How to weld reinforcement correctly

Rebar welding methods

The main requirement for concrete structures is strength and durability.

To prevent the monolithic building from deforming during shrinkage, during the process of pouring the concrete solution, a special metal frame is installed - concrete reinforcement is performed.

To create such an armored belt, steel rods are used, which are tied together with wire or welded. Welding reinforcement is considered the most reliable fastening, so let’s look at it in more detail.

Types of fittings welding according to GOST

According to the GOST 14098-91 standard, joining of reinforcement can be:

• electroslag semi-automatic;
• bath-suture;
• electric arc manual;
• contact;
• bathroom.

In this case, the welded joint itself can be:

• lap (for electric arc manual welding);
• butt;
• tee (resistance spot welding, which uses one electrode in the bath).

Let's take a closer look at the most common methods of welding reinforcement.

Overlap welding

This technology is most often used for reinforced frame elements that are not subject to increased loads. This means that such welding of reinforcement for the foundation is not suitable. The same applies to structures experiencing heavy bending loads. This type of connection is considered the most unreliable and least durable.

The principle of such joining of metal rods is to connect the rods in the longitudinal plane, with their ends offset by up to 30 cm from each other. The more overlap is made, the greater strength the welded structure will have.

Overlapping reinforcement welding is performed on both sides of the joint, which can cause inconvenience if one of the welds is on top and the other on bottom. In this case, it can be very difficult to reach the bottom seam.

Healthy! In order for the rods to fit together better, their ends must be cleaned with an iron brush and treated with abrasive tools so that the mating surfaces are flat.

Reinforcement frames must be welded in a certain mode, which will depend on the cross-section of the metal rods. Let's say you use products with a diameter of 5-8 mm. In this case, it is necessary to use electrodes with a cross section of 3 mm for welding. For 8-10 mm rods, you will need a 4 mm consumable. If the diameter of the rods is more than 10 mm, then electrodes with a diameter of 5 mm should be used.

Healthy! You can use any electrodes for overlap welding of reinforcement, but most often builders use ANO and MR consumables.

It is also necessary to take into account the current strength that will be required for rods of different diameters:

• for rods with a diameter of 5 mm, 200 A will be required;
• 6 mm – no more than 250 A;
• 8 mm – 300 A;
• 10 mm – 350 A;
• 20 mm – 450 A.

For more information about lap joints, watch the video:

Spot resistance welding

In this case, the process of joining the rods occurs in an automated and mechanized mode. Contact welding of reinforcement is considered the fastest due to increased productivity. However, this method has two significant drawbacks:

1. Rods can only be welded in a workshop; therefore, it is impossible to carry out welding work directly on site.
2. Welding equipment is heavy, and the devices consume a lot of electricity.

Resistance welding technology is based on the fact that current passes well through metal bodies. In places where the resistance is increased (at the points of joining of the rods), a greater release of thermal energy occurs, due to which the rods melt and join.

There are two methods of resistance welding:

1. continuous reflow (used when using fittings of the highest class A-1);
2. melting intermittently, taking into account the preheating of the rods (applied to other classes of fittings).

If the reinforcing frame is welded with continuous reflow, then this will require a current density of 10 to 50 A/mm2. In this case, welding will take no more than 20 seconds (depending on the cross-section of the steel rods).

It is also necessary to take into account the specific pressure of the clamps, which will also depend on the cross-section and class of the rods. For example, for reinforcement of the highest class A-1, a pressure of 30 to 50 MPa will be required, and for rods A-2 it will be necessary to increase this figure to 60-80 MPa.

Healthy! Before using sponges for welding, they need to be cleaned or changed, since the quality of the work performed will depend on this.

Welded seams produced by contact welding must be checked visually. If the learned joint resembles a flattened structure, equipped with sides between the two ends of the rods, then the work was done efficiently. If a barrel-shaped structure is formed at the junction, then such a connection will not be reliable.

Butt welding

If desired, butt welding of the reinforcement can be performed. In this case, the two ends of the rods are simply welded and connected with straight ends. However, it is worth considering that such butt welding will not meet all the necessary GOST requirements; the design will be unreliable and less durable. That is why, in order to make a butt connection, bath welding of reinforcement is used.

Features of bath welding

The essence of this technology is the melting of steel rods, which are immersed in a special form made of low-carbon steel material - a bath (you can make it yourself or buy a ready-made matrix).

After this, the ends of the reinforcement bars are melted with electrodes (with a cross section of 5-6 mm) at a fairly high current of the order of 450-550 A.

When the melted liquid metal fills the bath, the reinforcing bars are connected, which turn into a single rod, the cross-section of which will depend on the dimensions of the mold.

Healthy! If welding of reinforcement using the hot tub method is performed at low temperatures, then the current power must be increased by 15%.

This type of welding is suitable for columns, foundations and other structures that will bear heavy loads. In addition, this method is used for:

• large reinforcement products (bar diameter 2-10 cm);
• reinforcement in the form of a lattice (when the frame is laid in several rows);
• joining flanges made of steel strips of the largest cross-section;
• connections of complex frames.

Using a bath for welding reinforcement allows you to join rods both horizontally and vertically. Thanks to this, the procedure for creating seams is greatly simplified; edging of the structure is not required.

What this type of welding process looks like is clearly shown in the video:

Let us consider in more detail this method of connecting reinforcing elements.

Bath welding technology

To weld yourself, follow these steps:

• Clean the ends of the rods with a wire brush until a metallic shine appears. It is necessary to process at least 3 cm from the edges.
• Weld the two ends of the rods to the bath. The distance between the ends of the products being welded must be at least 1.5 times the cross-section of the electrodes. If you use a three-phase arc, then the gap can be increased to 2 diameters of the consumables.
• Start melting one end of the rod until molten metal begins to form in the bath.
• Move the electrode to the other end (of the other rod) and melt it in the same way.
• Melt the ends of the reinforcement alternately until the bath is filled so that the liquid metal completely covers the rods. As soon as this happens, you need to start slowly rotating the electrode in a circle between the rods being processed. This is necessary for uniform heating of the molten metal before it cools. If the steel cools unevenly, cracks may form at the seams, which will significantly reduce the strength characteristics of the reinforcing frame.

When the metal has completely cooled, you can weld the corner and other joints (if necessary).

