Currently, the construction of the majority of both residential and industrial buildings used reinforced concrete products. The lion's share of the market is occupied by the production of plates, this type of concrete products has a wide range and various purposes. The most popular are hollow reinforced concrete slabs, but apart from them there are still a number of concrete products.
In all this diversity, we will try to understand now.
What are the plates
At first glance it may seem that there is nothing difficult in the choice of plates. Just contact the factory and you will bring everything. But not everything is so simple, each product has its own purpose and so that you are not deceived, it is desirable to understand the labeling.
A few words about labeling
- As you may have already noticed, any marking consists of a series of alphanumeric designations, where each position characterizes a certain parameter of the product. Take, for example, the PC 57-15-12-8T.
- The first two letters indicate the type of plate "PC". In this case, we are dealing with a slab for the floor, in the construction of which there are round voids.
- The next number of numerical designations gives an idea of the dimensions of the structure, that is, the length, width and height (thickness). The data is indicated in decimeters, so in our case the plate will be about 5,700 mm long, the product will be 1,500 mm wide and 120 mm thick.
- The last figure in the designation gives an idea of the maximum permissible load of 1 cm ?. For our design, the permissible load will be equal to 800kg / cm ?.
- The last letter in the row will indicate the type of concrete, in this case it is a heavy grade of concrete.
Important: it is interesting that in some cases the figure characterizing the thickness of the product may not be indicated, since reinforced concrete hollow-core slabs often have a standard thickness of 220 mm.
Common types of products
As mentioned earlier, the first 2 letters characterize the type of product, now let's see what they are.
- If the head is one letter "P", then you are dealing with a solid reinforced concrete structure. In length, they can reach 6m, width ranges from 1.2m to 1.5m. In thickness, they are 120, 160 and 220 mm.
- This is a solid reinforced monolith, with a large weight of 625kg to 3.6t. It is characteristic that constructions with a thickness of 120 mm are desirable to be equipped with additional sound insulation.
- Reinforced concrete hollow core slabs are labeled as "PC". In view of their great popularity, they have the widest range of sizes offered, only the thickness of 220 mm remains unchanged. The weight of the product is best recognized directly at the factory, some designs can reach a weight of 5 tons. Hollow products are distinguished by optimal sound and thermal insulation characteristics.
- Also produced a large range of special-purpose products "PS". These letters can be marked with reinforced concrete eaves slabs, reinforced concrete parapet slabs, as well as all kinds of custom-made products.
- For industrial buildings are often used ribbed design "PR". Often with their help roofing structures are mounted. In some sources, they may be referred to as "hip", Among all the concrete products, they have the largest size and increased strength characteristics. In length, such a plate can reach 18m, with a width of up to 3m and a rib height of 600 mm.
- For more reliable fixation of columns in high-rise buildings, so-called “RP” spacer plates are used.. As a rule, their sizes do not exceed 1.5m.
- Colons on the ground floor for industrial buildings are reinforced with monolithic structures made of heavy concrete "PT".
- A special place is occupied by the so-called reinforced concrete wall slab or wall panels.. Panel buildings have long been known. Such technology is common in high-rise and industrial construction.
- The configuration and parameters of the panels may be different. Since the prefabricated houses are large, often under some architectural projects, plants produce products with individual parameters..
- Currently, reinforced concrete wall plate is available in 3 versions. This is a solid cast single-layer construction of concrete with a low heat transfer coefficient. A two-layer structure consisting of a concrete base and a thermal insulation coating.
- Three-layer plate, made in the form of a sandwich. Where the top and bottom of the concrete, and inside the insulation. The design has enhanced heat and sound insulation characteristics.
Tip: you can often come across ads that sell reinforced concrete wall slab used. Before you buy, learn in detail about the exact dimensions and characteristics of the product, because they can often be non-standard.
The video in this article shows the manufacture of wall panels.
Subtleties of work with concrete products
In frequent construction, reinforced concrete hollow-core slabs are considered to be the most demanded. But when the product is selected and the design delivered, there are still many related issues, in particular how to store and mount. Plus, it is often necessary to cut off a slab or cut a non-standard hatch.
Storage of structures
Although flat precast concrete products have a sufficiently large margin of safety, they can crack if not properly transported or stored. Given the fact that the price of them on average ranges from 150 to 500U. it will be an unpleasant surprise.
As for delivery, it is often a headache for the transport company, and we will tell you about the rules of warehousing now.
- First of all, it should be noted that flat structures should be stored exclusively horizontally.
- Concrete is a hygroscopic substance, that is, with prolonged contact with moisture, it works like a sponge. Therefore, products must be at a sufficient distance from the soil. The base must be strong and have a waterproofing gasket.
- If the plates are stacked, wooden strips between them are about 50 mm thick, and all the planks should be on the same vertical line. From the edges of the slats are set at a distance of 50 cm.
- Provided that you have a reasonably strong base, there should not be more than 10 products in one pile.
Important: lean on the wall plate, leaving them in an inclined position, even for a short time is strictly prohibited. Because the likelihood of cracks.
