What is rigid reinforcement

How to choose construction reinforcement: the use of corrugated and smooth reinforcement

2018-08-05

This building material is widely used to create frames of buildings and structures. For the foundation, two types of reinforcement are most often used:

1. A500 class worker. Its purpose is to prevent the cement mixture from reaching critical elongation. Also, due to the presence of a cross-section, this material provides reliable adhesion to concrete.
2. Assembly class A240. It is used to fill the spatial frame, providing additional strength to the poured structure.

Corrugated and smooth steel reinforcement: main differences and advantages

Corrugated steel reinforcement is made from high-carbon hot-rolled steel, the finished rods have longitudinal and transverse ribs. Due to its structure, monolithic adhesion of the reinforcement to the concrete is achieved. The entire range of corrugated fittings includes about 30 standard sizes and is classified depending on:

• diameter (6-80 mm);
• cross-sectional area (2.83-12.57 m2);
• mass 1 meter (0.222-9.870 kg).

The advantages include:

• high resistance to corrosion and humidity, loads and deformation;
• increased degree of reinforcement and plasticity of the material;
• simple and convenient installation, long service life of the profile.

What is smooth reinforcement? Let's figure it out. This material has a smooth, non-corrugated surface and is made from various grades of carbon steel. Smooth steel reinforcement is used to reinforce the internal spaces of buildings with their subsequent concreting. The range includes 20 standard sizes and is classified depending on:

• diameter (3-40 mm);
• cross-sectional area (0.071-12.56 m2);
• mass 1 meter (0.055-9.87 kg).

The advantages include:

• resistance to chemical aggressive substances;
• increasing the load-bearing capacity of buildings of various types;
• high weldability rates.

When to use grooved and when to use smooth?

Corrugated reinforcement is a solution for simple and lightweight, but durable frames of concrete structures. It is less suitable for the manufacture of structures for auxiliary purposes (with the exception of lightly loaded ones). Due to its strength and perfect adhesion to concrete, this material guarantees the stability of buildings and objects.

Smooth reinforcement is the choice for reinforcing concrete structures; it can be used in any form (mesh, twisted strands, three-dimensional frame). This material can also be used in the construction of auxiliary structures (ceilings, gratings, fences, fences).

PKD-Stal will help you select building materials of the required type and size: the sale of metal and reinforcement structures is the company’s key specialization.

Source: https://newsvo.ru/pravilnyj-vybor-stroitjelnoj-armatury.dhtm

Reinforcement and its types

One of the most popular queries on the Internet on the topic of rolled metal is: “How many meters of reinforcement are in one ton.” We will answer it at the end of the article, but its topic is broader - metal reinforcement, its types, application and a little history.

Typically, the term “rebar” refers to flexible rods in the form of rods or welded mesh. Sometimes other types of rolled metal are “welded” to the reinforcement - I-beams, channels and angles, calling it rigid reinforcement. This type is used primarily in welded structures. But in our article, by the term “reinforcement” we will mean only flexible reinforcement, or more precisely, the proven reliable and popular steel rod reinforcement.

Reinforcement refers to rods of various shapes, cross-sections, metal strands and ropes that absorb part of the stress (tensile and shearing) that occurs in the product, which appears in reinforced concrete elements from the own weight of structures and external loads.

Another definition of reinforcement: elements that are not part of the main composition, but provide strength and efficient operation of the entire structure.

A little history

With the advent of concrete, construction became much easier. Before this, metal beams were also used, but in combination with clay (the first structures of this type were discovered on the island of Sicily, dating back to approximately 400 century BC). However, the adhesion of clay bricks and iron beams for reinforcement was not strong.

Moisture penetrated into the resulting cracks, the metal rusted and the buildings rapidly collapsed. The invention of concrete marked the beginning of the massive use of reinforcement: the adhesion of concrete and metal reinforcement turned out to be very strong. The combination of the opposite properties of cement and metal rods - compression and elongation - was also successful.

All this ensured the high popularity of concrete products in construction.

Types of fittings

Construction reinforcement is divided into types according to several indicators: 

• production material - metal (steel) and non-metal;
• appearance - rods, wire, rope;
• functions performed - prestressed (for floor slabs) and non-tensioned (for reinforced concrete panels, foundation);
• profile - smooth, periodic profile (various grooves), round (rounded rod, along the length of which two longitudinal ribs and transverse protrusions are applied, running in three passes along a helical line);
• purpose - installation, working, distribution and clamps;
• installation method - welded and knitted (frame, mesh);
• location in the reinforced concrete frame - longitudinal (partially takes on the load of the structure) and transverse (prevents cracks);
• manufacturing complexity - light (up to 12 mm in diameter), heavy (12-40 mm);
• physical and mechanical properties - hot-rolled, thermomechanically hardened in the flow of mills, mechanically hardened in a cold state.

