Overall dimensions of floor slabs. What are hollow slabs
Currently, 3 types of multi-hollow floors are most common, differing not only in name, but also in the method of manufacture, as well as geometric dimensions:
- PC - typical,
- PB; PPS - bench molding,
- 1.6PB; PNO; PBO - lightweight.
In this article, we will consider what geometric dimensions each of these types have, as well as the diameter and location of the holes.
PC board dimensions
These are the most common panels, which are produced in metal molds, with mesh (length up to 4.2) or prestressed (over 4.5) reinforcement. Product marking contains geometric dimensions in length and width, as well as the load and sometimes the method of reinforcement. For example, PC 51-18-8. Length 5.1, width 1.8, load 800 kgf/m2.
Standard panel width can be 1; 1.2; 1.5 and 1.8. Most often there are plates of 12 and 15 dm. Usually, they can dial any required width of the opening. Deviations in this dimension cannot exceed 6 mm.
The length, as a rule, varies from 1.8 to 7.2 meters, but there are panels up to 9 meters. The actual length is always less than the nominal length, i.e. indicated in the marking, by 2 cm. This must be taken into account when calculating the support of the slab on the wall. The maximum deviation is 8 mm for lengths up to 4 meters and 10 mm for longer products.
Panels are usually produced with holes with a diameter of 159 mm. In terms of GOST, this is a 1PK slab. The distance between the holes is 185 mm from center to center of the voids. It must be understood that these are the figures laid down by the State Standard, the actual sizes of specific manufacturers may differ from those declared.
Dimensions of floor slabs PB
These panels are produced using a relatively new bench molding technology without the use of moulds. The main feature is the use of prestressed reinforcement, regardless of the length, as well as the concrete grade M-400 and higher. Decoding marking is similar to PC.
The width depends on the installed stand, as a rule, it is 1.2 meters, but there are tracks of other widths. Just 12 dm is the most convenient for filling the average opening.
The length is very variable and can be from 1.8 to 12, depending on the load received and the height of the slab. As a rule, a typical load of 800 kgf/m2 for a height of 220 mm can be obtained with this technology up to a length of 9.6 meters. Further, either falls load bearing capacity or increase the thickness of the panels.
The diameter, shape of the holes, as well as the distance between them is determined by the equipment manufacturer and the project. For each plant, these parameters are individual. Usually round holes have a slightly smaller diameter, for example 150 mm, in order to provide pressure resistance of the overlying wall at the ends without the use of additional reinforcement
Size of lightweight floor slabs
If standard hollow floors have a thickness of 220 mm or more, then lightweight floor slabs are designed for a height of 16 cm, which imposes certain restrictions on the length of these products.
According to the standard manufacturing technology (using molds), Ryazan Plant No. 2 produces PNO panels up to 6.3 meters long and 10, 12 and 15 dm wide.
According to the technology of bench molding - lightweight 1.6PB and PBO, without a drop in bearing capacity can be up to 7.6 meters. Further already only smaller loading.
The diameter of the holes, of course, is smaller, and differs from manufacturer to manufacturer. So, for example, at the Voskresensky ZhBKiI plant, it is 102 mm.
For the construction of residential buildings, civil and industrial buildings, the use of overlapping structures is typical: wooden, monolithic reinforced concrete, as well as hollow core slabs made of reinforced concrete. The last products in this list have long attracted attention due to their features and advantages. The price of lightweight plates is quite democratic, while their quality is not inferior to full-bodied counterparts. Before choosing the type of overlap and its dimensions, it is necessary to calculate permissible load, get acquainted with the classification, purpose, technical and price parameters.
Hollow core slabs are regular-shaped rectangular reinforced concrete panels with longitudinal channels parallel to which reinforcement (steel ropes) is laid. Holes come in different configurations: cylindrical, pear-shaped, rectangular. The most popular are the options with six round voids with a diameter of 159 mm.
Standard sizes vary within the following limits:
- thickness - 22-30 dm;
- width - 9.9-35 dm;
- length - 11.8-98 dm.
Most often, structures of 22x15x60 dm are used in construction, which are mounted using a crane, the lifting capacity of which is not more than 5000 kg.
Plates are divided into three types:
- PK series - with round voids with a diameter of 114-203 mm, poured into the formwork;
- PG series - panel thickness - 260 mm, pear-shaped cavities;
- PB series - a product manufactured using advanced technology of continuous molding on special long stands; the standard thickness of the PB is 220, the diameter of the voids is 60 mm.
Reinforced concrete panels have a number of advantages compared to monolithic ones.
