Floor slabs for industrial buildings: GOST, types, sizes, installation

Monolithic ones are one of the most reliable building surfaces.
Made using reinforcement and high grades of concrete, they have strength, density, frost resistance, resistance to mechanical and atmospheric influences, and can last for many decades.

Monolithic concrete floors are often used where lifting equipment cannot travel to transport reinforced concrete slabs, and where horizontal structures (spans) for interfloor, attic, basement and staircase spaces are non-standard.

How monoliths are constructed, what are the regulatory requirements and technical characteristics for them, the creation process, advantages, reinforcement and other nuances, we suggest you learn from this article.

Description of solid structure

A monolithic floor is a slab of arbitrary dimensions, determined by the adopted design, and manufactured directly at the construction site. The monolith has a rectangular or square shape . It consists of a concrete composition poured onto reinforced strong rods of strong grade steel, laid and welded in the form of a mesh.

To obtain a monolith, a formwork form is installed on the marked area of ​​the building, into which reinforcement is laid, and then the concrete mixture is poured and compacted on top, leaving it until it hardens (dries) completely.

The resulting floor slab must have a thickness of at least 8 (cm), according to standards 12-20 (cm), and rest on structural (load-bearing walls). The formwork to create a monolith is formed from wood, plywood, and auxiliary beams made of non-corroded metal. Sometimes racks are used for floors, and the reinforcement frame can be composed of a lower layer, as well as a supporting one.

The resulting horizontal structure
is suitable for all types of residential and industrial buildings .
The strength, rigidity and density of the surface evenly distributes the load. The monolith is immune to vibrations and mechanical stress, which makes it indispensable in seismically active regions. Concrete surfaces repel water well and are not self-igniting or fire hazardous. It is convenient to work with the monolith, and with the help of construction tools to arrange various communications. The types of cement used for concrete are M300, 400, 500, crushed stone, sand and water.

The thickness of the concrete floor is 200 (mm) using 12 (mm) rods welded together into a mesh with cells 200 x 200 (mm). The load standards that a monolithic surface can accept are 150 kg/m2.

Monolithic floors are considered necessary building elements in the construction of complex architectural structures, with special parameters and special configuration parameters. In addition, they are ideal for foundations, roofing and spans between floors.

Destination

In the construction of low-rise private houses, multi-story buildings, and industrial facilities, the following slabs are used:

• floors;
• fundamental;
• wall (external and internal).

They form the basis of buildings. During the construction of roads not only for ground transport, but also for air transport. The plane puts a lot of load on the runway, and a concrete slab can handle it. In this case, the following types of coatings are used:

• road;
• sidewalks.

Road ones are constantly being improved. They perfectly solve problems when efficiency and reliability are needed. When constructing reinforced concrete fences, you cannot do without concrete slabs. Although they are not so in demand.

Return to contents

Types and types of such reinforced concrete floors

There are several types of reinforced concrete structures. Each presented type has its own purpose, and its creation completely depends on the developed project. Varieties of monolithic floors are divided into the following groups.

According to the method of support

There are such varieties:

• 2 sides - on two opposite parallel load-bearing walls, capable of withstanding external loads of up to 800 kg/m2;
• 3 sides - with the help of end reinforcement they are laid on three structural walls, with a load rating of 1600 kg/m2;
• 4 sides are structures reinforced with reinforcement, which are used only for multi-story construction, and have the highest strength (cement M500, 700), with loads from 2400 kg/m2.

By establishment depth in mm

Types of floors according to the depth of the establishment:

• 40 – contour, 2 long, 1 short side;
• 50 – 2 sides, span up to 4.2 (m), 2 short, 1 long sides;
• 70 – 2 sides, with a span of more than 4.2 (m).

By typical features

There are the following types:

• ribbed - in cross section they resemble the letter “H”, have upper or lower ribs;
• beamless - solid structures that can rest on any side, depending on the project;
• beam - have auxiliary, main or intersecting beams, which are formed together with the ceiling, thanks to the special formwork shape.

There are also such types of monolithic slabs as:

1. classic (full-bodied);
2. caisson (for the basement foundation);
3. Swedish (insulated with waterproofing);
4. on a profiled sheet (using permanent formwork in the form of a profiled sheet);
5. cup-shaped (regular or inverted).

The maximum support depth of a monolithic slab should not be more than 150 (mm).

Calculation of a monolithic ribbed floor

The structure is calculated using special programs, with the initial data being shear forces, bending and torque moments. Snow and seismic loads must be taken into account. A graphic model of the floor is drawn up, the dimensions of the ribbed floor slab, the area of ​​the reinforcement, and the dimensions of the spans are calculated. Based on the calculation results, products with the required parameters are selected.

