Reinforced concrete slab. Reinforced concrete slabs: dimensions, characteristics, prices

The application of scientific and technical novelties is especially noticeable in the construction - in different areas of the planet there are structures, the erection of which would have been unthinkable some time ago.

New materials, new machines and tools allow you to build faster, higher, more reliable. But there are elements in the construction technology that do not lose relevance for a very long time. Such is the reinforced concrete slab - the principle was invented a century and a half ago, but without it the most futuristic projects do not do.

Patent of 1867

Many know the story of the French gardener Josef Monier, who strengthened his thin-walled concrete barrel with a frame of metal rods and covered it with a layer of cement mortar. The resulting monolithic article possessed properties unattainable for other materials. Monier patented in various countries ways of producing reinforced concrete of various designs, including a reinforced concrete slab for walls and partitions.

Professional builders made their amendments to the development of the inventor: he had the reinforcement exactly in the middle of the concrete layer, and calculations showed that the arrangement of the reinforcing cage should be chosen based on the specific situation, taking into account the loads acting on this structural unit. Thus, horizontal slabs of a slab are more logical to reinforce, placing the rods closer to the lower plane of the slab, where the greatest tensile forces are.

Improvement of technology

Today the concrete is given the properties necessary for the most exclusive situations. Power elements - reinforcing cages - can be spatial and flat, there appeared prestressed (string, beam) reinforced concrete with improved structural qualities. Various additives in concrete slow or accelerate grasping and gaining strength. Reinforced concrete is widely used in the construction of unique, single objects, as well as mass, economical buildings.

Technological, durability, durability, moisture, bio-and fire resistance, economy - these advantages will determine the use of reinforced concrete in the future. Monolithic slabs of slabs or made for prefabricated housing construction will be in demand for a very long time, because, among other things, consisting of natural components, these structures are environmentally friendly and easily amenable to recycling and reuse.

Types of reinforced concrete slabs

On a place of application distinguish base, road and plates of overlapping. Such a product can be manufactured in the factory, then delivered to the construction site and installed. Most often, a reinforced concrete slab, like other products of prefabricated housing construction, is fixed by welding with embedded metal parts.

The plate can be manufactured in place. A monolithic slab, both foundation and for interstorey roofing and roofing, is particularly often used in non-standard architectural objects or where the use of cranes necessary for the installation of precast concrete products is difficult. The market offers a sufficient number of devices (including formwork), making this process affordable and for self-construction.

Floating foundation

Such a construction of the base under the building is not the cheapest option, but often the most logical one. Monolithic reinforced concrete slab, repeating in terms of the outline of all the outer walls of the first floor, is often called a floating foundation. This means that the load from individual parts of the building is transferred to the ground base evenly, the slab operates as a single element, it is not susceptible to deformation due to the soils, a large depth of freezing or a high groundwater location. Of course, this is all really for a foundation slab made with proper quality.

An important and quite costly step from the point of view of the device of such a foundation is the preparation of a sandy base on which the slab will be cast. It is necessary to perform a certain amount of excavation work, to fill and compact the sand - spilling water or tamping.

Installation of foundation plate

The bottom layer is usually a roll geotextile, which does not allow seepage into the solution. Then the concrete leveling preparation for waterproofing is done. After the hardening of this layer, rolled waterproofing rolls out with overlapping and sizing.

Reinforcement is the device of two interconnected mesh layers. Reinforcement rods of the lower layer are installed in special locks, so that it is recessed into the concrete layer. Concreting is convenient to carry out directly from the mixer through the tray, concrete pump, etc. After the prescribed period of recruitment, the reinforced concrete slab-foundation is ready for the erection of the house.

Monolithic slab

In low-rise construction such a slab of overlap cast in the formwork in place is used very often. To this there are specific prerequisites. In addition to the common qualities of reinforced concrete - strength, fire resistance, uniform distribution of perceived loads - there are specific advantages in choosing this technology. The main of them - the lack of the need for heavy construction equipment and the possibility of overlapping any form in the plan.

Calculation of the required thickness of the plate and the scheme of its reinforcement is better entrusted to specialists. In other cases it is necessary to know the following. The plate is made not thinner than 150 mm, while the thickness of the slab is determined on the basis of the length of the overlapping opening, in the ratio range 1:30 - 1:35. When reinforcing it is necessary to remember the reinforcement of the edge of the plate with U-shaped and L-shaped staples.

Technology features

In the market there are many options for reusable formwork for monolithic floors. But buying it for an amateur builder is too expensive. Although there are opportunities to take such professional equipment for rent, and this would be the best option - guaranteeing the speed and quality of the device overlap. In any case, use as a support telescopic racks are much more convenient than boards or bars, because to set the leveling of the formwork is very important.

Concreting must be carried out in one step, with compaction and vibration of the mixture. It should be the first three days to moisten the concrete with sprinkling to avoid cracks from uneven drying.

Precast reinforced concrete

The erection of buildings from reinforced concrete products made on special factory lines is considered the most suitable for mass multi-storey housing construction. But for small-sized cottages prefabricated slabs are quite an option. Reinforced prefabricated slabs are a cheaper option of overlapping, they can be mounted in any weather, and the installation speed is much higher.

