Reinforced concrete slabs are used in building construction to redistribute loads from the weight of furniture, equipment, snow and others heavy elements directly onto the load-bearing walls or columns of the building. They divide the space of the structure transversely vertically or cover top floor for the manufacture of roofing.
Floor elements are used in the construction of large shopping and industrial complexes, entertainment centers, cultural and public spaces, multi-storey residential buildings. In private construction, prefabricated reinforced concrete slabs are successfully used for flooring and covering upper floors, creating a reliable and durable house frame.
According to the form of internal content, reinforced concrete products are divided into types: hollow and ribbed.
Depending on the thickness, cavity dimensions and method of support on load-bearing elements, hollow core slabs are divided into categories in accordance with GOST.
With different support method
a) 1pc thickness is 220mm, voids are formed with a diameter of 159 mm, support occurs on two sides, length from one and a half to six and a half meters, width from 1 to 3.5 m, 1 pct - support on three sides, 1PKK - trough four-sided support;
b) 2 pcs - slab height 220 mm, voids with a diameter of 140 mm, 2 pkt - support on three sides, length ranges from three to six meters, 2 pkt - four-sided support, length 2.5–6.7 m;
c) 3PK - 220 mm, voids are made diameter 128 mm, designations of the supporting sides are similar to the previous ones;
With support on only two sides
A) 4pcs slabs They are produced with a thickness of 260 mm, voids of 158 mm, in the upper belt there are cutouts along the entire contour. Cover spans up to 6 m, width up to 1.5 m;
b) 5 pcs- product body height 260 mm, hollow hole diameter 181 mm, length for spans up to 12 m, width 1.1 m, 1.25 m, 1.48 m;
V) 6 pcs plates are manufactured with a height of 300 mm, round voids of 204 mm are produced maximum length for large spans 12 m;
d) 7 pc-thickness products are provided 160 mm, round voids with a diameter of 115 mm, cover average spans up to 6.5 m, width 1.1 m, 1.25 m, 1.49 m, 1.81 m;
d) PG-voids pear-shaped, slab thickness 260 mm, purlin length 12 m, available in different widths, up to 1.5 m;
e) PB-series, produced using continuous forming technology on stands;
Ribbed floor slabs
In order to save light or heavy concrete mixtures, concrete was removed from the bottom layer of the slab, which does not work well under tensile loads, and has excellent resistance to compression. Under the influence of forces in top layer compression forces arise in the plates, and tension forces occur in the lower part.
Instead of concrete, slabs are provided along the entire length metal reinforcement inserts, withstanding tensile forces. To accommodate them, stiffeners are made of concrete. In ribbed slabs, to cover spans of more than 12 m, transverse convex grooves are additionally made in accordance with GOST.
Ribbed reinforced concrete products are divided into series according to GOST
- 1P are called slabs that have two strips of support on separate shelves of the crossbar; they are available in varieties from 1P1 to 1P8;
- The support on the crossbar is designated 2P and is available in a single version;
- In slabs of the 1P1–1P6 series, GOST provides for the installation of embedded parts at the junction of the ends, if required by the drawing documents;
- Prestressing of reinforcement is carried out before concreting in product forms 1P1–1P6 and 2P1;
- The reinforcement is not stressed electromechanically during the manufacture of types 1P7 and 1P8.
An example of decoding the designation of slabs according to GOST: 1P4– 2, At - VI P-1
- First three letters they talk about the standard size of the slab (1P4);
- Number 2 indicates the load-bearing capacity class of the product;
- At - VI - this is a typical designation of reinforcement from the assortment directory;
- The letters P and T determine the type based on the density of the concrete used in its manufacture. P-easy option, T-heavy concrete mixture.
The last digit separated by a dash shows the features of the view in the manufacture of reinforced concrete products. 1- the presence of various additional metal elements; 2-side ribs contain holes of 208 mm; number 3 indicates holes of different diameters on both sides;
Scope of application of reinforced concrete slabs according to GOST
GOST requirements for technical indicators
Finished slabs are subject to acceptance provided:
dimensions reinforced concrete products must comply with the standard approved technical documentation.
At the exit finished product carry out strength tests, crack resistance and rigidity. The indicators obtained during the experiments must not be lower than the normative ones provided for in the documents.
Parameters of compressive and bending strength, frost resistance, deviations in size from the norm are set out in the publication of GOST 13015.0–83;
The production and formation of the slab is carried out in strictly approved and developed forms. All metal embedded elements are manufactured from a certain class of steel, approved diameter. Processing is mandatory metal surfaces anti-corrosion compounds.
Concrete must meet the requirements according to GOST:
When manufacturing reinforced concrete products from lightweight concrete, its density per 1 m3 should be in the range of 1900–2100 kg. Heavy concrete density can correspond to 2250–2550 kg per 1 m3.