1. They significantly reduce the mass of building structures.
2. High sound insulation characteristics are achieved due to the fact that air cavities effectively dampen noise and sounds.
3. Voids perfectly serve as channels through which electrical communications (alarm, cables) are laid.
4. The air that fills the cavities plays the role of a heat insulator.
5. Installation of products (as opposed to monolithic floors) can be performed at low temperatures.
6. Reinforcement of floors with prestressed reinforcement helps to increase their endurance and strength.
Marking
The criteria for choosing reinforced concrete floors with internal voids are the design loads, the method of supporting the base, the type of concrete, the type of reinforcement, the dimensions, shape and dimensions of the voids. All these parameters are reflected in the plate designation.
1. Initial letters. They indicate the type of product - PC, PG or PB. PC overlaps are divided into 7 groups, features which are listed in the table.
| Designation | Thickness, mm | Hollow diameter, mm |
| 1pc (pc) | 220 | 159 |
| 2pcs | 220 | 140 |
| 3pcs | 220 | 127 |
| 4pcs | 260 | 159 |
| 5pcs | 260 | 180 |
| 6pcs | 300 | 203 |
| 7pcs | 160 | 114 |
2. Additional letters. Ceilings PB, PG and PK rest on the walls on two sides, but other reinforced concrete products are also produced. In the marking, this is marked with another letter: T indicates the possibility of relying on 3 sides (3PKT), K - on all four (for example, 2PKK).
3. Numbers. Linear dimensions of hollow core floor slabs. The first pair is the length in decimeters, rounded to the nearest integer (actually, 20 mm less). For example, if the number 63 is in the marking, then the size is 6280 mm. After the dot there is a second pair of numbers indicating the width of the product in dm, increased by 10 mm: for example, code 15 means a panel with a width of 1490. The final number (after the line) indicates the calculated load that the structure can withstand (in kilograms of force per m2), or its bearing capacity serial number.
4. Letter ciphers. If the panel is prestressed, then immediately after the numbers follows the steel grade of the reinforcement - for example, ATV. Next, the type of concrete is indicated: L - light, C - dense silicate, T - heavy (sometimes it is not marked).
5. Additional characteristics. They are indicated if the plate is designed for use in special conditions: with increased seismicity, aggressiveness of the gaseous medium. At the end are marked design features- for example, the letter a is set if the overlap has sealing liners at the ends.
Here is an example of marking a product of type 2PK 2680 mm long, 1290 mm wide with a design load of 3 kg C / m2, made of heavy concrete, reinforced with ATV prestressing reinforcement and intended for construction in seismically hazardous areas (up to 6 points): 2PK27.13- 3 ATV-C6.
Almost all panels supported on walls by two or three sides are reinforced with prestressed reinforcement. GOST 9561-91 allows not to mount it in such varieties:
- thickness - 220, length - 4780, cavity diameter - 140 or 159 mm;
- thickness - 260, maximum length - 5680 mm;
- thickness - 220, for any length and diameter of voids - 127 mm.
Use of concrete products with voids
Panels with through holes are most often chosen for arranging floors between floors in houses made of concrete, brick, cellular foam and gas blocks. The PB series is considered to be more perfect, plates of this type have a flat smooth surface, the technology makes it possible to obtain fully reinforced elements of different lengths, which, if necessary, play the role of "additional" products. Sometimes in such cases, workers fill the gaps between the formwork PCs or PG with a monolithic screed reinforced on their own. This design is inferior in strength to standard PB, the manufacturing process of which provides for vibrocompaction of concrete and its steam treatment.
The advantage of the PC is a rather large diameter of the channels. The use of products of this series is recommended if installation is planned. sewer pipes diameter 80-100 mm.
Price
The table shows the average price of different series of reinforced concrete hollow products from manufacturers in the Moscow region.
Company Floor designation Dimensions, mm Weight, t Cost, rubles Promstroizhbi PC 61-15-8 6080x1490x220 2,9 10 090 ZHBI-2000 PK 62-15-8 At800a 6100x1500x200 2,9 11 300 ZHZBK PC 63-12-8 6280x1190x220 2,2 8 900 (with delivery) SaviCom PB 66-12-8 6580x1195x220 2,33 11 100 – 11 870 Prices on reinforced concrete floors depend on the weight of the product, manufacturing technology, as well as the price policy of the supplier. Sometimes free delivery is offered in Moscow, more often the calculation of transport services is based on mileage. Seasonal promotions from manufacturers, wholesale orders, and the use of appropriate transport help to reduce the final cost.