This method performs welding in both horizontal and vertical planes.

Healthy! The distance from the rods to the walls of the matrix should be about 1.5-2 cm.

Docking of this type is carried out using inverters (220 V), transformers (380 V), semi-automatic devices or automatic machines.

The only drawback of this welding method is that it will not be possible to complete the entire procedure using just one electrode. You need to change consumables very quickly - in 5 seconds you need to remove the remnants of the used electrode and install a new one.

Bath welding is considered the most reliable and durable, since the processed rods form a very strong connection. This method is most often used to create armored belts for foundations and other structures. If we are talking about simpler elements, then it is enough to overlap them.

Source: https://zamesbetona.ru/armirovanie/svarka-armatury.html

Is it possible to weld foundation reinforcement?

When planning the construction of a residential building, every developer dreams that it will be stable and reliably protected from adversity. To do this, you should take a serious approach to achieving your goal, make efforts, and solve many problems.

Sometimes the question arises whether the reinforcement for the foundation can be welded. There is a debate going on among builders and private developers. Some confidently claim that it is better to weld frame elements rather than knit. Others doubt whether it is possible to weld foundation reinforcement.

Let's try to understand this issue.

A professional approach to foundation construction guarantees a long service life of the building. A strong base maintains its integrity, as it is resistant to cracks as a result of soil shrinkage. Ensuring the strength of the foundation using a space frame is a significant challenge. It is important to carefully consider the design features of a reinforced structure, for the manufacture of which steel rods or metal mesh can be used.

For small buildings, a strip-type foundation is often used as a foundation. If manufactured correctly, it ensures the stability of buildings for a long time. It is impossible to form a reliable foundation by pouring the foundation with a concrete mixture without additional reinforcement. In this case, as a result of deformation, after a certain period of time it will crack.

When laying the foundation, the reinforcement can be connected in two main ways: welding or tying

Properly performed reinforcement helps prevent premature damage to the integrity of the base. The range of reinforcement is determined by calculation.

The use of steel rods allows:

• significantly increase the strength of the foundation;
• ensure uniform distribution of current forces;
• dampen the soil reaction as a result of frost heaving;
• ensure a long service life of the building.

Strengthening the base protects it from cracks caused by deformation.

Knitting or welding - the methods used for connecting rods

To increase the strength of building foundations, various techniques are used. When constructing household buildings, country houses and light buildings, private developers add pieces of metal, glass fragments and various construction waste to the concrete solution. For light ancillary buildings this is acceptable. However, a durable residential building requires reliable reinforcement of the foundation using reinforcing bars or steel mesh. They are cut into pieces of the required size and placed in trenches.

There is no consensus on whether it is possible to weld foundation reinforcing bars together

To ensure increased strength of the base, the rods are combined into a power circuit using various methods:

• by tying together reinforcing bars or lattice pieces using tying wire. To increase flexibility, it is fired and allows you to quickly fix the frame elements using a crochet hook;
• using electric welding. In the manufacture of frames at industrial enterprises, resistance spot welding can be used. In domestic conditions, reinforcing bars are welded using the usual method.

Each method of fixing rods has certain advantages and weaknesses. Let's analyze each mounting option in detail.

How to knit a reinforcement cage - methods of fixing the rods

Tying steel bars into a metal frame is carried out using various methods. It is possible to order a ready-made frame assembled using knitting wire at a specialized enterprise. However, this entails additional costs associated with its delivery to the site. For small volumes of construction this is quite expensive and impractical. It’s easy to learn the knitting technique on your own and do all the work yourself.

Knitting reinforcement for the foundation is used somewhat more often than the welding method

Observe the following sequence of operations:

1. Develop a drawing or sketch of the future reinforcement grid.
2. Calculate the total number of areas to be fixed.
3. Cut pieces of wire with a diameter of 1.2 mm, 30 cm each.
4. Bend a piece of wire in half to form a loop and bring it to the joint of the bars.
5. Grab the ends of the wire with a crochet hook and pull through the loop.
6. Check the tightness of the wire covering the connection area.
7. Rotate the working device, ensuring that the parts are tightly tightened.

Using a crochet hook to secure parts is an inexpensive way to fasten elements. It does not require the use of special tools and allows the work to be completed with the help of auxiliary workers.

To reduce the duration of work and make knitting easier, you can use:

• a special gun that automatically feeds the wire. Working with it requires certain qualifications;
• household electric tool with a rotating chuck. An electric drill or screwdriver equipped with an attachment is quite suitable.

Knitting a frame is inherently the simplest way to connect

The main advantages of automated devices:

• significant increase in productivity;
• facilitating fixation in hard-to-reach areas;
• significant reduction in labor intensity.

Having mastered the technology of hand knitting, you can do the work of fixing the elements of the reinforcement frame on your own.

When planning to manufacture a reinforcing grid using the tying method, purchase the required materials and prepare the tools in a timely manner.

Knitting technology is easy to master on your own, following the recommendations given:

• Place the horizontal elements of the lower tier at a fixed distance from the soil level. You can ensure the required gap of 40–60 mm using plastic supports, wooden pads or waste bricks. The frame rods should not touch the ground.
• Ensure that vertical bars are installed at equal intervals between them. Maintaining a constant step will allow you to evenly distribute the load. It is important to protect the elements from contact with the soil using special supports made of non-metallic material.
• Fix the spatial frame reinforcement with binding wire. When performing work, check the reliability of fastening in the connection areas. The elements should not move when pouring concrete into the formwork.

If you have at least a little experience in the field of construction, knitting reinforcement is quite simple

• Maintain equal spacing between the reinforcement located in the horizontal tier, as well as between the vertical elements. It is important to additionally secure the corner reinforcement, which is prone to displacement during the concrete pouring process. The corner parts should not protrude beyond the contour of the base.
• Check the strength of the assembled frame under load. Place a wooden board on the top belt of the metal structure and stand on it. When moving along the board, the frame elements must remain motionless.

Additional fixation of the frame placed in the formwork using wooden blocks will ensure its immobility when filling the formwork with concrete mortar. When purchasing materials for the manufacture of power grids, comply with the documentation requirements for the use of fittings of the required brands and assortment.

