Floor slab weight 6x1 hollow. Hollow core slabs: weight, dimensions according to GOST and other technical characteristics, as well as types, marking and installation technology

The range of laying reinforced concrete slabs - from the formation of a foundation base for buildings made of wood (quick assembly), or the separation of the basement from the higher building of the house, to the installation of the attic floor at the completion of the upper floor. Also, in addition to the usual interfloor overlap, some types of panels are also used for the construction of walls.

Slabs when overlapping floors are able not only to receive and distribute heavy loads(the weight of the internal partitions, equipment, furniture, people located on them), but also serve as a reliable element of rigidity in the structure of the entire building.

The products are made of heavy concrete and, in addition to increased strength and fire resistance, they have high levels of water and frost resistance, as well as sound insulation. The upper and lower smooth surfaces of the product respectively serve as a floor and ceiling in the room and require minimal interior decoration.

There are several varieties of this building element. Its choice depends on the properties and characteristics of the slab required in each case, the area of its application and economic calculation.

Types of slabs (classification)

According to the structural structure, reinforced concrete slabs are of 3 types:

void;
solid (full-bodied);
ribbed.

Hollow core slabs

In private construction, hollow core slabs are most often used. Longitudinal circular voids lighten the weight of the slab, increase its thermal insulation characteristics and allow you to hide the wires of the internal wiring of engineering communications in them.

In view of the popularity and widespread use of ceilings with longitudinal voids, their production is gradually expanding and modernizing, adapting to the emergence of new materials and construction technologies. I must say that the shape of the voids can now be not only round, but also oval and vertical.

There are several brands or varieties of slabs with longitudinal voids:

PC

They have been widely used since Soviet times - they are made of heavy concrete, have round voids with a diameter of 140 or 159 mm inside, standard height 220 mm and mounting hinges. Which, after laying the floor, serve as an additional embedded part for fastening the plates to each other with anchors, by welding.

As a rule, in private low-rise construction, it is not required to fasten the slabs together after laying.

PNO (lightweight)

After some time, such a modernization of these structures appeared. The products are thinner (160 mm) and weight. Wherein reinforced with a special method and thicker reinforcement, it can withstand the same loads, just like the pc stove.

The use of lightweight products is considered more economical in comparison with PC plates in several parameters at once:

from the weight of the lightweight floor, less load is transferred to the foundation, and accordingly, materials are saved when erecting the foundation of the building;
the plates themselves are slightly cheaper than traditional PCs due to less material consumption for their manufacture;
transport costs are reduced during transportation - a larger number of reinforced concrete products are installed on a transport unit with the same volume and weight as when loading PC slabs.

Attention!

If the purchased slabs are not factory-sealed, the ends of the holes must be sealed at the construction site by themselves - poured with concrete mortar (grade M200) in the support area.

These products are made from heavy concrete only.

Bench panels (PB or PPS)

Reinforced concrete products of the latest generation. Products are manufactured on special benches of various widths using formless molding. This makes it possible to manufacture products, the length of which is not tied to GOST standards. That is, the slab is cut at the production stand for spans, according to an individual project, in increments of only 10 cm. The height of the structure can also vary from 160 to 300 mm, depending on the required length.

High grade of concrete (M400 - M550) and laying of prestressed lower reinforcement layers ensure high structural strength in all dimensional variants. The only drawback of this product can be considered a higher cost compared to PC plates.

It is the bench panels that can be mounted vertically - for the construction of the walls of frame houses.

Attention!

During production, if a short-sized slab is sawn off at the stand of the latter, then due to excessive compression of the prestressed reinforcement, the structure can bend (by bending the middle up). This defect is easy to notice upon visual inspection, in a stack among other products. And although such cases are quite rare, especially from good manufacturers, and up to certain values such a deflection is not considered a marriage, you should pay attention to this when buying.