It is difficult to use a prefabricated ceiling with a large weight, which has reinforced concrete slabs. Their dimensions are standard - this should be taken into account at the design stage. Another problem is the need to use a crane, even for a small area of overlap.

Types of prefabricated slabs

Solid, solid boards are used for special designs and assemblies: as additional elements or for the installation of channels for laying communications. They are distinguished by high strength and high weight.

Plates that have round or arcuate longitudinal voids are lighter and have better sound and heat insulating characteristics. Plates reinforced concrete hollow-core - the most used type of products for prefabricated floors. They are used for buildings with a reinforced concrete frame, panel housing, brick walls, etc. Vugs can be used for laying cables for various purposes - electrical, low-current.

The third type - ribbed or hipped, often used in industrial construction to block large spans. The thickness of the slab overlapping without taking into account the force ribs is 140-160 mm.

For the production of slabs, prestressed reinforcement is used, which makes their strength indicators similar to those of monolithic reinforced concrete floors.

Standard slab sizes

The use of prefabricated hollow flooring should be envisaged at the design stage of the future house. The standard size of the slabs can be a determining factor in the development of the layout of the future house. Overlapping, which requires plates of non-standard shapes or sizes, can be too costly.

Therefore, the design should include the use of standard formats: plate thickness - 220 mm, width - 1, 1.2 and 1.5 m, and length - from 2.4 to 9 m, multiple of 100 mm.

Methods for the production of slabs

In the production of hollow-core slabs, two main methods are used. One is more traditional, with the use of reusable forms for the production of slabs of unchanged, standard-set size. After installing the reinforcement and the elements forming the voids, the mold is filled with a concrete mixture and heated to accelerate the process of solidification of concrete and its strength. Obtained in this way reinforced concrete slabs GOST 9561-91 prescribes to mark letters PC.

At another - more progressive - the plate is stretched on the stands, on the heated track in the form of a continuous strip of 100-200 m in length using a special molding machine. Pre-stressed reinforcement has the form of tensioned steel ropes of the required cross-section. When the mixture reaches a certain degree of strength, the ribbon is cut by the diamond tool into sections of the required length and even at the required angle. We get reinforced concrete slabs, the price of which is 20% lower than that of conventional - cassette - production methods. These plates are marked with PB symbols.

The designations of the hollow core plates have several alphanumeric groups of symbols. They mean type, length and width in decimeters, design load (in kPa), type and class of reinforcement. Example: PC 63-12-8-AtV - plate with round voids 63 dm long, 12 dm wide, permissible load - 800 kg per m ² , AtV - type of tensioned reinforcement.

Assembly of prefabricated panels

The quality of the prefabricated ceiling from hollow-core slabs directly depends on the correct preparation for installation, from careful and accurate implementation of the process of installing the plates with constant monitoring of the process using a measuring tool.

Ensure the reliability of the construction can only be done if the plate support plate is correctly made on walls or columns. The optimal depth of such support is chosen based on the construction of the wall, the material from which the supporting structures are made. For example, 70 mm of the plate support is sufficient for the metal beams, 75 mm for the reinforced concrete crossbars, 90 mm for the brick wall.

For walls where low-load-bearing elements are used, such as lightweight concrete blocks, gas silicate or polymer concrete panels, most professionals recommend reinforcement in the form of reinforced concrete armpoles at the top, on which the slabs will be based.

The professionalism of builders is clearly expressed in the course of assembly of prefabricated floors. If the fixing of the slabs by welding of the embedded parts with each other occurs with the use of non-unitary parts, and accidental wastes of reinforcement - one should be alert, too much risk of destruction of the entire structure of the building.

Road plates

An article called a plate is a parallelepiped with overall dimensions, in which the thickness is much less than the length or width. This fully applies to road slabs. They are used for the construction of hard road surfaces or aerodrome runways. Such a coating can be permanent or temporary, i.e., these plates can be used several times, and this is one of the advantages of the technology. Calculation of the reinforced concrete slab is performed proceeding from the field of application, the planned load for the coating and the service life.

When laying road slabs, it is very important to perform the necessary preparation of the base qualitatively - usually these are layers of gravel from gravel and gravel, and also a sand pillow of the required thickness and density.

Plate road and airfield, for permanent and temporary coverage. They differ in the thickness of the product and in the type of reinforcement used in its manufacture. All these data are reflected in the marking applied to the plates.

Example: 1П30.18-30AV - reinforced concrete slabs, dimensions - 3000х1750 mm, for permanent covering (2П - for temporary), designed for a car weighing 30 tons, reinforced steel of class АВ is used.

Right choice

Choose a suitable option for the construction of the foundation, walls, ceilings or covering roads and runways will help a well-designed project stage. Modern factories of reinforced concrete products offer a wide range of finished parts for the most specific tasks of the construction process.

Acquire reinforced concrete slabs, the price of which is quite reasonable, and the quality - to meet the standards and standards, the deal is quite real.