Ribbed ceilings. Technical characteristics and markings

Now reinforced concrete plants produce slabs from various types of concrete: structural light, heavy, dense silicate. Overall and connecting dimensions of building floors, their shape meet the requirements of GOST 28042-89. According to it, reinforced concrete ribbed prestressed slabs have dimensions of 3x12, 3x6, 3x18, 1.5x6, 1.5x12 m. The following types of floors with prestressed reinforcement are produced:

• with a flat top plate - PG (without holes), PV (with holes for ventilation devices), PF and PS (with holes for various types of lanterns), PL (with openings for an easily removable roof);
• shell slabs with a vaulted surface - POV, POF, POS, POL (have the same design features as the first type).

The marking includes:

• alphanumeric designation of standard size;
• load-bearing capacity (determined by the maximum permissible load);
• class of reinforcement, type of concrete, design features (dimensions and location of holes, presence of embedded parts);
• additional qualities (for example, earthquake resistance).

Reinforced concrete ribbed slabs 0.4 m high

Technical requirements for these products are contained in GOST 27215-87. In it, floors are classified according to which zone of the frame crossbars they rest on:

• 1P – on shelves; There are 8 standard sizes (1P1-1P8);
• 2P - on the upper part, there is 1 standard size 2P1.

1P1- 1P6, 2P1 are reinforced with stressed reinforcement, and 1P7, 1P8 are reinforced with non-stressed reinforcement. Marking includes: size, data on the greatest load, reinforcement class, density and permeability of concrete, presence of cutouts and embedded parts. Thus, a monolithic ribbed slab of standard size 1P2, the second in load-bearing capacity, with At-VSK reinforcement, made of lightweight concrete, operated in an aggressive environment, is designated as follows: 1P2-2 At-VSKL.

Reinforced concrete slabs 0.3 m high

Their production is regulated by GOST 21506-87. It provides three types of standard sizes, depending on the location:

• P1 - in rows;
• P2 – in rows and between columns;
• P3 - between columns and along the walls.

The floor designation according to GOST 21506-87 lists: standard size, maximum load code, type of reinforcement and concrete, presence of ventilation holes (according to the diameter, they are designated by numbers 1 - 3). Symbol for slab P1, with stressed At-V reinforcement, made of lightweight concrete for a normal environment, with an opening for a fan with a diameter of 1 m: P1-AtVL-N-3.

Installation of ribbed reinforced concrete slabs and floors

Floors can only be installed using a truck or tower crane. To grasp the product with the hook of a lifting mechanism, mounting loops are used. Their presence and condition are checked upon purchase and immediately before installation.

1. A layer of mortar necessary for joint strength and tightness is applied to the ends of walls, beams, piles intended for laying slabs. Premature hardening of the sand-cement mixture should not be allowed - this violates the integrity of the structure.

2. A spider with four slings is hung on the crane hook, the ends of which also have hooks. They are inserted into the hinges, after which the ceiling is raised, ensuring its horizontal position.

3. In addition to the crane operator, the installation is carried out by two slingers, who level the suspended load and control the accuracy of the installation.

4. The slab has technological slopes, so the upper plane is slightly smaller than the lower one. Because of this, gaps of 50–70 mm appear between adjacent panels, which are filled with mortar.

5. The mounting loops of adjacent plates are connected with a steel rod, the edges of which are bent inward and welded.

There must be an edge of at least 0.15 m wide on the outside of the building for bricklaying. The plane of contact of the product with the supporting element is also maintained at the same size.

Cost of floors

Due to the high labor intensity of molding work and complex formwork, the price of a ribbed floor slab is significantly higher than a regular smooth one.

Designation	Load, kg/m2	Length, mm	Width, mm	Height, mm	Price, rubles
2PG6	500	5 970	1 490	300	15 200
2PG6	400	5 970	1 490	300	12 400
4PV6	400	5 970	1 490	300	14 680
1P3	500	5 550	1 485	400	19 200

Regulatory Requirements

Important standards that relate to the creation, installation and operation of monoliths, establishing the class of concrete and the quality of reinforcement include the following technical documents :

• 
  GOST 13015-2012.

• GOST 12767-94.
• GOST 9561-2016.
• GOST 34028-2016.
• GOST 25192-82.
• GOST 26434-2015.
• SNiP 3.03.01-87.
• SNiP 52-01-2003.
• SP 52-103-200.
• SP 387.1325800.2018.
• SP 371.1325800.2017.
• SP 63.13330.2012.
• SP 70.13330.2012.

The presented standards emphasize that the reinforcement and pouring of a monolith must always be documented in an Act called “Inspection of hidden work.”

The Act is always signed by the chief engineer of the facility and the foreman, under whose leadership the laying, binding, welding and formation of the metal frame of the concrete floor took place.