Other types of slabs

Solid single-layer (1P, 2P)- are most often used in private construction for the installation of ceiling slabs. They are made of aerated concrete - 120 mm thick, and heavy - 160 mm thick.
Monolithic- if for some reason standard production boards are not suitable for the project, you can make it yourself. This is a fairly simple, but long and laborious process, it is justified by the possibility of using it for a wide variety of forms of coverage areas. The installation of load-bearing beams, formwork and reinforcing mesh will be required. Pouring with concrete (not lower than M200 grade) is kept in the formwork for the prescribed 28 days - until the full set of design strength. It is believed that monolithic structures have the highest bearing capacity if they are filled with N.
Ribbed- their design feature in the distribution of thickenings and thinner elements in accordance with the compressive and tensile loads. As a result, a high strength and load-bearing capacity of the slab is achieved. The main application is in industrial construction and in the installation of a base in high-rise buildings. But sometimes such slabs are found as overlapping garages. They are not used in residential construction due to the shape of the bottom side, which is inconvenient for finishing, having a concave hollow configuration and transverse stiffeners.

Ribbed floor slabs

The difference between PC and PB plates

If you opted for hollow core slabs, let's take a closer look. Let's take a look at the differences between traditional PC boards and stand panels with no form PB molding.

For convenience, the data are given in the table:

PC and PNO		PB or PPP
	Thickness
PC - 220 mm, lightweight - 160 mm		from 160 to 300 mm
	Length
PC - up to 7.2, sometimes up to 9 m, PNO - up to 6.3 meters, with a step determined by each manufacturer individually		Maximum length - 12 m, structurally depends on the size of the panel height. Slabs are cut to length according to the order, with a step size of 10 cm.
	Width
1.00; 1.20; 1.50 and 1.80 m		More often stands are 1.2 m, less often - 1.00 and 1.50 m

Basically - typical - 800 kgf / m2, but individual production with a load of 1250 is possible		In addition to the typical load 800, slabs are produced with a load from 300 to 1600 kgf / m2
	Armature
The lower reinforcement layer is prestressed only in slabs from 4.2 m in length. In shorter products, simple mesh reinforcement is performed.		The armature is prestressed in products of any length.
	Smoothness
Due to the long service life and wear and tear of the equipment, the concrete surface usually does not have the desired smoothness.		The latest benches and extruder smoothing provide a smoother, more attractive finish, but some minor exceptions are acceptable.
	Concrete grade
M200 - M400		M400 - M550
	Hole ends
Obligatory sealing of the ends of the holes		Not required due to the strength of the concrete grade

Calculation of the number of plates and from the sizes for a private house

If the construction of a private house building is carried out according to an approved project, then the dimensions and number of slabs are preliminarily calculated by engineers when developing this order. In general, such calculations are made according to the principle "Adjusting" the layout of the walls to the dimensions of the slabs, and not vice versa... But in private construction, anything can happen. And if the walls are already planned out or even ready and are waiting for overlap, then you need to calculate their number and sizes, taking into account certain rules:

the length of the slab is equal to the distance between the load-bearing walls plus the width of the support area of the slab on the wall (beam);
the width of the slab is selected on the basis of how many pieces from the assortment you have chosen will cover the transverse distance between the main walls (partitions are not taken into account). The long side of the hollow slab is laid close to the curtain walls, or overlapped by no more than 100 mm (up to the first void). For more details, see the article about;
if a small gap remains between the slabs or there is a small section of the room that does not fit into the slab configuration, it can be “closed” with partial monolithic casting, using formwork and reinforcement;

It is better to order products of "slow" sizes in advance, as it takes more time to wait for their production than to produce standard designs.

Attention!

In winter, floor slabs are much cheaper. But the area for their unloading needs to be prepared and leveled in the fall. You will also have to order a tractor to remove snow on the site and, possibly, on the access roads. But in the end, there will still be savings.

Standard slab sizes

Still, if possible, it is better to use slabs of standard sizes, since their purchase is much cheaper and takes less time.

At factories, the size ranges of the latest generation of products vary somewhat, but there are dimensional restrictions generally accepted by standards and specifications:

Slab type	Length (m)	Width (m)
PC, round cavities with a diameter of 140 mm	1,8 / 2,4 / 3,0 / 6,0	from 1.2 all sizes are divisible by 0.3 m
PC, round voids with a diameter of 159 mm and PB slabs	2,4 / 3,0 / 3,6 / 4,2 / 4,8 / 5,1 / 6,0 / 6,3 / 6,6 / 7,2 sometimes 9.0	from 1.0 and further all sizes are divisible by 0.3 m
PNO height 160 mm	from 1.6 to 6.3, sometimes 9.0	0,64 / 0,84 / 1,0 / 1,2 / 1,5
PPP	from 3 to 12, in 0.1 m steps	1,0 / 1,2 / 1,5
solid 120 mm high	3,0 / 3,6	4,8 / 5,4 / 6,0 / 6,6
solid 160 mm high	2,4 / 3,0 / 3,6	2,4 / 3,0 / 3,6 / 4,8 / 5,4 / 6,0
ribbed, height 30 mm	6,0	1,5