Reinforced concrete floor slabs are not the most important cost item in construction. But you need to choose them no less carefully than other materials for your home. They are very strong and durable, but they are very heavy. Therefore, even in the project, it is necessary to accurately calculate what load the walls and the base of the building can withstand, and only then determine the type and size of the plates.
Types and their features
The weight of a reinforced concrete floor slab depends to a greater extent on its dimensions, to a lesser extent on the type and specifications materials. Concrete concrete dimensions are set by GOST, so all panels are standard. There are relatively few separate types, but they fully satisfy the basic requirements for the construction of any objects: from private houses to skyscrapers and huge industrial buildings.
1. Solid.
Monolithic floor slabs are distinguished by the largest weight, since they do not have large voids inside. And their mass will be the higher, the stronger the brand of concrete used in the manufacture. Such panels are divided into types by thickness:
- 1P - have a standard size of 120 mm and an average weight of 4.3 to 7.1 tons;
- 2P - a little more powerful (160 mm), so they can weigh up to 8.7 tons
The disadvantage of full-bodied products is the complexity of their installation. The reason for this is the rather large dimensions and weight of the plate. But after all, no one manually lays hollow structures, so this minus should not be seriously considered.
Another type of reinforced concrete products for floors is additional elements. They have a standard length, tied to the main parameters of manufactured full-size products (1800-5000 mm), but a small width. Despite the modest dimensions, the weight of a solid slab cannot be called small - up to 1.5 tons, that is, it cannot be lifted and installed without special equipment. But for non-standard buildings, their use is quite justified, as it allows you to assemble any overlap from panels of existing standard sizes.
2. Lightweight.
The weight of hollow core floor slabs is reduced due to through technological holes. Depending on their shape and quantity, three additional types are distinguished:
- PC - with standard round chambers with a diameter of 159 or 140 mm (marked 1PC and 2PCs, respectively);
- PB - multi-hollow, with various options for technological holes;
- PG - products of medium thickness (260 mm) with elliptical chambers.
An increase in the total volume of voids in the body reduces the mass and at the same time the bearing capacity. Nevertheless, thanks to the longitudinal air chambers, lightweight concrete products acquire excellent thermal insulation and acoustic properties. So for the formation of basement and floors residential buildings they fit perfectly. Hollow slabs can replace monolithic products if it is necessary to reduce the weight load on the base of the building. The mass of standard 6-meter floors, depending on the brand of concrete, ranges from 2.8-3 tons.
Lightweight ribbed ceilings are a separate group, although they are full-bodied. These are U-shaped slabs, in which the bearing capacity and resistance to bending loads are increased due to solid-cast stiffeners. They are widely used for the construction of particularly strong ceilings and flat roofs.
Ribbed ceilings are made from any grade of concrete - from light to extra strong. In accordance with this, their mass can vary within 20%. Middle plate standard size weighs about 1.5-3 tons, and 12-meter panels for industrial construction reach 4-7 tons.
Not so long ago, light options made of polystyrene concrete began to appear. The use of insulating material as a filler significantly improved the performance characteristics of finished products: heat and sound insulation properties, weight, machinability. Although the strength has decreased compared to traditional reinforced concrete products, it is quite enough to cover their performance of 400-500 kgf / cm2.
A cubic meter of polystyrene concrete, even taking into account reinforcement, weighs about 1 ton, which is almost half that of standard full-bodied reinforced concrete panels, although it slightly exceeds the same indicator for hollow products.
Weight and prices
The cost depends not only on the mass, but also on the complexity of the manufacturing technology, the quality of the materials used. Therefore, the difference when buying products from different manufacturers can be significant. Other factors also play a role here:
- the pricing system selected at the factory;
- popularity of certain sizes;
- proximity to sources of raw materials;
- terms of delivery to the end user.
You can save a lot on this by getting acquainted with the offers of various manufacturers of reinforced concrete products.
| Marking | Dimensions (LxWxH), mm | Weight, kg | Price, rub/unit |
| corpulent | |||
| PRTm-3 | 1600x400x80 | 85 | 880 |
| TP-43-8 | 4300x800x220 | 1 400 | 13 300 |
| PTP 24-12 | 2400x1200x120 | 840 | 5 700 |
| Ribbed | |||
| 1P 7-2 | 5550x740x400 | 1 500 | 8 880 |
| 2PG-5 | 5970x1490x250 | 1 230 | 6 680 |
| 1P 3-1 | 5550x1490x400 | 2 650 | 14 900 |
| Hollow (H 220 mm) | |||
| PC 26.10-8 | 2580x990 | 78 | 3 370 |
| PC 30.15-8 | 2980x1490 | 790 | 4 800 |
| PC 50.12-8 | 4980x1190 | 1 320 | 5 050 |
| Polystyrene concrete | |||
| 36.10.3 | 3600x1000x300 | 1 150 | 8 740 |
| 42.12.3 | 4200x1200x300 | 1 610 | 12 600 |
| 51.15.3 | 5100x1500x300 | 2 450 | 18 400 |
For small objects, you can buy substandard or dismantled products - they are reliable enough to withstand the main loads, but at the same time they are much cheaper.