If the specification for the slab type specifies pre-tensioning of reinforcement, then it is released only after the concrete mixture has reached its design strength. Typically, this indicator is provided in whole days of hardening and is indicated in the drawing for the production of the slab or in the technical documentation for the building under construction.
Light types concrete mixture necessarily correspond to porosity indicators, taking into account tolerances and deviations.
The quality of all local materials and binding components involved in the production of concrete mixture must be within standard indicators in the relevant GOSTs.
When operating in an aggressive acidic or gaseous environment, the regulations for the production of products are determined in the documents for the building.
Conditions for conformity of reinforcing wire
GOST defines the name and classes of reinforcing steels permitted when using slabs in different operating environments. A separate list defines the types of steels that are not allowed for the production of products due to low technical indicators.
Metal mounting loops must withstand the weight of the hinge when moving, the embedded parts of the product, welded during the installation process, can take various loads up to working in extreme conditions. All elements laid in the concrete mixture must be calculated according to all indicators. Their shape, dimensions and diameter are clearly defined by GOSTs and are not subject to change.
Preliminary reinforcing steel stress, by tension, electromechanically or mechanically.
The voltage generated in the metal wire is measured with special devices, and it should not be lower than the nominal voltage by 10%.
Acceptance of finished products
The frost resistance of floor elements is checked by the labor control department on prototypes by large quantity freezing and thawing cycles. The results are recorded in special passports.
Porosity and water permeability thresholds are checked for each type of concrete mixture separately and documented in the necessary documents.
To be approved for use, the product undergoes a series of tests for strength, density, and hardness.
All metal elements are subject to visual and instrumental control for compliance with drawings, technical documentation and GOST. If necessary, a report is drawn up for hidden work on laying reinforcement.
Concrete porosity indicators must be exactly as in the project or in the order, comply with GOST.
The compliance of the slabs with the dimensions indicated in the drawings is carried out systematically and selectively. The surface is inspected in the same way for the appearance of microcracks.
When releasing, check the layer of protective concrete for metal on the edges of the slab using X-ray devices.
Rules for transporting floor slabs
All inscriptions indicating the brand of the slab, applied with contrasting color paint on the side or end surface so that they are visible when stacked on top of each other.
It is permitted to transport and deliver slabs to the construction site only if you have the appropriate passport indicating all technical specifications products.
For storage in hangars or outdoor construction sites slabs are stacked, not exceeding 2.5 m in height. Under each slab there is wood spacer in the form of a beam measuring about 50x50 mm; wooden elements are placed in corners or under protruding elements (for example, in ribbed products).
Application quality slabs flooring is important when constructing a building. If damaged, cracked or bent products are used in violation of overall dimensions, the strength of the building frame will decrease, which in difficult conditions can lead to collapse.
Can only be used for styling factory-made products with documents. You can also install used slabs, but first obtain the results of testing and inspection by construction experts in accordance with GOST.
Hollow-core reinforced concrete floor slabs are one of the most popular types of reinforced concrete products, intended for separating building levels and laying load-bearing structures. Technical conditions and standards are controlled by GOST 9561-91; their characteristics allow them to be used in any area of construction: from private houses to industrial facilities. Mandatory application nuances include the use of lifting equipment for laying and checking the load-bearing capabilities. It is easy to select the desired series; the labeling includes all the necessary information.
Externally, hollow-core panels are rectangular box with the correct geometry of the walls and ends, with longitudinal reinforcement, round or pear-shaped internal cavities located at equal intervals. For their production, heavy, light and dense silicate grades of concrete are used (for load-bearing systems their strength class is not lower than B22.5). The voids are located parallel to the main direction along the length (for types based on 2 or 3 sides) or to any of the sides of the contour for floors marked PKK.
The presence of a frame is mandatory; to extend the service life and enhance reliability, all metal placed inside is treated with anti-corrosion compounds at the manufacturing stage. The panels, supported on 2 or 3 sides, contain a frame of prestressed reinforcement. Depending on the purpose of the floor slabs, one of the following grades of steel is used: seven-wire strands with a section of 6P-7, periodic profile 5Vr-II, K-7 ropes, thermally strengthened At-V rods and other materials that comply with the standard (series 1 141.1 - main document regulating the process of release and quality control of products).
The main technical characteristics include:
1. Dimensions and weight of structures. The thickness is standard and unchanged (for most types - 220 mm), length varies from 2.4 m to 12, width - within 1-2.6 m. The exception is types supported on 4 sides (PKK marking), their dimensions vary from 3×4.2 to 3×7.2 m, respectively. Average weight 1 l.m. with a width of 1 m it is 360 kg.