Welding reinforcement for the foundation - work technology

Currently, along with bonding, welding of foundation reinforcement is also used. This method of connecting frame elements is used in the construction of multi-story buildings, the foundations of which absorb significant forces.

This necessitates the need to ensure increased strength of the joints. Welded fittings made from A400C corrugated wire are welded well, just like A500C rod.

Spot welding of reinforcement ensures reliable fixation of rods with a diameter of up to 25 mm.

Welding reinforcement can significantly simplify the process of laying the foundation as a whole.

Overheating of rods during welding work can cause the following negative phenomena:

• change in metal structure;
• reduction in strength properties.

When work is performed by experienced welders and assembly is carried out under laboratory control in industrial enterprises, these factors can be avoided.

The algorithm for manufacturing reinforcing bars by welding in industrial enterprises is carried out as follows:

1. Incoming quality control of purchased materials that will be used to assemble the frame is carried out.
2. Rods whose characteristics do not meet the requirements of regulatory documentation are rejected.
3. Reinforcing bars are cleaned of rust, straightened, treated with abrasive and cut into blanks of the required sizes.
4. The elements of the future frame are connected in one plane by light tack welding until final fixation.
5. The frame blanks are fixed with welding jigs at a distance corresponding to the requirements of the drawing.
6. The structure is tacked by welding and the dimensions of the space frame are checked for compliance with the documentation requirements.

It is equally important to choose the correct current value with which you will weld the frame.

The design features of welding jigs make it possible to assemble rods with a tolerance not exceeding 3 mm. The sequence of operations for manufacturing a frame by welding on a construction site is similar. Spot welding of reinforcement allows you to fix steel rods of a spatial structure located at different angles, as well as in a suspended state. The installation is equipped with conductive clamps, which expand its capabilities.

Boil or knit: which method to choose?

Careful consideration must be given before making a final decision about whether to use ties to fasten steel bars or fasten them by welding. Why do some builders weld reinforcement while others knit it? Each method has its own advantages and weaknesses.

To avoid mistakes, you should listen to the advice of professionals:

• For massive multi-story buildings that place a significant load on the foundation, it is advisable to use welding. At the same time, it is important not to burn out the reinforcement, so as not to weaken the strength of the connection;
• for small residential buildings and country houses, you can use the connection of parts of the reinforcing lattice using knitting wire. This method of fixation ensures the strength of such buildings.

When using welding, it is important to eliminate the possibility of burnout, which weakens the strength of the joints. It is undesirable to use the welding connection method in seismically active zones, as well as on problematic soils, where the integrity of the foundation may be compromised as a result of soil displacement.

However, welding has a number of advantages:

• allows you to perform work at an accelerated pace;
• provides increased rigidity of the space frame;
• increases the load capacity of the base.

When constructing private buildings, it is better to use the knitting method. Advantages of this method:

• ease of implementation and no need for special equipment;
• the ability to perform work without the involvement of qualified specialists;
• absence of increased stresses in the joining areas.

The disadvantage of the knitting method is the insufficient rigidity of the reinforcement grid. However, when constructing light buildings, this drawback is not significant.

Making the right decision is a serious task. The problem of choice remains. Knitting is a simple method that does not require significant costs. And welding, although more expensive, provides increased strength. You should think it over carefully and, if necessary, consult with professionals. It is important to ensure the strength of the foundation, which determines the longevity of the building.

Source: https://pobetony.expert/armirovanie/pochemu-nelzya-svarivat-armaturu-dlya-fundamenta

Connecting reinforcement by welding: is it possible to weld?

To reliably connect the elements of the reinforcement frames for the foundation, resistance welding is used.

Welded reinforcement cage for the foundation

Docking of rods can be done by other methods, which have their own advantages and disadvantages.

Pros and cons of welding reinforcement for the foundation

Welding reinforcement to create frames using resistance welding has one significant drawback - a decrease in the strength characteristics of the rods in the heating zone.

This phenomenon is due to the fact that the strength of the rods is ensured by preliminary hardening of their structure, and the electrodes, when performing resistance welding, lead to tempering of the steel. As a result, the reinforcement for creating frames becomes more fragile.

In addition, the resulting welded joint does not respond well to bending. Thus, the structure of A500C brand rods can be deformed at the stage of compacting the foundation concrete when using vibrators.

Reinforcement brand a500c

When using bath welding of rods, the brittle seam may collapse when creating a foundation on malleable types of soil.

If subsidence of the structure occurs, then the reinforcement made of steel grade A500C is subjected to bending forces.

This leads to destruction of the welded joints of the frames. In this regard, it is not recommended to weld foundation reinforcement in swampy areas.

The main advantage of hot flash butt welding is the high speed of the work. This is especially important for large construction volumes.

The production of frames can be carried out by placing rods made of steel grade A500C in the longitudinal and transverse directions.

The frame can be welded at the intersection of the rods. The advantages of connecting rods made of steel grade A500 with resistance welding using the pool method are:

• low cost of consumables;
• low time costs;
• the possibility of obtaining high-strength frames.

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How to choose weldable fittings?

To create frames for concrete foundations, you can use reinforcement made of steel grade A500C. In most cases, they must be welded using contact welding.

It is recommended to use steel products with a circular cross-section, and for shallow strip foundations, rectangular plates can be used.

The choice of fittings is carried out according to diameters . On the modern market there are rods with a cross section from 5 to 32 mm.

It should be taken into account that the larger the cross-section of the rods, the stronger the frame connection will be.

The cost of such rods will be more expensive than usual, and therefore the choice must be made taking into account the strength of the products and their cost.

When choosing rods for the foundation, special attention is paid to their length, taking into account which you can calculate the consumption of products.

Now you can purchase reinforcement with lengths of 6, 9 or 11.7 m, and use a special machine to bend it.

The choice of the presented steel products should be determined by the type of foundation, as well as the characteristics of the soil.

The higher the bearing capacity of the soil, the smaller the cross-section of the reinforcement can be used.

For private construction, you can use products with a cross-section range from 10 to 16 mm. For foundations built on weak-bearing soil, it is better to use products with a thickness of at least 16 mm.

When choosing a suitable consumable material for frames, it is important to consider that rods with a cross-section of 10 mm cannot withstand the load for a long time and their use will be irrational.
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Technological map of the frame and reinforcement consumption

The technological map greatly simplifies the process of butt welding of reinforcement products. It includes data on the features of butt welding technology, the procedure for installing foundation frames and the location of rods.