Weight

It is important to know the weight of the slabs when calculating structures. But this is the responsibility of the designer, who draws up the project for the house. It is useful for a private developer to know the mass of slabs when they are delivered to the site and installed.

In the first case, it is necessary to select the carrying capacity of the transport. Most likely, two vehicles will be required for delivery.

For the installation of the slabs, a crane is used, when ordering which you will also be asked about the weight and dimensions of the slabs. Each crane has its own lifting capacity. Since the weight range of the slabs is in the range of 960-4800 kg, a 5-ton truck will be enough in any case.

Depending on the concrete used, the mass of a standard 6x1.5 m hollow core slab varies from 2.8 to 3.0 tons.

Since in private construction the most common slabs with a thickness of 160 mm and 220 mm, we give their weight per linear meter for a slab width of 1500 mm:

Here are some more standard slabs:

Plate marking

According to GOST, all types of plates have their own standards. Their observance is necessary in the design of objects and in the installation calculations. Each plate has a marking - a special encrypted inscription, reflecting not only the overall dimensions of the product, but also its main strength and design characteristics. Once you understand the values of one brand of slabs, you can easily read the rest, regardless of whether the slab sizes are standard or custom made.

The first letters in the specification indicate the type of construction (PC, PNO, PB, PPS). Further, the length and width values (in decimetres, rounded up to an integer) are enumerated through a hyphen, and again through a hyphen - the maximum permissible weight load on the structure, in centners per m2, excluding its own weight (only the weight of partitions, interior decoration, furniture , equipment, people). At the end, a letter addition is possible, denoting additional reinforcement and the type of concrete (t - heavy, l - light, i - cellular)

Consider an example and decipher the marking. Plate specification PK-60-15-8АтVт means:

PC - plate with round voids;
60 - length 6 m (60 dm);
15 - width 1.5 m (15 dm);
8 - mechanically it is possible to load the structure up to 800 kg per m 2;
AtV - presence of additional reinforcement (class AtV)
t - made of heavy concrete.

The height of the product is not indicated, because refers to the standard size of this product (220 mm).

Also, the letters in the marking inform:

PC - a typical plate with round voids,
HB - single-row reinforcement;
NKV - double-row reinforcement;
4НВК - four-row reinforcement.

Useful video

A representative of one of the factories talks about the size of the products:

This article is introductory and provides a general overview of reinforced concrete slabs. Given the impressive weight of the structures, when using them, an engineering calculation of foundations and load-bearing walls is desirable, taking into account the required safety margin.

Hollow core slabs are widely used in industrial and civil construction. Their function is to divide the internal space of buildings under construction into floors, as well as transfer the load from the structures lying above to the walls and foundation. Slabs are part of a precast reinforced concrete floor, which today is considered the most popular and practical in both low and high-rise construction.

What is a hollow core slab

The hollow core slab is a 220 mm thick reinforced concrete slab with voids with a diameter of 159 mm. Voids are cylindrical cavities that penetrate the slab in the longitudinal direction.

Similar hollow core slab device chosen for a reason. The purpose of the voids is to reduce the weight of the structure. In turn, a decrease hollow core slab masses allows:

Load the floor immediately after installation without concrete screed.
Reduce the consumption of concrete and reinforcement, thereby reducing the cost of construction.
Simplify the process of transportation and installation.
Reduce the load on the foundation and walls, which allows them to be erected from less heavy structures that are much cheaper.

Other functions of voids:

Providing a high level of sound and thermal insulation due to the air inside the holes.
Creation of conditions for communications, which reduces the time for finishing.
Increase in the useful volume of the structure.
Possibility of construction in earthquake-prone areas.

Weight of hollow core slab per 1 m 2 large enough even if there are voids, therefore, powerful lifting equipment is used for installation. For example, the total weight is 712 kg, and for 1 m 2 - 712 / 2.4 · 1 = 297 kg / m 2. Knowing how much does a hollow floor slab weigh, you can collect loads to calculate the bearing capacity of walls and foundations.

