Reinforcement is called a steel product, having the form of a long rod with a circular cross section. The main purpose of this type of rolled steel is to improve the quality of concrete structures. There are several varieties of fittings, each of which is made in strict accordance with GOST standards.
Appointment
Concrete is an extremely compressive material. The structures poured out of it are capable of supporting the enormous weight with absolutely no harm to themselves. However, unfortunately, in tension this material is very fragile, just like in bending. Because of this feature of concrete, many problems can arise during the construction of buildings and structures: cracking of the foundation and walls as a result of the action of spring heaving forces, destruction of floors due to too high vertical load, etc. The tensile strength of concrete is only 10-15 % compressive strength.
This problem is designed to solve metal fittings. The coefficient of thermal expansion of steel is close to that of concrete. This makes it possible to use materials in a complex. The most popular in low-rise construction is reinforcement 12 mm in diameter. Concrete structures, reinforced with frames connected by it, are characterized by high compressive strength and, at the same time, acceptable tensile strength.
When erecting foundations, which account for the main load during spring heaving, the use of reinforcement is a prerequisite. Often this type of metal rolling is also used in the construction of walls (reinforcement of masonry, upper stiffness belt). Mesh fittings are used when pouring floors and screeds. It is also used in the manufacture of concrete walkways, blind areas, etc. When erecting multi-story buildings, as well as houses on problematic soils, reinforcement of 16 mm and thicker is more often used.
Among other things, this type of metal rolling also improves such an indicator as the fatigue strength of concrete, as well as the resistance of structures to mechanical influences from the outside.
Production material
Since reinforcement is a very important element of the reinforced concrete structures of a building, special demands are made on its quality. The raw material for the production of metal products of this type is special reinforcing steel. To improve its mechanical properties, it is alloyed with manganese and silicon. To give the reinforcement special strength, titanium and chromium are treated.
Varieties in diameter
In construction, reinforcement of different thicknesses can be used. In this regard, there are certain standards established by the norms of SNiP. So, for example, for the foundations of buildings with very light frame-shield walls erected on stable soils, rods with a diameter of 10 mm can be used. In the construction of private houses of almost all other types, as already mentioned, 12 mm reinforcement is used.
Types of manufacturing method
The production of 12 mm reinforcement (steel), as well as rods of any other thickness, is carried out according to two main technologies:
- By hot rolling steel. Such products are called rod.
- By drawing steel in a cold state. This is the so-called wire view.
The production of 12 mm fittings is not a very complicated process, but it requires the use of special equipment and exact compliance with all the required technologies.
Finished frames and nets are produced at specialized enterprises. The procedure for their manufacture includes the following steps:
- If the source material is supplied in bobbins, unwinding is performed.
- Editing wire or rods.
- The fittings are cut into pieces of the required length. This and the previous operations are performed on special correct cutting machines.
- The following is the assembly of the frame or mesh elements. This operation is performed on special welding machines. In some cases, the elements are connected using manual welding.
Sometimes reinforcing cages and nets are made directly during the construction of buildings (usually low-rise). In this case, the structure may be welded or wire bound. The first method is less time consuming. When using the second, a more durable frame is obtained. The fact is that in places of welding, steel subsequently rusts faster.
Surface type
On this basis, only two types of reinforcement 12 mm are distinguished:
- Smooth, representing the usual rods or round wire.
- Corrugated. On the surface of such reinforcement there are transverse (usually sickle-shaped) and longitudinal ribs. This design can significantly increase the adhesion of the frame elements to concrete.
Types of working conditions
In frames, the following types of reinforcement are usually used:
- distribution;
- working (12 mm rods themselves);
- assembly;
- clamps.
According to the operating conditions, the 12 mm reinforcement is divided into:
- Harnessed. It is used when special strength of the concrete structure is needed (in earthquake-prone areas, in ceilings of high-rise buildings, in parts of bridges subjected to vertical loading, etc.).
- Unstressed. Stacked without pre-tensioning. Used in conventional concrete structures.
Armature weight 12 mm
When erecting small private buildings, the amount of metal needed is usually calculated in linear meters. Manufacturers often sell fittings by weight. This may cause some difficulties in the calculations. In order to find out how many kilograms of reinforcement is necessary in a particular case, the weight of a running meter should be multiplied by the required length of the material. The first indicator depends on the type of reinforcement and is determined by special tables.
So, the weight of the reinforcement 12 mm (manufactured in accordance with GOST) is 0.89 kg / linear meter. Suppose, for the construction of a house requires 25 m of rental. Therefore, you need to buy 25 x 0.89 = 22.25 kg of rods.
Marking and cost of fittings
Smooth metal rolling 12 mm is marked with the letter A1, grooved without perforation - A3. Also, by marking, you can find out the method of manufacturing the fittings (A - hot-rolled, B - cold-made) and the grade of steel used (numbers). The product may be delivered in bays or rods. For example, the designation of fittings "A3-A500C" is deciphered as follows:
- the material has a corrugated surface (A3),
- made by hot rolling (A),
- steel grade - 3PS (A500C)
The price of metal products of this type depends primarily on its thickness, as well as on the brand. How much can 12 fittings cost? The price of rods of this diameter - hot-rolled (the most popular variety) - varies between different suppliers in the range of about 22-29 thousand rubles per ton. Of course, when buying, you should ask the seller for a certificate of compliance with GOST. Marking on reinforcement is usually affixed already at the time of rental. If this was not done during the manufacture of rods and rods, their ends are marked with indelible paint. So, for example, A500C steel is marked with white and blue, A600C with yellow and white, etc. You can find out the exact correspondence for other types of rod using special tables.
Thus, reinforcement - one of the most popular types of rolled metal on the market - can be produced in different ways from various steel grades, have a smooth or corrugated surface, be thick or thin. 12 mm rods are among the most sought after varieties. When buying them, as well as when purchasing any other fittings, you should first of all pay attention to the marking and type of surface.