Monolithic cover. Floor slab: calculation, installation
Concrete or individual blocks, monolithic overlap can be done independently. It must be resistant to vibration, and also have a fairly impressive strength. You can install such a structure between floors and under the attic. The slab can take a wide variety of shapes, which eliminates planning restrictions when designing a house.
Preparatory work
Before you start work, you should know how the formwork is installed, reinforced by reinforcement, as well as finishing pouring. When it is planned to equip a monolithic ceiling, the calculation should be made exclusively for spans within three meters. Other situations are also possible. If we are talking about longer spans, then a beam monolithic ceiling is used. If you will be pouring a reinforced concrete floor of a monolithic type, then you will have to make a concrete reinforced slab, the dimensions of which will be calculated taking into account the design parameters of the building. As an average calculation, a value of 1 to 30 can be taken into account. This suggests that for a span of 6 meters, a slab with a thickness of 200 millimeters will be needed.
Formwork calculation
Before a monolithic floor slab is poured, it is necessary to calculate the formwork. You can use a certain scheme for this. It takes into account the layout of wooden formwork beams and the placement of telescopic props. But you can use the ratio that was presented above.
Arrangement of formwork for pouring a monolithic slab
Monolithic overlap is poured into the formwork, which is based on a tripod. They allow you to install racks on uneven ground.
Monolithic overlap should begin to be equipped after support posts have been mounted over the entire surface of the site. The distance between them is determined according to the scheme, which takes into account the load created by the overlap. In this case, the thickness of the structure is taken into account. A unifork is installed at the upper end of the racks. The longitudinal beams are mounted, which are strengthened to the walls. On top of the beams, which are located along, transverse beams are mounted. On top of the latter, waterproof plywood is covered, which can be replaced with steel shields.
The monolithic floor slab must be perfectly horizontal, therefore, in the end, the structure must be checked using the building level, and if necessary, the height must be adjusted by adjusting the racks. In order to prevent the leakage of cement mortar, which can seep through the cracks, roofing material should be laid on the formwork flooring. These manipulations must be performed before pouring the solution.
Floor slab reinforcement
After the calculation of the monolithic overlap is made, you can proceed to further work. The pouring is preceded by a reinforcement procedure. For this, reinforcement should be used, the diameter of which varies from 8 to 16 millimeters. In this case, the grid cells can be square and have sides equal to 150 or 200 millimeters. After the reinforcing mesh is connected, it must be placed five centimeters higher in relation to the lower plane of the future slab. Strengthening with a mesh of the lower and upper parts of the slab can be done using rods that have different diameters.
The device of a monolithic floor quite often involves the use of rods of more impressive sizes when it comes to lower reinforcement. This is due to the fact that the monolithic slab works on bending. The reinforcement should be joined with some overlap, while the joints should be spaced apart.
Carrying out the pouring of a monolithic slab
The device of a monolithic overlap at the next stage involves pouring. At the same time, one cannot do without the use of special equipment, which is a concrete pump truck.
Filling technology
When choosing a brand of material for pouring the floor, you should prefer the one that is determined by the value "400". The concrete mixture should be poured in layers, the thickness and pouring period of each layer will depend on temperature factors that affect the setting time. It is important to take into account the depth of vibration processing. If the mixture is subjected to compaction using a manual vibrator, then the filling should be carried out at 1.25 of its working part. The entire thickness of the monolithic floor should be subjected to such an impact. In this case, the deep vibrator must be immersed through the last layer, penetrating 15 centimeters deep into the previously laid layer. During the entire pouring, it is necessary to analyze how integral the formwork remains, as well as its strengthening and supporting elements. When monolithic reinforced concrete floors are poured, the formwork must be constantly checked for defects. If any, then the supply of concrete mix should be stopped. This will eliminate the occurrence of flaws. Concreting of floors should not be carried out without technological breaks. In this case, it is necessary to make working seams. They are arranged exclusively in those places where there is the smallest bending moment.
Final works
As soon as monolithic reinforced concrete floors harden, and also gain their strength, which takes about 30 days, the formwork can be dismantled. If the second floor slab is being concreted, then even partial dismantling of the formwork props that hold the first floor slab is unacceptable ahead of schedule.
Features of the work
It is worth noting that pouring a monolithic floor is considered not the easiest and cheapest option to implement, but in the end it is possible to obtain a structure that is versatile and durable. This makes the monolithic reinforced concrete floor the most popular among the rest.
If the installation is done by hand, then moisture-resistant plywood is used for formwork, the thickness of which should not be less than 2 centimeters. As for the formwork boards, this parameter should not be less than 2.5 cm.
When erecting a building, in some cases there is a need to arrange a reinforcing element, which is called a belt. In this case, the reinforced concrete tape runs along the perimeter of the building and acts as a support for the structure.
In order to raise the mesh during the formation of the reinforcing layer, special stands made of plastic are used. The second layer of the mesh should be laid out at the same distance from the upper plane of the future structure. To fasten two layers of meshes at the right distance, it is necessary to prepare special stands, which are made of reinforcing bars. All mesh layers and elements must be interconnected with wire.
It is important not only to reinforce the monolithic floor to obtain a reliable structure, but also to moisten after pouring, which is carried out within a week. Then constant hydration will no longer be required. However, it is still necessary to control the drying of the surface.
Prefabricated floor slabs
Quite often, the basement floor is made of prefabricated slabs, which are reinforced concrete products manufactured in a factory. In this case, the calculation of a monolithic overlap is not required. Such structures can be hollow or full-bodied. Installation of prefabricated slabs will be impossible without the use of a truck crane. These plates have other limitations, for example, expressed in the fact that factories produce structures whose length does not exceed 9 meters. This boils down to the fact that such slabs cannot be used for a basement floor with an impressive area. When laying the plates are mounted on a layer of mortar, the thickness of which is within 20 millimeters. After the installation is completed, the seams between the elements are cemented. These manipulations should not be delayed, as over time the gaps become clogged with debris.
Prefabricated-monolithic slabs
Quite often, prefabricated monolithic floors are also used, which have 4 elements in their composition. It is important to take into account their difference from those described above, which is expressed in the fact that such slabs can be laid without using a truck crane. Every master should note this for himself. Installation work should begin with the installation of reinforced concrete beams and laying blocks between them. The latter are laid out in one row from the two ends of the beams. This makes it possible to install the beams at the right distance from each other. After that, you can start working with the remaining blocks. Prefabricated monolithic floors must be reinforced, and then concreted.