Here special attention is paid to deviations, which according to standards must be within the following limits :

• + 20 (mm) – for individual working rods;
• + 10 (mm) – for mesh rows;
• 15 (mm) – from the design thickness of the concrete layer, 5 (mm) to 200 (mm) thickness;
• 70% – and higher (strength of concrete mixture).

If the concrete composition has already been laid and compacted into the formwork, it is prohibited to add water to the composition to create mobility of the solution. The line of the monolith plane should not be deviated by more than 30 (mm), therefore, when marking and forming the formwork, pay attention to the accuracy of the distribution of the concrete mixture. For surface joints, a deviation of only 3-5 (mm) is permissible.

The resulting monolithic surfaces are divided into 4 main classes, which have certain dimensions and depend on the type of concrete, steel frame and the degree of complexity of their creation.

The finished monolith is not allowed to have:

• stains of rust and grease, except for class A7 floors;
• exposed areas of reinforcement and concrete seals, with the exception of specially left parts of the frame for further connection and welding;
• reinforcement not treated with anti-corrosion agents;
• the presence of cracks on the surface, chips and large shells from 4 to 20 (mm).

In addition to meeting standards, it is necessary to use only high-quality labeled materials in work. At the same time, manufacturers must provide certificates, guarantees and all necessary accompanying documentation for manufactured products.

To eliminate all irregularities and form a smooth monolithic surface, ready for finishing, it is allowed to grind it in any convenient way.

If in a construction project the floors are made curved, then the requirements for them are formalized in the documentation as separate paragraphs.

Advantages and disadvantages

The products are easily and quickly installed, provided that equipment is involved. Boards with a ribbed structure have various advantages:

• Strength and endurance. Preventing deformation and destruction is ensured by transverse and longitudinal stiffeners.
• Polydimensionality. Numerous selections allow you to select materials for large construction areas.
• Durability. Strengthening the technical characteristics is achieved by adding chemical compounds and fittings.
• Easy to use. The building material does not require maintenance; finishing work is sufficient.
• Installation. If you have specialized equipment, installation of ribbed slabs takes place in a short period of time.

Characteristics and parameters

An important parameter of the monolith is its thickness , which should be at least 180-200 (mm). The thickness indicator is 1/30, as this indicates that its dimensions should be at least 30 (mm) per 1 (m) of flooring.

The greater the distance between the walls, the thicker the monolith should be. But for small expected loads they can be made 10-15% smaller.

In addition, the finished floor is created from non-combustible materials, and therefore must comply with the technical group “NG”. Also important technical characteristics include :

1. 
   Strength – 390-400 kg/cm2.

2. Mobility P3-P4.
3. The concrete grades used are from M400.
4. Frost resistance – F
5. The most common concrete class is B30.
6. Hardness – Zh3-Zh4.
7. Water resistance - group W12.

When constructing monoliths, all performance indicators are taken into account in the calculations, since projects are drawn up for structures of different types of complexity. Monoliths are reliable, can withstand heavy loads, and are well attached to load-bearing walls. The variety of filling options depends on the formwork shape . Due to its rigidity, the formation of cracks at the joints is eliminated.

The main feature of reinforced concrete floors is that they simultaneously serve as a ceiling on one side and a floor on the other.

You can read more about the characteristics of monolithic floors in this article.

Calculation of the number of slabs and their sizes for a private house

The dimensions of the slabs and the layout of their layout on the floor are usually determined in the house construction project. But in Russian private housing construction, any miracles are possible. Often, under the slogan of saving, somewhere on the Internet, a house project is sought or the most inexpensive project is ordered. It is dangerous to build according to such sources, so the developer has to deal with the slabs during construction. But this is not scary if you approach the solution of the problem responsibly, understanding the main points - the need and dimensions of floor slabs:

The length of the slabs is the distance between the supporting walls plus the distance required to securely support the slabs on the load-bearing walls.

The width of the slabs is selected so as to completely cover the structure. During new construction, walls are built taking into account the size of the floor slabs. Products are laid closely, flush against the walls, without leaning on them. Non-load-bearing (interior) partitions are not taken into account in the calculations: the slabs are laid on top without support or against the partitions.

If it is impossible to provide complete overlap, the remaining area is poured with monolithic concrete with reinforcement into the prepared formwork. It is better to add the missing part of the ceiling with a monolith than to cover it with a “reserve” and then cut off the excess. You cannot cut factory-made stressed slabs yourself without a professional understanding of the process.

Important! In cases where the supporting load-bearing walls are made of block porous materials (aerated concrete, foam concrete, expanded clay concrete, wood concrete and others), an armored belt is installed along the walls. Reinforced concrete floor slabs are installed only after the reinforced belt concrete has completely set.

Reinforced belt

Reinforced belts are often formed as the last layer of a structural wall, before creating roof slabs, as well as in multi-story buildings. This additional reinforcement - a reinforced concrete reinforcement belt - gives additional protection to load-bearing walls , which will protect them from cracks in the future, since the ceiling takes on part of the load-bearing load from the upper floors or roof.