Smooth and corrugated reinforcement

The main characteristics that immediately catch your eye are the presence or absence of corrugation. To the question: “is smooth or corrugated reinforcement better?” - there is no definite answer. They are simply different and are used according to their properties.

The smooth profile is marked as A1, and the periodic profile is A2, A3, A4, A5 and A6. The most popular are products A1 and A3. Smooth fittings are mainly produced with a diameter of 6-40 mm. The thinnest is wire.

Profiles of medium and large thickness are produced in measured and unmeasured rods.

Products of class A1 are made from steel grade with a significant yield strength. Smooth reinforcement bends and welds well. It does not “adhere” to concrete as well as corrugated concrete, but has better fluidity. This is a universal fitting that people like to use in extreme weather conditions, when A3 class products can crack (due to the lower “fluidity” of the material). Also, smooth profiles are used as blanks in the production of hardware, bolts, etc.

Transverse and longitudinal grooves, evenly spaced along the entire length of the rod, perfectly adhere concrete to reinforcement. Due to this, it is used as the main reinforcing element of reinforced concrete products.

For the manufacture of class A3 products, high-alloy steel with admixtures of silicon, titanium, chromium, manganese, etc. is used. This makes the reinforcement resistant to physical stress.

Corrugated reinforcement is used where such strength is especially necessary: ​​floors, ceilings, high-rise structures, overpasses, bridges.

According to the types of corrugation, fittings are distinguished:

• ring,
• sickle-shaped
• mixed (experimental).

Steel for reinforcement

Although fittings are made from different metals, most often they are made of steel. Steel has sufficient strength and excellent elongation. Both of these properties are important for creating reliable reinforced concrete products.

Proper quality reinforcing steel has a good combination of “yield” and “tensile strength.” To achieve the best quality of steel, the chemical composition of the metal and the method of manufacturing rods or wire are adjusted.

For better weldability, a composition with a reduced carbon content is selected.

Reinforcement mesh

For large-scale construction, reinforcing mesh is used. The reinforcement bars are welded or knitted immediately before pouring concrete and the finished mesh is rarely transported. Products made of special steel are used for welding.

Or use a special welding wire. The disadvantages of welding include increased fragility of the product in the welded area and poor response to bending. The bonded frame is stronger and more flexible.

If, of course, the mating conditions are met and high-quality wire is used.

GOST for fittings

In conclusion, let’s add a little about the standards for the manufacture of fittings. There are a lot of them. Let's name the main ones:

• Steel rod reinforcement - GOST 5781-82.
• Thermomechanically strengthened reinforcement - GOST 10884-94.

Manufacturing plants often produce products based on their own specifications. Metal products made not according to state standards, but according to technical conditions, are no worse. Different problems require different ways to solve them. By producing products according to their own specifications, most factories strive for unification, focusing on STO ASChM 7-93 “Rolling of periodic profiles from reinforcing steel.”

It is not necessary to know the standards for the fittings you buy, just as there is no need to rely only on them in search of quality products. It is more important to know the quality indicators of products and trust the seller (manufacturer) from whom you buy.

When purchasing reinforcement, it will be necessary to convert linear meters into tons, since the price is most often indicated per ton of material. How many meters in one ton will depend on the diameter of the rods: the thinner they are, the more meters will fit in one ton.

A special rolled metal calculator or a table for calculating reinforcement will help you convert meters of reinforcement into tons.

Let's take, for example, the most popular reinforcement with a diameter of 12 mm: one linear meter will weigh 0.888 kg, and a ton of reinforcement will contain 1126.13 linear meters.

You can view the range and prices of reinforcement and welded mesh in the online store.

Source: https://www.1metallobaza.ru/blog/armatura-stalnaya-chto-nuzhno-znat-o-ney

Reinforcement - what is it?

Reinforcement of reinforced concrete structures, an integral part of reinforced concrete structures, designed to strengthen concrete, resisting tensile (less often, compressive) forces. Flexible steel reinforcement is mainly used (in the form of separate

rods or welded mesh and frames); sometimes - rigid reinforcement (rolled I-beams, channels, angles). Fiberglass, bamboo and other materials can also be used as reinforcement.

There are different types of reinforcement: working, installed in reinforced concrete structures in accordance with the calculations, assembly and distribution, intended to form frames and meshes together with the working reinforcement and installed for structural reasons.

The variety of types of structures determines the need for special manufacturing. reinforcing steels, which must have different strength characteristics and have sufficient plastic properties.

The most common reinforcement is rod (hot-rolled, thermally and stretch-strengthened), which, depending on strength, is divided into 7 classes (available in diameters from 6 to 90 mm), and wire reinforcement, in the form of wire (diameter from 3 to 8 mm), strands, ropes , welded and woven mesh.