In addition, the technological map allows you to easily calculate the consumption of materials. It can describe the scope of application and organization of the entire range of work.

The technological map may include requirements for the speed and quality of work, information about acceptance, etc.

Technological map of the foundation reinforcement frame

To calculate the consumption of reinforcement, you need to know the exact dimensions of the foundation and its type. The greatest consumption of rods is for a tiled foundation.

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Along with this, the consumption of products made from steel grade A500C is minimal when constructing strip and pile foundations.

For example, we can consider a foundation whose depth is 0.7 m with a width of 0.3 m. When calculating the consumption, it should be taken into account that the reinforcement is made using 4 rods made of steel grade A500C.

The connection of longitudinally located elements with vertical and horizontal crossbars can be done in increments of 50 cm.

Source: https://armaturniy.ru/svarka/mozhno-li-svarivat.html

Is it possible to weld reinforcement for the foundation - features of the work

The start of construction of a building is preceded by the formation of a reliable and strong supporting foundation. Often, developers opt for a strip foundation or a conventional monolith, inside which reinforcing frame structures are installed.

In this regard, many people ask whether it is possible to weld reinforcement for the foundation. There is no definite answer to this, and before making a final decision, you should learn in more detail about the types of connections of metal rods into a frame base.

Is it possible to weld reinforcement for the foundation?

Today, welding of foundation reinforcement is used quite often. This method of connecting metal rods of a frame system is used in the construction of multi-story buildings, the foundations of which are subject to significant load impacts. This explains the need to achieve increased strength at connection points.

Welded reinforcing metal made from wire with a corrugated surface A 400 C (A 500 C) is perfectly welded. Using spot welding, reliable fixation of steel elements with a diameter of up to 2.5 cm is achieved.

In general, welding metal reinforcement greatly simplifies the process of arranging the foundation as a whole. It is better to entrust the work to an experienced welder or organize assembly at the enterprise. Inept actions can cause negative phenomena, which include:

• violation of the structure of metal rods;
• decrease in strength index.

Advantages and disadvantages

To finally understand the question of whether it is possible to weld reinforcement for the foundation, you should find out all the positive and negative aspects of this connection option.

The foundation system welded in industrial workshops significantly reduces construction time, allowing for the rapid installation of frame systems and meshes into the foundation body. Note that welded products have the following positive characteristics:

• allow you to create a strong and reliable foundation that can withstand significant loads;
• increase the rigidity index of the finished spatial module;
• financial costs for consumables are reduced;
• In a short period of time, a frame base with a high strength index is prepared.

There are also negative points:

• connecting reinforcement by welding is not recommended for use in seismically unstable regions, on complex soil compositions with long-term shrinkage;
• at a heated point, the strength of the metal decreases, the reinforcement becomes brittle;
• connections made by welding have a poor bending effect; the vibrators used for compaction cause the structure of the elements to deform.

Selection of fittings

Elements for reinforcing the foundation are represented by metal rods having a smooth or ribbed surface. They are placed inside concrete structures to increase their strength and resistance to negative influences.

Today, such rods are most often made of steel, but there are elements made of new materials that are more durable. One such example is fiberglass.

In addition, products made from reinforcement differ in the thickness of the rods, the value of which varies between five and twenty-five millimeters. The final choice of reinforcement during the construction of a particular facility is based on the expected load on the foundation and other factors.

The rods from which the reinforcement structure is made are connected to each other to increase the strength of the foundation. Note that reinforcement with a ribbed surface in most cases is used as the main one to redistribute the load effects created by the structure and soil composition. With the help of ugly rods, the necessary orientation is provided for the ribbed elements inside the foundation base.

Reinforcement with a ribbed or smooth surface must be fastened together, so you should know how to weld reinforcement for the foundation.

The recommended version of the reinforcement used for arranging a concrete base is A 500 C. It is best to use round rods, and when installing shallow foundation strips, rectangular plates.

It is necessary to take into account one feature - the strength of the future frame depends on the size of the reinforcement section. In addition, when choosing, the length of the rods is taken into account, the parameters of which can be used to determine the consumption of metal products.

When building a private house, it is allowed to use reinforcement whose diameter varies between ten and sixteen millimeters. Metal rods, the thickness of which is at least 1.6 cm, are laid in foundation foundations built on weak-bearing soil compositions.

Materials and equipment

Continuing to understand the question of whether it is necessary to weld reinforcement for the foundation, you need to pay attention to the devices and consumables used for this purpose.

It is recommended to use an inverter that performs resistance welding and operates on direct current. It is much more efficient than its transformer counterparts, which require variable current.

The semi-automatic unit works with special electrodes capable of cooking in an environment saturated with protective gases. The equipment has a special mechanism with protective properties that feeds electrodes automatically.

An inexpensive but outdated option is a welding transformer, which connects the fittings using electrodes that receive alternating current. This type of equipment works through a rectifier that converts alternating current into direct current. Like other equipment, resistance welding units are divided into two groups - professional devices and household ones.

The electrodes used for welding change the chemical composition of the connecting seam. Such elements are based on metal rods coated with a special composition that burns during welding.

This consumable material is marked as follows:

• “U” – resistance welding is allowed for products made of low-alloy metal;
• “L” – frames can be formed from alloyed metal;
• “T” – heat-resistant alloys are welded;
• “B” - such electrodes are recommended for joining high-alloy steel products;
• “N” – with their help additional layers are deposited.

In addition to the consumables discussed here, solid or flux-cored wire is used during welding, with the help of which weld deposits are formed.

Flux-cored wire has a special composition that facilitates the formation of a seam and increases its quality level. The diameter of such wire varies from 0.3 to 12 mm.

For a semi-automatic unit, it is recommended to use wire 0.3 – 1.6 mm.

Subtleties of welding work

To completely dispel the myth of why you can’t weld reinforcement in the foundation, you need to know the specifics of performing all the actions.