The formed belt is somewhat reminiscent of a reinforced concrete beam with closed edges. Its elements are rods with a diameter of 12 (mm), laid and fastened in the form of a frame, as well as concrete poured over it. The additional purpose of a reinforced belt is especially recommended during the construction of buildings with subsiding soils or in an unfavorable climatic and seismically active zone, to reduce deformation on the walls of the building.

Also, reinforced belts help to connect the frame and foundation of a structure, level the horizontal planes of structural walls, and become a reliable basis for floors. Rods are laid and welded into wooden formwork, pre-installed around the perimeter, forming a continuous circular structure, and then ready-made concrete is poured.

The height of the structure must correspond to 30 (cm) . During the arrangement, precise measurements are taken and poured along the beacons and construction lacing. You can also use laser rangefinders in your work.

You can insulate a reinforced belt with ordinary polyurethane foam, using a special technology, when holes are made in the solution into which a foam composition is introduced. Additionally, the reinforced concrete belt can be covered, but only after the ceiling has been installed.

The reinforced belt takes more than 1 week to dry. It is best to install the floors after the composition has completely hardened.

PB

Rice. 5. 1PB plate

Concrete hollow-core slabs PB are produced according to working drawings of the IZH 976 series using the method of continuous formless molding. They are provided with support only on 2 sides. Support depth - from 9 to 15 cm. Width of reinforced concrete products - 1000, 1200 1500 mm, height - 220 mm, length can be any in the range from 1 to 10.8 m. Scope of application: covering and overlapping of monolithic and brick buildings of general, civil and residential purposes.

Main characteristics:

• The material of manufacture is heavy concrete grade M400, compressive strength class B30.
• Types of formless technology used in Russia are “one-step” vibration molding, two-layer split molding, and extrusion.
• The basic design load (typical) is 800 kgf/m; upon request, it is possible to manufacture products designed for loads from 300 to 2100 kgf/m.

PB reinforced concrete slabs are reinforced longitudinally, so they can be cut both transversely and diagonally without compromising their strength characteristics.

Technology and pouring process

The rules for the formation of a monolithic concrete floor are determined by the current GOSTs and SNiPs. First of all, a project with calculations must be submitted, according to which the thickness and dimensions of the monolith, the type of reinforcement used, the grade of concrete and the formwork will be determined.

Prefabricated removable formwork, with horizontal and lateral surfaces, is installed and securely fastened along the finished reinforced belt, structural (load-bearing) walls and supporting supports (beams, racks, channels). Then the installation steps are as follows :

1. Laying film or lubricating the mold with automotive oil.
2. Structural reinforcement - laying rods or knitting mesh (+ welding), depending on the formation of the layer - with one layer of reinforcement, or with two, with end clamps of 400 mm pitch.
3. Pouring the prepared concrete composition into the formwork without construction waste, with the formation of engineering holes along pre-marked paths. Filling must be done immediately to the end to prevent the formation of additional seams.
4. Work with the composition and leave it until it dries and gains strength for several weeks.

To ensure that the solution is distributed evenly, it is leveled with a smoothing iron and a vibrator is used to better fill the mold. The solution for large surfaces is supplied to the site using a stationary concrete pump.

If the solution is prepared on site, then all the necessary components are mixed in an automatic concrete mixer. The best temperature for working with concrete is 12-25 °C.

The easiest way to measure the thickness of a monolith is with special construction probes. It is most convenient to use formwork with telescopic supports, as they are height adjustable.

All information about the construction and pouring of a monolithic floor is here.

Installation

During the installation of panels, you must adhere to certain rules. A truck/tower crane is used to lay U-shaped slabs. If interfloor floors are created from slabs, it is imperative to take care of equipment capable of lifting reinforced concrete products of the required dimensions to the specified height.

In Moscow and the regions, it is not difficult to find companies that provide such special vehicles for rent. Fastening of the plates is carried out thanks to the presence of loops for installation/rigging work.

Floor installation process:

• Applying a layer of fresh concrete mortar to the ends/surfaces where it is planned to attach the slabs.
• Using four slings, the panel is carefully hung horizontally on a hook and then raised to the desired height.
• The plate is leveled in space, and it is installed in place. All work is carried out quickly so that the cement does not have time to harden.
• The panels must be laid evenly, the gap is maintained at a maximum of 7 centimeters, then filled with mortar, which ensures a smooth surface of the ceiling.
• All mounting loops of the slabs located nearby are fastened with a reliable steel rod and must be attached to the wall of the house with anchors.

By installing the slabs in this way, it is possible to obtain a flat, even floor surface. If you need to remove an unnecessary part of the slab (make a hole in it for a hatch or shorten it in size), do this using an ordinary grinder and metal/concrete discs, scrap.