2. Load-bearing capacity. Depending on the grade of concrete and the intensity of reinforcement, slabs with voids can withstand from 450 to 1200 kg/m2. The standard value for the most popular series with round holes is 800 kg/m2, if it is necessary to exceed it, products are made to order.
3. The fire resistance limit of hollow-core panels is 1 hour; if necessary, it is increased by strengthening the reinforced frame.
The structures are valued for their reliability, light weight, good tensile strength due to the presence of internal voids, the ability to hide communications, resistance to moisture, open fire, biological influences, heat and soundproofing properties, durability. An important advantage is considered to be high geometric accuracy, which simplifies the installation process and subsequent finishing.
| Type | Actual thickness, mm | Length (maximum, inclusive), m | Reduced slab thickness (ratio of concrete volume to area) mm | Diameter of voids, mm | Nominal distance between void centers, not less than mm |
| 1pc, 1pkt, 1pkk | 220 | 7.2 (up to 9 for slabs for industrial buildings supported exclusively on 2 sides) | 120 | 159 | 185 |
| 2PK, 2PKT, 2PKK | 7,2 | 160 | 140 | ||
| 3PK, 3PKT, 3PKK | 6,3 | 127 | |||
| 4pcs | 260 | 9,0 | 159 * | ||
| 5pcs | 12 | 170 | 180 | 235 | |
| 6pcs | 150 | 203 | 233 | ||
| 7pcs | 160 | 7,2 | 90 | 114 | 139 |
| PG | 260 | 12 | 150 | ||
| PB | 220 | Depends on molding parameters | |||
*there are additional cutouts in the upper zone.
The main standards for width are PK-10, PK-12 and PK-15. All types have holes round shape, the exception is PG - slabs with pear-shaped voids. For options marked PKK, beveled ends are allowed.
All sizes reinforced concrete floors with holes inside are unified (including the interval pitch along the length), deviations do not exceed 5 mm. The thickness indicated in the table characterizes the cost-effectiveness of the product.
Marking of hollow core slabs
Standard decryption includes:
1. A number characterizing the size of the diameter of the internal holes according to GOST 9561-91. Omitted for 1 PC; in most price lists there is a simple designation - PC.
2. Type. Indicated by 2 or 3 letters, contains information about the shape of the voids, the manufacturing method and the number of supported sides. Of all varieties, PB is produced by continuous molding.
3. Dimensions of hollow-core floor slabs: the first is the length (of the side not supported by bearing structures), then the width, in dm, rounded up. The thickness is not indicated; this value depends on the type of product. The actual dimensions are always smaller: 20 mm in length, 10 mm in width.
4. The fourth mandatory point is a number reflecting bearing capacity reinforced concrete products.
5. Type of reinforcement. Can be skipped for non-tensioned frames.
6. Brand of solution: not indicated for heavy solution, used in the majority of products. The letter L means the use of lightweight concrete, C - dense silicate.
7. Others, additional characteristics or design features products. These include resistance to seismic influences or aggressive gases, and the presence of embedded elements.
Scope and features of application
The main purpose is to organize a reliable prefabricated floor in objects with load-bearing walls(also used during construction). In private and low-rise construction they are used to lay the main floors, separate floors and attic space, arrangement pitched roofs V outbuildings, platforms and as a fence. Their load-bearing capacity fully corresponds construction requirements(the standard norm when calculating taking into account the weight of people and furniture is 150 kg/m2, the actual value exceeds it several times). Soundproofing characteristics allow us to provide reliable protection from noise even when installing single-layer floors.
Long slabs (up to 9 m for 1 pcs, 12 for 4 pcs, 5 pcs, 6 pcs and PG) are intended for installation in public buildings, the rest are considered universal and are recommended for residential buildings, including individual ones. When choosing dimensions, the need to comply with the standard for laying on supports is taken into account - from 7 to 15 cm, depending on the material of the walls (minimum - for dense brick, maximum - for aerated concrete). When converted into squares, the cost of 1 m2 for floors 1 m wide is more expensive than for products with 1.2 or 1.5 m, this is explained by the ban on cutting them crosswise. The use of concrete products of the PC series allows:
- Get reliable design, designed for significant weight loads.
- Improve the building's insulation capabilities.
- Ensure a perfectly flat horizontal floor (with correct placement and checking supports).
- Improve waterproof, fireproof and acoustic protection building.
