel is a reinforced concrete slab with a lower surface of constant cross-section, which is ready for painting, and a flat upper surface.

Single-layer solid reinforced concrete (reinforced concrete) panels, which have a thickness of 140 mm, can cover a span of up to 3.6 m. 16 cm, or expanded clay-reinforced concrete, which have a thickness of 18 cm.

The hipped panel has the form of a slab, which is framed along the contour with ribs facing in the form of a cornice. they are also arranged from flat reinforced concrete panels having a thickness of 14-16 cm. The type of overlap will depend on which span should be blocked. The maximum span is 12 m.

Installation of a beam structure

Interfloor prefabricated reinforced concrete structures beam type consist of T-beams and filling between the beams. The filler in this case will be a roll of lightweight concrete and gypsum concrete slabs, having a thickness of 80 mm and a length of 395 mm, reinforced with slatted wooden or bar frames. In the attic floors - lightweight concrete slabs, which have a thickness of 90 mm and a length of 95 mm, reinforced with welded steel mesh.

Seams in slabs and beams are filled with cement mortar and rubbed. Ground and attic floors it is imperative to insulate, and interfloor - soundproof. To do this, sand or expanded clay bedding, a layered coating with an elastic gasket should be used in the slabs.

It is recommended that sound and heat insulation in slabs be carried out not by increasing the weight of building structures. Due to the fact that the elements of beam structures have a relatively light weight, they are often used in buildings that are equipped with low-capacity cranes (about 1 t).

In the process of installing reinforced concrete beam floors in sanitary facilities, a waterproofing layer should be included in the slabs. For this, 1-2 layers of roofing material on bituminous mastic are most often glued over the flooring or panels for this. Beam ceilings are used if it is necessary to cover a span of 3-7.5 m.

Installation of monolithic buildings

Monolithic structures are made according to pre-installed formwork. Such ceilings on slabs will serve as an additional rigid frame of the building in the process of transferring the load to the load-bearing walls from the floor. Their device requires a certain professional skill. It must be carried out according to the project under the guidance of a specialist builder.

Manufacturing such structures in situ has some advantages. To do this, you do not need to have special transport or any lifting equipment. To move and raise concrete, it is enough to have small-scale mechanization.

The basis of monolithic structures is laid in Monier slabs. In it, the reinforcement is placed in places of tension, meaning the lower part of the slab. This is due to the fact that steel has a tensile strength 15 times greater than concrete. The reinforcing frame of the slab should be located at a distance from the formwork walls at a minimum distance of 3-5 cm. This is necessary so that the concrete can fill this space.

The span, which is covered with a monolithic slab, should have a maximum length of 3 m. For plumbing pipelines, care should be taken to install metal or vinyl sleeves that have inner diameter more than the pipeline being laid. The gap of the pipeline and metal sleeves must be minted with tarred tow.

The disadvantage of such monolithic structures is the installation of wooden formwork over almost the entire area of ​​\u200b\u200bthe house. However, this does not mean at all that it is necessary to expose the formwork all at once. Overlapping can be performed in separate spans, while transferring the formwork as the concrete sets.

The bearing capacity will be provided with the help of reinforcement. Intermediate joints of the rods along the entire length are undesirable. On the outer side of the ceiling, the minimum layer of concrete must be at least 2 cm. The span must be concreted in one working cycle.

Formwork installation

For the installation of a monolithic reinforced concrete floor, it will be necessary to install a horizontal removable formwork.

Such formwork can be made of wooden boards (from cut boards that have a thickness of 25-35 mm) or waterproof plywood that has a thickness of at least 20 mm. If the formwork panels, which are made of boards, have gaps, a layer of waterproofing film is needed over the formwork. It will be needed so that the liquid solution cannot flow out.

Removable formwork should be laid on transom beams, which will be supported by supporting vertical posts. Racks can be telescopic, made independently from round timber with a diameter of 8-15 mm and beams, or factory-made.

The formwork must be installed without gaps, strictly horizontally. Steel reinforcement in the form of a mesh with cells measuring 200x200 mm is laid and tied with a soft knitting wire along a horizontal structure.

Rebar frame

The reinforcement on the formwork is laid in such a way that a gap of at least 25 mm remains between it and the formwork. To do this, use standard special plastic coasters or make them yourself from wood, plywood or other material. What material to choose is up to everyone. Any of the above will be needed.