What are thermal inserts?

Cold bridges can form between the ceilings, leading to heat loss in the building. Therefore, during the construction process, specialists use embedded elements with good thermal conductivity, which are called thermal liners.

The products are made from durable material such as Penoplex, which retains heat well. Together with the insulation applied to the finished monolith, they create a general outline.

The issue of thermal liners (layers of thermal insulation material) is resolved at the planning stage. A diagram of their laying between the connecting elements of the floor is drawn in advance.

Penoplex thermal liners are produced by manufacturers in three main size ranges :

• 150 x 150 x 200 (mm);
• 300 x 150 x 200 (mm);
• 600 x 150 x 200 (mm).

Products of any group have an ideal rectangular shape, and their advantages include:

• thermal conductivity index – 0.033 W/(mˑ°K);
• strength coefficient – ​​20 t/m2;
• resistance to water, fungi and mold;
• quick installation;
• environmental friendliness;
• resistance to external factors;
• durability (more than 60 years).

The products can be laid along the entire perimeter of the ceiling in private and multi-storey buildings. To do this, step back up to 100 (mm) from the edge, leaving a step for the thermal insert of 250 (mm). An important feature of insulating layers is that reinforcement can be laid directly into them . And concrete pouring is done on top of the reinforcement.

Thermal liners for monoliths can additionally provide good sound and heat insulation. You can work with them in any weather.

Marking

An example of marking hollow core slabs.
Looking at the abundance of concrete floors, the average person does not suspect how much useful information is contained in the product labeling. Of course, the technical properties of these products are much more extensive, although initially this information is sufficient. The marking of foundation coatings shows the necessary parameters: designation of length, width, height and type.

For example, floor and coating slabs are:

• PTP – flat;
• PPS – rifled;
• PBO - lightweight.

Road slabs have their own markings, which indicate their size (in decimeters) and the load (in tons) that they can take.

Marking is carried out in accordance with State standards, which represent a set of laws of strength. It states:

• the type of panel itself;
• its length and width;
• bearing capacity, load;
• reinforcing steel class;
• type of concrete;
• additional characteristics (resistance to external influences, volume, weight and others).

Of great importance is the calculation of reinforcement, what coefficient the reinforcement occupies in concrete. The characteristics of the volume of the slab are related to its elasticity and strength. Typically it is at least one percent of the volume of concrete (m3). Labeling is a personal passport for each unit of product; it will help you make the right choice.

Return to contents

Strengthening concrete slabs

Many builders use additional reinforcement for monoliths. This manipulation consists of applying an additional layer of reinforced concrete composition to the surface. To do this, the ceiling is washed with water, cleaned and notched with a chisel. If there are exposed areas of reinforcement, they are cleaned of dust and rust. The depth of the notches is 0.5-1 (cm).

Strengthening concrete floor slabs helps not only to further strengthen the surface, but also to restore their integrity, improve technical characteristics and load-bearing capabilities.

Restoring integrity is necessary if there is:

• exposed reinforcement;
• visible wear - the presence of defects, cracks, detachments and screeds, etc.

In order to correctly perform reinforcement, it is imperative to carry out calculations based on the collected documentation, after a visual inspection and measurements of defects.

Metal channels, pipes, and beams with a large cross-section are used as reinforcing reinforcement for floors. The entire surface is covered using a reinforced mesh with cells of at least 150 x 150 (mm). If the mesh is made from rods, then their diameter should be 14-18 (mm).

Existing cracks and defects are repaired using one of the methods - shotcrete (applying concrete mortar from a special spray gun under a given pressure over the entire frame).

Ribbed slab reinforcement

The selection of reinforcement, carried out in the SCAD computer complex, is based on the methodology of M.I. Karpenko. It describes the deformation of reinforced concrete with cracks using an anisotropic solid body model. It is based on the theory of deformation of reinforced concrete with cracks. According to this, deformations depend on shear and normal forces.

Scheme of reinforcement of a ribbed floor slab: 1 – reinforcement mesh in the span of the slab; 2 – reinforcement mesh above the secondary beams.

The peculiarities of reinforced concrete lie in the patterns that establish the connection between movements and forces. The apparatus for calculating shells and slabs is based on them. The shell has 6 degrees of freedom, and the plate has only 3: two rotations and vertical movement.

The selection of reinforcement is carried out not only by strength, but also for the 1st and 3rd categories of crack resistance. The area of ​​reinforcement selected for strength will be significantly smaller, since the width of the cracks is uncontrollable due to the lack of additional reinforcement to ensure the permissible opening width of the cracks. Calculation using the traditional method, which has certain limitations, does not provide control over the size of the selected reinforcement taking into account crack resistance.

Causes of defects and cracks

Various shortcomings that may appear on a monolith are largely related to the quality of materials and non-compliance with technical installation standards when working with consumables.