In prestressed structures, prestressed reinforcement made of reinforcing steel with high tensile strength [900 MN/m2 (90 kgf/mm2) or more] is used. Improving the adhesion of reinforcement to concrete is achieved by imparting an effective periodicity to its surface. profile.

Classification of fittings

Reinforcement is classified according to a number of criteria: by purpose, orientation in the structure, conditions of use, and by the type of material from which the reinforcement is made.

By purpose

According to their purpose, fittings are divided into:

• working fittings
• constructive
• distribution
• assembly room
• anchor (embedded parts)

By orientation in design

Classification of reinforcement by orientation:

• transverse - reinforcement that prevents the formation of inclined cracks from emerging shear stresses near the supports and connects the concrete of the compressed zone with reinforcement in the tensile zone;
• longitudinal - reinforcement that absorbs tensile stresses and prevents the formation of vertical cracks in the tensile zone of the structure.

According to application conditions

According to the conditions of use, it happens:

• prestressed reinforcement;
• non-stressed reinforcement.

Prestressed reinforcement in prestressed reinforced concrete structures can only be working.

Application of fittings

The joint work of reinforcement and concrete is ensured by their adhesion along the contact surface. The adhesion of reinforcement to concrete depends on the strength of concrete, the amount of its shrinkage, the age of concrete and the cross-sectional shape of the reinforcement and the type of its surface.

There are five possible types of contact between reinforcement and concrete:

• connections on shear bonds;
• friction;
• adhesion (connection by concreting a steel reinforcement element);
• compression of reinforcement with concrete after its shrinkage;
• electrochemical interaction of steel reinforcement and cement mortar.

If the reinforcement has been pre-tensioned, it is called prestressed. Tension serves to increase the strength of a reinforced concrete structure by preventing the formation of cracks, reducing deflections and reducing the structure’s own weight - since significantly less reinforcement is required by weight.

In reinforced concrete products, reinforcing products are mainly used, which are interconnected reinforcing steel rods. The main methods of connecting rods are electric welding and wire knitting. Instead of knitting with wire, special reinforcement clamps made of spring steel are used. Gas welding, as a rule, is not used.

Main types of reinforcement products:

• flat reinforcing grids (grids);
• spatial reinforcement frames.

Source: http://xn----itbibooabrjld.xn--p1ai/index.php/2011-09-13-03-34-43/427-2011-09-24-05-06-34

Fixed polystyrene foam formwork

Formwork is required to form the boundaries of pouring the concrete mixture to obtain a monolithic base. Most often, formwork is used when pouring monolithic foundations, walls and ceilings during capital construction.

In construction, it is customary to distinguish between two types of formwork: removable and permanent type. Recently, permanent polystyrene foam formwork has become especially popular. There are three types of permanent foam formwork:

Cellular. This type of formwork consists of many hollow single blocks, fastened together in a special way, like a children's honeycomb construction set. The cavities allow the solution to pass freely into the formwork. Reinforcement is made by both vertical and horizontal connections installed inside polystyrene foam cells. Cellular blocks are manufactured industrially.

Classic. In this case, polystyrene foam boards installed on both sides are used to enclose the future monolithic structure. The plates are connected to each other with metal ties. The classic version resembles standard formwork for pouring concrete from boards or plywood.

Improved. This method practically repeats the classic version, but instead of standard metal ties, the slabs are connected to each other with beams made of metal or wood. This allows you to compensate for the forces of the solution aimed at crushing the mold. To increase the strength characteristics, struts and stops are also used.

The main advantage of the improved system is the ability to erect structures of any thickness and configuration. In this case, the step of rearranging the ties does not matter.

Manufacturers, in addition to standard straight foam panels for advanced formwork, produce corner elements that allow you to maintain a right angle when pouring monolithic structures.

Advantages

Advantages of permanent polystyrene foam formwork:

• The main advantage of fixed structures made of lightweight materials is the presence of an auxiliary function. In addition to forming a space for pouring concrete, polystyrene foam formwork simultaneously serves as insulation . Walls and foundations built using monolithic technology will not require additional insulation, which will save significant money. If you use traditional wooden formwork instead of expanded polystyrene, even without dismantling it after completion of the work, this effect will still not be achieved. With a reduced thickness of the monolithic floor, polystyrene foam boards allow you to retain up to 35% more heat than when constructing walls made of concrete or brick of standard thickness;
• In addition to retaining heat inside the building, the permanent foundation formwork made of polystyrene foam protects from moisture , which is especially important in the off-season and winter. As a result, the service life of a monolithic foundation, even in unfavorable conditions, increases by 20%;
• ease of assembly of formwork. Even an untrained builder can assemble permanent formwork from expanded polystyrene with his own hands;
• general reduction in construction costs. If we take into account that a significant part of the estimated cost is the cost of the foundation and walls, and the use of permanent formwork allows you to reduce the thickness of the wall due to additional thermal insulation and, accordingly, reduce the cost of the foundation, the overall benefit, compared with the traditional method, can reach 30%;
• the use of expanded polystyrene helps to achieve uniform strength gain in concrete at low temperatures (up to +5°C) . Thermal insulation keeps the temperature of the solution inside and at the edges of the pour at approximately the same level, so the hardening process occurs more evenly, which increases the strength characteristics of concrete. In wooden formwork, the solution quickly cools along the edges and the initial temperature inside is maintained, as a result of which the strength gain is uneven and the quality of the concrete decreases.

