Structures for the device of overlapping between the floors of a building under construction are reinforced concrete products. They are made with concrete admixtures from a number of heavy grades, light type structural concrete with a dense structure, as well as from reinforced silicate concrete. The floor slab finds its main application in the construction of the bearing part of the horizontal planes of large-panel buildings. The payload on the products must 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 a 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 forming the floor are the following:
- PPS - cut reinforced concrete slabs;
- ribbed or with trough profile;
- hollow (multi-hollow);
- monolithic.
Marking of hollow core slabs means the following:
- 1P - concrete single-layer structures with a height of 120 mm;
- 2P - the same plate, but thicker (160 mm);
- 1pc -multi-hollow (220 mm), inside which there are round voids with a diameter of 159 mm;
- 2pcs - same plate, cavity diameter - 140mm;
- PB - multi-hollow with a height of 220 mm, the method of formation - without the use of formwork.
Hollow core slabs, whose dimensions are within standard limits, remain one of the most convenient construction details. They do not ignite, do not rot, are extremely durable and reliable, and are resistant to moisture.
The dimensions of the floor slabs consist of the parameters of a parallelepiped, inside of which there are voids in the form of cylindrical pipes. The presence of these containers gives the structure the property of bending rigidity, which makes it possible to withstand significant loads. Moreover, voids greatly facilitate the process of laying all possible communications inside them during the construction of a building.
Standard overall dimensions of floor slabs are a solid guarantee of adequate cost of reinforced concrete products. However, structures with dimensions outside the usual ones can be created according to individual drawings. Although it is better for the economical developer to consider the use of standard sizes due to the higher cost of manufacturing non-standard slabs as a result of additional costs.
Typical dimensions of floor slabs with voids range from 2.4 to 6.6 m in length, which depends on the catalog with a series for a typical product. The usual width can be 0.6 - 2.4 m at intervals with different steps. 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 PC hollow core floor slabs are encrypted in the marking of each product, and they should be understood in this way, for example, PC 72.15-8:
- PC means the following: hollow core slab with round cavities 159 mm in diameter, maximum height 220 mm, both sides are intended to be supports;
- 72 - product length in decimeters (that is, in millimeters - 7180);
- 15 - width in decimeters (or calculated 1500 mm);
- 8 is the load that the slab can withstand, in kPa.