Comments:

Floor panels are the main part of any building. They include load-bearing elements that load the walls, or individual supporting elements. According to the material of the bearing element, reinforced concrete structures are distinguished. The price of floors is 20% of the total cost of the building.

The composition of the floor panels contains load-bearing elements that exert a load on the walls.

Reinforced concrete floors - the main panels in the construction business

Currently, potential developers prefer to take panels made of reinforced concrete material. In turn, they are divided into:

1. Prefabricated.
2. Monolithic.

Panels must have characteristics such as strength, rigidity, fire resistance, reliability, and quick installation properties. If a building is being built where high humidity is implied during operation, then the floor panels must be resistant to moisture. In country houses, you can often find the use of these structures made of reinforced concrete panels with the presence of round voids. Basically, their length can reach up to 6800 mm, and their width - up to 2400 mm.

Reinforced concrete structures have a huge number of advantages. They have high strength, long operational period and most importantly, they are fire resistant. When creating a project for the construction of a house or any other building, potential developers try to enlarge them in order to reduce the number of installation actions and butt contacts. Prefabricated type reinforced concrete floors are divided into 3 main classes:

1. In the form of flooring (tiled form).
2. Large-panel.
3. Beam.

Deck-shaped structures have flat or ribbed components of the same type in their composition, which must be mounted tightly. Their connection is carried out by means of a special cement mortar. Consequently, they include load-bearing reinforced concrete parts, which have high rates of thermal insulation and sound insulation.

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Interfloor large-panel reinforced concrete structures

According to the design features, interfloor large-panel structures made of reinforced concrete may have a layered floor. They are lightweight, soundproofing abilities are carried out using a special layered floor structure or the presence of a continuous air gap in the thickness of the ceiling. The floor panels themselves can be solid, hollow and hipped. The hipped panel is a special type of slab, which is framed along the contour with ribs. The ribs are always directed downward.

As for the attic and basement panels, they are necessarily insulated, and the interfloor ones are soundproofed. Therefore, expanded clay or sand bedding, layered coatings with the presence of elastic gaskets are used for these actions. It should be borne in mind that the increase in sound and heat insulation characteristics should be carried out by increasing the mass of building structures. Since the components of beam floors have a low mass, they are used on construction sites. If reinforced concrete floor panels are involved in the construction sanitary facilities or in rooms with high humidity, it is necessary to apply a waterproofing layer.

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What are monolithic panels?

Monolithic ceilings are mounted on the installed formwork. Installation of monolithic floor panels is not easy. They transfer the load from the floor to the existing load-bearing walls. They are also able to be an additional rigid frame of any structure. Their device involves working only with a professional who has the skills and experience with these structures. Compared to other panels, monolithic have several advantages:

1. There is no need to use special equipment for loading and lifting.
2. It is enough to use small mechanization.
3. High tensile strength.
4. Long operating period.
5. Robust design that can withstand heavy loads.

Looking at the piles of reinforced concrete slabs, an ordinary citizen does not suspect how much important information they can inform a specialist builder. This is not surprising, because in Everyday life we rarely see such structures.

If we are talking about a new building, then the customer installation work it will be useful to know what types and sizes of floor slabs exist, as well as what is their maximum bearing capacity according to GOST.

At first glance, the differences between hollow core slabs are only in their length, thickness and width. However, specifications These structures are much more extensive, so we will consider them in more detail.

State standard - a set of laws of strength

All basic requirements for hollow core slabs, including their purpose and strength characteristics, describes GOST 9561-91.

First of all, it indicates the gradation of the plates depending on their thickness, the diameter of the holes and the number of sides with which they rest on the walls.

In addition to different thicknesses and geometric dimensions, hollow core slabs are classified according to the method of reinforcement. GOST specifies that panels that rest on walls on 2 or 3 sides must be made using prestressed reinforcement.

The practical conclusion that follows from this for the developer is that it is impossible to punch holes for engineering communications, violating the integrity of the working fittings. Otherwise, the slab may lose its bearing capacity (crack under load or collapse).

Paragraph 1.2.7 of GOST 9561-91 makes important exceptions, allowing the manufacture of certain types of plates not to put prestressing reinforcement in them.

They belong to the following panels:

• 220 mm thick with a length of 4780 mm (voids with a diameter of 140 and 159 mm);
• Thickness 260mm, length less than 5680mm;
• Thickness 220 mm, any length (voids with a diameter of 127 mm).