Characteristics of EPS formwork.

Flaws

These permanent structures for concreting have their disadvantages:

• a structure erected using permanent formwork cannot be rebuilt or reconstructed. When planning construction, especially individual construction, you need to take this feature into account and immediately approve the final design of the building. It is also important to accurately mark and immediately lay all communications at the time of pouring monolithic walls;
• It is very important to carefully adjust all blocks in such a way as to prevent breaks. Loose formwork will cause moisture to penetrate into the base and cause fungus to form. It is especially important to pay attention to this drawback for novice builders who assemble permanent foam formwork with their own hands;
• The main disadvantage is the impossibility of directly pouring the solution at temperatures below +5°C. There are also problems at high temperatures - in hot weather it will be necessary to additionally moisten the hardening solution;
• dense protection with polystyrene foam boards does not allow the walls to “breathe”. To correct this drawback, designers need to provide in advance for the installation of a forced-type ventilation system. Only this approach will help cope with the greenhouse effect indoors, while maintaining thermal insulation benefits.

Popular manufacturers and prices

Prices may vary depending on the region and seasonality, but for the most popular manufacturers the average cost will be:

• A straight wall block 50 mm thick produced by Mosstroy will cost about 500 rubles, a more complex corner element - 780 rubles. Additional elements cost about 30 rubles on average.

• The cost of standard blocks from Samara “ Thermomonolit ” will be 750-780 rubles. The higher price is justified - in addition to polystyrene, plastic is added to the formwork blocks, which gives the product increased strength.

• The most expensive blocks include products from the Moscow plant " Technoblok " - their price reaches 2,500 rubles. But such a difference with standard products from other manufacturers is justified. Each element is covered with cladding in the form of artificial stone. No additional external finishing is required for this material.

Installation instructions for polystyrene foam formwork

The construction of monolithic structures with permanent forms does not require high qualifications. Even novice builders can handle this work, and for a small project only two people will be enough. Before you begin, you need to prepare the required number of polystyrene foam blocks and agree on timely delivery of concrete.

The installation process is divided into several stages.

Formwork assembly

To install the first row of blocks, you will need to prepare a waterproofed base. Vertical reinforcement bars connecting the wall being built and the foundation are mounted in advance, and the blocks are placed on top of them.

When assembling the first row, you should especially carefully check that the dimensions correspond to the project in order to prevent even the slightest deviations.

Subsequent rows are erected with an offset of half a block, so that the seams are bandaged and the structure becomes more rigid.

Reinforcement tying

In addition to vertical reinforcement, designed to secure the base and wall, to ensure the strength of the monolith, it is necessary to create horizontal connections. In each row, horizontal rods are laid overlapping. They are connected to each other with steel wire, which is also used to connect them to vertical rods. Rigid reinforcing mesh prevents heavy concrete from pushing light blocks out.

Pouring concrete

Before starting work on pouring the mortar into the formwork, all communications should be laid. After concrete gains strength, it will be impossible to install wiring and plumbing pipes inside the walls. To pour monolithic walls into polystyrene foam forms, concrete with fine fillers is used.

It is prohibited to pour more than three rows of formwork. After pouring, the concrete is compacted with a vibrator and leveled. Gradually increasing the formwork and pouring the mortar, the design parameters are achieved.

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Source: https://blog.brigada174.ru/nesemnaja-penopolistirolnaja-opalubka/

Fiberglass reinforcement

What is good and what is not so good. Metal reinforcement, as an obligatory component of virtually the entire range of reinforced concrete products, is perhaps the only building material that until recently had no alternative.

However, technological progress and the achievements of modern science in the field of construction have managed to break this stereotype.

In the seventies of the last century, the first tests of composite reinforcement took place and their results gave reason to assert that a worthy replacement exists and has a great future.

View from the outside

Externally, metal and fiberglass reinforcement are very similar. Meanwhile, there is a significant difference between them. For example, by color. So the silver and, often, rusty color was replaced by a material with a definitely more positive visual perception.

Let us note right away that yellow, beige, black, green, blue and other colors are in no way gradations of the material according to one or another indicator and depend only on the preferences of the manufacturer.

