Reinforced concrete slabs are used in building structures to redistribute the loads from the weight of furniture, equipment, snow and other heavy elements directly onto the load-bearing walls or columns of the building. They divide the space of the structure transversely vertically or cover the last floor for the manufacture of roofing.
Overlapping elements are used in the construction of large shopping and industrial complexes, entertainment centers, cultural and public premises, multi-storey residential buildings. In private construction, precast concrete slabs are successfully used to cover and cover the upper floors, creating a reliable and durable frame of the house.
According to the form of the internal content, reinforced concrete products are divided into types: hollow and ribbed.
Depending on the thickness, dimensions of the cavity and the method of bearing on the supporting elements, hollow core slabs are divided into categories, according to GOST.
With different support method
a) 1pc - thickness is 220mm, voids are formed with a diameter of 159 mm, the support occurs on two sides, the length is from one and a half to six and a half meters, the width is from 1 to 3.5 m, 1 pct-support on three sides, 1PCK- trough four-sided support;
b) 2 pc-plate height 220 mm, voids with a diameter of 140 mm, 2 pck-support on three sides, the length is from three to six meters, 2 pck-four-sided support, 2.5–6.7 m in length;
c) 3PK - 220 mm, voids are performed diameter 128 mm, the designations of the bearing sides are similar to the previous ones;
Supported only on two sides
a) 4pcs - slabs produced with a thickness of 260 mm, voids 158 mm, cutouts are provided in the upper belt along the entire contour. Cover spans up to 6 m, width up to 1.5 m;
b) 5 pcs- product body height 260 mm, diameter of hollow holes 181 mm, length for spans up to 12 m, width 1.1 m, 1.25 m, 1.48 m;
v) 6 pc cookers made with a height of 300 mm, round voids of 204 mm are produced with a maximum length for large spans of 12 m;
d) 7 pc-thickness products are provided for 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;
e) PG voids pear-shaped, slab thickness 260 mm, purlin length 12 m, different widths are available, up to 1.5 m;
e) PB-series produced by the technology of continuous forming 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 for tensile loads, and perfectly resists compression. Under the influence of forces, compression forces arise in the upper layer of the plates, and tension in the lower layer.
Instead of concrete along the entire length of the slab, metal reinforcement inserts that can withstand tensile forces. For their placement, 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 subdivided into series according to GOST
- 1P slabs are called, which have two bearing bands on separate girder shelves, available in varieties from 1P1 to 1P8;
- The support on the crossbar is designated 2P, it is produced in a single version;
- In the plates of the 1P1-1P6 series, GOST provides for the installation of embedded parts at the junction of the ends, if this is required by the drawing documents;
- The prestressing of the reinforcement is carried out before concreting in the forms of products 1P1-1P6 and 2P1;
- The reinforcement is not electromechanically stressed during the manufacture of types 1P7 and 1P8.
An example of decoding the designation of plates according to GOST: 1P4-2, At - VI P-1
- First three letters talk about the standard size of the plate (1P4);
- Number 2 denotes the product's load-bearing capacity class;
- At - VI - this is the type designation of reinforcement from the catalog of the assortment;
- Letters P and T determine the type by the density of the concrete used in the manufacture. P-light version, T-heavy concrete mix.
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 208 mm holes; number 3 - speaks of holes of different diameters on both sides;
Scope of reinforced concrete slabs in accordance with GOST
GOST requirements for technical indicators
Finished slabs are subject to acceptance provided:
The overall dimensions of reinforced concrete products must comply with the standard approved technical documentation.
At the exit of the finished product, strength tests, crack resistance and toughness. The indicators obtained during the experiments should not be lower than the normative ones provided by the documents.
The parameters of compressive and flexural strength, frost resistance, dimensional deviations from the norm are set out in the edition 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 made from a certain grade of steel, approved diameter. It is mandatory to treat metal surfaces with anti-corrosion compounds.
Concrete must meet the requirements according to GOST:
In the manufacture of reinforced concrete products from lightweight concrete, its density per 1 m3 should be in the range of 1900–2100 kg. Heavy concrete in terms of density can correspond to 2250–2550 kg per 1 m3.
If the task for the type of plate provides pre-tensioning of the reinforcement, then releasing it is performed only after the concrete mixture has set the design strength. Usually, such an indicator is provided in whole days of hardening and is indicated in the drawing for the production of a slab or in the technical documentation for a building under construction.