Initially, reinforcement of the required diameter and length is prepared, corresponding to the design specifications for the arrangement of the foundation frame. After this, the following algorithm of actions follows:

• purchased material is checked for quality;
• Rejection is carried out, during which metal blanks are identified whose characteristics do not meet the requirements of regulatory documents;
• steel rods are cleaned of corrosion, straightened, coated with an abrasive compound, and cut into blanks of the required sizes;
• all elements of the future frame structure are connected in a common plane using light tack welding units, final fixation is carried out later;

• blanks for the future frame part are fixed with special jigs at distances determined by the design drawings;
• the structures are tacked by welding, the compliance of the frame parameters with the data in the design documentation is specified;
• The final working stage is the final welding of the frame.

When following the technological stages of welding reinforcing bars at a construction site, remember that it is better to use a special unit for inverter welding.

The main indicators of the modes during operation of the welding machine are:

• electrode cross section;
• the magnitude of the type and polarity of the electric current;
• electric arc voltage indicator;
• speed of welding work;
• number of approaches.

When using the contact welding method and determining its operating parameter, the main indicator is the strength of the current used, on which the quality characteristics of the resulting weld and the work productivity indicator completely depend.

The choice of electrode diameter is made taking into account the thickness of the metal being connected. It must be remembered that the operating mode is based on the level of electrical current.

When the electrode used is thicker than four millimeters, it is recommended to reduce the standard current by ten to fifteen percent. When deciding on the polarity mode, give preference to reverse.

Due to the fact that when working on a constant electric current, thermal energy is actively generated, the likelihood that burns will appear in the metal material increases.

The latest welding units can convert alternating electric current, and after switching on the appropriate mode, the electric current supplied to the electrode rod turns into direct current.

When choosing a speed mode, make sure that the bath filled with hot steel is located above the surface of the edges. It is best to select a mode in which the width of the welding seam is one and a half to two times the diameter of the electrode rod.

Having assembled the reinforcement structure intended for the foundation, it is necessary to carry out a simple test. A board is laid on the surface of the frame, on which a person begins to walk. If the frame system is assembled according to the design drawings, it will not bend due to weight.

Before starting to supply the concrete mixture, the reinforcement system is further strengthened in order to be securely fixed in the foundation body.

Conclusion

Let us repeat that the question of why it is impossible to weld reinforcement for the foundation does not have a clear answer. Some builders do not recommend using this method of joining metal, while others claim that there is nothing wrong with it, and the frame turns out to be strong and reliable. The final decision must be made taking into account the characteristics of the building under construction and the factors affecting the foundation.

Source: https://betonov.com/fundament/stroitelstvo/mozhno-li-svarivat-armaturu-dlya-fundamenta.html

How to weld reinforcement with your own hands

Reinforcing bars are used to strengthen concrete foundations, monolithic walls, and mesh laid under the road surface. Welding of reinforcement is carried out in the workshops of reinforced concrete factories and at facilities under construction. The assembled frames and meshes are subjected to static and dynamic loads. The strength of the metal structure depends on the quality of the seams. There are several methods for hot joining reinforcing bars. Each has its own disadvantages and advantages.

Features of welding reinforcement

All methods of fastening reinforcing bars are regulated by GOST 14098-91. When creating lattice frames, it is possible to obtain cross connections comparable in strength to reinforcement. It is preferable to connect the rods end-to-end, increasing them to the required length.

The strength of end-to-end frames is higher than when welding overlapping reinforcing bars. The alignment and symmetry of load distribution is disrupted. The metal is welded by surfacing and melting.

The reliability of the molten joint is higher than that of surfacing, but the method is not applicable on construction sites when welding reinforcement at height.

Before hot processing, the metal should be cleaned so that there is no rust or metal particles in the working area. For butt joints, the edges are aligned with a cutter.

Welding methods

More often the rods are welded end-to-end, less often - overlapping. The quality of the seam in butt welding is higher; metal penetration is provided over the entire joint area. The overlapping fastening of the rods is unreliable and is not designed for bending or torsion. The work is carried out using a consumable electrode. Is it possible to weld reinforcement without surfacing? It is discussed in the “Contact spot” section. In the meantime, in detail about each of the methods of fastening reinforcing bars using the surfacing method.

overlap

Welding of reinforcement for frames experiencing a small load on bending and torsion is done overlapping, the rods are overlapped by 15–30 cm. With this method, metal consumption increases.

The angle of inclination of the electrode is up to 15° to the vertical, the seam is made on opposite sides of both rods or welded with an overlap using a side continuous seam. For work, consumable electrodes of different brands are used. Details in the last section of the article.

The welding site is pre-cleaned with a wire brush. Some electrodes can be used against rust.

Welding of overlapping reinforcement is carried out for frames experiencing low bending and torsion loads

For a high-quality weld, it is important to select the correct current parameters. A small table of the weldability of reinforcement depending on the diameter of the rods (data averaged for rods of grades A500C and A400C):

Source: https://svarkaprosto.ru/tehnologii/kak-varit-armaturu-svoimi-rukami

How to weld reinforcement

When laying the foundation of a multi-story building, welding reinforcement for the foundation is one of the critical processes. If there are other methods for assembling reinforcing inserts, welding is the most productive.

It is important to comply with the requirements of GOST - 14098-2014, to use the most suitable welding methods for specific projects.

Basic reinforcement methods

Reliable connection of reinforcement is made using one of three methods:

• electric arc or contact welding;
• crimping of reinforcement bars;
• connection using tying wire.

Welding of reinforcement is performed in several ways, but has disadvantages. The main disadvantage is the disruption of the metal structure due to its heating and a decrease in strength at the weld site.

Such a joint does not work well in bending. If the seam is of poor quality, the joint may be damaged when the part is poured with concrete. Therefore, it is not recommended to use this method on soils with a high level of movement (quicksands, marshy areas).

It should be noted that when using the contact method and ready-made frames, welding can be used in such difficult conditions. The main advantage of welding reinforcement is speed and high level of productivity.

GOST 14098 recommends the use of reinforcing steels with index C. Products with this marking ensure high quality joints.

Knitting with special wire

To reinforce the foundations of private households, it is recommended to tie the reinforcement with a special binding wire. This is a fairly simple and affordable method for small construction.

In this case, it is necessary to lay the lashes and join them with a slight overlap. Then, using mild steel wire, these places must be tied and tightened using a special tool.

Such a frame made of wire and reinforcement has high strength and does not violate the strength of the base metal. The joint turns out to be movable and will not collapse when the structure subsides.