On a note

Today there is an opinion on the market that fiberglass reinforcement of certain colors is of higher quality or more durable. We dare to dissuade you of this. Such a wide palette is nothing more than a marketing ploy by trading organizations. In other words, the color of composite reinforcement does not have any influence, nor does it participate in the gradation of the qualities and properties of a given material.

Fiberglass reinforcement: quality and structure

The basis of the composite reinforcement material is fibers:

• Basalt;
• Carbon;
• Glass;
• Armid.

The binder for each type is complex polymers. It is their merit in the strength, ductility and other performance properties of fiberglass reinforcement.

In cross-section, fiberglass reinforcement can have either a circle or a circle with glass spiral winding. The standard winding pitch is 15 mm. The second option demonstrates greater adhesion to concrete and cement mortars and is therefore a priority for builders.

Fiberglass reinforcement: physical and performance qualities

Speaking about the advantages of composite reinforcement for foundations, let's start by listing them:

• It has a lower specific weight (as a clear example, we point out that one meter of steel reinforcement weighs the same as nine meters of carbon fiber reinforcement);
• Does not corrode and therefore does not destroy reinforced concrete structures;
• Does not conduct electric current (valuable both during installation and operation);
• Does not create radio interference;
• Not a heat conductor;
• Economical in financial terms;
• Has unlimited length (within reasonable limits, of course);
• Compact (if necessary, can be transported in coils;
• The manufacturer guarantees 80 years of trouble-free operation;
• Resistant to chemical influences;
• Has an attractive aesthetic appearance.

On a note

Since metal reinforcement in reinforced concrete products is replaced with composite reinforcement, in everyday life their names are also replaced with fiberglass reinforced concrete.

Composite reinforcement

Fiberglass reinforcement: application and installation

Installation of composite reinforcement during the construction of foundations is carried out similarly to metal reinforcement. When constructing a frame structure, the rods are fastened using wire twists or special staples (ties).

Let us add that when installing foundations, it is allowed to use carbon fiber mesh, individual rods and classic frames - all this refers to discrete reinforcement.

Dispersed allows for the direct addition of reinforcement scraps to concrete. Such reinforcement is used mainly in the construction of unloaded foundations.

The areas of application of alternative reinforcement extend to almost all areas of the construction of low-rise buildings and objects for various purposes, and especially to their foundations. The concrete poured into such foundations is called glass fiber concrete.

A separate branch of the use of non-metallic fittings can be called the arrangement of the adjacent space. This:

• Fences of flower beds, greenhouses and front gardens;
• Supports for individual flowers, shrubs and trees in the garden. Here, the color scheme of composite rods is of particular relevance;
• Composite rods are readily used in the construction of walls and partitions from gas and foam concrete blocks .

Fiberglass reinforcement screed

We choose, we calculate, we don’t make mistakes

State standard 31938-2012 regulates the main dimensions of non-metallic reinforcement, indicating both absolute values ​​and numbers of compliance with the classics - steel reinforcement.

One of the main differences between steel and plastic reinforcement bars is its geometry. If the metal one has a cross-section close to a circle, then the carbon fiber one has a cross-section close to an oval. In this case, the smaller size is called the “internal diameter”, and the larger one is called the “external diameter”. This is where difficulties begin in determining the required size. The generally accepted way out of this situation is to calculate average values.

On a note

Any options for one or another selling organization to convince you of a different payment procedure is a surefire reason to turn to their competitor.

As a clear example, we provide a comparison table for some ranges of fittings

Steel fittings GOST 5781-82	Composite reinforcement GOST 31938-2012
Diameter, mm	Sectional area, sq.mm	Tensile strength N/sq.mm	Inner diameter, mm	Sectional area, sq.mm	Tensile strength N/sq.mm
6	28,3	390	5,95	27,83	1100
8	50,3	390	7,15	40,1	1100
10	78,5	390	8,34	54,6	1100
12	113,1	390	9,53	71,26	1100
14	154	390	10,71	90,5	1100
16	201	390	11,92	111,33	1100

What is priority - fiberglass or steel?

This question is not simple and the answer to it most likely needs to be sought in a comparison of the main parameters. We will try to achieve certainty on this issue. So,

• Metal rods have elasticity and plasticity, while composite products have only elasticity;
• In terms of tensile strength, non-metallic products are several times higher than steel ones: 1300 and 390 MPa;
• Thermal conductivity coefficient for fiberglass: 0.35 W/m*C0 – and 46 for steel;
• The density of steel reinforcement is 7850 kg/m3, composite reinforcement is 1900 kg/m3;
• Fiberglass products are not afraid of corrosion, while for a competitor made of steel this is a real scourge;
• Fiberglass reinforcement is neutral to electric current, does not magnetize, which means it is ideal for rooms with radio equipment, and cannot be replaced in the construction of laboratories and technical centers;
• Fiberglass reinforcement practically does not bend, which limits its use in reinforcing floor slabs and other concrete products;
• As a result of the supply of non-metallic reinforcement in rolls, cost overruns during purchase and waste during installation are practically guaranteed.

