Application of rebar in construction
Application of various types of rebar in different parts of the building
Different forms of rebar application
Corrosion and resistance to rebar bending
The use of rebar in various industries, especially in the construction industry, has brought great progress. This steel section; and in its newer types of fiberglass; It is made in different forms and standards and today it is considered an integral part of the construction industry. The reason for this is the unique mechanical properties of this section.
Each type of rebar is used in a certain part of the building according to its characteristics and appearance; That is, the specifications of rebar a1, a2, a3 and their differences are used in other industries, including spring making and construction of art structures, in addition to the mentioned cases. In fact, rebar is one of the most widely used steel sections in civil and construction projects, which includes the largest share of tonnage in the steel prepared for a project.
In this article, we will first examine the use of rebar in building construction. Then, we also describe the different shapes made with this section. Finally, we will introduce its application in other industries.
Application of rebar in construction
The main application of rebar is in construction and to strengthen concrete. Concrete, naturally, despite having high compressive strength, does not have much tensile strength. This means that if the concrete expands or contracts due to temperature changes, it will crack.
Since the 18th century, civil engineers have gradually realized the help that rebar can give to solve this problem. The thermal expansion coefficient of this section is very close to concrete. For this reason, the rebar planted in the heart of the concrete receives the tensile pressure applied to it due to temperature changes and prevents the concrete from cracking. It should be noted that no material can prevent 100% of concrete from cracking; But the rebar can keep the cracks to a very small and low-risk level.
One of the applications of this steel product is to use it to increase the thermal resistance of the building. The rebar that is placed on the joists after concreting the roof is called thermal rebar. This product, in addition to increasing the tensile strength of roof concrete, prevents it from falling during a fire. Thermal rebar is used in beam block roofs, steel deck and chromite roofs.
But what makes rebar and concrete bond? This is where the treads work. The treads on the rebar well surround the wet concrete and establish a high level of physical contact with it.
Application of various types of rebar in different parts of the building
In each country, there is a specific standard for rebar production and marking. Types of these standards include European, American, Chinese, Russian, etc. In our country, according to the long-standing tradition of the iron smelting company, the Russian standard prevails. Based on this, four types of rebar are produced in the following order.
Simple rebar without tread or A1
Ribbed rebar with one rib row or A2
Ribbed rebar with two rows of ribs in opposite directions or A3
Twisted or A4 ribbed rebar
Each of these sections are different from each other in terms of mechanical and chemical properties in addition to their appearance. In fact, what determines the use of rebar is its appearance differences and its mechanical and chemical properties. The reason for the difference in properties is also because each cross-section is made of a special alloy of steel that is different from each other especially in the percentage of carbon, nickel and chromium. What is rebar and what are its types can help in understanding its use.
Application of rebar A1
This section cannot create a good bond with concrete due to the lack of tread. For this reason, it is forbidden to use it as resistance and thermal rebar. Also, the alloy of this product has the lowest amount of carbon; Therefore, it is softer than other rebars and loses its strength sooner against heat.
The application of A1 rebar made of carbon steel is mostly in joints and quenching operations.
Application of rebar A2
The alloy of this steel section has more carbon than the A1 bar. For this reason, it is harder and should not be subjected to welding except in necessary cases. This stage is also called semi-hard. A2 rebar is used in concrete body, construction of shear walls and damping.
Because only one row of tread is used on it, the tensile strength it gives to the concrete is minimal. Therefore, its use is not recommended for areas with extreme temperature changes.
Application of rebar A3 This iron product also has a higher carbon percentage and, as a result, more hardness than the previous two bars; Instead, its tensile and compressive strength is higher. The engagement of this rebar with concrete is greater than type A1 due to the two rows of treads on it. This stage is also called hard. A3 rebar is mostly used in columns and beams. This rebar should not be welded under any circumstances. Application of A4 rebar It is the hardest type of rebar available in the country, with which concrete conflict reaches the maximum possible. Also, its tensile and compressive strength is higher than other similar types. For this reason, this product is used in areas such as desert areas that have extreme temperature changes during night and day or winter and summer. It is also common to use it in shear wall, bending frame and column. Different forms of rebar application In addition to its usual shape, rebar is called straight or longitudinal rebar; They are made into different geometric shapes and used in the building. We will examine these problems below: silence Khamut is a rectangular section obtained by bending the rebar. The purpose of using rebar in this way is to prevent longitudinal rebars from protruding from the concrete due to the increase in length. Khamut also increases the tolerance of concrete shear forces and prevents it from cracking due to pressure. To make Khamut, rebar is used that has high bending capability. This work is done by cold bending machines. This operation must be done under a temperature higher than five degrees Celsius.
vault rebar
This rebar is a bridge that can be placed between two rows of parallel reinforcement mesh. The application of this section and parallel reinforcements is in the concreting of the floor and foundation of the structure. According to the necessary distance between two mesh networks, the height of the vault bar can also be changed.
