In the implementation of the processes associated with the construction of residential buildings and industrial buildings, high-quality reinforced concrete floors are used that are installed between floors. At construction sites, stacks of similarly constructed concrete products are stacked in appearance. It is difficult for an ordinary layman to see the differences among them. Only designers and builders are able to confidently separate hollow (multi-hollow) PB floor slabs in appearance from similar PC panels.
What are they and where are they used?
Reinforced concrete panels PB are widely practiced in the construction of industrial enterprises, as well as for overlapping floors of concrete floors of structures and residential buildings. The slab of reinforced concrete PB includes high-strength concrete, pre-tensioned reinforcing ropes, contains oval voids, has dowels on the side face. The PB panel makes it possible to create a horizontal concrete flooring, withstands high stresses, is designed to retain heat in rooms, and reduces noise.
The voids passing along the panel allow you to lay electrical wiring, and also reduce the mass of the structure, thereby reducing the load on the walls of the structure.
Reinforced concrete slabs PB are practiced in:
- frame construction;
- panel housing construction;
- prefabricated monolithic housing construction;
- the construction of buildings of stone, wall panels, blocks, bricks;
- low-rise buildings, the construction of household facilities and estate-type facilities.
Currently, there are thousands of samples of plate products manufactured in accordance with GOST 9561-91, which are divided according to the production methodology (conveyor, aggregate-flow, formwork-free), materials, durability and structure. The most common PC and PB boards.
Consider the features of this product in more detail.
- PB floor slabs are manufactured using a non-formwork method using special equipment using vibration sealing. The creation of products of the required length occurs by cutting concrete in the stage of solidification on the conveyor line with constant movement of the concrete mass. The footage into which the PB panel is cut is dependent on customer requests and is at most 12 meters. During the external inspection of the end part, it is easy to see that the PSU panel is reinforced with ropes. The plates are reinforced with strong steel reinforcement, guaranteeing high strength characteristics.
- A product marked with a PC is produced by filling concrete formwork with iron formwork with reinforcing bars and nets. The formed base is subjected to vibration compaction, heat treatment with further extraction of a fully finished structure. Length is not more than 7.2 meters.
PB and PC panels have a significant difference related to the specifics of the manufacturing process.
PB floor slabs made by continuous formless formation of a concrete massif without the use of formwork are known for good technical characteristics:
- high soundproof parameters;
- flawless external surface;
- the ability to withstand impressive mechanical stress, shock;
- an impressive margin of safety;
- possibility of application in various climatic regions;
- reduced weight;
- good heat-shielding characteristics;
- an extensive range of lengths of structures, predetermined by the specifics of production technology;
- the presence, if necessary, of an oblique cut of the end surface;
- resistance to penetration deep into the concrete massif of moisture, activating corrosion.
Panels must be manufactured in accordance with the requirements of this standard and technological documents approved by the manufacturer, according to the working drawings of projects of structures (buildings) or standard structures.
It is permitted, by agreement between the manufacturer and the customer, to manufacture panels that differ in size and type from those specified in this standard, while following the rest of the requirements of this standard.
Plates PB are made according to a relatively new method of molding on stands without the use of molds. A key feature is the use of prestressed reinforcement, regardless of length, and, of course, concrete of class M-400 and higher. Decoding marking is similar to PC.
The width depends on the stand on which the molding is carried out, it is mainly 1.2 meters, but there are tracks of a different width. Only a plate of 12 decimeters is more convenient for filling the averaged opening.
The length is rather inconsistent and varies from 1.8 to 12 meters, it all depends on the height (thickness) of the panel and the resulting load. Basically, a standard load of 800 kgf / m2 for a thickness of 220 millimeters using this technology can be made up to a length of 9.6 meters. After that, the ultimate load of the structure decreases, or the height of the plates increases.
The most common dimensions of the width of reinforced concrete panels in the factories of reinforced concrete products are: 10, 12, 15 decimeters, in other words, 1 meter, 1.2 meters and 1.5 meters. The most common parameters for the lengths of PB panels: from 24 decimeters to 90 decimeters.
The hole configuration, diameter, and the distance between them are set by the equipment manufacturer and the project. For any enterprise, these standards are individual. Typically, round holes have a slightly smaller diameter, for example, 150 millimeters, in order to guarantee reliability at the pressure of the wall located above the ends without the use of auxiliary reinforcement.
Reinforced concrete panels with a length of more than 100 decimeters (in other words, more than 10 meters) can be made according to the buyer's individual application and drawings of the plates, and in addition, PB panels can be made in other required sizes.
Advantages and disadvantages
PB panels have many positive qualities.
- Due to the presence of voids that dampen the vibration processes, good noise insulation properties are supported, reducing the consumption of raw materials, and facilitating the entire structure. This property applies equally to PC panels.
- Excellent quality of the outer planes, uniformity and smoothness.
- Impeccable configuration of the finished design.
- An impressive selection of sizes.
- Ability to purchase a panel designed for a variety of loads. These floor panels are capable of carrying a load of 600 to 1 thousand 450 kilograms per m2.
- Prestressing steel reinforcement in a plate of any length.
- Fire resistance and moisture resistance.
- The ability to cut panels at an angle of 45 degrees to overlap objects of a non-standard configuration, which makes it possible to reduce the number of monolithic zones in a precast-monolithic overlap.
But there are also disadvantages.
- The absence of hinges for installation makes it difficult to bond structures together and the procedure for mounting them in the intended position. There is a need to use a chalk.
- It is impossible to punch holes in PB panels because of the small width of the holes, which complicates the construction of house communications compared to PC boards, the round configuration and rather large void diameter of which will make it possible to punch holes for the pipeline without touching the reinforced partitions.
For comparison, the width of the holes that have PB formwork slabs of 60 mm, while for the panels of the PC series, the width of the hole is 159 mm. This makes it possible without complications to pass through them pipes with a diameter of 100 mm.
At times, experts allow punching holes for low-rise buildings, but such an operation is undesirable.
Marking and decoding
Information in the form of inscriptions on the structures of the floor slabs designates that these are panels that were manufactured at the enterprise of reinforced concrete products using the latest continuous formless molding technique using vibration exposure to the concrete mix for the current period.
Sample marking reinforced concrete panels ПБ 63-15-8 and decoding:
- PB - plate produced by formless molding;
- 63 - length, decimeters;
- 15 - width, decimeters;
- 8 - load in kPa (kilopascals) (kgf / m2 - kilogram / force per square meter);
- panel thickness - 220 millimeters.
So, we learned that reinforced concrete floors made of hollow (multi-hollow) panels of the type PB are the best option for solid construction and a universal solution that will make it possible to build you exactly the house you planned.
About what properties PB slabs have, see the next video.