Thus, with all the unique characteristics and physical indicators of composite reinforcement, we recommend using it for foundations with a great degree of caution. The use of non-metallic reinforcement for heavily loaded structures and areas where there is a high probability of destruction is prohibited. As for all other construction sites, here composite reinforcement has already confirmed its effectiveness and is the undisputed favorite.

Noteworthy information : Blind area around the house , Installation of a strip foundation with your own hands .

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Source: https://stroitelinfo.ru/zagorodnyj-dom/kompozitnaya-armatura

Reinforcement - what is it? Types and characteristics of fittings. Selection, design, cutting and bending of reinforcement

Today’s article is devoted to one very interesting topic that everyone who is involved in any way with traditional working professions needs to know: builders, plumbers, etc. So, the focus is on fittings and all the information about it.

Fittings are a set of additional parts and devices that are capable of ensuring the full operation or functioning of any device, equipment, structure, etc.

If we talk about the construction industry, then reinforcement most often means a reinforced concrete frame of a structure, which is made of steel rods.

Shut-off valves

In plumbing, the concept of fittings is also used. Most often, these are shut-off valves that allow you to block the flow of liquid.

Shut-off pipeline valves.

In everyday life, you often have to deal with fittings for a drain barrel. Typically, the use of the word "reinforcement" in this context requires an explanation of what kind of reinforcement is meant. When they simply say “reinforcement,” they mean construction reinforcement, and that’s what we’ll talk about.

Classes of building reinforcement

For the manufacture of metal elements, steel is used, which can withstand enormous loads. This feature is due to the fact that reinforcement is used in the production of building structures, the load and weight of which sometimes reaches several hundred thousand tons.

Metal profiles are manufactured in accordance with GOST 5781-82. But there are separate classes that bypass GOST standards and are produced according to TU or STO ASChM 7-93.

Mechanical properties and profile patterns divide the reinforcement into classes: AI (A240), A-II (A300), A-III (A400); A-IV (A600), AV (A800), A-VI (A1000).

If we talk about the first class AI (A240), then it is characterized by a smooth surface, but for all other classes the characteristic feature is a corrugated surface. The Roman numeral after the letter “A” indicates the strength of the steel from which the reinforcement is made.

Accordingly, the higher the serial number, the stronger the reinforcement. But here it is worth considering that with an increase in strength, the ductility of the profile automatically decreases. Therefore, this property must be taken into account when selecting reinforcement.

The lower the grade of the material, the easier it will bend.

In the process of producing metal profiles, thermally strengthened steel can be used. In this case, the letter “T” is added to the index. But the letter “B” is added if hood-strengthened steel was used in the production process. Often, the latter is used for the construction of large structures with a large thickness of concrete.

Most often, hot-rolled reinforcing steel is used for the production of reinforcement, which contains additional elements: manganese, silicon or more durable chromium and titanium.

Production of fittings

The fittings are manufactured in specialized workshops, as well as in reinforcement and welding plants. All stages of production are fully mechanized and automated.

Steel for reinforcement is delivered from warehouses to the workshop on special trolleys, then, using an overhead crane, the workpiece is sent to the area equipped for the production of reinforcement. The processes of straightening rods, cutting, welding, etc. are carried out there.

Storage of steel blanks is carried out on special racks. Often factories and workshops have two production lines:

• Manufacturing of fittings, which are supplied in coils;
• Production of reinforcement from bar steel.

Cutting and straightening of reinforcing steel is carried out on special machines.

Knitting reinforcement for the foundation

The foundation is the basis for the reliability and durability of any structure. And in order to build a high-quality and durable foundation, it is necessary to use reinforcement connected to each other. The simplest way is to bind the reinforcement; the joining process is called knitting.

What is needed for tying reinforcement?

There are two material options for tying reinforcement - wire and plastic clamps.

Wire

It should be 1.2-1.4 mm in diameter and have a round cross-section. It is precisely these characteristics of the wire that will allow for efficient and easy knitting. It is easily bent, quickly takes the required shape, and is also quite strong and durable. It is best to give preference to burnt steel wire.

So, directly for the knitting itself, pieces of wire 25-30 cm long are needed. There is no need to measure and cut the required length each time. It is enough to fold it several times (to the required length) and cut the bends with a grinder. This way you can significantly speed up the construction process.

You can knit the wire either manually, which will slightly slow down the construction work, or with the help of special tools, which will greatly facilitate and speed up the knitting process. In hardware stores you can find hooks for tying reinforcement. There are a large number of varieties of such tools, ranging from conventional to screw and semi-automatic models. But the best option may be a gun for tying reinforcement, which completely automates the entire process.

