In the construction of multi-storey buildings, different materials are used. However, concrete slabs are an integral element of any such structure. Ceilings in houses made of them ensure the reliability and safety of the construction structure. These products are used not only in the construction of houses. The dimensions of concrete floor slabs allow them to be used in the construction of a road network, channels for engineering systems.
Varieties
Concrete floor slabs are classified according to different criteria. Among them:
- Kind of concrete. Boards can be made from dense, light, heavy, silicate compositions.
- Internal device. Concrete floor slabs are solid (solid) or hollow (multi-hollow).
- Thickness, width and length. Regulatory parameters are set in GOSTs.
- Method of leaning on crossbars or load-bearing walls. Concrete floor slabs can be cantilevered (such products are used in the arrangement of canopies and balconies), beamed (on both sides),3-4 sided.
- Section profile. According to this criterion, beveled, rectangular, ribbed slabs are divided.
- Manufacturing method. Plates are prefabricated and monolithic.
- Production technology. Products can be made by vibration, casting, continuous method.
- Reinforcing method. Slabs are available in prestressed, regular, non-stressed.
Nuances
It must be said that the cost of hollow concrete floor slabs, reinforced with reinforcement, differs significantly from the price of monolithic products. Despite the fact that hollow slabs can withstand less load, they may well be used in the construction of interfloor floors. Due to the voids, the weight of the concrete floor slab is significantly reduced and, accordingly, the load on the walls. The foundation of the structure is thus under less stress.
Voids are located along the length of the concrete floor slab. Moreover, its indicator can not always be greater than the width. For a slab supported on 4 sides, the length is considered to be the smaller plan dimension. In other products, it will be the side that does not lie on the supporting structures.
Reinforcing mesh
It is used in reinforced concrete products. The reinforcing mesh significantly increases the cost of the plates. The solution provides reliable protection to metal rods from aggressive environmental influences, so they are not susceptible to corrosion.
Metal contributes to the preservation of concrete solidity. He takes on the burdenstretching. There is no metal reinforcement in concrete floor slabs. Accordingly, they are inferior to reinforced concrete products in terms of strength.
Monolithic slabs
Reinforced concrete products can have different shapes. Their frame is associated with the structure of the house and is integral with it. This reduces the thickness of the walls and the consumption of concrete mortar. The total cost of materials is thus reduced. However, monolithic products have a number of disadvantages. They are as follows:
- The period of curing of concrete in such products is quite long.
- For the installation of monolithic slabs, formwork is required.
Prefabricated reinforced concrete and concrete floor slabs significantly reduce the construction time of the building, as they are delivered to the construction site ready-made. In addition, there are significant labor savings. For houses of a simple configuration, it is more expedient to use prefabricated slabs.
Specific use of metal rods
Concrete floor slabs with stressed reinforcement are produced as one- or offset-stressed. Before concreting, the rods are stretched on different structures: matrices, bench stops, molding pallets.
When gaining strength, forces are transferred to the solution from the reinforcement located in the channels in the body of the structure or in the grooves located on the outside.
The adhesion of materials is provided by an injected anti-corrosion coating or solution. Hollow slabsare made heavily reinforced, regardless of their size.
Full body products
Solid slabs used for intermediate floors are produced in accordance with GOST 12767-94.
It is worth saying that such products are used in residential construction extremely rarely, due to their large weight. Such plates are indispensable when high mechanical loads are expected in the structure.
Parameters
Classification of solid slabs is carried out according to the method of support:
- 2 sides – 2PD – 6PD.
- On 3 sides - 3 Fri - 6 Fri.
- On 4 sides - 1P - 6P.
The thickness of the concrete floor slab is indicated in the digital marking:
- 100 mm – 1;
- 120 mm - 2;
- 140 mm - 3;
- 160 mm - 4;
- 180 mm - 5;
- 200 mm – 6.
The product dimensions in the plan are:
- Length – 3-6.6m;
- Width - 1, 2-6, 6 m.
Requirements
According to the state standard, reinforced concrete slabs should contain:
- Structural elements or embedded parts made in the form of rebar outlets. They are designed for docking with metal and reinforced concrete parts of the frame.
- Through channels. They are used to run electrical wires or other networks.
- Mounting loops.
Standards establish normative indicators of frost resistance and water resistance of plates, quality andstrength of materials, including metal rods. There should be no concrete overflows on the embedded elements. The pin extensions must be protected to prevent injury.
Attention is also paid to the appearance of products. There should be no chips, cracks, deep sinks on the surface of the plate.
Multi-hollow products
They are distinguished by high noise insulation, low thermal conductivity, relatively low weight and affordable cost. Both surfaces of the plate are front. During installation, one becomes the floor of the upper floor, the second - the ceiling of the lower.
The production of such plates is carried out according to the standards of GOST 9561-91. The state standard provides for the classification of products into the following groups:
- With round voids, supported on 2 sides - PC, on 3 sides - PKT, on 4 - PKK.
- Produced by Formless Continuous Molding - PB.
- With pear-shaped voids supported on 2 sides - PG.
Thickness of multi-hollow products 160-300 mm. The most popular is the size of 220 mm. Holes can be of different diameters (114-203 mm). It depends on the thickness of the plate. Product length 2.4-12 m, width - 1-6.6 m.
In these slabs, as in hollow ones, there must be additional elements described above. To strengthen the ends, they are sealed with cement mortar or another method provided by the standards is used.
Ribbed plates
They are commonly used in the construction of industrial buildings. Stiffening ribprovide high resistance to mechanical damage. The disadvantage of such products is an unattractive appearance.
Depending on the purpose, the plates can be mounted with ribs up or down. As a rule, the second option is common. Plates are made in accordance with GOSTs. For products with a height of 400 mm, the State Standard 27215-87 applies, for prestressed products with a height of 300 mm - standard 21506-87.
Light or heavy concrete can be used to produce ribbed slabs. Products apply:
- In unheated and heated rooms, outdoors.
- At temperatures from -40 to +50 deg. Temperature range may be extended if additional requirements are met.
- In areas with estimated seismicity up to 9 points.
- In gaseous low, medium or non-aggressive environments.
Classification of ribbed slabs is carried out depending on the method of support on crossbars:
- On the shelves - 1P.
- On the top of the beam - 2P.
At the same time, 1P plates have 8 standard sizes, and 2P - one. The length of products in the first case is 5.05 and 5.55, and the width varies from 0.74 to 2.985 m. Ribbed plates 2P have a standard size of 5.95x1.485 meters.
Prestressed products are available in three sizes. They differ in shape and width. The length of all standard 5, 65 meters. Width P1 - 2, 985, P2 - 1, 485, P3 - 0, 935 meters.
In the technical regulationdocumentation defines the requirements for reinforcing bars, concrete and finished products in general. In addition, possible tolerances are indicated. Concrete slab manufacturers must strictly comply with all requirements.
Conclusion
Concrete slabs are currently considered one of the most sought after building materials. Manufactured at the factory according to all the rules and in accordance with the standards, they are reliable, durable, safe. They are successfully used not only for the construction of apartment buildings and industrial buildings. Concrete slabs are often used in the construction of low-rise private houses.
Concrete slabs can be used at low temperatures, in harsh climatic conditions. One of their undoubted advantages is ease of installation. Prefabricated slabs are mounted quickly enough with relatively little labor. Their size makes it possible to cover fairly large areas of the structure in a short time. Difficulties may arise with the delivery of material to the construction site. For transportation, special vehicles with a high carrying capacity are used. To improve the quality, strength and reliability of products during production, special mixtures are added to the concrete solution.