If you were brought to the facility such reinforced concrete slabs ceilings, and their passport indicates non-tensioned reinforcement, do not rush to send the car back to the factory. These designs comply with building codes.

Features of manufacturing technology

Floor slabs are made different ways, which affects the quality of their front surface. Plates of PK and PG grades are cast in formwork, and PB panels are made in a continuous way on a conveyor line. The latest technology is more perfect than formwork manufacturing, so the surface of PB boards is more even and smooth than that of PK and PG boards.

In addition, conveyor production allows you to make PB slabs of any length (from 1.8 to 9 meters). This is very convenient for the customer when it comes to the so-called "additional" slabs.

The fact is that when laying out plates on a building plan, several sections are always formed where standard panels do not fit. Builders get out of the situation by filling such "white spots" with monolithic concrete right on the site. The quality is homemade design noticeably inferior to that achieved in the factory (vibration compaction and steaming of concrete).

The advantage of PK and PG boards over PB panels is that it is possible to punch holes in them for communications without fear of destruction of the structure. The reason is that their void diameter is at least 114 mm, which allows you to freely pass sewer riser(diameter 80 or 100 mm).

For PB plates, the holes are narrower (60 mm). Therefore, here, in order to skip the riser, it is necessary to cut the rib, weakening the structure. Experts say that such a procedure is unacceptable only for high-rise construction. When erecting low-rise housing, punching holes in PB slabs is allowed.

Advantages of hollow reinforced concrete slabs

There are many of them and they are all quite significant:

• Reducing the weight of building structures;
• The voids in the slabs dampen vibrations, therefore, such an overlap has good sound insulation;
• The possibility of laying communications inside the voids;
• Fire resistance and moisture resistance;
• High speed of installation work;
• Durability of the building.

Dimensions of hollow core slabs

Here, everything is unified to the maximum so that it is possible to manufacture a structure of any mounting size. The gradation of the width and length of the plates comes in increments of 100 to 500 mm.

Marking - floor slab passport

The developer does not need to know the intricacies of the technology used to manufacture a multi-hollow slab. It is enough to learn how to correctly decipher the marking.

It is performed in accordance with GOST 23009. The slab brand includes three alphanumeric groups separated by hyphens.

The first group contains data on the panel type, its length and width in decimeters (rounded to the nearest whole number).

The second group says:

• The bearing capacity of the slab or the design load (kilopascals or kilogram-force per 1 m2);
• For prestressed slabs, the class of reinforcing steel is indicated;
• Type of concrete (L - light, C - silicate, heavy concrete is not indicated in the marking).

The third group in the marking contains additional characteristics that reflect the special conditions for the use of structures (resistance to aggressive gases, seismic effects, etc.). In addition, here it is sometimes denoted design features plates (availability of additional embedded parts).

As an example explaining the principle of marking hollow core panels, consider the following design:

Hollow panel type 1PK, length 6280 mm, width 1490 mm, designed for a load of 6 kPa (600 kg / m2) and made of lightweight concrete using prestressing reinforcement class At-V).

Its marking will look like this: 1PK63.15-6AtVL. Here we see only two groups of characters.

If the slab is made of heavy concrete and is intended for use in a seismically hazardous area (seismicity up to 7 points), then the third group of symbols appears in its designation: 1PK 63.15-6АтV-С7.

The considered technical characteristics of floor slabs determine the scope of their application.

All types of multi-hollow panels are calculated based on the normative floor load - 150 kg / m2 (weight of people, equipment and furniture).

Load bearing capacity standard plate is in the range from 600 to 1000 kg/m2. Comparing the standard of 150 kg/m2 with the actual strength of the panels, it is easy to see that their safety margin is very high. Therefore, they can be laid in all types of residential, industrial and public buildings.

Plate type	Reduced plate thickness, meters	Average density of concrete slab, kg/m3	Plate length, meters	Building characteristics
1PC,1PCT, 1PCC			up to 7.2 inclusive	Residential buildings (sound insulation of premises is provided by the installation of floating, hollow, hollow or layered floors, as well as single-layer floors on a screed
1pc
2PCS, 2PCT, 2PCC				Residential buildings in which the sound insulation of residential premises is provided by the installation of single-layer floors
3PCS, 3PCT, 3PCC
4pcs				Public and industrial buildings
5pcs
6pcs
PG
7pcs				Residential buildings (low-rise and estate type)

This table contains the given thickness of the slab - a term not understood by beginners. This is not the geometric thickness of the panel, but a special parameter created to evaluate the cost-effectiveness of the panels. It is obtained by dividing the volume of concrete laid in the slab by its surface area.

