Structures for the device of overlapping between floors of a building under construction are reinforced concrete products. They are made with concrete impurities from a number of heavy grades, lightweight structural concrete with a dense structure, and also from reinforced silicate concrete. The main application of the floor slab is in the construction of the bearing part of the horizontal planes of large-panel buildings. The payload on the product should not exceed the prescribed norms of 6 kPa, while the weight of the structure is not taken into account. Hollow core slabs should be laid on the base (wall) at a distance of at least 150-200 mm, provided that the support is stronger than the product itself.
Among the main types of structures for the formation of overlap are the following:
- PPS - threaded reinforced concrete slabs;
- ribbed or with a trough profile;
- hollow (multi-hollow);
- monolithic.
Marking hollow core slabs means the following:
- 1P - concrete single-layer structures with a height of 120 mm;
- 2P - the same plate, but of a greater thickness (160 mm);
- 1PK - multi-hollow (220 mm), inside of which there are round voids with a diameter of 159 mm;
- 2PC - the same plate, cavity diameter - 140 mm;
- PB - multi-hollow with a height of 220 mm, the method of formation - without the use of formwork.
Hollow core slabs , the sizes of which are within the standard, remain one of the most convenient building parts. They do not ignite, do not rot, are extremely strong and reliable, and are resistant to moisture.
The dimensions of the floor slabs consist of parallelepiped parameters, inside which there are voids in the form of cylindrical pipes. The presence of these containers gives the structure the property of bending stiffness, which makes it possible to withstand significant loads. Moreover, the voids greatly facilitate the process of laying inside them all the possible communications during the construction of the building.
Standard overall dimensions of floor slabs are a solid guarantee of an adequate cost of reinforced concrete products. However, designs with dimensions beyond the usual can be created according to individual drawings. Although it is better for an economical developer to envisage the use of standard sizes due to the higher cost of manufacturing non-standard plates as a result of additional costs.
Typical dimensions of floor slabs with voids range in length from 2.4 to 6.6 m, which depends on the catalog with the series for a typical product. The usual width can be 0.6 - 2.4 m at intervals with different steps. The height (thickness) of the plates is taken at the level of 220 mm, and the total weight of the entire product is up to 2.5 tons.
The dimensions of the slabs of the hollow type PC are encrypted in the labeling of each product, and they should be understood in this way, for example, PC 72.15-8:
- PC means the following: a multi-hollow slab with round cavities with a diameter of 159 mm, a maximum height of 220 mm, both sides are intended to be supports;
- 72 - the length of the product in decimeters (that is, in millimeters - 7180);
- 15 - width in decimetres (or calculated 1500 mm);
- 8 - load that the plate can withstand, in kPa.