Light types of concrete mix necessarily correspond to the porosity indicators, taking into account tolerances and deviations.
The quality of all local materials and binders involved in the production of the concrete mix must be within the normative indicators in the corresponding GOSTs.
When operating in an aggressive acidic or gaseous environment for the release of products, the regulations are determined in the documents for the building.
Conformity conditions for reinforcing wire
GOST defines the name and classes of reinforcing steels permitted when using plates in different operating environments. A separate list defines the types of steels that are not allowed for the production of products with low technical indicators.
Metal mounting hinges must withstand the weight of the hinge during movement, the jammed parts of the product, welded during the installation process, can take various loads up to work in extreme conditions. All elements laid in a concrete mix must be calculated for all indicators. Their shape, size and diameter are clearly defined by GOSTs and are not subject to change.
Preliminary reinforcing steel stress, by tension, electromechanical or mechanical means.
The voltage generated in the metal wire is measured with special devices, and it should not be lower than the nominal by 10%.
Acceptance of finished products
The frost resistance of floor elements is checked by the labor control department on prototypes by means of a large number of freeze and thaw cycles. The results are recorded in special passports.
Porosity and water permeability thresholds check for each type of concrete mix separately and draw up in the necessary documents.
For permission to use, the product undergoes a series of tests for strength, density, hardness.
All metal elements are subject to visual and instrumental control for compliance with drawings, technical documentation and GOST. If necessary, an act is drawn up for hidden work on the installation of reinforcement.
Indicators of porosity of concrete 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. In the same way, the surface is inspected for the manifestation of microcracks.
At release, check the layer of protective concrete for metal on the edges of the slab using X-ray instruments.
Rules for transporting floor slabs
All inscriptions indicating the brand of the slab, applied with paint in a contrasting color on the side or end surface so that they are visible when stacked on top of each other.
It is allowed to transport and deliver slabs to the construction site only if there is an appropriate passport indicating all the technical parameters of the product.
For storage in hangars or on open construction sites slabs are stacked, not exceeding 2.5 m in height. Under each slab, a wooden gasket is made in the form of a bar with a size of about 50x50 mm; wooden elements are placed in corners or under protruding elements (for example, for ribbed products).
The use of quality floor slabs is essential in the construction of a building. If you use damaged, cracked or bent products with a violation of the overall dimensions, then 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 mount used slabs, but first obtain the results of testing and inspection by construction experts in accordance with GOST.
This standard applies to hollow-core reinforced concrete slabs (hereinafter referred to as slabs) made of heavy, light and dense silicate concrete and intended for the bearing part of the floors of buildings and structures for various purposes.
Plates are used in accordance with the instructions of the working drawings of the plates and additional requirements specified when ordering these structures.
It is allowed, by agreement between the manufacturer and the consumer, to produce plates that differ in types and sizes from those given in this standard, subject to the remaining requirements of this standard.
Plates are divided into types:
1PK - 220 mm thick with round voids with a diameter of 159 mm. designed to be supported on both sides;
1PKT - the same, for support on three sides;
1PCK - the same, for support on four sides;
2PK - 220 mm thick with round voids with a diameter of 140 mm, designed to be supported on both sides;
2PKT - the same, for support on three sides;
2PKK - the same for supporting on four sides;
3PK - 220 mm thick with round voids with a diameter of 127 mm, designed to be supported on both sides;
3PKT - the same, for support on three sides;
3PKK - the same, for support on four sides;
4PK - 260 mm thick with round voids with a diameter of 159 mm and cutouts in the upper zone along the contour, intended for support on both sides;
5PK - 260 mm thick with round voids with a diameter of 180 mm, designed to be supported on both sides;
6PK - 300 mm thick with round voids with a diameter of 203 mm, designed to be supported on both sides;
7PK - 160 mm thick with round voids with a diameter of 114 mm, designed to be supported on both sides;
PG - 260 mm thick with pear-shaped voids, designed to be supported on both sides;
PB - 220 mm thick, manufactured by continuous molding on long stands and designed to be supported on both sides.