It is best to purchase elements for a monolith (concrete mixture + metal reinforcement) from trusted manufacturers who are able to provide consumers with high-quality certified products.

The main defects of monolithic floors are considered to be:

1. 
   Appearance of cracks. Poorly compacted and vibrated areas, inappropriate temperature for work, poor composition, which contains a lot of water and sand.

2. Exposing the reinforced parts of the frame base. The thickness of the monolith was insufficient; not enough solution was poured.
3. Formation of voids and shells. Associated with the quality of pouring, irregularities in pouring and distribution of concrete along the formwork.
4. Obvious presence of foreign inclusions. Occurs due to inaccurate proportions and the use of unscreened or unsuitable material.
5. Incorrect placement of seams. The work was not carried out according to the plan, which is why the surface geometry became incorrect.
6. Presence of uncompacted areas. During the pouring process, there were no stages of uniform creation of the ceiling.

All these disadvantages also occur when:

1. unprepared soil base;
2. lack of concrete proportions;
3. using more sand and water than required;
4. poor compaction and vibration distribution of the composition;
5. failure to comply with the required floor thickness;
6. overconsumption of concrete composition.

To prevent defects, you need to accurately follow the installation and preparation steps in accordance with the design documentation. The specialist identifies existing deficiencies after a thorough visual inspection and taking the necessary measurements.

All imperfections are removed by additional reinforcement of the concrete surface. To do this, a layer of concrete is placed on a reinforced mesh. If there are large cracks, they are additionally tightened with anchoring, over which a mortar is poured.

Prefabricated floors

Prefabricated floors are divided into beam and slab; in the first case, the load-bearing beams are assembled with enclosing structures; in the second, ready-made reinforced concrete slabs are used.

Prefabricated wooden floor

A typical wooden floor includes several layers.

• Thermal insulation – slab, roll, backfill, sprayed (stone wool, expanded clay, ecowool, polyurethane foam, etc.). The thickness of the insulation layer depends on the selected material and thermal resistance standards in the region of construction, on average it is 200 mm for a basement floor. There is a gap between the insulation and the subfloor for ventilation. If the height of the logs is not enough, a wooden block of the required thickness is placed under the flooring.
• Waterproofing.
• Vapor barrier.
• Flooring - to lay the insulation, a skull block is stuffed onto the joists, on top of which the flooring is assembled from a rough board without the use of fasteners.
• Subfloor - not only tongue-and-groove boards laid directly on the joists are used as a finishing coating, but various composites that require a plank or slab base.

The lower wooden floor is combined with lightweight, columnar or pile foundations, less often with strip foundations. In some cases, floors on wooden joists are laid on top of monolithic bases for additional insulation.

Prefabricated slab floor

The installation algorithm is as follows.

Sealing of joints between slabs must be done with high-quality concrete to prevent their warping (work according to the key scheme), for which recesses are usually provided in the slabs for the formation of dowels.

• Preparation for the finished floor - if the surface of the slabs is relatively flat, and there is no plan for an underfloor heating system or a finishing coating that requires an ideal plane, you can do without pouring a rough screed. Thick preparation is replaced with a thin-layer self-leveling mixture or a specialized substrate.

Laying such massive structures requires the use of special equipment, which somewhat limits the application, since not every house under construction will have access to special equipment.

Advantages and disadvantages

Monolithic concrete floors, according to experts, have the following advantages :

1. High load-bearing capacity and durability. The structures are resistant to seismic loads and can withstand any mechanical and vibration impact, including shock waves.
2. Good density and strength, thanks to the included components having good adhesion to each other.
3. Possibility of installation directly on site, with your own hands, in any desired span size, formed along structural walls or columns.
4. The composition used is environmentally friendly, made from natural ingredients that are safe for human health.
5. Creation of the required thickness of the concrete span, in accordance with the design, without loss of strength characteristics and the required surface rigidity, as well as prevention of exposure of reinforced parts.
6. A sufficient level of fire safety and the impossibility of spontaneous combustion.
7. There is no need for mandatory replacement of all load-bearing elements, as well as the use of bulky construction equipment.

disadvantages to concrete floors:

1. Certain temperature conditions and a strictly allotted amount of time are required to perform work with concrete.
2. The process is labor-intensive and costs are high, compared to the use of reinforced concrete floor slabs by 20%.

The advantages of concrete monolithic floors are much greater than the disadvantages, which makes it possible to achieve strong, reliable structures and safety for further operation.

Fast and accurate formation of a monolith, with guarantees, is possible for any legal construction company that has all the necessary tools, mechanisms and consumables for this.

Types of floor slabs, sizes, GOST: basic standards

Monolithic frame buildings, the essence of which is the formation of one continuous slab over the entire surface of the floor, are gaining increasing popularity. The main disadvantages of a monolithic structure are its high cost, the need to create a preliminary frame and the non-stop process of pouring concrete. That is why ready-made reinforced concrete products do not lose their relevance and are actively used, especially in private buildings.

