Why is this kind of overlapping used?
Reinforcement of slabs has several advantages. First - there is no need to resort to the help of construction equipment, in particular, a crane. The second, which is very important, this method allows you to make overlapping for rooms with non-standard sizes. And the third is the strength of the structure. Monolithic overlap is much stronger than wood floors, it can withstand high stresses and fireproof. So, the overlap of a tree is able to withstand 25 minutes of fire, and monolithic - more than an hour.
Note! Monolithic overlap can be done by one's own hands, however, an accurate technological calculation of its load is necessary.
In the construction of private facilities, the use of monolithic ceilings is common. When installing this overlapping, the correct calculation and use of the reinforcement plays an important role. The thickness of the plate is calculated with respect to the thickness of the span and is taken in the ratio 1:30.So, if the width between the span of bearing walls is 6 meters, then the thickness of the monolithic plate will be 0.2 meters. If you specifically reduce the thickness of concrete, then increases the consumption of metal, if the thickness increases, the consumption of concrete, too, becomes greater.
ABC of ceiling mounting
Reinforcement of a monolithic floor slab occurs using a reinforcement with a cross section of 8 to 14 millimeters, depending on the design load. If the slab thickness is less than 150 millimeters, it is possible to make the reinforcement in one layer, if the thickness is more than 150 millimeters, the reinforcement is carried out in two layers.
In this case, one reinforcement mesh lies at the bottom of the plate, and the other - in the upper part. In the grid, the reinforcement is connected by wire. The size of the cells is made in 150x150 mm or 200x200 mm. All grids are created from rods of the same cross-section. Additional reinforcement is used in some places:
- In the middle part of the plate the lower grids are used;
- The upper grids are used on the supports;
- In the places of accumulation of load and hole - separate areas of concentration of voltage.
Additional reinforcement is done with the help of separate rods 400-1500 millimeters long, depending on load and spans. Often, a solid primary reinforcement is used, and an additional core is used only for holes. Note! It is recommended to make the formwork for the entire length.
An important stage in monolithic slab installation is the installation of formwork. Wood can be used for this purpose. The forms of the formwork are fixed firmly and reliably, because the weight of concrete can reach 300 kilograms per square meter. For the formwork a protective layer of reinforcement is used, at least 20 millimeters. For this, supports are placed under the grid in the formwork. Further, the entire structure is poured with concrete M200, and 4 weeks after complete drying, the overlap will be ready.
What forces act on the design?
The scheme for reinforcing the slab plate differs depending on the type of the product, but the general principles in reinforcement remain unchanged. This is due to the general method of operation of all reinforced concrete structures: the load is from top to bottom, and most often it is distributed over the entire surface area.
This principle indicates that the main working armature is the lower one, because the upper part of the structure receives compressive loads, which the concrete itself is perfectly tolerated. The lower part in turn experiences tensile loads, therefore it absorbs the main load force on the entire structure.
Standard reinforcement plate consists of:
- Working rods at the bottom of the plate;
- The working rods of the upper part( they are smaller in diameter or the same as the upper ones);
- Reinforcement, which redistributes the load;
- Stand for wire rod.
Important! Reinforcement schemes may vary, so it is necessary to consult a specialist.