The simplest reinforcement tying scheme:

1. Fold a piece of wire in half;
2. Pass the wire under the reinforcement at the junction of the two rods;
3. Insert the hook into the loop formed;
4. Pull the remaining edge of the wire with your fingers to the hook and throw it over it, bending it slightly;
5. We begin to make rotational movements of the hook, twisting the two ends of the wire;
6. After making up to 8 turns and making sure that the fastening is secure, we remove the hook from the loop.

Knitting reinforcement with wire.

Reinforcement clamps

These are specially designed embedded parts that are used to create a protective layer of varying thickness in concrete around the reinforcement. These parts are made of polyethylene. The scope of application of clamps is spatial fastening:

• Reinforcing bars;
• Reinforcement frames;
• Reinforcing mesh.

To ensure good strength of a concrete structure, it is necessary that the reinforcement inside the concrete is not too low or too high and at some distance from the edges of the concrete structure.

That is, there should be a layer of concrete around the reinforcement on all sides. In this case, maximum structural strength is achieved. Retainers help with this.

You can find out more about these devices in a special article: fixtures for fittings, also known as stands and racks for fittings, types, characteristics, application.

Plastic clamps for fittings.

Another very useful tool when working with reinforcement is a spring formwork clamp. It allows you to conveniently connect the opposite walls of the formwork into which concrete is poured with reinforcement. You can read more about it in a special article - fastening formwork with a spring clamp.

Clamps and studs from reinforcement

To hold the elements of the reinforcement frame, additional elements are used: clamps, studs, additional frames and others. They are made from reinforcement or shingle rods.

More information about their varieties and application can be found in the article: clamps from and for fittings.

Rebar bending

Reinforcement of corners should be done using curved reinforcement with an overlap of at least 80 cm on both sides. Curved reinforcement is also necessary for the manufacture of connecting elements that work in tension. But for the information of many, only steel reinforcement can be bent. Fiberglass cannot be bent. It is permissible to bend steel rods only mechanically. The bending points should not be sharp, but smooth.

Today there are a huge number of devices with which you can bend reinforcement. The principle of operation of all is the same, the differences are only in the designs themselves and the bendable diameter. It all depends on the equipment model.

The principle of operation of the device. The reinforcement is secured between the central and thrust shafts. But with the help of the third bending shaft, the steel is bent in the desired direction. The thrust roller prevents deformation of the reinforcement along its entire length. The equipment can be manual or mechanically driven.

Manual device for bending reinforcement. Device for bending reinforcement with a mechanical drive.

So, reinforcement is that part of the foundation without which the walls of any building cannot exist.

After all, only thanks to a steel profile can the reliability and strength of any structure be ensured.

In order to determine what kind of reinforcement and how much is needed when building a foundation, it is necessary to make special calculations, which you can read about on a separate page of our website: how to calculate reinforcement for a foundation.

Source: https://dompodrobno.ru/armatura/

Reinforcement for concrete - which one is better to use?

Heavy concrete is a durable material that has a high “load-bearing” “compressive” capacity. At the same time, its ability to perceive tensile and bending stresses leaves much to be desired.

Therefore, to ensure the resistance of structures to all types of mechanical loads, concrete reinforcement is used, which is laid in the structure at the stage of preparation for pouring. Concrete without reinforcement can withstand only minor bending and tensile loads. When a certain value, measured in MPa or kgf/cm2, is exceeded, the structure begins to crack or completely collapse.

Concrete reinforcement: types and classification

Reinforcement used in modern construction is classified according to the following factors:

• Material of manufacture: carbon steel or fiberglass.
• Production technology and physical state: rod, rope and wire.
• Section profile type: round, smooth or grooved.
• Work of reinforcement in concrete: prestressed or non-prestressed.
• Purpose: working, distribution and installation.
• Installation method: welded or tied with mild steel, copper or aluminum wire.

Diameter of fittings, mm	Profile	Purpose
6	smooth	assembly/for forming clamps
8	installation / possible use as reinforcing elements of bored piles
10	periodic (grooved, ribbed)	working/used for small buildings taking into account soil parameters
12	working/the most common options for the construction of a strip or slab reinforced concrete base
14
16	working/used for large houses on difficult soil

Also, concrete reinforcement with reinforcement can be transverse or longitudinal in nature:

• Transverse reinforcement eliminates the formation of inclined cracks from shearing mechanical loads and connects the concrete of the compressed zone with the reinforcement in the “stretched” zone.
• Longitudinal reinforcement absorbs tensile loads and prevents the occurrence of vertical cracks in the loaded area.

What type, type, diameter and quantity of reinforcement to use in each specific case is indicated in the design documentation for a particular building or structure. However, many developers who build houses and structures without a design are interested in a common question: what is the consumption of reinforcement per 1 m3 of concrete necessary to ensure the durability of the structure. Let us consider the consumption of reinforcement per cube of concrete in more detail.