In addition, the lower prices of concrete floor slabs and the sizes of products, which are presented in large quantities in retail outlets, allow you to choose the appropriate option for each specific construction project, depending on the allocated budget and architectural design. The slabs are easy to install and help speed up the process of building construction, and their installation does not require additional installation work. Another significant advantage is the lack of shrinkage in reinforced concrete floor slabs.

Solid slabs are characterized by a high level of strength, high weight and low sound and heat insulation properties

Such structures are characterized by increased rigidity, they are resistant to moisture and temperature changes, and have high heat and sound insulation properties. Gas-tight structures are also used in the construction of residential buildings. In most cases, the permissible load on floor slabs is 800 kg/m², and the maximum pressure for which the products are designed starts from 8 kPa. Since houses built using floor slabs have been built for a long time, a long service life can be noted. The proposed list considers the main types and sizes of floor slabs according to GOST:

1. Multi-hollow. They have a width from 1 to 3.6 m, a length from 1.7 to 9 m. The thickness, depending on the model, varies from 16 to 30 cm. They are distinguished by the presence of hollow through holes.
2. Prefabricated ribbed. According to GOST standards, the dimensions of ribbed floor slabs are represented by such parameters as height - up to 40 cm, width - up to 3 m, length varies from 6 to 18 m.
3. Solid additional structures. Length – from 1.8 to 5 m, height – 12-16 cm.

Interesting information! All characteristics and dimensions of reinforced concrete products (floor slabs) are regulated by GOST 21924.2-84. Depending on the type of product, they can additionally be equipped with fittings outlets, as well as local cutouts and holes.

The dimensions of the ribbed reinforced concrete floor slab are dictated by the length and width of the room

When choosing reinforced concrete structures for construction, in addition to the main parameters, it is important to take into account the weight of the products, which will influence the type of lifting equipment used. Often on construction sites there are cranes designed to lift structures weighing up to 5 tons. For example, a concrete slab with a volume of 2 m³ or more can weigh from three to 4.5 tons, which may be too much for a conventional crane.

Hollow-core floor slabs: dimensions, main types

This is the most common type of reinforced concrete products, which is most often produced by industrial enterprises. Due to their features and variety of sizes, hollow-core concrete slabs are widely used for industrial, multi-story and private buildings. The presence of cavities helps to cope with the laying of communications and heating mains.

The almost completely flat and smooth surface of the round-hollow panels allows not only to quickly install interfloor ceilings, but also simplifies the work on making floor screeds and decorating the ceiling. The presence of voids does not affect the ability of the slabs to withstand heavy loads. Depending on the internal cross-section, as well as the shape and diameter, the following types of cavities are distinguished:

• round;
• oval;
• semicircular.

Schematic illustration of the dimensions of a hollow core slab

In addition to the fact that the presence of voids significantly reduces the weight of floor slabs, hollow-core panels also have other advantages, which include:

1. Saving concrete mixture during production, which reduces the cost of finished products.
2. Good performance properties. Hollow-core floor slabs have a high level of noise and heat insulation, which improves the quality of the finished building.
3. Facilitate the process of laying communications. The voids inside the slabs are used for laying not only cables, but also other communication lines, for example, pipes of different diameters.
4. Large selection of sizes and prices of reinforced concrete floor slabs. In production you can find panels of almost any size, including non-standard dimensions, but they will cost a little more.
5. Lightening the entire structure. Due to the fact that hollow-core slabs have less mass, there will be little impact on the foundation, which will have a positive effect on the stability of the entire structure.

Hollow core slabs are the most popular type of reinforced concrete products

Features of production and advantages of using certain types of products

Depending on the characteristics of production, hollow-core slabs are divided into hollow-core formwork (HC), hollow-core lightweight (VLO) and hollow-core formwork-free (PB). The production process for manufacturing hollow core slabs looks like this:

1. The concrete solution is poured into a prepared metal formwork with reinforcing elements and a metal mesh located inside.
2. Then, under the influence of vibration, the concrete is well compacted and processed in a hydrothermal box, the temperature in which is 80 ° C, and the absolute humidity reaches 100%. Over the course of 7-12 hours, the temperature inside the box steadily decreases.
3. After the mixture has completely hardened, the finished reinforced concrete slab is removed using fixed steel eyes, which facilitate the installation of the panels. At the warehouse, all slabs are marked and receive technical documentation.

As for lightweight concrete floors, they are considered a modernized version of PC slabs, which are characterized by a reduced thickness. If the standard size of reinforced concrete floor slabs is 22 cm, then the thickness of the lightweight version is only 16 cm, which, in turn, affects the final weight and volume of the product. Thus, the volume of a lightweight concrete slab 2.4x1 m will be equal to 0.38 m³, and the volume of a standard PC slab of the same size already reaches 0.52 m³, while the weight of the first slab will be 550 kg, and the second will already be 750 kg, which indicates a significant difference in weight.