Cost of slabs for installation of floors
| Series | Load-bearing capacity, kg/m2 | Dimensions (length×width×thickness), mm |
Weight, kg | Price for 1 piece, rubles |
| PC 16.10-8 | 800 | 1580×990×220 | 520 | 2 930 |
| PC 20.12-8 | 1980×1190×220 | 750 | 4 340 | |
| PC 30.10-8 | 2980×990×220 | 880 | 6 000 | |
| PC 36.10-8 | 3580×990×220 | 1060 | 6 410 | |
| PC 45.15-8 | 4480×1490×220 | 2120 | 12 600 | |
| PC 60.18-8 | 5980×1780×220 | 3250 | 13 340 | |
| PC 90.15-8 | 8980×1490×220 | 4190 | 40 760 | |
| 2PC 21.12-8 | 800 | 2080×1190×220 | 950 | 3 800 |
| 2PK 62.10-8 | 6180×990×220 | 2425 | 8 730 |
Floor slabs refer to structures with load-bearing capabilities that separate floors or different temperature zones. The products are made of concrete and reinforced concrete; the second type is considered universal and is suitable for both horizontal and vertical placement. The main criteria for their selection include the type of slab, dimensions and weight, load-bearing capacity, void diameter, additional conditions applications. This information must be indicated by the manufacturer in the labeling; the order of arrangement of symbols is regulated by GOST 23009-2016.
Depending on the design There are solid (full-bodied) and hollow varieties. According to the method of arrangement, they can be monolithic, prefabricated monolithic or prefabricated. Hollow-core reinforced concrete floor slabs, which combine light weight and reliability, are in maximum demand. Their technical specifications and marking is regulated by GOST 9561-91, based on the thickness, number of sides, shape and diameter of voids, 15 main types are distinguished.
Solid products, depending on their shape and functional purpose, are divided into:
1. Solid beamless panels with smooth surface, optimal for bookmarking ceilings. They are in demand in private construction, valued for their ease of finishing, their use implies a refusal suspension systems. A significant part is made of cellular concrete.
2. Ribbed - with vertical stiffening ribs that act as supports. The reliability of such floor slabs is explained by the removal of concrete from areas subject to tensile loads and an increase in its volume at compression points. The characteristics and designations of this variety are regulated by GOST 28042-89. The main scope of application is civil and residential construction; in private houses they are not economically feasible.
3. Caisson (frequently ribbed or often beamed) groups. They are a monolithic slab laid on top of square cells of floor beams. Thus, on the one hand they have a smooth surface, on the other they resemble waffles.
These structures are designed for operation under heavy loads; they are practically not used in private construction (according to SP 52-103-2007, they are recommended when the span of one room exceeds 12-15 m).
Standard marking of floor slabs, regardless of their type, consistently includes:
- Designation of the type of design and product.
- Dimensions in numbers: length and width, height refers to standard sizes and is not indicated.
- Load-bearing capacity of floor slabs (1 unit in numerical value corresponds to withstand 100 kg/m2).
- Class of the tested fittings.
- Additional characteristics and properties, such as: resistance to aggressive environments, seismic influences, low temperatures, designation of embedded elements or holes (if any).
Explanation of symbols
Types of overlap are marked with letters; the number in front of them is indicated for hollow-core varieties and characterizes the diameter of the internal holes. Examples of possible designations and their interpretation for popular solid types are given in the table:
Hollow core panel markings include letter designation the number of sides to support the slab (“T” corresponds to three, “K” to four). The absence of a third letter implies support for the structure on both sides. Decoding the main types in in this case:
| Designation of slabs | Thickness, mm | Type of voids, features | Nominal distance between centers of voids in slabs, not less than mm | Diameter, mm |
| 1 PC (1 may not be specified) | 220 | Round | 185 | 159 |
| 2pcs | 140 | |||
| 3pcs | 127 | |||
| 4pcs | 260 | The same, with cutouts in the upper zone along the contour | 159 | |
| 5pcs | Round | 235 | 180 | |
| 6pcs | 233 | 203 | ||
| 7pcs | 160 | 139 | 114 | |
| PG | 260 | Pear-shaped | Assigned in accordance with the parameters of the molding equipment of the manufacturer of hollow core slabs | |
| PB | 220 | Manufactured by continuous forming | ||
The main difference between PC and PG panels and PB panels is the manufacturing method: the first two are poured into formwork structures, the latter is molded continuously (conveyor technology). As a result, floors marked PB are smoother and more protected from external influences surface. They are less limited in length and are suitable for rooms with non-standard dimensions. The disadvantages of molding plates include narrower holes (the diameter of the voids when marking PB does not exceed 60 mm), unlike PC and PG, they cannot be drilled through for laying communications, at least this rule applies to high-rise buildings.
The length and width of each type are also limited by the standard; they are indicated in decimeters and rounded up. Actual size Reinforced concrete hollow-core slabs are usually 10-20 mm smaller. The following digital designation characterizes the design load of the slab; this indicator depends on the quality of the concrete and the reinforcement metal used. The reinforcement class is not always indicated; its mention is mandatory only for prestressed structures. If necessary, its designations are guided by the technical conditions for reinforcing steel.