Estimated prices

Dozens of standard sizes are used in construction hollow core slabs, so a detailed description of their prices would have to devote a separate article. We will indicate the price parameters of the most "running" panels (self-delivery):

• PK 30.12-8 - from 4,800 rubles / unit;
• PK 30.15-8 - from 5,500 rubles / unit;
• PK 40.15-8 - from 7,600 rubles / unit;
• PK 48.12-8 - from 7,000 rubles / unit;
• PK 51.15-8 - from 9,500 rubles / unit;
• PK 54.15-8 - from 9,900 rubles / unit;
• PK 60.12-8 - from 8,200 rubles / unit;
• PK 60.15-8 - from 10,600 rubles / unit;

Installation of hollow core slabs

The main condition for the high-quality installation of panels is strict observance of the calculated parameters of support on the walls. Insufficient support area leads to the destruction of the wall material, and excessive - to increased heat loss through cold concrete.

Installation of floor slabs must be carried out taking into account the minimum allowable support depth:

• on a brick - 90 mm;
• for foam concrete and aerated concrete blocks- 150 mm;
• on steel structures - 70 mm;
• for reinforced concrete - 75 mm;

The maximum depth of embedding slabs into walls should not exceed 160 mm (brick and light blocks) and 120 mm (concrete and reinforced concrete).

Before installation, each slab must be filled with voids (with lightweight concrete to a depth of at least 12 cm). Laying the panel "dry" is prohibited. For uniform load transfer on the walls, a mortar “bed” with a thickness of no more than 2 cm is spread before laying.

In addition to observing the standard support depths, when installing floor slabs on fragile blocks of their gas or foam concrete, a monolithic reinforced concrete belt should be laid under them. It eliminates the punching of blocks, but requires good external insulation to eliminate cold bridges.

During the installation process, the deviation of the difference in the marks of the front surfaces of adjacent panels should be constantly monitored. You need to do this in the seams. Don't listen to the builders who put the panels in "steps" and tell you that it's impossible to lay them evenly.

Building codes establish the following tolerances depending on the length of the slabs:

• up to 4 meters - no more than 8 mm;
• from 4 to 8 meters - no more than 10 mm;
• from 8 to 16 m - no more than 12 mm.

Ceiling structures must meet the requirements for strength, fire resistance, sound insulation and thermal insulation. All these characteristics are possessed by reinforced concrete slab type. They are used in the construction of industrial, multi-apartment and individual buildings.

They serve as intermediate floors, where their lower surface acts as a ceiling, and the upper floor of the upper room. Also, the slabs are laid on garages, sheds and other buildings for household purposes, thus forming a roof. Often they are used as a foundation.

Types of floor slabs

There are 2 types: monolithic slabs ceilings and voids. The first are distinguished by a large margin of safety and bearing capacity. Among the serious drawbacks are their weight, high thermal conductivity and low soundproofing properties. Such products are often used for the construction of public and industrial buildings.

Floor slabs photo

• Hollow concrete products are used in the construction of private houses due to their cheaper cost and light weight compared to monolithic counterparts. This factor, of course, does not allow you to do without special equipment for the delivery of a PC to the site and installation, but, nevertheless, it makes it possible to significantly reduce the load on the load-bearing walls and foundation. And as a result, reduce the cost of their arrangement, using a smaller amount of building material.
• The voids that run along the entire length of the concrete product can be round, oval and polygonal in shape. They can be used when laying communications using cable channels, plastic boxes or corrugated pipes.

Hollow core slabs guarantee:

• good heat and sound insulation qualities;
• fire resistance;
• load distribution on load-bearing walls;
• high mechanical strength;
• durability.

Thanks to the smooth surfaces of the plates, all further Finishing work will pass with not only minimum investment funds for leveling the ceiling (floor), but also with less labor.

floor slab dimensions

• Floor slabs are produced in lengths from 1880 to 6280 mm in increments of 100 mm.
• The thickness of the floor slab is 220 mm. The standard product width is 990, 1190 or 1490 mm, although you can find plates with other sizes.
• The weight of the floor slab is determined by its dimensions, approximately this indicator varies from 500 to 1500 kg. Concerning bearing capacity units of the product, then on average it is 800 kg per 1 sq.m.