Solid slabs have a lot of weight, so the support must be much stronger than reinforced concrete

Due to the fact that more dense reinforcement is used in the production of the slab using thicker reinforcement, it can withstand the same weight as hollow PC slabs. Accordingly, the use of PNO slabs is considered more economical, because they are slightly cheaper in price, and the load on the foundation will be even less. Due to the fact that such slabs take up less volume, more slabs can be delivered by truck in one delivery, which reduces the cost of delivering products.

Related article:

Reinforced concrete blocks: a universal material for the construction of reliable buildings

Scope of use. Varieties of blocks by type, size and area of ​​application. The procedure for installing reinforced concrete blocks.

The slabs, which are produced without the use of formwork, are made through a process of continuous casting of concrete mixture, and the final shape of the panel is given by a molding machine. This production principle allows us to produce slabs of great length - up to 9 meters, which, at the request of the customer, can be cut into any lengths with an accuracy of several centimeters. This makes it possible to use concrete floor slabs of different sizes to design complex architectural elements.

Basically, the thickness of the slabs is 22 cm, although in some cases you can find products of different heights. The main advantage of PB slabs is the ability to use products in a vertical position for the construction of walls.

This is interesting! Most industrial production produces formwork slabs, because they do not require the purchase of additional equipment to produce them.

The dimensions of hollow core slabs are convenient for covering spans up to 12 m long, and the shape is suitable for laying communications

Price

Construction services are regulated by construction companies according to price lists, which are attached to cooperation agreements, or are listed on official websites. However, during work seasons the price may vary significantly . Also, a changing and growing market sets its own prices for consumables and services.

To determine the cost, the region is also important - the cities of Moscow, St. Petersburg, as well as the northern regions, the price for the services provided is always higher than other subjects of the federation.

On average, the price for the work of craftsmen + consumables from them can be presented in the following table:

Completed monolithic works	Unit	Price, rub.)
Installation of reinforcement (rods), binding (mesh) and welding of frames	m2	4 200
Preparation of the base of the monolith, with marking, mixing the components of the solution, pouring along the laid reinforcement	m3	5 400
Formation of concrete pillars under the base in formwork forms	m3	4 100
Creation and installation of concrete lintels for floors	1 PC.	600
Creation of floors and foundations for columns and architectural arches	m3	4 000
Floors with a thickness of 200 mm in multi-storey buildings	m3	9 000

Construction companies often give discounts to their clients, and also offer on-site measurements, calculations and drafting services for free. It is also profitable to buy building materials from them, since they purchase them directly from manufacturers at wholesale prices, which are always lower than market prices.

The cost of a monolith depends on the area of ​​its creation. Labor costs can be much higher than purchasing ready-made reinforced concrete slabs, but there are undeniable advantages of its operation.

More information about the cost of monolithic floors here.

Other types

Other types of reinforced concrete slabs: transitional, slope reinforcements, beds. They are made of heavy concrete grade M400, compressive strength class - B30, water resistance - W8, frost resistance - F200-F300.

A bench is a flat rectangular product for road construction. Purpose: interface of engineering structures with embankments and dams. At the ends, on both sides or only on one, a reinforcement outlet may be provided, designed for a strong connection with other elements.

Rice. 7. Lying down

Transition slabs generally have the same purpose as the beds, only the latter serve as the foundation. There are straight (P) and oblique (PC) products. PCs have an end slope at an angle of 50-75°; they are laid in places where a road and another structure (bridge, tunnel) form an oblique intersection.

Slope strengthening slabs - square and rectangular products. Types: P-1, P-2, P-1K, PB-1, B-8 with beveled corners. Scope of application - road construction, purpose - protecting the slopes of highway embankments from sliding, maintaining the roadway and soil base in a stationary position. To form a green slope, lattice products PR-3i are laid: after installation, the cells are covered with soil and sown with grass.

Prefabricated slab floor

The width of the supporting platform for slabs in brick walls must be at least 100 mm. During installation, the slabs are laid on a layer of mortar. If there are no factory plugs on the voids, the holes at the ends of the slabs should be sealed.

In houses made of lightweight blocks (foam concrete, polystyrene concrete, wood concrete, porous ceramic), a monolithic reinforced concrete belt 200 mm wide and 100–150 mm high is poured to absorb the load from the prefabricated slab floor.

The main advantages of flooring made from ready-made slabs are high speed of installation, the ability to carry out work in winter (at a temperature not lower than –10 ° C) and precisely known strength characteristics of the slabs, the manufacturing processes of which are strictly regulated and carefully controlled.