The next marking point concerns the brand of concrete used (not indicated for heavy groups). Other types include: cellular (I), light (L), dense silicate (S), fine-grained (M), heat-resistant (W) and sand concrete (P) compositions. For floor slabs intended for work in conditions of exposure to aggressive environments, resistance is indicated in literal expression: normal permeability (N), reduced (P) and especially low (O). Another indicator is seismic resistance: structures designed for such loads are designated with the letter “C”. All Additional features indicated in product labeling Arabic numerals or letters.
Cost of slabs
| Marking | Dimensions: L×W×H, cm | Weight, kg | Load-bearing capacity, kg/m2 | Retail price per piece, rubles |
| Hollow core slabs with round holes supported on 2 sides | ||||
| PC-16.10-8 | 158×99×22 | 520 | 800 | 2940 |
| PC-30.10-8 | 298×99×22 | 880 | 6000 | |
| PK-60.18-8 | 598×178×22 | 3250 | 13340 | |
| PK-90.15-8 | 898×149×22 | 4190 | 40760 | |
| Floor slabs, bench formless formation. Products are placed on 2 end sides | ||||
| PB 24.12-8 | 238×120×22 | 380 | 800 | 3240 |
| PB 30.12-12 | 298×120×22 | 470 | 1200 | 3950 |
| PB 100.15-8 | 998×145×22 | 2290 | 800 | 29100 |
| Ribbed ceilings without an opening in the shelf | ||||
| 2PG 6-3 AIV t | 597×149×25 | 1230 | 500 | 12800 |
| 4PG 6-4 AtVt | 597×149×30 | 1500 | 820 | 14150 |
Looking at the stacks reinforced concrete slabs, the average citizen has no idea how much important information they can inform the specialist - the builder. This is not surprising, because in Everyday life we rarely come across such designs.
If we are talking about a new building, then the customer installation work It will be useful to know what types and sizes of floor slabs exist, as well as what their maximum load-bearing capacity is according to GOST.
At first glance, the differences between hollow core slabs are only in their length, thickness and width. However, specifications These structures are much more extensive, so we will look at them in more detail.
State standard - a set of laws of strength
All basic requirements for hollow core slabs, including their purpose and strength characteristics, describes GOST 9561-91.
First of all, it indicates the gradation of the slabs depending on their thickness, the diameter of the holes and the number of sides with which they rest on the walls.
Except different thicknesses and geometric dimensions, hollow-core floor slabs are classified according to the method of reinforcement. GOST indicates that panels that rest on walls on 2 or 3 sides must be made using prestressed reinforcement.
The practical conclusion that follows from this for the developer is that you cannot punch holes for utility lines, violating the integrity of the working fittings. Otherwise, the slab may lose its load-bearing capacity (crack under load or collapse).
Clause 1.2.7 of GOST 9561-91 makes important exceptions, allowing for the manufacture of certain types of slabs not to install prestressed reinforcement in them.
They refer to the following panels:
- Thickness 220 mm with length 4780 mm (voids with a diameter of 140 and 159 mm);
- Thickness 260 mm, length less than 5680 mm;
- 220 mm thick, any length (voids with a diameter of 127 mm).
If such reinforced concrete floor slabs were brought to your site, and their passport indicates non-tensioned reinforcement, do not rush to send the car back to the factory. These structures comply with building codes.
Features of manufacturing technology
Floor slabs are made different ways, which is reflected in the quality of their front surface. PC and PG grade slabs are cast in formwork, and PB panels are made continuously on a conveyor line. The latest technology is more advanced than formwork manufacturing, so the surface of PB slabs is more even and smooth than that of panels of the PC and PG brands.
In addition, conveyor production makes it possible to produce PB slabs of any length (from 1.8 to 9 meters). This is very convenient for the customer when it comes to so-called “additional” slabs.
The fact is that when laying out slabs on a building plan, several areas are always formed where standard panels do not fit. Builders get out of the situation by filling in such “blank spots” monolithic concrete right on site. The quality is so homemade design noticeably inferior to that achieved in factory conditions (vibration compaction and steaming of concrete).
The advantage of PC and PG panels over PB panels is that you can punch holes in them for communications without fear of structural destruction. The reason is that their void diameter is at least 114 mm, which allows free passage of a sewer riser (with a diameter of 80 or 100 mm).
PB slabs have narrower holes (60 mm). Therefore, to pass the riser, you have to cut the rib, weakening the structure. Experts say that such a procedure is unacceptable only for high-rise construction. When constructing low-rise housing, punching holes in PB slabs is allowed.