Table 19
|
Plate type |
Reduced slab thickness, m |
Average density of concrete slab, kg / m 3 |
Slab length, m |
Characteristics of buildings (structures) |
|
Up to 7.2 incl. |
Residential buildings in which the required sound insulation of residential premises is provided by the device of hollow, floating, hollow-free layered floors, as well as single-layer floors along a leveling screed |
|||
|
Up to 9.0 incl. | ||||
|
Up to 7.2 incl. |
Residential buildings in which the required soundproofing of residential premises is provided by the installation of single-layer floors |
|||
|
Up to 6.3 incl. |
Residential large-panel buildings of the 135 series, in which the required sound insulation of the premises is provided by the installation of single-layer floors |
|||
|
Up to 9.0 incl. |
Public and industrial buildings (structures) |
|||
|
Up to 12.0 incl. |
||||
|
Up to 7.2 incl. |
Residential buildings of low-rise and manor type |
Explanations for the table. 19
|
Term |
Explanation |
|
Single layer floor |
Floor consisting of a covering (linoleum on a heat and sound insulating base), laid directly on the floor slabs or on a leveling screed |
|
Single-layer floor on a leveling screed |
Floor consisting of a coating (linoleum on a heat and sound insulating basis) laid on a leveling screed |
|
Hollow floor |
Floor, consisting of a hard surface on logs and soundproofing pads, laid on floor slabs |
|
Voidless laminated floor |
Floor consisting of a hard surface and a thin acoustic layer, laid directly on the floor slabs or on the leveling screed |
|
Floating floor |
A floor consisting of a covering, a rigid base in the form of a monolithic or prefabricated screed and a continuous sound-insulating layer of resilient-soft or loose materials, laid on floor slabs |
The shape and coordination length and width of the slabs (except for slabs of the PB type) must correspond to those given in table. 20 and hell. 9-11. For buildings (structures) with a design seismicity of 7 points or more, it is allowed to make slabs having a shape that differs from that indicated in the drawing. 9-11.
The structural length and width of the slabs (except for slabs of the PB type) should be taken equal to the corresponding coordination size (Table 20), reduced by the value a1 (the gap between adjacent slabs) or a2 (the distance between adjacent slabs in the presence of a separating element between them, for example, antiseismic belt, ventilation ducts, crossbar ribs), or increased by a3 value (for example, for slabs supported on the entire thickness of the staircase walls in buildings with transverse load-bearing walls). The values of a1, a2 and a3 are given in table. 21.
The shape and dimensions of plates of the PB type must correspond to the established working drawings of the plates, developed in accordance with the parameters of the molding equipment of the manufacturer of these plates.
Table 20
|
slabs |
Slab drawing number |
Coordination dimensions of the slab, mm |
|
|
Length |
Width |
||
|
From 2400 to 6600 incl. with an interval of 300, 7200, 7500 |
1000, 1200, 1500, 1800, 2400, 3000, 3600 |
||
|
1000, 1200, 1500 |
|||
|
3600 to 6600 incl. with an interval of 300, 7200, 7500 |
From 2400 to 3600 incl. with an interval of 300 |
||
|
From 2400 to 3600 incl. with an interval of 300 |
From 4800 to 6600 incl. with an interval of 300, 7200 |
||
|
From 2400 to 6600 incl. with an interval of 300, 7200, 9000 |
1000, 1200, 1500 |
||
|
6000, 9000, 12000 |
1000, 1200, 1500 |
||
|
1000, 1200, 1500 |
|||
|
From 3600 to 6300 incl. with an interval of 3000 |
1000, 1200, 1500, 1800 |
||
|
6000, 9000, 12000 |
1000, 1200, 1500 |
||
Note. The length of the slabs is taken as follows:
the size of the side of the slab not supported by the supporting structures of the building (structure) - for slabs intended to be supported on two or three sides;
the smallest of the dimensions of the slab in plan - for slabs intended to be supported along the contour.
Plates of types 1PK, 2PK, 3PK, 5PK, 6PK, 7PK Plates of types 1PKT, 2PKT, 3PKT
1 – 1 1 – 1
NS 
litas of types 1PCK, 2PCK, 3PCK
2
–2
Heck. 10. Plate type 4PC
1
–1 2–2
Heck. 11. Plate type PG
1
–1 2–2
Notes (edit) to hell. 9-11
1. Plates of types 1PKT, 2PKT, 3PKT, 1PKK, 2PKK and 3PKK can have technological bevels on all side edges.
2. Methods for strengthening the ends of the plates are shown in Fig. 9-11 as an example. It is allowed to use other reinforcement methods, including reducing the diameter of the voids through one on both supports without sealing the opposite ends of the voids.