What you need to know before buying a PC

• The presence of traces of rust and grease on the surfaces of the product is not allowed.

• The maximum allowable cracks are 0.1 mm, but their complete absence is better.
• All edges of the slabs must have a maximum flat surfaces without bulges and depressions.
• Permissible deviation from the nominal value in length - 10 mm, thickness - 5 mm, width - 5 mm.
• The product must have the appropriate quality certificates.

Before you start laying floor slabs, you need to know that:

• the rough side of the plate should be facing up, and the smooth side down;
• fitting of products is carried out on their lower sides;
• Reinforced concrete products should rest on 2 short sides, the long side is not recommended to be placed on the wall;
• you will need components for a sand-cement mortar;
• laying of plates is carried out close to each other without gaps;
• crane services are hourly, so everything necessary is prepared for his arrival so that the work goes without a hitch;
• slabs should rest only on load-bearing walls, the rest internal partitions(walls) are erected after the installation of the ceiling;
• for a well-coordinated installation to help the crane, you will need at least 2, and preferably 3 people;

• before rough finishing, the voids of the slabs are filled with crushed stone or expanded clay.

Preparing walls before installing floor slabs

• Bearing walls are leveled. They should be as even as possible in height, the allowable difference is a maximum of 10 mm. You can identify the difference in heights by means of a long beam, which is placed on two opposite walls. Placed on top of the beam building level, and the longer it is, the more accurate the result.
• Thus, all supports under the floor slabs are checked. It is important to take measurements as often as possible. To do this, a beam or bar is installed in the corners of the building, then moves every 1-1.5 m. The relevant data can be written on the walls with chalk or a marker.
• Next is the highest and low point and laid out concrete mix using a cellular metal mesh. Supports erected from foam concrete, slag, gas silicate blocks are necessarily reinforced. This can be done by means of a reinforcing belt with a height of at least 15 cm.
• Armopoyas evenly distributes the load, prevents deformation of the walls and protects the floor slabs from breaking.

• The formwork is assembled from the most even boards in accordance with the values ​​obtained, that is, the edges may have various meanings in height. You can use a special U-shaped profile. The structure is arranged around the entire perimeter of the house box, including non-load-bearing walls, especially if the building is made of lightweight block materials.
• To knead the sand-cement mortar, 1 bucket of cement (M500) and 3 buckets of sand are taken, so much water is needed so that the mixture is neither liquid nor thick. Sand must be sifted to remove pebbles, which will contribute to the destruction of the layer under the weight of the slab.
• After pouring, the solution is pierced with a trowel or piece of reinforcement to prevent the formation of air gaps. Rammer should be given increased attention.

• Before laying floor slabs, voids must be sealed to prevent freezing. If the concrete products have been stored at the construction site for a long time, then it is recommended to drill one or two holes in the areas where the voids pass, through which excess moisture will escape. It should be noted that the holes are sealed with concrete mortar, and during installation, the slab should be facing down.
• Factory voids are filled with expanded clay or large pieces of one and a half bricks are simply inserted, and the remaining gaps are closed with cement mortar. Although recently factories have been producing slabs with closed voids.
• The mixture in the formwork should dry well, gain strength, this will take at least 3 weeks.

Crane platform

• The soil where the lifting equipment will stand must be compacted. It is impossible to install a crane near a house under construction in the presence of a basement. The supporting "leg" of the special equipment creates a very significant load on the ground, which can lead to the collapse of the basement wall.
• For loose or bulk soils, it is recommended to order a crane with a longer boom. If the work is carried out in spring or autumn, when the soil is saturated with moisture, the platform for the truck crane is laid out with road slabs (used products can be used). Because technology can get bogged down in slush under its own weight.

Slab lining

• It is not recommended to cover two spans with one slab. Such a load under certain circumstances can lead to its cracking. If just such a laying scheme was chosen, then in this case it is recommended to make an incision with a grinder with a diamond disk (to its depth) exactly in the center of the middle wall.
• If a crack nevertheless occurs, then it will go exactly in the direction of the notch, which is quite acceptable.
• Unfortunately, it is not always possible to complete the overlap with whole slabs. Sometimes they have to be lined both in width and in length. Here you need a sledgehammer, a grinder with a diamond disc, a crowbar and muscle strength.