But the low productivity does not allow this method to be used in multi-story construction, so reinforcement is knitted on small foundations.

Selecting brand and diameter

For work using electric welding, it is recommended to use A500C brand fittings. The most popular in industrial conditions is resistance electric welding using the bath method.

According to GOST, it is recommended to use blanks of round cross-section, but in the case of reinforcing a strip foundation, the use of rods of rectangular cross-section is allowed.

Depending on the laying conditions, the reinforcement section for the foundation is selected. The industry produces products with a diameter range of 5 – 32 mm.

As the thickness of the rods increases, the reliability of the frame connection increases, but the price of the foundation also increases. Therefore, it is important before work to select the optimal option for the diameter and length of the reinforcement rods.

The choice of thickness is influenced by the density of the soil. The higher this indicator, the smaller the cross-section can be used.

Lap joint

In conditions where there are no significant loads, the reinforcement sections are welded overlapping. The most dangerous for such a connection are bending deformations.

The overlap method is used for minor joints that do not carry significant overloads. This is the connection of two parts in the same plane with an overlap of 150 mm, and subsequent welding of the joints on both sides.

It should be taken into account that it is better to overlap as much as possible. The larger the joint surface, the higher the strength of the connection. It is not recommended to weld a joint larger than 300 mm.

Before welding, the workpieces should be prepared. For a tighter joining of the parts, it is recommended to grind a flat on the joint side and remove the stiffeners from the rods.

This increases the joint density and seam area. It is necessary to remove scale and rust from the ends of the reinforcement sections with a metal brush.

Often a situation arises when it is impossible to weld the joint on the other side. In this case, the seam will be weakened and the connection unreliable. In this case and when performing work on foundations that require a high level of strength, pool welding is used.

Electric welding in the bath

Bath welding is an effective and reliable method of permanently connecting the reinforcing layer of the foundation. With this method, the ends of the workpieces are joined end-to-end and placed in a special metal mold, made taking into account the diameter of the rod.

Then the welder fills the weld pool with molten metal, which, when cooled, produces a reliable and durable connection of the rods.

Before work, you need to clean the edges of the parts with a brush and select a bath of a suitable diameter. The baths are manufactured in industrial conditions and are produced in accordance with the cross-section of the reinforcement.

It is possible to manufacture such devices yourself from sheet metal about 2 mm thick. The main thing is to leave small gaps for the melt to pass through and completely fill the bath.

Then the reinforcement is laid out on a flat surface, inserted with the ends into the bath and pressed with clamps for welding. The parts are welded and the seam is allowed to cool.

Selection of the optimal mode

A number of factors influence the welding process and the strength of the resulting joint. The most significant of them:

• electrode brand and diameter;
• the magnitude of the welding current and its polarity;
• speed of electrode guidance;
• number of passes.

The main quantity influencing the quality of the weld is the strength of the welding current and its polarity. Correct selection of these parameters ensures high performance.

Depending on the thickness of the metal rods and the selected diameter of the electrodes for welding the reinforcement, the current strength is adjusted. The standard indicators indicated on the pack of electrodes should be set slightly less.

When selecting polarity, preference is given to its reverse value, which will avoid large heating and burn-through. The welder must maintain the speed of movement, taking into account the slight elevation of the metal above the edge of the parts.

For fittings, electrodes of such brands as UONI-13 55 and DSK50 are used. OZS-12 has proven itself well. But most often they use proven and inexpensive brands MP-3 and ANO-21.

Resistance spot welding

The most common method of connecting reinforcement is frame spot welding. The main difference between welding reinforcement cages and other methods is the absence of high temperatures when melting the electrode, as well as the equipment of the welding site with an automatic and semi-automatic line.

This feature allows you to obtain a strong connection of reinforcement with sufficiently high labor productivity. But with the help of such welding it is not possible to work on the road. The operation is performed only on a stationary basis. The equipment is quite bulky and consumes a lot of electricity.

The process of welding parts is based on the property of metal to conduct electric current. As electrical resistance increases, significant heat generation occurs. At the junction, the reinforcement heats up and melts, resulting in a permanent interatomic connection of the metal of two workpieces.

When choosing a welding mode, you must adhere to the basic rule. The width of the weld seam should be several times greater than the diameter of the reinforcement.

Recommendations for work

Operations such as welding of masonry mesh and reinforcement frames are carried out using special equipment. Rods with a diameter of no more than 26 mm are connected using spot welding machines. For larger thicknesses, the work is carried out using manual electric welding.

When welding meshes and frames made of cold-rolled steel, the mode is selected with a high welding current, but welding occurs in small sections. The joined ends must be cleaned of rust, grease and dirt.

When working on resistance welding, you should periodically clean the contact surfaces of the electrodes, the diameter of which must be at least 12 mm.

Foundation reinforcement is one of the main works when laying the foundation of a building. The service life of the house depends on the quality and reliability of the joints . Therefore, welding of frames and enlarged assembly must be carried out by a qualified specialist.

Source: https://svaring.com/welding/detali/kak-svarivayut-armaturu

Is it possible to weld reinforcement for the foundation?

The welding method for fastening reinforcement segments with wire is often used in practice. The method is used on steel and composite reinforcement. The latter appeared relatively recently and is rarely used in private construction. Copying the foundation is necessary to enhance the strength of the structure and increase the service life of the building. State connection standards have been developed for the installation of reinforced concrete structures.

What is written in GOST regarding welding of reinforcement

The reinforcement rules GOST 4098-2014 came into force as the national standard of the Russian Federation on July 1, 2015. The development was carried out by the Research Institute of Concrete and Reinforced Concrete named after. A. A. Gvozdeva OJSC Research Center (Construction). The standard applies to welded connections of rod and wire reinforcement in the foundations of prefabricated and monolithic reinforced concrete structures. The document specifies the standardization of connections by size, type and design.

Welded reinforcement for the foundation - application features

In the construction of architectural structures, the main task is to prepare a strong foundation that will withstand the internal compression reinforcement of the wall supports and the underlying soil. The basis of the foundation is concrete, which consists of sand, cement and water; when hardened, it can withstand heavy loads. The physical characteristics of the cement material cannot guarantee the absence of deformation of the base of the structure.