3. The dimensions and shape of the groove along the longitudinal upper edge of the 1PKT, 2PKT and 3PKT slabs (Fig. 9b) and along the contour of the 4PK type slabs (Fig. 10) are set in the working drawings of the slabs.
4. In slabs intended for buildings (structures) with a design seismicity of 7-9 points, extreme voids may be absent due to the need to install embedded products or release reinforcement for connections between slabs, walls, anti-seismic belts.
Table 21
|
Scope of plates |
Additional dimensions taken into account when determining the structural size of the slab, mm |
|||
|
length |
widtha 1 |
|||
|
a 1 |
a 2 |
a 3 |
||
|
Large-panel buildings, including buildings with a design seismicity of 7-9 points Buildings (structures) with walls made of bricks, stones and blocks, with the exception of buildings (structures) with a design seismicity of 7-9 points Buildings (structures) with walls made of bricks, stones and blocks with a design seismicity of 7-9 points Frame buildings (structures), including buildings (structures) with a design seismicity of 7-9 points |
10 - for slabs with coordination width less than 2400.20 - for slabs with coordination width 2400 and more |
|||
Voids in slabs intended to be supported on two or three sides should be placed parallel to the direction in which the length of the slabs is determined. In slabs intended to be supported on four sides, voids should be placed parallel to either side of the slab outline.
The nominal distance between the centers of the voids in the slabs (with the exception of slabs of types PG and PB) should be taken at least, mm:
185-in plates of types 1PKT, 1PKT, 1PKK, 2PK, 2PKT, 2PKK, 3PK, 3PKT, 3PKK and 4PK;
235-in plates of 5PK type;
233 "" "6PC;
139 "" "7PC.
The distance between the centers of the voids of slabs of types PG and PB is assigned in accordance with the parameters of the molding equipment of the manufacturer of these slabs.
The slabs should be made with recesses or grooves on the lateral edges to form intermittent or continuous dowels after monolithing, ensuring the joint work of the floor slabs for shear in the horizontal and vertical directions.
By agreement of the manufacturer with the consumer and the design organization - the author of the project of a specific building (structure), it is allowed to make slabs without grooves or grooves for the formation of dowels.
Plates should be made with reinforced ends. Strengthening of the ends is achieved by reducing the cross-section of the voids on the supports or filling the voids with concrete or concrete inserts (Fig. 9-11). When the design load on the ends of the slabs in the zone of support of the walls does not exceed 1.67 MPa (17 kgf / cm 2), it is allowed by by agreement between the manufacturer and the consumer, to supply plates with unreinforced ends.
Reinforcement methods and minimum dimensions of the fittings are set in the working drawings or indicated when ordering plates.
Plates are designated with grades in accordance with the requirements of GOST 23009. The plate grade consists of alphanumeric groups separated by hyphens.
In the first group, indicate the designation of the type of slab, the length and width of the slab in decimeters, the values of which are rounded to the nearest whole number.
The second group indicates:
the calculated load on the slab in kilopascals (kilogram-force per square meter) or the serial number of the slab in terms of bearing capacity;
steel class of prestressed reinforcement (for prestressed slabs);
concrete type ( L - lightweight concrete, C-dense silicate concrete; heavy concrete is not indicated).
In the third group, if necessary, indicate additional characteristics that reflect the special conditions of use of the plates (for example, their resistance to aggressive gaseous media, seismic effects), as well as designations of the design features of the plates (for example, the presence of additional embedded products).
An example of a conventional designation (brand) of a slab of type 1PK 6280mm long, 1490mm wide, calculated for a design load of 6 kPa, made of lightweight concrete with prestressing reinforcement of class At-V:
1PK63.15-6A T VL
The same, made of heavy concrete and intended for use in buildings with a design seismicity of 7 points:
1PK63.15-6A T V-C7
Slabs should be made of heavy concrete in accordance with GOST 26633, structural lightweight concrete of dense structure with an average density of at least 1400 kg / m 3 in accordance with GOST 25820, or dense silicate concrete with an average density of at least 1800 kg / m 3 in accordance with GOST 25214 of classes or grades in compressive strength specified in the working drawings of these plates.