• To facilitate the process, use a beam or board of the appropriate length. Lumber is placed under the slab strictly along the line of the future cut. At some point, the concrete product will break under its own weight.
• First, a grinder is cut on the upper surface of the plate along the marked line. Further, by means of a sledgehammer, blows are applied along the entire length of the concrete goods. Hits should be applied as often as possible. If the cut falls on a hollow hole, then the plate will break pretty quickly.
• When cutting the slab in width, considerable effort will have to be applied. The fittings that come across are cut off with a welding machine or a cutter. It is not recommended to use a grinder, as the disc may “bite”. But if only this tool is available, then do not cut the metal rod to the end - leave 2-3 mm. Perform the final break with a crowbar or sledgehammer.

Carrying out the cutting of the slab, all possible consequences fall on your shoulders! No manufacturer will give official permission to carry out these works.

• If there are not enough whole slabs for a complete overlap, and the remaining space is small, then you can avoid the laborious cutting process using the two methods listed below:
• The last or first slab does not adjoin the wall in length. The formed void between the slab and the supporting wall is laid with bricks or blocks. Cement strainer, performed upon completion of construction, will reliably unite and fasten the masonry with the slab.
• This method is good if the existing concrete panels are laid butt-to-butt, and the remaining distance is distributed between the two supporting walls and filled in as described.

• It should be remembered that if the empty opening is more than 30 cm, then when pouring the screed, reinforcement is performed in this area.
• The plates are mounted close to the walls, and the empty gap remains between the plates themselves. Thick moisture-resistant plywood is attached to the lower surfaces of the reinforced concrete products, reinforcement must be laid with a call to the upper surfaces of the plates.
• Thus, something will turn out in the form of a formwork, which is poured with concrete mortar. After complete drying, the plywood is dismantled, and a general screed is made over the boards.

Installation of floor slabs

• For work you will need a crane and at least 4 people (crane operator, slinger and 2 assistants). A prepared concrete solution with a thickness of not more than 20 mm is laid out on the bearing supports with a reinforcing belt. The plate rises in a horizontal position at the desired height. All actions, namely the movement and direction of the load, are carried out under the guidance of the slinger.

Installers accept the floor slab, adjust the optimal location. Before the slings are removed by means of crowbars, the concrete panel is guided to the installation site with maximum accuracy:

• from the slab to the wall along the long side, a minimum distance of 50 mm is left;
• there should be no gap between the plates;
• the width of the support on each short side of the boards must be at least 150 mm.

Inspection of concrete floor slabs

• After installation of the ceiling, the evenness of the surfaces of adjacent plates is checked by level. If the height difference is more than 4 mm, then the plates are reinstalled. The concrete products are lifted again by a crane, and, in accordance with the situation, the solution is removed or added.
• It is impossible to dilute the seized concrete layer with water, the solidified mixture is completely removed, and a freshly mixed one is applied in its place. As soon as the leveling is completed, they proceed to fixing the plates between themselves and to the load-bearing walls.

Anchoring of reinforced concrete floor slabs

Upon completion of the installation work and after the leveling of the plates has been carried out, they are anchored. If there is a project, then a special scheme should be present in the documents. Otherwise, anchoring is done as follows:

• anchor loops are mounted to the load-bearing walls and go onto the floor slabs by about 40-50 cm. As a rule, two fasteners are enough for the entire length of the panel (they are located a meter from the edge of the slabs). In the same way, one anchor is set in width;

• if the docking of the plates occurs along their short side, then these sections are fixed diagonally using working holes with reinforcement located in them. In their absence, you can use special fasteners with L- and U-shaped forms;
• between themselves, concrete slabs are fastened at the points of the mounting holes. Metal rods must be stretched as much as possible and fixed by welding, at least at three points.
• After that, the eyes and seams between the slabs are filled with fine crushed stone, and then sealed with sand-cement mortar. It is not worth delaying with these works, as construction debris can get into the holes.

Features of the technology of installation of floor slabs

• Hollow core slabs are widely used in the construction of low-rise and individual buildings. Although they are smaller and lighter than their monolithic counterparts, they nevertheless require thickened walls and reinforced foundations. In addition, they will not be able to block buildings that are complex in architecture.
• But, despite these shortcomings, the plates provide a reliable overlap, characterized by a long service life. Their use is justified in cases where the plates become the basis for flooring. roofing material, that is, they act as a flat roof.

Floor slabs video

When preparing and installing floor slabs, it is important to take into account many technical issues, which means that you need to have certain knowledge and skills. If you are unsure of the calculations, contact a specialized organization where they will draw up a project in accordance with all the requirements of SNiP.