In what sizes are hollow core slabs produced?

Standard length of hollow core slabs is equal to 3 m. This is the most common standard size that is used in the construction of many civil buildings. For example, in most residential buildings, the width of the rooms is designed to be 3 m, therefore, 3 m slabs are used for floors.Another common size is 6 m.

Generally, dimensions of hollow core slabs are subject to a unified modular system in construction (EMC), which provides:

Unification. This is the name of limiting the standard sizes of prefabricated parts and structures in order to bring them to uniformity.
Typing. Choice of the most economical reusable elements from the whole number of unified elements.
Standardization. Approval of typed constructs as standards (samples).

EMC's goal is to simplify and reduce the cost of construction. The result of typing in construction was the development of a unified product range based on the module (M). The basic model is 100 mm. When designing buildings and structures for its construction, an enlarged module is used - 2M, 3M, 6M, 12M, 15M, 30M, 60M, etc.

Principles of plate marking

Hollow core slabs most often they are designed using the M and 3M modules, that is, their dimensions are multiples of either 100 mm or 300 mm. Dimensions and some characteristics of slabs are always displayed in their markings. For example, the designation is deciphered as follows:

PC - hollow core plate.
60 - length in decimeters, as well as the number of modules, i.e. 60M, which is equal to 6000 mm.
12 - width in decimeters or modules, i.e. 12M, which is equal to 1200 mm.
8 - bearing capacity, kgf / m 2.
AtV - use of class V prestressing reinforcement (At).

The markings are usually applied to the side of the board.

The designation AtV is not present in the designation of all plates. For lengths up to 4780 mm, slabs can be produced with stress-free reinforcement. In this case, the designation is simply omitted. For longer lengths, it is the AtV prestressing reinforcement that should be used. Its voltage is carried out in an electrothermal way.

Additionally, the marking may contain:

The letter "L" means lightweight concrete.
The letter "C" stands for dense silicate concrete.
Index "1" - the holes of the slabs are sealed from the ends.

In general, labeling principles hollow core slabs are determined GOST 9561 "Reinforced concrete hollow-core floor slabs" and GOST 26434 "Reinforced concrete floor slabs - basic parameters and types".

In reality, the dimensions of the slab are somewhat different from those indicated in the marking:

10 - 990 mm;
12 - 1190 mm;
15 - 1490 mm;
24 - 2380 mm;
48 - 4780 mm;
60 - 5980 mm, etc.

Hollow core slabs can have a length from 980 to 8990 mm, which is fixed in the marking with numbers from 10 to 90. Weight and volume of hollow core slabs.

Varieties of hollow core slabs

In addition to standard PC plates, there are several other varieties:

PB - slabs made by formless forming on a conveyor. In the manufacturing process, a special reinforcement method is used, which allows you to cut slabs without losing their strength. PB has a smoother surface, which makes it easier to finish floors and ceilings.
PNO - lightweight slabs, also manufactured without formwork. The main difference from PB is the smaller thickness, which is 160 mm.
HB is an internal type of flooring with one row of prestressed reinforcement.
NVK is an internal type of flooring, but already with two rows of stressed reinforcement and a thickness of 265 mm.

Device and units of support of the plate

Difference between PC and PB

PC floor slabs are classic. They were the first to be made with voids back in Soviet times. PB is a new generation floor slab, but also hollow. The main difference between the two is the way of production.

PC board manufacturing technology:

Reinforcement is placed in the metal formwork.
Concreting of a metal form is carried out.
To remove air bubbles, the entire mold is vibrated.
Then it is placed in a special chamber for drying for 6-7 hours.
At the end, the finished slab is removed and stored.

The main difference in the production of PB slabs is the absence of formwork, hence the name of the method - no formwork. The production steps are as follows:

Thin cables are stretched throughout the stand of the heated platform.
The molding machine passes over this area and leaves a strip of concrete slurry behind it.
From above, the semi-finished slab is covered with a film (the length of the workpiece can reach 190 m).
Products are dried.
At the end, the workpiece is cut to the dimensions required by the customer.