| Hollow-core floor slabs GOST 9561-91 | ||||
| Name | Dimensions (LxWxH, mm) | volume, m3 | Weight, t | Price for 1 unit with VAT, rub. |
| PK 24-12-8 AtV T | 2380x1190x220 | 0,36 | 0,9 | 4306 |
| PK 27-12-8 AtV T | 2680x1190x220 | 0,40 | 1,01 | 4799 |
| PK 30-12-8 AtV T | 2980x1190x220 | 0,44 | 1,11 | 5429 |
| PK 33-12-8 AtV T | 3280x1190x220 | 0,49 | 1,22 | 5934 |
| PK 36-12-8 AtV T | 3580x1190x220 | 0,53 | 1,32 | 6439 |
| PK 39-12-8 AtV T | 3880x1190x220 | 0,57 | 1,42 | 6944 |
| PK 42-12-8 AtV T | 4180x1190x220 | 0,61 | 1,53 | 7383 |
| PK 45-12-8 AtV T | 4480x1190x220 | 0,65 | 1,62 | 7532 |
| PK 48-12-8 AtV T | 4780x1190x220 | 0,69 | 1,73 | 8004 |
| PK 51-12-8 AtV T | 5080x1190x220 | 0,73 | 1,83 | 8474 |
| PK 54-12-8 AtV T | 5380x1190x220 | 0,78 | 1,95 | 8910 |
| PK 57-12-8 AtV T | 5680x1190x220 | 0,82 | 2,05 | 9347 |
| PK 60-12-8 AtV T | 5980x1190x220 | 0,86 | 2,15 | 9886 |
| PK 63-12-8 AtV T | 6280x1190x220 | 0,90 | 2,25 | 10421 |
| PK 72-12-8 AtV T | 7180x1190x220 | 1,01 | 2,53 | 13405 |
| PC 24-15-8 AtV T | 2380x1490x220 | 0,50 | 1,25 | 4774 |
| PK 27-15-8 AtV T | 2680x1490x220 | 0,55 | 1,38 | 5397 |
| PK 30-15-8 AtV T | 2980x1490x220 | 0,60 | 1,52 | 5916 |
| PK 33-15-8 AtV T | 3280x1490x220 | 0,65 | 1,61 | 6642 |
| PK 36-15-8 AtV T | 3580x1490x220 | 0,70 | 1,75 | 7265 |
| PK 39-15-8 AtV T | 3880x1490x220 | 0,74 | 1,85 | 7784 |
| PK 42-15-8 AtV T | 4180x1490x220 | 0,80 | 2,02 | 8407 |
| PK 45-15-8 AtV T | 4480x1490x220 | 0,88 | 2,2 | 8834 |
| PK 48-15-8 AtV T | 4780x1490x220 | 0,94 | 2,35 | 9437 |
| PK 51-15-8 AtV T | 5080x1490x220 | 0,99 | 2,48 | 9861 |
| PK 54-15-8 AtV T | 5380x1490x220 | 1,05 | 2,63 | 10427 |
| PK 57-15-8 AtV T | 5680x1490x220 | 1,10 | 2,75 | 11010 |
| PK 60-15-8 AtV T | 5980x1490x220 | 1,14 | 2,85 | 11744 |
| PK 63-15-8 AtV T | 6280x1490x220 | 1,19 | 2,98 | 12343 |
| PK 72-15-8 AtV T | 7180x1490x220 | 1,34 | 3,35 | 16734 |
Hollow-core reinforced concrete floor slabs are used in the construction of load-bearing structures of buildings and structures. The voids inside the slabs are designed to improve sound insulation and reduce the weight of the structure. The top side of the floor slabs will be the base of the floor and the bottom side will be the ceiling. Hollow-core floor slabs are used in the individual construction of houses, in the construction of residential and industrial multi-storey buildings.
According to the external shape, the floor slabs are divided into flat and ribbed. Flat slabs, in turn, are hollow-core and solid. Our company produces hollow-core floor slabs PC... The diameter of the round voids is 159mm, the thickness of the slabs is also standard and is 220mm. These slabs are intended to be laid on top of load-bearing walls, supported on both end sides.
