Reinforcement reception is common in almost all areas of construction. With its use make steps for stairs, porch made of concrete, monolithic slabs for floors. The essence of reinforcement lies in the organic combination of different materials into a single whole. For example, reinforcement and concrete. Concrete has, by its very nature, very high strength, but it is too brittle for fracture. The metal, which is a part of the armature, is elastic. Therefore, the combination of these two materials creates a kind of synergy, that is, the properties of reinforced concrete are much better and more useful properties of concrete or metal separately. Reinforced concrete is able to withstand such vibrations and vibrations that will never carry ordinary concrete. In its essence, the armature plays the role of a skeleton for concrete products, because without it, it would simply crumble to pieces at the first load.
What you need to know about the reinforcement of the
floors For reinforcing concrete use reinforcing steel rod. Its thickness varies from 8 to 14 mm with a plate thickness of up to 150 mm.when buying ready-made slabs, it is necessary to take into account the fact that they are produced in factories as solid, ribbed and hollow. Especially popular is the latter option. This is due to the fact that, thanks to the voids inside the concrete monolith, such slabs have a relatively small weight, excellent thermal insulation, poor sound permeability, and also withstand deformation well.
Manufacture of slabs made of heavy concrete. Their standard dimensions are characterized by three values: length - 4, 5 or 6 m, thickness - 140, 180 or 220 mm, permissible load - 150, 190 or 230 kg / m2.
It should be understood that the purchase plates during the laying always form joints, which can be stepped, which negatively affects the evenness of the surface formed by them. If we make the reinforcement of a monolithic slab overlap with our own hands, then we will get a uniform and even surface without joints.
What are the possibilities of reinforcing the
? Application of reinforced concrete structures allows not only to insulate the building, but also to accelerate the process of its erection. Relatively small weight of slabs with reinforcement reduces the load on the foundation. The very same design turns out to be strong enough and can sustain not only a long and considerable stress, but also a serious impact of fire. In case of fire, reinforced concrete slabs keep the building for an hour, while the wooden crumbles within 25 minutes.
The use of monolithic floor slabs with fittings makes it possible to erect buildings and structures with any degree of complexity. With their help, you can easily adjust geometric features of the room, as well as create non-standard overlapping, both in size and shape. Since the supports for such boards are not only the walls of the building, but also various arches with columns, the planning possibilities increase at times.
How you can make a monolithic slab of
with your own hands In the construction literature you can find a very simple formula, with which it is easy to calculate the thickness of the overlap. Take the length of the span and divide it by 30. The result obtained is the optimal thickness of the future plate. The classical scheme for reinforcing slabs involves placing the working rods in the upper and lower parts of the slab. This redistributes the load of all the reinforcement and supports from the rod. With a plate thickness of less than 80 mm, it will be sufficient to use a wire mesh, not a reinforcing bar. Only it is necessary to make it so that it is inside the monolith. For this purpose, the mesh is raised 2.3 cm above the surface to be poured.
The reinforcing bar is connected with each other by wire or by welding. The first way is faster and more convenient. For binding use a special hook, which you can make yourself, and you can buy in the store. In the case where the board assumes a thickness of about 150 mm or even more, two layers of reinforcement will be required. Layers are made one on top of the other, fastening together with crosspieces. The size of the resulting cells should vary from 150 to 200 mm. For normal strength when self-made slabs, it is worth using a rod with the same cross-section. In order to increase the strength even more, it is possible to tie the reinforcement with rods from 40 to 150 mm in length to the main structure.
The distribution of the load on the entire structure occurs in such a way that the main part of the load falls on the bottom layer of the reinforcement. In this case, the top layer is susceptible to compressive influences like concrete. Reinforcement is made by pouring concrete into the formwork over the entire surface of the floor.
In general, the whole process of creating a concrete floor slab is divided into three components: installation of formwork, reinforcement and pouring of concrete. Consider them all.
Formwork for pouring monolithic overlapping resembles a horizontal "deck" of a special moisture-proof plywood, the thickness of which is 18-25 mm or a 40 mm thick, close-cut board. Install it on a reliable supporting beams from a wooden beam( 80-100x100 mm), located horizontally.
Horizontal bar beams are supported by strong vertical posts that are ready, special( telescopic) or prepared independently from a solid 100x100 mm log, a round log having a diameter of 80-100 mm, and also strong metal pipes or a channel.