Thanks to the special production method, PB can be cut at an angle of 30-90 °. From this, their bearing capacity will not change in any way. By GOST dimensions of hollow floor slabs PCs affect their manufacturing technology. From a length of 4.2 m, such structures cannot be cut. This is due to the fact that at the ends of the products there are special stops for prestressing reinforcement. At cutting hollow core slabs it is necessary to cut off these stops together with the end, and they are responsible for the bearing capacity of the structure.

At the same time, PB slabs do not have mounting loops, which complicates and increases the cost of their installation. Hollow holes cannot be used for a hook, as this can lead to destruction of the end face, and then the hook will break out. Therefore, the installation is carried out only with the use of special traverses.

The choice between PB and PC plates is carried out specifically for each facility under construction, based on the characteristics of the layout and budget. Difference between characteristics of hollow core slabs PC and PB are presented in the table.

Criterion
Bearing capacity, kgf / m 2	Standard - 800	A wider range is from 300 to 1600.
Maximum length, m
Concrete grade
Using prestressed reinforcement	With a length of 4.2 m.	For all designs, regardless of length.
Hollow core slab weight	Lighter ones are 4-6% lighter than PB.	Heavier than PC.
Surface quality	Due to the forming in the metal formwork, the surface quality is slightly worse than that of the PB.	The minimum number of defects, which allows you to save on finishing work.
Support methods	Available in several types: PC - support on 2 sides; PKT - support on 3 sides; PKK - support on 4 sides.	Can only be supported on 2 sides.
Other important features	The increased diameter of technological voids allows you to lay engineering communications in them, for example, sewer pipes (in the case of construction walls on hollow core slabs). The presence of mounting loops facilitates transportation and installation.	Perfect geometrical dimensions with minimal tolerances. Large selection of standard sizes with a step of 100 mm. The ability to cut the end piece at any angle.

Note: PB slabs give the designer more freedom, since here the dimensions of the slab are not tied to the standard ones - it can be cut into blanks of different dimensions.

Comparison of hollow core slabs PC and PB

The nuances of installing hollow-core floor slabs

The standard average size of the bearing surface is 100-120 mm. But the specific amount of support depends on what the structure is based on:

For reinforced concrete - 70 mm, maximum - 160 mm.
On a brick wall: minimum 80 mm, maximum 160 mm.
For gas and foam concrete: minimum - 100-120 mm, optimally - 150 mm.
On steel structures - 70 mm.

note : These are only approximate values - the specific bearing value is selected depending on the calculations performed.

You can not increase the amount of support to 20 or more centimeters. In this case, the structure will not work as a slab, but as a clamped beam, due to which the loads are distributed differently than was accepted in the calculations.

For installation, a crane with a lifting capacity is used, which, with a small margin, covers the weight of the slab. As a rule, the type of crane, the paths of its movement along the construction site and the points from which the installation will be carried out are indicated on the construction master plan.

General technology for laying floor slabs:

Cleaning the surface where the structure will be laid from debris.
Laying a reinforcing bar in the place of contact between the slab and the base of the reinforcing bar - it will help prevent the squeezing out of the cement mortar and strictly control the verticality of the installation of structures.
"Spreading" of the cement mixture is also called mortar "bed". Its thickness is 2 cm, and it is necessary for reliable adhesion of the slab to the walls.

Preparing mortar "bed" for the stove

The following is very important - you cannot block 3 walls at once with one slab. In this case, stresses arise in it that are not provided for by the reinforcement scheme. As a result, the structure may simply crack. If it is not possible to lay the slab in another way, then from above, in the place of resting on the middle partition in the structure, they make a cut with a grinder.

Is it really necessary to close up voids

When building cottages and other low-rise buildings in the warm season, it is not necessary to close up voids. You can either leave them or fill them with polyurethane foam.

The area where the slab is pinched undergoes significant loads and can be destroyed.
The ingress of water into the voids in the winter, if construction was suspended at this time, can provoke the appearance of cracks, since the ice is larger in volume than water.

If the house was left without a roof for the winter and you know that water got inside the slabs, you need to drill a hole in them through which water can flow out. Otherwise, the frozen water will simply burst the stove from the inside.

To seal the voids to the bearing depth, use a masonry mortar on screenings or coarse sand. Holes for mounting hinges can be sealed with any mortar.