To withstand foundation shifts that occur due to temperature changes and other natural factors, metal is used that provides reliable fixation. Reinforcement is a mandatory process during construction. During the operation of the structure, settlement occurs, and the soil under the foundation becomes compacted. The process should take place evenly along the entire length of the strip foundation. In such cases, internal forces do not arise in the foundation.

You can achieve uniformity and reduce settlement by using foundation strips with reinforcement, the width of which determines the magnitude of the load.

The foundation is the basis of an architectural structure; when laying the foundation of connections, two methods are used for strength: welding and bonding. Each of them has its pros and cons.

Some builders prefer to use welding to strengthen the foundation; in this case, the connection is made at the intersection of the reinforcement.

The method is quite simple and reliable; special attention is paid to the reinforcement of the corners so that the steel elements are the connecting link of one and the other wall.

Advantages and disadvantages of the method

During welding at high temperatures, the metal heats up, as a result of which it loses its main characteristics: strength and rigidity. That is why there are disagreements in the application of this method in the construction of the foundation for a building. Welding materials are divided into categories:

• frame structures;
• meshes made by welding;
• welded rods.

The strength of the foundation is guaranteed when welding is performed correctly. Professional welders are well aware that before work, the surface of the reinforcement to be processed must first be prepared.

The construction of the foundation affects the strength of the entire structure; for this, when carrying out welding work, it is necessary to minimize the loss of properties of the reinforcement. Preparation for work begins with the selection of electrodes; for rods with a diameter of 14 mm they use (ANO-21), (To). You can purchase electrodes in a specialized store. After cooking each joint, you must wait for it to cool completely and check for microcracks; if there is no defect, the work has been done efficiently.

To increase the fit of fittings, welders use the method of stripping metal ends by grinding or stripping. There are four types of welding systems:

• cross;
• T-bar;
• overlap;
• butt.

It is better not to use the T-bar method, since the bending strength will be low, and accordingly the quality of the foundation strip will decrease.

Subtleties of welding work

The quality of welding work depends on the skill and experience of the welder. The first thing a welder does is prepare the material for work:

• checks steel rods for quality;
• during the inspection process, performs rejection;
• metal rods are cleaned of corrosive deposits, coated with an abrasive compound, and cut into blanks;
• connects frame structure elements using light welding clamps;
• finishing fixation is carried out after light connections using special conductors, according to the project drawing;
• The final stage is welding the entire frame.

Which is better: knitting or welding reinforcement for the foundation?

Many builders believe that using welding reinforcement for the foundation is an unreliable method, while others claim that strength will not be affected. The developer must decide on the use of this method, taking into account the design of the architectural structure and the factors influencing the foundation.

Popular

Source: https://dvabrevna.ru/fundament/mojno-li-svarivat-armaturu-dlya-fundamenta.html

Welding reinforcement

The reinforcement consists of rods of different diameters, having a smooth and ribbed surface. Reinforcement is a popular structural element used in many fields.

This building material is used in the following industries:

• production of reinforced concrete structures of domestic and industrial profiles: foundations, load-bearing walls, floors and columns;
• construction of special hydraulic structures;
• construction of frames;
• production of metal mesh for various purposes;
• arrangement of pedestrian zones and road surfaces.
• creation of other important products.

The main advantages of fittings should be highlighted:

• simplicity and ease of use;
• high strength;
• high thermal conductivity coefficient;
• a wide selection of rods depending on diameter, section profile, principle of application, purpose, production method, etc.;
• durability of reinforcement structures.

ATTENTION! We immediately warn you that if what is said in this article contradicts what was said in the technical specifications you received for welding a critical structure, do as indicated in the project. This page contains information applicable to low-rise construction and the use of rebar in decorative products.

Welding features

The process of welding reinforcement has its own peculiarities: the welding seam during cross welding has a short length due to the small contact area; as a result of welding this material, a perpendicular connection occurs. This connection can form a kind of lever, the main load of which falls on the site of the weld.

These specific characteristics require a special approach. To do this, there are several ways to weld reinforcement. The correct choice of the necessary technology can reduce costs and guarantee high-quality results.

Methods

There are several methods for welding reinforcement. Each method is used depending on the specific situation and to solve certain problems.

Arc welding

Electric arc welding is used by specialists in the following situations:

• work with large diameter fittings;
• fastening of reinforcement from steels of different grades.

The welder should use electrodes whose composition is similar to the composition of the products being welded, as well as a welding transformer, inverter or other source of welding current.

The main advantage is the ability to use conventional welding equipment. The main disadvantage is that connections created by this method are not able to withstand increased loads . The technology of welding reinforcement using manual arc welding is used when installing frames, metal structures and meshes.

Bathtub butt

The butt welding method is used for butt welding of reinforcement. For this method, the performer will need a special device. The bath ( bracket-plate for welding reinforcement) serves as a barrier to the flow of molten metal. The essence of the process is that the ends of the reinforcement rods to be welded are located inside the bath. Then they are melted one by one using electrodes. The electrode should lightly touch the rod, since welding is carried out at high current values.

For materials with a diameter of 5-6 mm. a current of 400-450 A is used. Low temperatures help increase the current by another 10-15%. The deposited metal fills the bath and the two rods are fastened into one monolithic connection.

It should be noted that this method is the most preferable due to the minimal costs of welding materials and metal, as well as due to the production of strong and reliable structures. Another advantage of this method is the ability to work with large diameter fittings - 20-100 mm.

There are three types of staples, the division is carried out depending on the raw material. Steel forms are one-piece, i.e. the bath becomes part of the welded structure. Copper and graphite pads are removed from the joint after the work is completed. They can be reused later. Graphite molds must be calcined before use, as they easily absorb moisture.

What brands of electrodes are used to work with different types of fittings will be indicated below.

Foundation connection

As mentioned earlier, reinforcement is most actively used in the construction industry, in particular in capital construction. Therefore, welding reinforcement for the foundation is a popular and in demand process.

Foundations bear significant loads, so their strength must be at a high level. Overheating of the metal leads to a change in structure and weakening of strength characteristics.

Consequently, welding should be carried out at specialized enterprises or at construction sites by highly qualified performers.

