When building walls from aerated concrete, there comes a time when you need to take care of the construction of floor floors, they can be made of wooden beams or concrete slabs. If we compare with buildings erected from brick, then when installing floor slabs on the walls of foam and gas blocks, a reinforcing belt should be located that will distribute the loads.
Monolithic slabs
Monolithic overlap in the house of aerated concrete can be performed using a reinforced concrete slab. This technology is used today in the field of construction by private craftsmen and professional teams. The grounds are strong and reliable, but they have an impressive weight, which should be taken into account when erecting walls from building blocks. In order for the slabs to be evenly distributed by their weight and not violate the integrity of the system, when installing floor slabs, an additional structure should be made that looks like a concrete or brick belt. In the first case, the slab rests on a concrete tape measuring 150x250 mm. It is placed around the perimeter of the wall. The tape is reinforced with reinforcement with a diameter of 10 mm. At the next stage, concrete M-200 is poured.
When a monolithic ceiling in the house is made of aerated concrete, a temperature 2-cm gap should be left, which should be located between the end of the reinforced concrete slab and the wall. To eliminate the cold bridges, the reinforcing belt and the plate are additionally insulated, and extruded polystyrene foam plates can be used. It is best to choose those that are 50 mm thick. The second option, which involves the use of a brick belt, involves masonry of red burnt bricks. It is laid in three rows. This option is the most common when the distribution belt.
Brick belt
In this case, there is no need to equip the formwork, it is enough to form a reinforcing frame of rods. However, before laying bricks, wall blocks should also be reinforced with reinforcement. To do this, you need to make the grooves, laying reinforcing bars in them and filling them with cement mortar. The masonry is reinforced with a masonry net, which is located between the rows. A reinforced concrete monolithic slab should go 14 cm deep into the wall. This will be enough to ensure rigidity and stability of the structure.
Features of the monolithic belt device
A monolithic overlap in a house made of aerated concrete may include a monolithic reinforcing belt. For a building made of aerated concrete, this part of the work is mandatory. Among other things, it plays the role of load distribution from floors, walls of the upper floor and the payload from interior items, people and equipment. The reinforcing belt will compensate for the lack of aerated concrete, which is expressed in the ability to work in bending.
Despite the fact that aerated concrete is able to undergo compression, the absence of a reinforcing belt will cause an uneven load on the bearing walls. As a result, cracks may appear in them, as a result of which some blocks may even burst. For the device of a strapping or reinforcing circuit, heavy types of concrete and reinforcement should be used, the last of which corresponds to class A III.
A monolithic ceiling in a house made of aerated concrete may have a reinforcing belt, which is equipped with one of the existing methods. It can be as follows: concrete blocks must be mounted on the outer edge, sometimes silicate brick is used as an alternative solution. Between the edge of the floor and these products fittings are laid, it must be bandaged. You need to choose a material with square cells, the side of which corresponds to 10 cm. The external and internal corners should be fixed with steel brackets, after which the reinforcing belt must be filled with concrete.
The choice of overlap for the house from the gas block
Interfloor ceilings in a gas concrete house can be prefabricated or monolithic. They can be arranged on metal or wooden beams using hollow core slabs of cellular, heavy concrete or precast-monolithic structures. A monolithic slab, which is made on the construction site, can act as the basis for the overlap. Wooden and concrete floors have their own advantages and disadvantages, however, given the popularity of aerated concrete, which is increasingly used in house building today, the following criteria come to the fore:
- construction speed;
- installation cost;
- material cost;
- the need for the use of special equipment.
Construction from aerated concrete, the projects of which can be found in the article, provides for the arrangement of the ceiling, the choice of which for maximum loads and strength characteristics, as a rule, is not relevant, because the listed types provide these qualities at a level sufficient for the category of construction objects. Thus, the calculated data range from 500 to 800 kg of load per 1 m 2 area. Interfloor ceilings in a house made of aerated concrete should be made of materials that have less weight and maintain strength characteristics at the proper level. They must have a long service life, low cost, resistance to external influences of a chemical or natural nature.
Monolithic aerated concrete floors
Low-cost houses made of aerated concrete can be supplemented with aerated concrete floor slabs, which have the same characteristics and properties as walls. This choice can be called justified, especially if we take into account the thermal conductivity of materials, which turns out to be the same. Having settled on this option, you may prefer prefabricated monolithic structures, products that are reinforced aerated concrete slabs, or monolithic slabs. In the first case, during installation, it is necessary to reinforce with reinforced concrete joints.
Today on sale you can find floor slabs of aerated concrete, which are made to individual sizes. However, the average length is 6 m, and the width is limited to a range of 1.5 to 1.8 m. The thickness is 30 cm, the design load per 1 m 2 is 600 kg. Such plates are made only by the autoclave method, while their density corresponds to the limit of D500. Quite often, monolithic plates are supplemented with a tongue-and-groove connection, this allows you to obtain a tight fit of the elements to each other, while installation is performed in the shortest possible time. In one shift, a team of 4 people will be able to complete the overlap, the area of which varies from 50 to 120 m 2 .