Note: on average, the depth of filling the voids is 12-15 cm.

Finally

Hollow core slabs are a common type of building structures, without which it is difficult to imagine the construction of buildings for any purpose today. The use of such slabs allows to reduce the load on the perimeter of the structure, which reduces the cost of construction of the foundation and walls. Due to the lower weight, the hollows reduce the shrinkage of the building, which allows you to start finishing work earlier.

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, 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 just reinforced.

Such floor slabs (PC), although they have a significantly higher 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.

Weight

As for such an important parameter as weight, everything is very clear from the first try: 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: 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 shouldn't 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, 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 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, it is necessary 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.

Floor slabs are horizontal structures that perform the function of interfloor or attic partitions installed between the roof and the last floor of the house. In modern construction, they usually resort to installing concrete floors, and it does not matter at all how many levels the building has. In this article, we will look at the types and sizes of floor slabs that are most often used on construction sites. These products make up the bulk of the products that are manufactured at the precast concrete factories.

Purpose of the structure

The supporting structures are made of heavy or lightweight concrete, and their structure is reinforced with reinforcement, which gives strength to the products. In the modern building materials market, all standard types of reinforced concrete slabs are presented, which can be divided into several categories depending on their width, length, weight, and other equally important parameters that affect the main characteristics of the products.

The most common method for classifying concrete panels is to subdivide them according to their cross-section. There are also several more distinctive characteristics that we will definitely consider in our article.

Hollow-core reinforced concrete panels PC

These are one of the most common types of products produced in precast concrete factories, which are equally well suited for the construction of a private and multi-storey building. Also, hollow-core PC products are widely used in the construction of massive industrial buildings, with their help they provide protection for heating mains.

Hollow-core floor slabs are characterized by the presence of voids

The smooth flat surface, which the round-hollow concrete panels have, allows you to mount reliable floors between floors that can withstand impressive loads. This design is equipped with cavities with sections of various shapes and diameters, which are:

round;
oval;
semicircular.

Technological voids, which are filled with air during installation, are in high demand due to this feature, which speaks of the advantages of this particular configuration of blocks. The indisputable advantages of a PC include:

Significant savings in raw materials, which allows you to reduce the cost of the finished product.
High coefficient of thermal and noise insulation, which improves the performance of the building.
Hollow-core panels are an excellent solution for laying communication lines (wires, pipes).

Reinforced concrete structures of this type can be conditionally divided into subgroups, and then we will tell you what kind of hollow-core floors are and by what criteria they can be attributed to one or another subgroup. This information will be important for the correct choice of material, depending on the technological requirements of the construction.

The slabs differ in the way they are installed: 1 PCT has three support sides, while 1 PCT can be installed on all four sides.

It is also necessary to pay attention to the size of the internal voids - the smaller the diameter of the holes, the more durable and stronger the hollow-core panels. For example, samples 2PKT and 1 PKK have the same width, thickness, length and number of support sides, however, in the first case, the diameter of the hollow holes is 140 mm, and in the second - 159 mm.

As for the strength of products manufactured by factories, its performance is directly affected by the thickness, which on average is 22 cm.There are also more massive panels with a thickness of 30 cm, and when pouring lightweight samples, this parameter is observed within 16 cm, while in most cases lightweight concrete is used.

We should also mention the bearing capacity of PC products. For the most part, PC hollow-core slabs, according to generally accepted standards, withstand a load of 800 kg / m2... For the construction of massive industrial buildings, slabs made of stressed concrete are used; this parameter is increased to a design value of 1200-1250 kg / m2. The design load is a weight that exceeds the same value for the product itself.

Manufacturers produce reinforced concrete panels in standard sizes, but sometimes the parameters can vary significantly. The length of the PC can be varied in the range of 1.5m - 1.6m, and their widths are 1m, 1.2m, 1.5m and 1.8m... The lightest and smallest slabs weigh less than half a ton, while the heaviest and heaviest specimens weigh 4,000 kg.

Hollow-core structures are very convenient to use, because the developer always has the opportunity to select the material of the required size, and this is another secret of the popularity of this product. Having familiarized ourselves with the most common PC products, which include hollow-core floor slabs, having considered their types and sizes, we suggest switching to other products for a similar purpose.

