A wide selection of various kinds of metal products allows not only to strengthen the structures to the required level, thereby creating reliable buildings, but also greatly affects the process of erecting any objects, accelerating it several times.
Basic characteristics of fittings
It is worth starting the enumeration of the characteristics of class A400 fittings with the fact that it is still very often called by the old A3 marking. Turning to its properties, it is important to know several basic differences. The first of these is its surface. The ribbed surface of this reinforcement affects its price, increasing it. This is due to the fact that creating corrugated reinforcement using metal is more difficult than smooth. But you must understand that the adhesion to concrete in such a product is higher. In addition, because of its surface, A400 class reinforcement can be successfully used both in the manufacture of reinforced concrete slabs for flooring and for pouring the foundation at a construction site.
Decoding and diameter
What class of valves does the A400 represent? To answer this question, it will be enough to decipher its designation. The letter A in the marking indicates that the metal product is a hot-rolled or thermomechanically hardened reinforcing bar. The number 400 indicates the yield strength of this product is 400 N / mm 2 .
It is important to understand that one of the most important characteristics of the reinforcement will be its diameter. Naturally, this indicator will be different. GOST under the number 5781-82 establishes the release of a product with a diameter of 6 to 40 mm. By production it is allowed to use such steel grades as 35GS and 25G2S. If such a raw material as steel 32G2Rps is used in the manufacture of reinforcement, the diameter of the final product can be at least 6 mm and not more than 22 mm. Due to the large amount of source material, as well as the final product, i.e. reinforcement, choosing a suitable class for the construction of a particular object will not be a big problem. What class of valves 400 to choose for the construction of the object? It is best to rely on the recommendations of specialists.
Diameter selection
Many people who are not too familiar with the basics of construction and are poorly versed in materials can underestimate certain properties. When choosing this product, diameter is an essential indicator of elasticity. The larger the numerical value of this characteristic, the greater the load the reinforcement can withstand and return to its original form before it bends or breaks.
There is another very important factor that is often encountered when buying. The diameter of valves of class A400 does not correspond to what is declared in the catalog, for example. It is very important to know that if you measure this indicator with a vernier caliper, then it will be larger, and if in a smooth place, then less. Since the surface is corrugated, it cannot have a single indicator along the entire length. Because of this, the numerical characteristic of this parameter is determined by the arithmetic mean. In addition, even in the state document it is indicated that the corrugated reinforcement may have a slight deviation of the diameter from the declared, but provided that this does not affect the bearing capacity in any way.
Influence of diameter on storage and transportation
It is important to understand that the characteristics of the rods, or rather their diameter, will even affect the method of storage and transportation of products. For example, it is possible to transport corrugated fittings, the diameter of which is less than 12 mm, by winding it in coils. This method has several advantages. Firstly, the transportation process itself is facilitated, and it also becomes more convenient to store. Secondly, storage in coils allows you to avoid such a defect as bending of reinforcement in any place, which will significantly affect the strength of the product.
A400 class valves, which have a larger diameter, can be transported in the form in which it is, that is, rods. This is possible due to the fact that bending or bending such a thick metal is already quite difficult, and the occurrence of a slight bend is not so scary.
What valves are A400 or A3?
Currently, when buying fittings, many people are faced with a problem such as different markings. Most often, this problem happens with the A400 and A3. Many people have a question, what is the difference if these products have the same appearance, the same production process and the raw materials from which they are made, as well as the same performance characteristics. It is worth noting that the price per ton of reinforcement is the same. The answer to the question is quite simple. This is one and the same reinforcement. The only difference is that the name A3 is considered classic, but the A400 brand appeared quite recently. Here it can be added that S400 marking is also found. This is the same type of product, the scope remains the same as everything else. It's just that this name is made according to a different classification of the product.
Special Varieties
The usual type of fittings A3 or A400 is used in ordinary building construction. However, there are some special varieties of material that are also used, but much less frequently.
- AT400. This subspecies of the metal rod is characterized by the fact that it undergoes heat treatment, during which changes occur with the crystal structure of the grid. Due to this effect, it is possible to achieve a strong increase in the strength of the product without increasing its diameter.
- A400C. This type differs from the rest in that it can be welded together. Typically, the reinforcement is interconnected using a special wire, if it is necessary to create some kind of frame or solid structure. Simple rods during welding will be very hot at the joints. And they, as you know, the first give slack at critical loads, since when welding the crystal lattice of the material, which is responsible for strength, is damaged. The A400C is made so that it does not have such a drawback, and it can be connected with both wire and welding.
- A400K. Special corrosion-resistant reinforcement with a highly specialized application profile. Most often used for such works as arranging the foundations of bridges, etc.
Impurities in the composition
It is important to note that some characteristics of A400 fittings with 12 mm diameter or any other depend on impurities. It is important to understand that impurities are present both in the composition of specialized brands of reinforcement and in conventional ones. The most commonly used additives are additives such as carbon, silicon, manganese, chromium, copper, aluminum, nickel, sulfur and phosphorus.
Of course, the mass fraction of these additives that make up the rods is very small. If we talk about the numerical value of these coefficients, then they are in the region of hundredths, and some in the region of thousandths of a percent. The quantitative content of these impurities is established by GOST, and the slightest violation of the composition prescribed in the document will be immediately noticeable by the deterioration of the quality of the finished product.
Profile Difference
Continuing to talk about the characteristics of the reinforcement, it is important to note that they have a different surface. In other words, they have a different profile of ribs. May be a crescent or annular profile. This is a very important factor, since the scope of use of the product also depends on it. Another interesting parameter is the weight of the 400 reinforcement. Depending on the diameter, it varies from 0.25 to almost 40 kg (in one meter of reinforcing bar).
An annular profile of reinforcement is most often used if it is necessary to erect a powerful structure that will have a large number of objects made of concrete. This type of ribs on the product is able to provide reliable adhesion of metal to concrete, and is also suitable for reinforcement.
The sickle-shaped profile is most often used by specialists if it is important to give greater strength to an already finished product before rupture. It is worth adding that not so long ago there appeared products that have a combined type of profile, which is good in adhesion to concrete, and also provides reliable protection against tearing.
Finished Product Parameters
The price of reinforcement per ton is made up of what materials were used for production. Special types of steel will cost more. The cheapest type of reinforcement will be a rod with a diameter of 8 mm. The cost for one will be about 40 rubles. About 193 units will go into a ton, which means that the cost will be about 40,000 rubles.
As mentioned earlier, the minimum diameter of the rod is 6 mm, and the maximum is 40 mm. Finished products can be from 6 to 12 in length. It is also important to add that there is such a parameter as the curvature of the rod. This parameter for valves 400 is allowed no more than 0.6% of the length of the rod. It is also worth noting that a less thick product is wound into a skein, while thicker ones are stored only separately and look like a long metal rod.