A400 class fittings: characteristics, application

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

A wide selection of various kinds of metal products allows not only to strengthen structures to the required level, thereby creating reliable buildings, but also greatly affects the process of erecting any objects, speeding it up several times.

Basic characteristics of fittings

It is worth starting the listing of the characteristics of A400 class 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 a few 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 it is more difficult to create corrugated reinforcement using rolled metal than smooth. But it must be understood that the adhesion to concrete of such a product is higher. In addition, due to its surface, A400 class rebar can be successfully used both in the manufacture of reinforced concrete slabs for ceilings and for pouring foundations at a construction site.

Decoding and diameter

What class of A400 fittings does it represent? To answer this question, it will be enough to decipher itdesignation. The letter A in the marking indicates that the metal product is hot-rolled or thermomechanically hardened rebar. The number 400 indicates the yield strength of this product is 400 N/mm2.

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 products with a diameter of 6 to 40 mm. In production, it is allowed to use such steel grades as 35GS and 25G2S. If in the manufacture of reinforcement such a type of raw material as 32G2Rps steel is used, then 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, that is, reinforcement, choosing the appropriate class for the construction of a particular object will not be a big problem. What class of reinforcement A400 to choose for the construction of the object? It is best to rely on the recommendations of specialists in this.

Choice of diameter

Many people who are not very familiar with the basics of construction and poorly versed in materials may underestimate certain properties. When choosing this product, the diameter is the most important indicator of elasticity. The higher 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 the A400 class rebar does not correspond to that stated in the catalog, for example. Here it is very important to know that if you measure this indicator with a caliper in the place of the rib, then it will be more, 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 corrugated reinforcement may have a slight deviation in diameter from the declared one, but on condition 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 way products are stored and transported. For example, it is possible to carry out the transportation of corrugated reinforcement, the diameter of which is less than 12 mm, by winding it into coils. This method has several advantages. Firstly, the transportation process itself is facilitated, and it also becomes more convenient to store it. Secondly, storage in coils allows you to avoid such a defect as bending of the reinforcement in any place, which will significantly affect the strength of the product.

Class A400 rebar, which has a larger diameter, can be transported in the form in which it is, that is, in rods. This is possible due to the fact that it is already quite difficult to bend or unbend such a thick metal, and the occurrence of a small bend is not so scary.

Which armature A400 or A3?

Currently purchasingfittings, many people are faced with such a problem as different markings. Most often this problem happens with the A400 and A3. Many people wonder 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 should be noted that the price per ton of rebar is the same. The answer to the question is quite simple. It's the same armature. The only difference is that the name A3 is considered classic, but the brand A400 appeared quite recently. Here we can add that the S400 marking is also found. This is the same type of product, the scope has remained the same as everything else. It's just that this name is made according to a different classification of the product.

Special varieties

Regular type A3 or A400 rebar is used in normal building construction. However, there are some special varieties of material that are also used, but much less frequently.

• AT400. This subspecies of a metal rod is characterized by the fact that it undergoes heat treatment, during which changes occur with the crystalline structure of the grid. Thanks 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. Usually, the reinforcement is connected to each other using a special wire, if it is necessary to create some kind of frame or one-piece structure. Simple rods atwelding will be very hot at the joints. And they, as you know, are the first to give slack under critical loads, since the crystal lattice of the material, which is responsible for strength, is damaged during welding. The A400C is made in such a way that it does not have such a drawback, and it can be connected both with wire and welding.
• A400K. Special corrosion-resistant fittings that have a highly specialized application profile. Most commonly used for jobs such as bridge foundations, etc.

Impurities in 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 here that impurities are present both in the composition of specialized brands of fittings and in ordinary ones. The most commonly used additives are carbon, silicon, manganese, chromium, copper, aluminium, nickel, sulfur and phosphorus.

Of course, the mass fraction of these additives, which are part of 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 in the quality of the finished product.

Profile difference

Continuing to talk about the characteristics of reinforcement, it is important to note that they have different surfaces. In other words, they have a different profileribs. Can be crescent or ring 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 A400 rebar. Depending on the diameter, it varies from 0.25 to almost 40 kg (in one meter of reinforcing bar).

The annular reinforcement profile is most often used if it is necessary to build a powerful structure that will have a large number of concrete objects. This type of ribs in 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 in the event that it is important to give greater strength to the finished product before breaking. It is worth adding that recently there have been 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 rebar per ton is based on 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. A ton will include about 193 pieces, 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 fittings A400 is allowed no more than 0.6% ofrod length. 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.