Prefabricated ribbed (U-shaped) panels

These reinforced concrete structures got their name due to a special configuration with two longitudinal stiffeners, and they are used in the construction of non-residential premises and as load-bearing elements for laying heating plants and water supply networks. To strengthen reinforced concrete products at the stage of their pouring, reinforcement is carried out, which, together with a special shape, leads to savings in raw materials, gives them special strength and makes them resistant to bending. It is not customary to install them as jumpers between floors for a residential building, since here you will have to face an unaesthetic ceiling, which is quite difficult to supply with communications and sheathe cladding. It also has its own subspecies, let's consider what differences the products have within the same group.

The ribbed slab structure is highly durable

The first and main distinguishing feature of U-shaped structures is their size, or rather, in terms of height, which is 30 or 40 cm. In the first case, we are faced with products that are used in the construction of public buildings and as jumpers between the upper floor of the house and the attic. For massive large-scale commercial and industrial buildings, slabs with a height of 40 cm are usually chosen.The width of ribbed floors can be 1.5 or 3 m (for more durable samples), and their weight ranges from 1.5 to 3 tons (in rare cases up to 7 t). Precast ribbed concrete slabs are characterized by the following lengths:

12 m.
18 m (rare).

Solid additional structures

If it is necessary to obtain a particularly strong overlap between the floors of a house, they resort to the help of solid jumpers, since they can easily withstand a load of 1000-3000 kgf / m2, and they are used mainly in the installation of multi-storey buildings.

Solid lintels allow for the installation of a high-strength overlap

Such products have disadvantages, because their weight for relatively small dimensions is quite impressive: standard samples weigh from 600 kg to 1500 kg... They also have weak thermal and noise insulation indicators, which does not allow them to adequately compete with hollow PC samples. The length of this type of panel ranges from 1.8 m to 5 m, and the thickness is 12 or 16 cm.

Monolithic structures

The previous and this type of panels have the same scope and are installed where there is a need to create a strong structure that can withstand overload. Such a partition does not contain cavities and is created directly on the construction site according to the available accurate calculations, therefore it can take any configuration and dimensions, limited only by the area of the object being erected.

In the article, we described in detail what types of floor panels are, what standard dimensions they have and where they are most often used, so you can choose the necessary products for the upcoming construction and get a strong durable structure that can serve you for at least a century.

Floor slabs are horizontal structural elements of a rectangular building that divide the space into floors. In addition to the load-bearing function, such slabs are part of the "skeleton" of the structure, responsible for the rigidity of the entire building. They are based on concrete, so they have a number of advantages: strength, durability, fire resistance, resistance to weathering. The disadvantages include: relatively high mass, presence of own stresses, high thermal and acoustic conductivity.

In order to simplify design and construction, the dimensions of the floors have led to a certain standard. Now the developer does not need to know all the intricacies of the production technology, it is enough to be able to decipher the marking. Marking means encrypted information about dimensions, main strength and design indicators.

It is performed in accordance with GOST 23009 and is divided into 3 groups, which are separated by a hyphen. The first group includes data on the type of panel, in the second geometric characteristics (length / width). In the third group, strength indicators, the class of steel reinforcement and the type of concrete are indicated. Let us analyze the decoding of PC-48.12-8At-V-t, where:

PC - hollow panel;
48 - length 48 dm (4.8 m);
12 - width 12 dm (1.2 m);
8 - for a uniformly distributed load of 800 kg per m2;
At-V - prestressing reinforcement (class At-V);
t - the type of concrete is heavy.

Element height 220 mm is not indicated, as it is standard for this type of product. Depending on the method of production, the slabs are divided into:

prefabricated (factory);
monolithic.

The latter are made directly at the construction site.

The process consists of assembling the formwork, installing reinforcing bars and meshes, placing concrete and dismantling the formwork. Based on the design solution, reinforced concrete slabs can be like this.

Solid (full-bodied). The panel is flat, with high strength, low sound and heat insulation. Simple enough to manufacture, but more material-intensive. They have an impressive weight (600-1500 kg) with a small size. Most often they are used as interfloor floors of high-rise buildings.