Advantages of hollow reinforced concrete slabs
There are a lot of them and they are all quite significant:
- Reducing the weight of building structures;
- The voids in the slabs dampen vibrations, so this type of flooring has good sound insulation;
- Possibility of laying communications inside voids;
- Fire resistance and moisture resistance;
- High speed of installation work;
- Durability of the structure.
Dimensions of hollow core slabs
Here everything is unified to the maximum so that it is possible to make a design of any installation size. The gradation of the width and length of the slabs occurs in increments from 100 to 500 mm.
Marking – passport of the floor slab
The developer does not need to know the intricacies of the technology used to manufacture hollow core slab ceilings It is enough to learn how to correctly decipher the markings.
It is carried out in accordance with GOST 23009. The stove brand includes three alphanumeric groups separated by hyphens.
The first group contains data on the type of panel, its length and width in decimeters (rounded to the nearest whole number).
The second group indicates:
- Load-bearing capacity of the slab or design load (kilopascals or kilogram-force per 1 m2);
- For prestressed slabs, the class of reinforcing steel is indicated;
- Type of concrete (L - light, S - silicate, heavy concrete is not indicated in the markings).
The third group of markings contains additional characteristics reflecting special conditions application of structures (resistance to aggressive gases, seismic influences, etc.). In addition, the design features of the slabs (the presence of additional embedded parts) are sometimes indicated here.
As an example to explain the principle of marking hollow-core panels, consider the following design:
Hollow-core panel type 1PK, length 6280 mm, width 1490 mm, designed for a load of 6 kPa (600 kg/m2) and made of lightweight concrete using prestressed reinforcement class At-V).
Its marking will look like this: 1PK63.15-6AtVL. Here we see only two groups of characters.
If the slab is made of heavy concrete and is intended for use in a seismic zone (seismicity up to 7 points), then a third group of symbols appears in its designation: 1PK 63.15-6AtV-C7.
The considered technical characteristics of floor slabs determine their scope of application.
All types of hollow-core panels are calculated based on the standard load on the floor - 150 kg/m2 (weight of people, equipment and furniture).
Load bearing capacity standard plate is in the range from 600 to 1000 kg/m2. Comparing the standard of 150 kg/m2 with the actual strength of the panels, it is easy to see that their safety margin is very high. Therefore, they can be installed in all types of residential, industrial and public buildings.
|
Slab type |
Reduced slab thickness, meters |
Average density of concrete slab, kg/m3 |
Slab length, meters |
Building characteristics |
| 1pcs,1pkt, 1pcs |
up to 7.2 inclusive |
Residential buildings (sound insulation of premises is ensured by installing floating, hollow-core, hollow-core or layered floors, as well as single-layer screed floors | ||
| 1pc | ||||
| 2PK, 2PKT, 2PKK | Residential buildings in which sound insulation of residential premises is ensured by installing single-layer floors | |||
| 3PK, 3PKT, 3PKK | ||||
| 4pcs | Public and industrial buildings | |||
| 5pcs | ||||
| 6pcs | ||||
| PG | ||||
| 7pcs | Residential buildings (low-rise and estate type) |
This table contains the given thickness of the slab - a term that is not understood by beginners. This is not the geometric thickness of the panel, but a special parameter created to assess the efficiency of the slabs. It is obtained by dividing the volume of concrete placed in the slab by its surface area.
Approximate prices
During construction, dozens of standard sizes of hollow core slabs are used, therefore detailed description Their prices would have to be devoted to a separate article. We will indicate the price parameters of the most popular panels (pickup):
- PC 30.12-8 – from 4,800 rub./unit;
- PC 30.15-8 – from RUB 5,500/unit;
- PC 40.15-8 – from RUB 7,600/unit;
- PC 48.12-8 – from 7,000 rub./unit;
- PC 51.15-8 – from RUB 9,500/unit;
- PC 54.15-8 – from RUB 9,900/unit;
- PC 60.12-8 – from RUB 8,200/unit;
- PC 60.15-8 – from 10,600 rub./unit;
Installation of hollow core slabs
The main condition quality installation panels, is strict adherence to the design parameters of support on the walls. Insufficient support area leads to destruction of the wall material, and excessive support leads to increased heat loss through cold concrete.
Installation of floor slabs must be carried out taking into account the minimum permissible depth of support:
- on brick - 90 mm;
- for foam concrete and aerated concrete blocks— 150 mm;
- on steel structures— 70 mm;
- for reinforced concrete - 75 mm;
The maximum depth of embedding slabs into walls should not be more than 160 mm (brick and light blocks) and 120 mm (concrete and reinforced concrete).
Before installation, each slab must be filled with voids (with lightweight concrete to a depth of at least 12 cm). Laying the panel “dry” is prohibited. To ensure uniform load transfer on the walls, before laying, spread a mortar “bed” no more than 2 cm thick.
