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 toolsallow 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.
Many know the history of the French gardenerJosef 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 manufacturing reinforced concrete of various designs, including a reinforced concrete slab for walls and partitions.
Professional builders have made their own amendments to thedevelopment of the inventor: he had the reinforcement precisely in the middle of the concrete layer, and calculations showed that the arrangement of the reinforcing cage should be chosen proceeding from the concrete 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.
Today, reinforced concrete is given properties,necessary for the most exclusive situations. Power elements - reinforcing cages - can be spatial and flat, pre-stressed (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, strength, 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 house-building 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 re-use.
On a place of application distinguish base,road and floor slabs. 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.Monolithic slabs, both foundation, and for the device of interfloor overlapping and roofing, are especially often used in objects of non-standard architecture or where it is difficult to use the cranes necessary for the installation of precast concrete products. The market offers a sufficient number of devices (including formwork), making this process affordable and for self-construction.
Such a construction of the base under the building is not the mostA cheap option, but often - the most logical. 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 uniformly to the ground base, the slab operates as a single element, it is not susceptible to deformation due to the freezing ground, a great depth of freezing or a high groundwater location. Of course, this is all true for a foundation slab made with proper quality.
Important and quite costly from all points of viewThe stage of the construction 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.
The bottom layer is usually a rollGeotextile, which does not allow seepage into the soil solution. Then the concrete leveling preparation for waterproofing is done. After the hardening of this layer rolled roll waterproofing with overlapping and sizing.
Reinforcement is a device of twointerconnected mesh layers. Reinforcement rods of the lower layer are installed in special fixatives, so that it is recessed into the concrete layer. Concreting is convenient to carry out directly from the mixer on the trays, concrete pumps, etc. After the prescribed period of recruitment, the reinforced concrete slab-foundation is ready for erection of the house.
In low-rise construction such a plateoverlap, molded 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 ability to block any shape in the plan.
Calculation of the required thickness of the plate and its circuitreinforcement is best 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.
In the market there are many options for reusableformwork for monolithic ceilings. 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, to 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.
The erection of buildings from reinforced concrete products,manufactured at 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 the prefabricated ceiling largeweight, which have 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.
Solid, solid boards are used forspecial designs and assemblies: as additional elements or for the installation of channels for the laying of communications. They are distinguished by their high strength and high weight.
Plates with round or arcuate longitudinalvoids, lighter and have better sound and heat insulation 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 slabs.
The use of prefabricated hollow flooring followsenvisage at the design stage of the future house. The standard size of the plates can be a determining factor in the development of the layout of the future house. Overlapping, which requires slabs 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.
In the production of hollow-core plates,two main methods. One is more traditional, using reusable shuttering forms for the production of slabs of unchanged, standard-set size. After installing the reinforcement and the elements that form the voids, the mold is filled with a concrete mixture and heated to speed up 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 - a platestretched 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. The prestressed 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 with a diamond tool into sections of the required length and even at the required angle. Obtained reinforced concrete slabs, the price of which is 20% lower than that of conventional - cassette - production methods. Such plates are marked with PB symbols.
Designations for hollow core slabs haveseveral alphanumeric groups of characters. 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 m2, АВВ - type of tension reinforcement.
The quality of the prefabricated ceiling from hollowplates 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.
It is possible to ensure the reliability of the construction, onlyif competently perform a support plate on the walls or columns. The optimum depth of such support is chosen on the basis of the construction of the wall, the material from which the supporting structures are made. For example, 70 mm of the support plate is sufficient for the metal beams, 75 mm for the reinforced concrete crossbars, 90 mm for the brick wall.
For walls, where the material usedelements with low bearing capacity - lightweight concrete blocks, gas-silicate or polymer-concrete panels, more often professionals recommend to create reinforcement at the top in the form of reinforced concrete armopoias, on which the slabs will be based.
The professionalism of builders is clearly expressed induring assembly of prefabricated floors. If the fixing of slabs by welding of embedded parts with each other occurs with the use of non-unitary parts, and accidental waste fittings - should be pricked up, the risk of destruction of the entire building structure is too great.
A product called a plate is a parallelepiped withOverall dimensions, in which the thickness is much smaller 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 the 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 are distinguished, forpermanent 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 labeling applied to the plates.
Example: 1P30.18-30AV - 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.
Choose the right version 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 comply with standards and standards, it is quite real.