During installation, the most crucial moment is the coordination of the timing of the manufacture of plates, the rental time of the crane and the period of transportation of the material to the site. If the house has aerated concrete walls, then precast monolithic slabs, which are assembled from T-shaped blocks, can be used as a ceiling. In this case, lightweight reinforced concrete beams are used , the length of which is 7 m and the height is 20 cm. The weight of the structure is approximately 120 kg, which allows installation without the use of construction equipment. The distance between the beams should be 68 cm, which provides support for the beam on each side, this is true if the length of the block is 60 cm.
When installing the first row, one side of the floor block will rest on the supporting wall of the building. The joints formed between the blocks will look like grooves, they are filled with concrete, its class must correspond to B20. As soon as all the floor blocks are in place, you should connect the reinforcing mesh, which is poured with a 5 cm layer of concrete. Its full setting will occur in 4 weeks, however, it is possible to partially load the structure after 7 days.
What floors to choose for a house from a gas block
If you are thinking about the question of which floors are better for a house from a gas block, then you should pay attention to the wood. It is the most preferred option for lightweight wall blocks. Such ceilings are lighter than concrete, they have less pressure on the walls during operation, and the design is simpler. Among other things, the cost of wooden logs, taking into account delivery and installation, will be less than the cost of reinforced concrete floor slabs. There is no need to hire an expensive crane, because everything is possible to do without the use of technology. Using wooden floors, it can be noted that installation is simpler. To do this, it will be enough to make a reinforcing belt, as is the case with concrete slabs. Beams will be laid on it. The lags before installation are covered with an antifungal compound, they will rest on the walls. They are wrapped with roofing material or any other waterproofing material. It is recommended to make a gash of the end of the beam, while the angle should be 60 °. In parallel, the insulation is laid. A 2 cm gap is left between the wall and the end, which is necessary for thermal expansion. Wooden logs are laid in the wall, they should be deepened by 15 cm.
Dimensions and cost of aerated concrete blocks
Aerated concrete blocks, the sizes and unit price of which will be indicated below, are used in construction today more and more often. The cost per piece is 130 rubles. The more massive the blocks are, the faster it will be possible to complete the construction. Material for the construction of walls will cost in the range from 3100 to 3600 rubles. per cubic meter. The standard length is 600 or 625 mm, the width can be 250, 300, 375, 400 or 500 mm. As for the height, it can be equivalent to 200 and 250 mm. Aerated concrete blocks (dimensions and unit price are discussed in the article) can also be designed for partitions. This material is sold at a price of 3200 rubles. per cubic meter. The main height and length remain the same as in the case described above, but the width can be equal to 50, 75, 100, 125 and 150 mm.
Calculation of maximum plate bending
The maximum thickness of a monolithic floor for aerated concrete walls of the house was mentioned above. The estimated load per 1 m 2 is also known, which is why it is possible to calculate the maximum bending of the plate. To do this, you should know the design resistance of concrete, the design resistance of the reinforcement and the class of reinforcement rods. The first parameter is Rb = 7.7 MPa, the second is Rs = 365 MPa, while the class of reinforcement used is A400C.
The distance from the edge of the plate to the reinforcement is 35 mm, the maximum bending moment should be calculated by the following formula: M = q * L 2 2/11. M = 695 * 2.52 / 11 = 395 kg / m. If the overlap has a lower reinforcing mesh, then it must fulfill the conditions under which am is less than ar. The second parameter is normative and is 0.440. While am is equal to M / (Rb * b * h02), here b is the width of the ceiling, which is 6 m, but h0 is the distance from the center of gravity of the reinforcement to the edge of the plate, which is 0.045 m. Moreover, am is 395 / (77000 * 6 * 0.0452) = 0.042. A value of 0.042 is greater than 0.440. If am is greater than ra, then there is a need to increase the concrete grade or increase the reinforcement cross section.
Based on the foregoing, it can be argued that the calculation of a monolithic overlap can be carried out by you yourself.
Why you should use a monolithic overlap
Despite the fact that today several types of ceilings for walls made of aerated concrete have been developed, monolithic ones have many advantages. They are chosen no less than wooden prefabricated monolithic ones. A monolithic overlap device is advisable, because such designs:
- economical;
- durable
- easy to install;
- fireproof.
It should also be noted the wide availability of materials for work. The only thing to pay attention to is that self-prepared concrete in private construction is not suitable. It is recommended to order it, because in production there are certain requirements and standards controlled by the state. If you perform the concrete yourself, then you cannot guarantee that it will meet the standards, it will be reliable and durable.
The device of a monolithic overlap may be accompanied by some difficulties, which are expressed in the fact that concrete will have to be raised to a great height. Therefore, there is a need to rent a concrete pump. Difficulties are also expressed in the fact that over the entire area it will be necessary to equip the formwork. It is made of durable and high-quality material that will be able to endure the weight of the concrete mix. There will be 500 kg per square meter, this is true if the concrete layer is 15 cm.
Conclusion
Concrete floors are arranged using formwork made of materials that must have a certain margin of safety, because the load will increase when pouring from a concrete pump. Experts advise using a square beam with a side of 100 mm for this. Plywood panels, the thickness of which varies from 18 to 20 mm, act as an alternative solution. As soon as the formwork is ready, you should make sure that it is horizontal using the building level.