Thus, welding reinforcement for the foundation includes several stages:

• The quality control department checks the quality of materials, low-quality fittings are rejected;
• the rods are cleaned of rust and other contaminants, marked and cut;
• the workpieces are connected into a flat structure by tackling the elements;
• the compliance of the design with the technical plan is checked;
• in case of discrepancy, an adjustment is made, in other cases, the length of the welds and the welding sequence are determined;
• The final connection of the entire structure is also carried out in stages: after welding the next seam, you should let it cool and check the metal for microcracks.

In addition, welded reinforcement structures are used in low-rise construction. Consequently, welding of reinforcement for the foundation can be carried out at home. In such cases, the performer will need simple manual or automatic welding devices (for example, an inverter).

Electrodes

For welding reinforcing bars, electrodes of types E42, E42A, E46, E46A, E50A, E55, E60 are used.

The most popular and popular brands are:

• Electrodes with basic coating UONI-13/45 are used for welding critical structures made of carbon and low-alloy steels. Advantages : the seam is resistant to cracking and has high quality characteristics.
• TMU-21U are used for manual arc welding of critical structures. Advantages : the composition of the electrode coating guarantees good quality of welding and connection; low level of splashing; arc stability; easy separation of slag.
• UONI-13/55U are intended for welding of fittings using the hot tub method. This brand is indispensable for ensuring high-quality welding.
• If the contractor has an inverter-type welding machine, then to weld the reinforcement you will need electrodes of the ANO-21 and MR brands. Main advantages : availability of these welding materials, the ability to carry out rust welding, welding can be performed in all spatial positions (except MP-3).
• Practice shows that OZS-12 electrodes are one of the best options for working with fittings. Pros : welding of products with a small amount of rust is possible; rutile coating prevents the formation of pores and protects the seam from the ingress of slag and oxidation; high strength of connections.

Technology of joining and joining by manual arc welding

When welding reinforcing bars, it is important to choose the right equipment and consumables, carefully check and control their quality.

The features of the work listed earlier should be taken into account. When increased demands are placed on the finished product, each welded connection must be performed with high quality. Because even one unreliable seam can lead to uneven load distribution and damage to the entire metal structure.

In some cases, to increase the rigidity of the structure, it is necessary to weld additional ribs. They will affect the strength for the better.

Source: https://WeldElec.com/info/kak-pravilno-varit/armatury/

How to weld reinforcement

Reinforcement, as a building material, is mainly used in various building structures, which need to be given a certain strength and the ability to resist external factors and loads.

For this purpose, special volumetric structures are created, which are installed in molds and filled with concrete. To create volume, it is necessary to secure the reinforcing bars in some way. There are two types of fastening: bonding and welding.

As for the latter, we can note electric welding with consumable electrodes and such an unusual process as contact welding of reinforcement.

But to understand how to weld reinforcement, you must first understand what this metal material is. Essentially, these are rods of different diameters made of steel that have a smooth or ribbed profile.

The reinforcement must be hardened, which gives it the necessary strength and rigidity. It should be noted that reinforcing bars made of fiberglass have recently begun to appear on the market.

Their main advantage is that such fittings do not rust, hence their endless service life.

The diameter of steel reinforcement varies between 5-80 mm, and its choice depends on the loads to which the concrete block, assembly or part is subjected. In this case, ribbed rods are used as the main element of the reinforcing structure, and smooth ones are used to fasten ribbed rods together and orient them inside the reinforcing frame. But in any case, the frame itself cannot be assembled without welding the reinforcement.

However, it should be noted that welding negatively affects the structure of the material. High temperatures of the welding process change the structure of the reinforcement, and not for the better. The hardened metal is exposed to heat, which causes it to be tempered. That is, a decrease in strength. Probably, everyone could conduct an experiment by hitting a welding joint with a hammer with a hammer. Cracks appeared from a strong impact, and some joints simply burst.

Types of welding of reinforcing bars

Welding of reinforcing bars can be done in three ways:

• Welding with a consumable electrode overlapping two rods.
• Butt.
• Contact welding.

Turned contact welding

The advantage of this type of welding of reinforcement is the absence of consumable electrodes, the ability to fully automate and mechanize the process itself, plus the high productivity of the work performed. And there are two drawbacks - welding can only be carried out in a workshop environment (not on site) due to the large mass of the welding equipment, and the welding machines themselves consume a fairly large amount of electricity.

The resistance welding process is quite simple. It is based on the ability of electric current to pass through metals, and in places with high resistance to release significant thermal energy. So this place in the connection of two reinforcement bars is the joint itself. It is here that a huge amount of heat is released, which brings the rods to a plastic state and partially to a liquid state. This is how welding happens.

Today two types of resistance welding are used:

• With continuous reflow.
• With intermittent preheating of the rods.

Typically, the first method is used for welding reinforcement of the first class (A-1), the second for other classes. Before welding reinforcement frames with a turned joint, the rods themselves are treated with an iron brush. If the cut was made with an autogen, it is recommended to remove the metal deposits with a chisel.

The main parameters of frame welding are the strength of the current being welded, its density at the clamps, the duration of the process, the pressure of the clamps and the length of the electrodes protruding from the clamps.

For example, if the reinforcement is welded using a continuous reflow method, then the current density should be in the range of 10-50 A/mm², the welding duration should be 1-20 seconds (it all depends on the diameter of the rods being welded).

As for the specific pressure of the clamps, the dependence on the cross-section of the rods and the grade of steel from which the reinforcement was made is again used. Eg:

• Fittings grade A-1 – pressure 30-50 MPa.
• A-2(3) – 60-80 MPa.

Experienced welders know that the cleanliness of the jaws of the clamps plays an important role in the quality of the resistance welding performed. Therefore, they are periodically cleaned or replaced with new ones. This means that a certain set of jaws is a necessary condition for a high-quality welding process.

A contact spot weld must be checked in the laboratory. But you can also carry out purely visual control. If the joint after finishing the work looks like a flattened structure with sides between the welded ends of the reinforcement, then this is high quality. If the joint is barrel-shaped, then one of the welding process parameters was selected incorrectly. This connection is not good.

Several types of welding of reinforcing bars make it possible to use one of them as a standard for the quality of the connection. Each technology is applicable in certain conditions for certain building structures. Therefore, before starting welding work, it is necessary to make a choice.

Source: https://svarkalegko.com/tehonology/svarka-armatury.html