Hollow-core slabs are capable of withstanding enormous loads, but it is worth paying special attention to the storage of these products. For storing slabs, it is necessary to prepare a flat surface in advance, pour and tamp a sand cushion. Never lay slabs directly on the ground. Place wooden blocks along the edges at the bottom of each slab. There should be two bars, at a distance of about 25-45 cm from each of the edges. It is absolutely not recommended to put bars under the middle part of the slab in order to avoid cracks, breaks. Stacking of hollow-core floor slabs is allowed in a stack no more than 2.5 meters high.
Floor slabs lie flat and without drops. To do this, it is necessary to achieve the position in one horizontal plane of all the upper rows of load-bearing walls. Before laying hollow-core slabs on walls made of blocks (foam concrete, aerated concrete, cinder block), it is necessary to make a reinforced concrete belt in advance. Its thickness should be within 15-25cm. When installing hollow-core slabs, the holes in them are sealed. This can be done in advance when the slabs are stacked on the ground. Hollow core slabs are laid on a thick mortar. The solution layer should not exceed 2 cm.
The mortar is applied over the brickwork. This is done in order to close the gaps, if there are differences, as well as for a better fit of the plates. The mortar sets in 15-20 minutes, during this period of time you can move the slab to align its position relative to the walls. To avoid hardening of the mortar, it is applied immediately before lifting the floor slab. The hollow core slabs are lifted by the mounting loops. After the first plate has been laid and leveled, they proceed to the installation of the next one. The slots at the joints are sealed with polyurethane foam and cement laitance.
Anyone who has ever 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, account for about 90% of the total weight of the house. Floor slabs (PC) can vary greatly both in weight and in size, depending on the specific purpose for which they are used.
Structural features of hollow core slabs
As you might guess, inside the reinforced concrete floor slabs (PC) are hollow, which is why they are marked when sold as hollow. But the holes inside such plates, contrary to error, can have not only oval, but also round, square and other shapes.
Supporting scheme of a hollow floor slab However, in most cases, floor slabs (PC) have exactly cylindrical hollow circles inside.
It is interesting that floor slabs (PC) can be both unreinforced and reinforced. Reinforced concrete floor slabs (PC) will be exactly reinforced.
Such floor slabs (PC), 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, the very method of installation, depends on what kind of 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, then this can lead to unpleasant consequences, which, of course, must be avoided.
Layout of hollow core slabs on the second floor Characteristics of hollow core slabs
The size
The final cost also depends on the size of the hollow PC; in addition to parameters such as width and length, weight is also important.
PC sizes vary as follows:
- the length of the PC size ranges from 1180 to 9700 millimeters;
- the width of the PC size ranges from 990 to 3500 millimeters.
The most popular and demanded are hollow-core panel slabs, the length of which is 6000 mm and the width is 1500 mm. The height or thickness of the panel is also important (it would be more correct to speak of height, but builders usually say “thickness”).
So, the thickness that hollow-core panels can have is always the same value - 220 mm. Of course, the weight of the floor panel is also of great importance. The concrete floor slabs must be lifted by a crane with a minimum lifting capacity of 4-5 tons.
Comparative table of coordination dimensions of hollow core slabs The length and weight of the panels are essential for construction, the length is even less important than the weight.
The weight
As for such an important parameter as weight, everything here is very clear the first time: the range of products manufactured 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.
Usually, cranes are used, as noted above, with a lifting capacity of at least 5 tons (of course, the cranes must lift the weight with some margin).
The weight of panels with the same marking may differ, but not significantly: 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 has been exposed to rain, then it will a priori be slightly heavier than a product that has not been exposed to rain.
Types of loads
To begin with, it should be noted that any overlap presupposes the presence of the following 3 parts:
- The upper part, with a floor where people live. Accordingly, the panel will be loaded by the floor covering, various insulation elements and, of course, concrete screeds - the main component of the load;
- The lower part, with the presence of a ceiling, its finishes, lighting fixtures. By the way, you should not be skeptical about the presence of lighting devices. Firstly, the same LED lamps require partial destruction of the plate with a puncher for laying 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;
- Constructional. It combines both the upper and lower parts at once, as if supporting them in the air.
The hollow core slab is the structural slab that supports both the upper and lower floor slabs in the air!
By the way, do not discount dynamic load as well. It is, as you might guess, created by the 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 it is normal to move a heavy piano in a small two-story house from one place to another once, then daily movement will create a much greater negative impact on the hollow-core slab. It is unlikely to fall, but subsequently there may be serious problems with ventilation.