How much reinforcement is needed per cube of concrete?

This is a legitimate question asked by many developers of private and country houses who are constructing capital construction projects without developing an expensive project.

When determining the amount of reinforcement per cubic meter of concrete, the following factors are taken into account: operating conditions in a particular region of Russia (soil condition, depth of soil freezing and height of groundwater), weight of the structure, type of structure and technical characteristics of available reinforcement.

Approximate consumption rates for steel reinforcement with a diameter of 12 mm for the strip foundation of a private house with the following dimensions of 9x6 meters are 18.7 kg per 1 m3 of heavy concrete.

Noting that the calculation of the characteristic - consumption of reinforcement per m3 of concrete should be carried out in each specific case individually. In accordance with the requirements of the current regulatory document SNiP 52-01-2003, in general, the amount of longitudinal reinforcement cannot be less than 0.1% of the cross-sectional area of ​​the structure.

As an example, consider the section of the strip foundation of a private house 1 meter high and 0.5 meter wide. To strengthen it, you will need 1x0.5 = 0.05 m2 of reinforcement of the corresponding section.

Abstracting from the regulatory documents regulating the amount of reinforcement per 1 m3 of concrete, we will inform the readers of this publication of practical consumption standards that ensure a high level of strength and durability of a private building.

Sample calculation of reinforcement for a foundation

Correctly laid working reinforcement on the foundation will increase its tensile and bending strength. There is also auxiliary fittings installed vertically. It provides shear strength.

Both options use different types of reinforcement, which should be taken into account:

• The first steps begin with vertical rods being driven in along the perimeter of the formwork assembled in a strip pit. In this case, the same distances between the rods are maintained - 50-80 cm. The diameter of the reinforcement itself is in the range of 0.8-1 cm, and the height of the rods is equal to the depth of the pit.
• Horizontal belts are knitted to the auxiliary rods at the bottom and top, the number of rods in which is selected taking into account the recommendations given in the table:

Belt width, cm	Number of rods
No more than 40 cm	2
More than 40 cm	3

If the pit is deep enough, it is allowed to lay four rods in horizontal belts.

• The distance from the outer edge of the belt to the end point of the vertical rod should not exceed 10 cm.
• In order for the reinforcement frame to be a single fixed structure, special attention must be paid to connecting the corners. Here it is better to use a system of cross belts, combining the rods of two horizontal belts. It would not hurt to use reinforcement mesh to strengthen the corners.

It is also necessary to take into account this point - the reinforcement for a strip foundation should not lie on the ground. It is recommended to use a concrete base. Before the final assembly of the frame is carried out, the first pour is made with a thickness of 5-7 cm. When the concrete has hardened, the lower and upper chords can be welded (or tied) to each other.

A little math

Before you begin strengthening the strip foundation, it is necessary to calculate the reinforcement. This will allow you to stock up on the right amount of material in advance and select the right parameters.

First, they consider the diagram of the future house in order to determine the number of strips for the foundation. A standard building has four external walls and several internal ones (in our case, let there be two load-bearing ones), which means there are six foundation strips in total.

Mathematical calculations can be considered on a specific option.

For example, a square-type house is being built with a wall length of 10 m. The number of rods in each of the main belts is taken to be 2. In this case, the calculation of the reinforcement will look like this:

1. The length of the house is multiplied by the number of strips and the number of rods in two belts:
   10 x 6 x 4 = 240 m - the total length of the main reinforcement with rods d = 12 mm.
2. The length of the internal walls is added to the perimeter of the house (let’s say each is 10 m):
   40 + 2 x 10 = 60 m - the total length of the tape.
3. The previous parameter is multiplied by 5.4 - the average coefficient for each meter of tape:
   60 x 5.4 = 324 m - the total length of auxiliary reinforcement

The calculation was made for a tape 80 cm high and 40 cm wide. The mathematical operations are quite simple, so calculating the required number of rods is not difficult.

If we are talking about the foundation, then this is reinforcement with a diameter of at least 12 mm, welded or connected in a cell format with dimensions of 50x50 millimeters. The walls of a building made of concrete can be reinforced in the longitudinal direction in increments of 0.4-0.5 meters. At the same time, the adhesion of the reinforcement to concrete is ensured by its design features - longitudinal and transverse corrugation.

Conclusion

In conclusion, it is worth noting that there are no systemic recipes for reinforcing structures that are acceptable for all possible cases and cannot be. A private developer deciding how much reinforcement per 1 m3 of concrete should be guided by climatic conditions and the mass of the planned structure.

These are variable quantities that need to be clarified in each specific case of construction of a building and structure.

Source: https://cementim.ru/armatura-dlya-betona/