In addition to observing the standard support depths, when installing floor slabs on fragile blocks of gas or foam concrete, a monolithic concrete slab should be laid underneath them. reinforced belt. It eliminates the squeezing of blocks, but requires good external insulation to eliminate cold bridges.
During the installation process, the deviation of the difference in elevations of the front surfaces of adjacent panels should be constantly monitored. This needs to be done at the seams. Don’t listen to builders who install panels in “steps” and tell you that it is impossible to lay them straighter.
Building codes establish the following tolerances depending on the length of the slabs:
- up to 4 meters – no more than 8 mm;
- from 4 to 8 meters – no more than 10 mm;
- from 8 to 16 m – no more than 12 mm.
Anyone who has at least once dealt with the construction of a house knows how important hollow reinforced concrete slabs or floor panels are. Hollow-core concrete floor slabs, in fact, make up about 90% of the total weight of the house. Floor slabs (PC) can vary greatly in both weight and size, depending on the specific purposes for which they are used.
Structural features of hollow core slabs
As you might guess, the inside of reinforced concrete floor slabs (RC) are hollow, which is why they are labeled for sale as multi-hollow. But the holes inside such slabs, contrary to misconception, can have not only oval, but also round, square and other shapes.
Scheme of supporting a hollow core slab However, in most cases, floor slabs (PCs) have cylindrical hollow circles inside.
Interestingly, floor slabs (PC) can be either unreinforced or reinforced. Reinforced concrete floor slabs (PC) will be reinforced.
Such floor slabs (PCs), although they have a significantly greater weight, which ultimately increases both the load on the building and the cost of construction, however, have a large margin of safety. Installation of floor slabs, namely the installation method itself, depends on what support the slabs will be placed on, because support is also an important criterion.
For example, if the support of the slab is not stable enough, this can lead to unpleasant consequences, which, of course, must be avoided.
Scheme of laying a hollow core slab on the second floor Characteristics of hollow core slabs
Size
Its final cost also depends on the size of the hollow core PC; in addition to parameters such as width and length, weight is also important.
PC sizes vary as follows:
- the length of the PC ranges from 1180 to 9700 millimeters;
- The width of the PC ranges from 990 to 3500 millimeters.
The most popular and in demand are hollow-core panel slabs, the length of which is 6000 mm and the width of 1500 mm. The height or thickness of the panel is also important (it would be more correct to talk about height, but builders, as a rule, say “thickness”).
So, the thickness that multi-hollow panels can have is always the same value - 220 mm. Great importance has, of course, the weight of the floor panel. Concrete plates the ceiling must be lifted by a crane with a minimum lifting capacity of 4-5 tons.
Comparative table of coordination sizes of hollow core floor slabs The length and weight of the panels are vital importance for construction, length is an even less important indicator than weight.
Weight
Regarding this important parameter, like weight, everything here is extremely clear the first time: the range of products produced in Russia ranges from 960 kilograms to 4.82 tons. Weight is the main criterion by which the method by which the panels will be installed is determined.
Typically, cranes are used, as noted above, with a lifting capacity of at least 5 tons (of course, cranes must lift weight with some margin).
The weight of panels with the same markings may differ, but only slightly: after all, if we consider the weight with an accuracy of one gram, anything can affect it.
Comparative characteristics of the main brands of hollow core slabs If, for example, a product is caught in the rain, then it will a priori be slightly heavier than the product that was not exposed to rain.
Types of loads
To begin with, it should be noted that any overlap requires the presence of the following 3 parts:
- The upper part, with the floor where people live. Accordingly, the panel will be loaded by the floor covering, various insulating elements and, of course, concrete screeds- main component of the load;
- The lower part, with the presence of the ceiling, its decoration, and lighting fixtures. By the way, you shouldn’t be skeptical about the availability of lighting fixtures. Firstly, the same LED lamps require partial destruction of the plate with a hammer drill to lay the cable. Secondly, if you take large rooms, with columns and halls, huge crystal chandeliers can hang there, which will give a greater load than any other device or type of decoration. This must also be taken into account;
- Structural. It unites both the upper and lower parts at once, as if supporting them in the air.
A hollow core slab is a structural slab that supports both the upper and lower parts of the floor in the air!
By the way, you should not discount the dynamic load. It, as you might guess, is created by people themselves, as well as the things they move. All this affects the properties and states of the panel.
Diagram of a hollow core slab with holes For example, if you once transport a heavy piano in a small two-story house from one place to another is normal, but daily movement will create much more on a multi-hollow slab Negative influence. It is unlikely to fall, but there may be serious problems with ventilation later.
Based on the type of load distribution, they are divided into 2 groups:
- distributed;
- point.