To determine the need for materials for the construction of formwork, you need to calculate the area of the entire floor and its thickness. The latter is 10 to 20 cm, depending on the width of the span and the load planned for future operation. The strength of the formwork should be such that, without the slightest deformation, it is possible to withstand the weight of concrete and the reinforcement to be embedded in it. With a slab thickness of 20 cm, the weight of the resulting slab is about 500 kg per m2.Surface formwork is best done from ordinary or laminated 20 mm plywood. When using plywood with a laminate coating, you get an ideally smooth ceiling, which does not require a large amount of finishing work. The height of the formwork is determined using a level or a building level. To do this, beat off the horizontal line, which should correspond to the height of the future overlap, along the perimeter of the entire span.
When using telescopic racks, they are installed primarily along the edges, using tripods and machines( crowns).The rails are installed in the longitudinal direction of the beam at a distance of 2 m. Only after this, you can install intermediate racks. It is not necessary to do tripods at all. Usually it is enough to equip this structure with 30-40% of the racks. The distance between the intermediate supports is made from the calculation of the thickness of the overlap and the thickness of the racks themselves. Averaged over one rack with a load of 900 - 1200 kg should be allocated no more than 1 m2 of formwork.
If it is decided to use self-made racks, then their length should correspond to the height of the installation of the lower part of the longitudinal beams. Install self-made racks in steps of 1 m on a solid foundation or thick trimming boards with a sufficient area. Longitudinal logs are placed transverse at a distance of 0.5 m from each other, and sheets of thick plywood are placed on top of them. The upper surface of this structure must be strictly horizontal and correspond to the previously fixed level.
When applied to the upper part of the timbering of edging boards, they must be aligned closely, and a dense polyethylene film or roofing material should be placed on top of them. Along the entire perimeter of the timbering formwork, a side of the uniform height corresponding to the thickness of the ceiling is mounted. At the corners it must be securely connected.
How to independently reinforce a concrete slab
Class A3 steel reinforcement is produced by the hot rolling method. It is 8 to 14 mm in diameter with a smooth or ribbed surface. It is best suited for the independent creation of a monolithic reinforced ceiling. The first grid is mounted in the lower part of the proposed plate, and the second one is respectively in the upper one. The formwork must be exposed in such a way that both grids are inside the plate monolith. The distance from the top grid to the surface should be at least 2 cm. In the grid, the reinforcement should be tied with a knitting wire, forming cells with sides of 200 or 150 mm. Today there are special machines for binding reinforcement, but you can do this with a conventional hand hook.
fittings The use of a welding machine is advisable only when you are good at handling it, because inept actions can lead to the thinning of the rods in the welding places, which will necessarily lead to destruction. Through the entire length of the grid there should not be any breaks, so if the length of the rods is insufficient, they should be lapped at least 50 cm. At the same time, all joints must be staggered. On all edges of the grid are connected in U-shaped figures. You only need to bend the rods if you need it without heating. Recalibration of metal disrupts its internal structure, which can lead to fracture of the rod. In those places where additional loads are assumed, reinforce in a special mode with additional rods. When reinforcing, one should take into account those places where engineering communications will take place. If possible, it is best to immediately leave the holes by inserting a piece of pipe. Particularly requires the reinforcement of the entire support area on the walls and columns. In the latter case, the amplifications must be volumetric.
Pouring of concrete mix
After all the mesh from the fittings is connected, you can start pouring it. For this, it is best to use a concrete pump. If the amount of work is not very large, then it is quite possible to manage without it. In this case, you will need at least two assistants who will mix concrete in the concrete mixer and lift it to you for pouring. In the process of filling the formwork with concrete mortar, it is necessary to periodically compact the mixture. The best construction for this is a special construction vibrator, but if you do not have one, you can simply tap it with a hammer on the formwork or open parts of the reinforcing mesh from time to time.
During the process of solidification, considerable shrinkage of concrete occurs, which can lead to the appearance of microcracks during the accelerated drying process. In this regard, for several days, the slab should be poured with water, especially in hot weather. However, you need to know that water should be sprayed from a hose with sprinkler nozzle or watering can, as a direct jet can damage the surface of uncontaminated concrete. Sometimes to avoid the appearance of cracks under the lowest layer put a special polymer mesh, and the rest of the construction is already built on top of it. In other cases, the polymer mesh is used as the main reinforcing element. This is done where it is impossible to build reinforcement from rods and even wires.
Full hardening of concrete will occur no earlier than 3 to 4 weeks. Until that time, it is not worthwhile to do any work on the site and disassemble the formwork. After this period, the formwork is dismantled and a concrete slab is produced, which is a rough ceiling for the premises below it. In this way, you can create even curved overlaps of any configuration.
When building your own house or cottage it is quite possible to create independently concrete slab ceilings with fittings inside. This construction is much more reliable and durable than wood, but it is only to be built on strong concrete or brick walls. The use of light concrete blocks or wood as a wall material excludes this possibility, since such walls can not withstand the weight of the reinforced concrete floor.