How to cut concrete products
Of course, modern industry produces a wide range of sizes, but there are situations when it is necessary to adjust the plate that is already available with your own hands.
In this case, the instruction is as follows.
- First of all, you need a grinder with a diamond disc, scrap and a sledgehammer. Also the perforator equipped with a drill with diamond tipped will not prevent.
- Initially, the plate is laid on any transverse support, which must be clearly below the cut line.
- Next, the grinder makes a cross-section to the maximum possible depth.
- After this, with a sledgehammer, it is necessary to tap along the cut line both along the plane and from the sides. As a rule, it takes about 10 hits. The plate, under its own weight, will burst itself.
- Scrap, in areas of internal voids, punched through holes and widens the rift.
- Reinforcement cage is better to cut with a gasoline or gas cutter, but for lack of such, you can use the grinder.
Tip: the armature at the fault site is in a tense state, so if you cut it with a grinder, you should not cut it completely. Since it is likely to capture the disk. Make an incision, and smash the rest with a crowbar or hammer.
- If you need to cut the product along, then the algorithm of actions is about the same. Put the slab on the supports, make a longitudinal incision, knock the construction with a sledge hammer, expand the rift and cut off the reinforcement. Just try to make an incision over the empty chamber.
- The attic hatch is usually made of a rectangular shape. The main rule for its arrangement is that it is impossible to cut the hatch in one plate. It should be done at the junction of two structures, cutting equal segments from both plates. The technology described above, but the long side of the hatch should be located along the product.
What to do if the width of the plates is not enough
- If the calculations show that for some reason after the installation of structures should be a gap of about half a meter, then you can do so.
- It is necessary to retreat from each edge of 250 mm and lay the structure tightly butt. The gaps that remain between the side walls and the overlap are closed with a cinder block, laid butted to the slab using the mortise method. The upper rows will fix this laying and the gap will be eliminated.
- Using a similar approach, with the arrangement of the overlap of a private house you can save a little. So with a large square house, the designs are stacked with a gap of up to 300 mm.
- The remaining clearance between the products needs to be filled with a solution; the most optimal solution here is to use peskobeton with a brand not lower than M300.
- The instruction is as follows: from the bottom of the lumen, you need to tie up the formwork shields and arm the resulting sing. If the opening width is more than 150 mm, it is recommended to drill end symmetrical holes and insert the transverse reinforcement rods into them, linking them with the longitudinal reinforcement.
With the preparatory questions we figured out, now proceed to the subtleties of installation. First of all, it should be noted that the upper level of the walls should be clearly aligned over the horizon. It is not allowed to drop heights even by 2 - 3 cm.
This can easily be checked with a hydro level or laser level. The missing height needs to be poured with concrete; naturally, installation will begin only after the mortar has completely set.
Important: Experts recommend to arrange intermediate columns of supports from inside the building. They are needed in case the slab slides off the edge of the wall. It is not worth overhauling them, since after the installation is over there will be no need for them.
Arrangement of the reinforcing belt
- If a house is built from gas silicate or foam concrete blocks, then their fortress is not enough to reliably hold reinforced concrete hollow core slabs. In this case, on the perimeter of the building is equipped with a self-leveling, reinforced frame.
Important: the slab should go on a brick wall at a distance of at least 120 mm, on a wall of porous concrete at least 250 mm.
- An alternative to such a load distributor may be a belt made of full-fired burnt bricks laid in 3 rows, with mandatory internal reinforcement.
- The structure is cast with a thickness of at least 120 mm and a width of 2 250 mm First, formwork is made into which the metal frame is inserted from reinforcement with a section of 8 - 12 mm. After that, the belt is poured with concrete with the mark M200 - M400. Such a belt will not only be a reliable support for concrete products, but will also compensate for the deformation changes during shrinkage of the building.
- Plates should be laid on cement-sand mortar with a thickness of 20 - 30 mm. Since the payment of the crane is hourly, it is better to lay the solution in advance, it is allowed to install reinforced concrete products on the solution that has gained strength up to 50%.
- The construction should be directed by 2 people, special attention should be paid to the accuracy of the entry of the slab on the wall, since the product can only be moved along the wall. Excess solution will be squeezed out, and the design will take the right place.
- The plate should rest only on 2 opposite edges, if there is a transverse support, that is, the probability that the structure will burst during shrinkage, and unpredictable. To avoid negative consequences, an incision is made on the top plate in the middle of the intermediate support. In this case, even if the structure bursts, the crack will be predictable.
Important: some craftsmen are advised to lay reinforcement bars under the slab, and so, this can not be done. Moving the plate will be really easier, but it may slip, plus the load will not be evenly distributed.
- After laying, anchoring must be performed, that is, the plates must be tied (welded) to each other and attached to the supporting structures. The most common option is a cross diagonal mating. Used for this reinforcement section of 12 mm.
I also want to note that reinforced concrete hollow core slabs must be sealed before installation. In other words, the holes from the ends are sealed. The material is used any, it can be cement-sand mortar, polyurethane foam or wool for insulation (find out here how to count concrete on the foundation).
On the video in this article you can find additional information on the subject of concrete products.