By the type of load distribution, they are divided into 2 more groups:
- distributed;
- point.
An example is worthwhile to understand the difference between the two. The same huge crystal chandelier that weighs under one tone is a point load. But a stretch ceiling with a frame over the entire surface of the slab is already a distributed load.
Construction of a technological line for the production of hollow core slabs But there is also a combined load that combines point and distributed. For example, a bathtub filled to the top. The bath itself is on legs, and its pressure on the legs is a kind 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.
Difficult, but you can figure it out. And you need to! After all, the calculation for floors and hollow core slabs during construction will still need to be done.
Hollow core slab grades
As a matter of fact, hollow core slabs do not even have brands as such. We are talking about marking, which reflects some parameters. A small example is enough.
Layout of hollow core slabs on the girder Let's say the panel has the following markings: PC 15-13-10 PC - means a hollow slab; all numbers indicate technical parameters.
15 would mean that the panel is approximately 15 decimetres (1.5 meters) long. Why approximately? It's just that the length can be 1.498 meters, and on the marking produced they have the right to round this figure to 1.5 meters (15 decimeters). The number 12 means that the product has a width of 10 decimeters. The last number (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 consider the load per square meter, here it will be 1000 kilograms per 1m². In general, everything is not so difficult.
The brand of panels always looks like PC-XX-XX, if sellers offer other options, then you should be on your guard.
Load calculation
Calculation of the limiting effect
Calculation of the ultimate exposure is a prerequisite for building design. The dimensions and other parameters of the panels are determined by the old solid Soviet GOST under the number 9561-91.
Hollow core slab device with a reinforced screed In order to determine the load that will be applied to the product, it is necessary to indicate the weight of absolutely all elements that will "press" on the floor on the drawing of the future structure. Their total weight will be the ultimate load.
First of all, you need to take into account the weight of the following elements:
- cement-sand screeds;
- gypsum concrete partitions;
- weight of 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, ultimate load for each specific product.
Optimal load calculation
It is clear that the maximum permissible level is a critical indicator, which in no case can be brought to it. 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. As a result, it turns out that the maximum allowable load value is 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 (for example, its value is 800 kilograms per 1m²). 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 (500kg / m²), you need to subtract the received one (200kg / m²). The result will be an indicator of 300 m². But that's not all.
Diagram of a hollow core slab with waterproofing Now from this indicator it is necessary to subtract the weight of furniture, finishing materials, the weight of people who will constantly be in the room or in the house. "Live weight" and all elements, their load, let it be 150 kg / m². It is necessary to subtract 150 from 300. As a result of all, the optimal permissible indicator will be obtained, the designation of which will be 150 kg / m². This will be the optimal load.
Benefits 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 corpulent products;
- high strength indicators, despite the fact that the bottom of the panel is hollow;
- reliability;
- the sediment at home will be much less intense than when using full-bodied 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 fooled when buying.
Diagram of the device of reinforcing blocks in a hollow floor slab Sometimes (this is rare, but still) sellers try to sell low-quality panels, the so-called lightweight ones. They, for example, may have markings showing that the product is designed for a load of 500 kilograms per square meter, but in fact this parameter is several times lower.
This is not even a fraud, it is a criminal offense that must be punished to the fullest extent of the law. After all, if you buy a panel designed for a lower load, there is a serious risk of collapse of buildings. This situation can be observed not only in the provinces, but even in Moscow or St. Petersburg.
In general, when buying such products, you need to be extremely careful. It is important to remember that any design mistake can even have tragic consequences.
Video
You can watch a video where experts tell in detail about the features of various types of hollow core slabs.
Hollow-core reinforced concrete floor slabs are one of the most demanded types of reinforced concrete products, intended for dividing building levels and laying load-bearing structures. Technical conditions and norms are controlled by GOST 9561-91, the characteristics allow them to be used in any area of construction: from private houses to industrial facilities. The mandatory nuances of the application include the use of lifting equipment for laying and checking the bearing capacity. It is easy to select the desired series, the marking includes all the necessary information.
Externally, hollow-core panels represent a rectangular box with the correct geometry of 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 at least B22.5). The voids are located parallel to the main direction along the length (for views based on 2 or 3 sides) or any of the sides of the contour for overlaps marked with PAC.