Otka rebar
Edka means duck in Russian. The shape of this product is named this way because of its similarity with the body of a duck. Edka rebar is used to connect the beam to the lower wings of the beam. This is done to ensure that the beams do not move out of their original place. Edka rebar is made in two forms, one-sided and two-sided.
Rebar
Pin rebar is also used transversely like Khamut. The name of this product represents its shape, although it is also known in the market as fake and crocheted. Pin rebar is used to strengthen the connection of longitudinal rebars and Khamut and strengthen the shear resistance of Khamut. Its diameter is usually thin and A2 rebar is used in its construction. The shape of this product is like a long rebar whose two ends are bent at angles such as 90 or 135 degrees.
stirrup bar
This cross-section has the same application as vault rebar and hook rebar, with the difference that it is used to keep two rows of vertical reinforcement mesh parallel. The shape of this rebar is like the English letter U and it is mostly used in concreting walls and slabs.
Negative moment rebar
The negative moment bar is installed on the support to withstand the additional loads or the so-called negative anchors of the beam. This product has a similar appearance, like a long rebar, but the place of use and its type of use are different. The negative moment rebar is used in the highest part of the concrete roof and between two adjacent openings.
Zigzag rebar
Another name of this section is truss and it is made of zigzag connection of simple or ribbed bars. The use of zigzag rebar is in the construction of the roof, and welding or hooks are used to connect the rebars.
coiled rebar
Coil is a thin rebar that is used to strengthen concrete structures, roofs, brick columns, blocks, and walls. The beam is the main destination of coiled rebar in the building. It is also used as a wire between two parallel bars in a zigzag bar.
bed rebar
This method of using rebar includes two parallel rebars to which a zigzag wire is welded. This combination is used to increase the bending and shear strength of concrete, increase vertical load and more strength against earthquakes.
Application of rebar in other industries
It is true that rebar is not used in any industry as much as the construction industry, but we cannot not talk about its uses in other industries as well.
One of the most widely used rebars in other industries is type A1. A type of this section made of carbon steel has a special use in blacksmithing. Also, A1 rebar made of alloy steel is used in automobile manufacturing, aviation industry, manufacturing of industrial parts such as bolts and nuts.
If stainless steel is used in the construction of A1 rebar; Aviation, hospital equipment, chemical, oil and petrochemical industries will also be its customers.
There is another type of rebar, which is called tensile rebar. This rebar is the same regular rebar with or without treads on which various stretching operations have been performed to reach the desired diameter. The application of tensile bars is in the following industries:
• Automobile manufacturing, especially in the start system
• Industrial machinery such as drilling, agricultural machinery, threading and turning
• Production of all kinds of screws, nuts, hinges, bearing shafts and other tools and accessories
• Chain making
Also, the application of coiled rebar is also significant in the following industries:
• Barbed wire and tow wire
• Metal mesh
• Spring making
• Production of nails and screws
Corrosion and resistance to rebar bending
In all cases of using rebar, the issue of corrosion and rust is a challenge. A product that is produced without coating or necessary measures to deal with this phenomenon is called black rebar. This section cannot be used in areas where the percentage of moisture and chemical pollutants is high. For this reason, epoxy coated rebar, galvanized rebar and stainless rebar are more commonly used in these areas.
Another issue is rebar welding and bending. In order to be able to subject ribbed sections to this operation, they are prepared in the following two ways:
• Thermodynamic ribbed bars or TMT
• HSD ribbed bars
These two bars, because they are produced at a very high temperature, have high flexibility and can be welded. Using these two steel sections increases the structure’s resistance to earthquakes, and for this reason, these sections are used in the construction of roads and bridges in urban structures.
Application of rebar in brief
Rebar is one of the main materials in various industries. The most important application of this steel section is in construction. The main purpose of using rebar in construction is to increase the strength of the structure by increasing the tensile strength of concrete.
Depending on the type and shape of rebar, different applications are defined for it. In terms of structure, four types of rebar A1 to A4 are produced in our country; Type A1 is without tread and cannot be used in concrete. This rebar can only be used around concrete structures and connections. The other three types are used in different forms of khamut, stilt, hook, vault, etc., in different parts of the building, from the foundation to the roof, block beams, slabs, and walls.
In addition to the construction industry, the use of rebar in other industries, such as automobile manufacturing, tools and types of wire, urban structures and industrial machinery, is also noteworthy, so knowing the price of rebar is very important for most of the industry players. Finally, please share your opinions and experiences with us.