To understand the difference between these two types, it is worth giving an example. The same huge crystal chandelier, which weighs one tone - this is a point load. And here suspended ceiling with a frame over the entire surface of the slab - this is already a distributed load.
Construction of a technological line for the production of hollow core slabs But there is also a combined load, combining point and distributed. For example, a bathtub filled to the top. The bathtub itself stands on legs, and its pressure on the legs is a type of distributed load. But the legs standing on the floor are already a point load.
Its cost directly depends on the weight of the hollow core slab.
It's complicated, but you can figure it out. And it is necessary! After all, calculations for floors and hollow core slabs during construction will still need to be made.
Brands of hollow core slabs
As a matter of fact, hollow core slabs don’t even have brands as such. We are talking about markings that reflect some parameters. It is enough to give a small example.
Scheme of laying a hollow core slab on a crossbar Let's say the panel has the following markings: PC 15-13-10 PC - means hollow core slab; all digital designations indicate any technical parameters.
15 would mean that the panel is approximately 15 decimeters (1.5 meters) long. Why approximately? It’s just that the length can be 1.498 meters, but on the marking the manufacturer has the right to round this figure to 1.5 meters (15 decimeters). The number 12 means that the product is 10 decimeters wide. The last digit (in this case 10) is the most important indicator.
This is the load that the material can withstand (maximum permissible). In our case, the maximum load will be 10 kilograms per 1 dm². Usually builders calculate the load per square meter, here it will be 1000 kilograms per 1 m². In general, everything is not so difficult.
The panel brand always looks like PC-XX-XX; if sellers offer other options, then you should be wary.
Load calculation
Calculation of limiting impact
Calculation of limiting impact - required condition when designing a building. The dimensions and other parameters of the panels are determined by the old, good Soviet GOST number 9561-91.
Construction of a hollow core slab with a reinforced screed In order to determine the load that will be exerted on the product, it is necessary to indicate on the drawing of the future structure the weight of absolutely all elements that will “press” on the ceiling. Their total weight will be the maximum load.
First of all, you need to consider the weight of the following elements:
- cement-sand screeds;
- gypsum concrete partitions;
- weight flooring or panels;
- thermal insulation materials.
Subsequently, all the obtained indicators are summed up and divided by the number of panels that will be present in the house. From here you can get the maximum, maximum load on each specific product.
Calculation of optimal load
It is clear that the maximum permissible level is a critical indicator, which cannot be brought to under any circumstances. Therefore, it is best to calculate the optimal indicator. For example, a panel weighs 3000 kg. It is needed for an area of 10 m².
It is necessary to divide 3000 by 10. The result is that the maximum permissible value load will be 300 kilograms per 1 m². This is a small indicator, but you also need to take into account the weight of the product itself, for which the load was also calculated (let’s say its value is 800 kilograms per 1 m²). From 800 you need to subtract 300, the result is 500 kilograms per 1 m².
Now you need to roughly estimate how much all the loading elements and objects will weigh. Let this figure be equal to 200 kilograms per 1 m². From the previous indicator (500 kg/m²) you need to subtract the resulting one (200 kg/m²). The result will be a figure of 300 m². But that's not all.
Diagram of a hollow core slab with waterproofing Now you need to subtract the weight of the furniture from this indicator, finishing materials, the weight of people who will constantly be indoors or in the house. “Live weight” and all elements, their load, let it be 150 kg/m². From 300 you need to subtract 150. As a result, the optimal permissible indicator will be obtained, the designation of which will be 150 kg/m². This will be the optimal load.
Advantages of hollow core slabs
Among the advantages of these products are the following:
- relatively small load on the perimeter of the entire building, in contrast to the same solid products;
- high strength indicators, despite the fact that the panels at the bottom are hollow;
- reliability;
- settlement of the house will be much less intense than when using solid products (in fact, this advantage comes from the relatively low weight);
- relatively low cost.
In general, hollow-core panels are one of the most important building materials. Today it is produced by only a few factories throughout vast Russia. The main thing, as noted above, is not to be deceived when purchasing.
Diagram of the arrangement of reinforcement blocks in hollow core slab floors Sometimes (this is rare, but still) sellers try to sell low-quality panels, so-called lightweight ones. For example, they may be marked indicating that the product is designed for a load of 500 kilograms per square meter, but in reality this parameter is several times lower.
This is not even fraud, it is a criminal offense that should be punished to the fullest extent of the law. After all, if you buy a panel designed for a smaller load, there is a serious risk of building collapse. This situation can be observed not only in the provinces, but even in Moscow or St. Petersburg.
In general, you need to be extremely careful when purchasing such products. It is important to remember that any design mistake can even have tragic consequences.
Video
You can watch a video where experts talk in detail about the features various types hollow slabs.