In the construction industry, concrete products make up a large part of the materials used, especially in multi-storey buildings. One of the most commonly used is the hollow slab. It is a reinforced concrete rectangle, which has voids in the form of hollow pipes, very convenient for laying communications. This type of shape makes it possible to acquire resistance to bending. Installation is possible only on a more solid base with a width of at least 15-20 cm for a brick wall, at least 7-10 cm for a concrete wall. They are moisture resistant, fire resistant, resistant to fungus, mold, excellent soundproofing and quite durable.
Application and Specifications
Overlappings are necessary for the construction of roofs, as interfloor partitions and other load-bearing structures. The main competitors are wooden and monolithic slabs. Wooden ones are not initially applicable for multi-storey construction, they are fire hazardous, short-lived, prone to decay. They are limited by a certain margin of safety and possible load. Monolithic ones are more laborious to install, that is, they don’t have the same speed in work (within one day), but unlike hollow ones, leaning is possible on walls made of almost any type of material. Also, the technology of their assembly does not require heavy equipment, and the length of the plates is more variable. The load on the foundation, despite the weight, is minimal due to the voids.
Production is carried out in accordance with GOST 23009-78. It provides for a special marking, which contains dimensions, concrete grade, stress, withstand load, as well as characteristics of features (sizes of openings, additionally embedded details for strengthening the structure, special properties, etc.). Installation is carried out using special equipment for mounting ears. They are not suitable for aggressive environments. Before installing a certain type of slab, it is necessary to calculate the possible load on the walls. Failure to comply with the rules for laying can lead to serious problems, including deformation and cracks. The multi-hollow ones are more prone to fracture.
The causes of fractures may lie in the reinforcement used in the manufacture, its corrosion. If the crack is not of critical size, it can be repaired. Such problems are extremely rare, as they have good strength properties and are often used in multi-storey panel construction and in the construction of industrial buildings. 
Types of plates
Products of this type are divided into multi-hollow floor slabs, GOST 9561-91, and the marking contains the letters PB. And ordinary empty s various sizes holes 140 mm and 159 mm in diameter, marked respectively 2PC and 1PC. The designation kgf / sq. Means the amount of permissible load in hundreds of kilograms per 1 sq.m.
Hollow-core floor slabs are lightweight, they are used where it is necessary to reduce the load on the foundation. Hollow are used for buildings with brick walls or built from concrete blocks. Both types are reinforced to increase the rigidity of the structure.
Hollow core slab assortment table, standard thickness 220 cm.
Length x width (m) | Price, rubles |
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9 491 — 11 000 |
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The data given in the table are for Moscow and the Moscow region with an average price for the region. In Russia, there are several large manufacturers offering the widest range: StroyKhimIndustriya LLC (Volgograd Region), KSK (Ivanovo Region), ARMABETON (Moscow), Odintsovo Plant reinforced concrete structures. The list includes series up to 6 m, the range of many companies currently offers a wider range of sizes (up to 9 m), any width (less than 1.5 m) and even thickness (200-400 mm).
Operation features
When using a floor slab in an attic structure, insulation will be required. The calculated load is designed taking into account the support on 2 walls, if you make support on 3 walls, then the load will be distributed incorrectly. This is not suitable for a balcony, since the support will only be on one side. In multi-storey construction, this will not be allowed, but in cottages such a mistake is often made.
Despite all the apparent strength, they are very fragile and can be damaged very badly if transported incorrectly. In this regard, it is recommended during transportation to lay between the plates wooden blocks around the perimeter. Some builders are trying to save money by purchasing used boards, which is highly discouraged. Depending on wear, size and external condition, it can cost up to 30% of the original price.
Overlappings of this type can be additionally reinforced, reinforcement is laid to the bottom wall and between round voids. Strengthening can be two-row, multi-row. This is reflected in the additional marking of the product (NV, NVK, NVKU, 4NVK).