Ribbed (U-shaped panels). Their distinctive feature lies in the alternation of thickened and thinner elements, due to which the necessary bending stability is achieved. They are more often used in the construction of industrial structures, since in residential construction this configuration is difficult to finish. (P2)

Hollow. They are the most common type of concrete products. They represent a parallelepiped with cylindrical voids, thanks to which the slab works well for bending moment, withstands heavy loads, allows to bridge large spans (up to 12 meters), and facilitates the laying of communications.

PC- the most popular type of reinforced concrete floor, inside there are holes with a diameter of 140 mm and 159 mm, the thickness of the product is 220 mm.

PNO - an upgraded model with a smaller thickness of 160 mm. It can withstand heavy loads due to thicker reinforcement bars. Lighter than conventional hollow-core models, so this option is more economical.

Standard sizes

Standard dimensions of slabs are specified in GOST 9561-91. We will present them in the form of a table.

Type of slabs	Length (m)	Width (m)
PC (1PC, 2PC, 3PC) void diameter 159 mm, supported on both sides	from 2.4 to 7.2 times 0.3	from 1.0 to 3.6 times 0.3

PKT (1PKT, 2PKT, 3PKT) with a hole diameter of 140 mm	1,8 / 2,4 / 3,0 / 6,0	from 1.2 to 3.6 times 0.3
	from 1.6 to 6.4, there are up to 9.0	0,64 / 0,84 / 1,0 / 1,2 / 1,5
	6,0 / 9,0 / 12,0
Ribbed
Solid, height 120 mm	3,0 /3,6 /6,0/6,6
Solid height 160mm		2,4 / 3,0 / 3,6 / 4,8 / 5,4 / 6,0

Weight

Weight is one of the most important characteristics. In addition to calculating the distribution load, it will determine how the slab will be delivered to the construction site and installed. For this, the lifting capacity of the crane is calculated. Installation, as a rule, is carried out by a truck crane with a minimum lifting capacity of 5 tons.

The range of product weights in Russia varies from 960 kg to 4.82 tons.

Table "Standard weight of products"

Plate type	Thickness, mm	Width, mm	Length, mm	Estimated distribution load without taking into account its own weight, kg / m2	Weight kg / 1m p.


Standard PC specification
PK 48.12-8At-V-t
PK 48.15-8At-V-t
PK 51.15-8At-V-t
PK 54.12-8At-V-t
PK 54.15-8At-V-t

How to calculate correctly?

Initially, it is necessary to correctly arrange the slabs on the plan. Basic rule: floor slabs are supported only on two sides. Since the slab has a lower working reinforcement, local loads (posts, columns) must not be allowed. An important point will be on which walls the floors will be based (walls made of cinder concrete, brick, concrete), which affects the calculation of loads.

Determine the estimated length of the slab. It is smaller than the real one and is the distance between the most distant adjacent walls. It is set by geometric parameters. The next step is collecting loads. In order to determine the load on each product, it is necessary to indicate on the plan all the weights acting on the floors.

This includes: sand-cement screeds, thermal insulation, floor coverings, partitions.

Having summed up these components, you need to divide the resulting value by the number of plates. Thus, the maximum permissible load for each product can be obtained.

Naturally, it is impossible to load the building frame as much as possible in order to avoid reaching a critical level, for this the optimal value is calculated. For example, a slab weighs 2400 kg, it is intended for a site of 10 m2. It is necessary to divide 2400 by 10. It turns out that the maximum allowable value is 240 kg per 1 m2. The weight of the product itself, for which the load was calculated, should also be taken into account (assume that its value is 800 kg per 1 m2). Then it is necessary to subtract 240 from 800, which gives an indicator of 560 kg per 1 m2.

The next step is roughly assume the weight of all loading items. Let's say that it is equal to 200 kg per m2, then we subtract 200 kg per m2 from our previous indicator of 560 kg per m2 and we get 360 kg per m2. The last step is to determine the weight of people, finishing materials, furniture. On average, this is 150 kg per m2. Then you need to subtract 150 from 360. We got an optimal load of 210 kg per m2. The maximum bending moment can be calculated using the formula: Mmax = q * l ^ 2/8, where l is the span length.

In the next step the class of concrete and the cross-section of the reinforcement are selected according to the assortment... The last step is to check the limit states.

Drawing 1. Layout of slabs in a panel house.

Drawing 2. Private house.

Drawing 3. Multi-storey building.

For a video on the dimensions and weight of floor slabs, see below.