The presence of a frame is mandatory, to extend the service life and increase reliability, all the metal placed inside is treated with anti-corrosion compounds at the manufacturing stage. In panels supported on 2 or 3 sides, a frame made of prestressed reinforcement is laid. Depending on the purpose of the floor slabs, steel of one of the following grades is used: seven-wire strands with a cross section of 6P-7, a periodic profile of 5Br-II, ropes K-7, heat-hardened rods AT-V and other materials corresponding to the standard (series 1 141.1 - basic 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), the length varies from 2.4 m to 12, the width is within 1-2.6 m.The exception is the types based on 4 sides (PKK marking), their dimensions vary from 3 × 4.2 to 3 × 7.2 m, respectively. Average weight of 1 running meter with a width of 1 m is 360 kg.
2. 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 demanded 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 reinforcement cage.
Structures are valued for their reliability, light weight, good tensile strength in bending due to the presence of internal voids, the ability to hide communications, resistance to moisture, open fire, biological influences, heat and sound insulation properties, durability. An important advantage is considered to be high geometric accuracy, which simplifies the process of installation and subsequent finishing.
| Type of | Actual thickness, mm | Length (maximum, inclusive), m | Reduced slab thickness (ratio of concrete volume to area) mm | Diameter of voids, mm | Nominal distance between the centers of voids, not less than mm |
| 1PC, 1PCT, 1PCK | 220 | 7.2 (up to 9 for slabs for industrial buildings, supported exclusively on 2 sides) | 120 | 159 | 185 |
| 2PC, 2PCT, 2PCK | 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 area.
The main standards for width are PK-10, PK-12 and PK-15. All types of holes have a round shape, with the exception of PG - slabs with a pear-shaped void. For variants with PKK marking, beveled ends are allowed.
All dimensions of reinforced concrete floors with holes inside are unified (including the spacing along the length), deviations do not exceed 5 mm. The given thickness indicated in the table characterizes the economy of the product.
Hollow-core slab marking
Standard decoding includes:
1. A figure characterizing the size of the diameter of the inner holes according to GOST 9561-91. Omitted for 1PC, in most prices there is a simple designation - PC.
2. Type. It is indicated in 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 the continuous molding method.
3. Dimensions of hollow-core floor slabs: first comes the length (the side not supported by the supporting structure), then the width, in dm, rounded up to a larger value. 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 item is a number that reflects the bearing capacity of a reinforced concrete product.
5. Type of reinforcement. May be skipped for non-tensioned frames.
6. Grade of mortar: not indicated for heavy, used in the predominant share of products. The letter L means the use of lightweight concrete, C - dense silicate.
7. Other, additional characteristics or design features of products. These include resistance to seismic influences or corrosive gases, the presence of embedded elements.
Scope and application features
The main purpose is to organize a reliable prefabricated floor in objects with load-bearing walls (they are also used during construction). In private and low-rise construction, they are used for laying the main floors, dividing floors and attic space, arranging pitched roofs in outbuildings, platforms and as a fence. Their bearing capacity fully complies with construction requirements (the standard rate, when calculated taking into account the weight of people and furniture, is 150 kg / m2, the actual value is several times higher). Soundproofing characteristics allow reliable protection against noise even when installing single-layer floors.
Long slabs (up to 9 m for 1 PC, 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 the 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 due to the ban on their cross-cutting. The use of reinforced concrete products of the PK series allows:
- Get a reliable structure designed for significant weight loads.
- Improve the insulating capacity of the building.
- Provide a perfectly level horizontal slab (with correct placement and checking of supports).
- Improve water resistance, fire safety and acoustic protection of the building.
The cost of slabs for the installation of floors
| Series | Bearing capacity, kg / m2 | Dimensions (edit) (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 | |
| PK 30.10-8 | 2980 × 990 × 220 | 880 | 6 000 | |
| PK 36.10-8 | 3580 × 990 × 220 | 1060 | 6 410 | |
| PC 45.15-8 | 4480 × 1490 × 220 | 2120 | 12 600 | |
| PK 60.18-8 | 5980 × 1780 × 220 | 3250 | 13 340 | |
| PK 90.15-8 | 8980 × 1490 × 220 | 4190 | 40 760 | |
| 2PK 21.12-8 | 800 | 2080 × 1190 × 220 | 950 | 3 800 |
| 2PK 62.10-8 | 6180 × 990 × 220 | 2425 | 8 730 |