How to knit reinforcement for a slab

How to knit reinforcement for a monolithic slab - DIY foundation

The construction of private houses of various designs, using standard building materials (brick, concrete floor slabs), requires the construction of a solid monolithic foundation.

It will have to hold the entire structure without moving on the ground.

In order to do this, you can turn to professionals and pay a hefty sum, or you can make such a foundation yourself, and this publication will help with this.

Types of monolithic foundation

According to the general rules of construction, houses that will be made of traditional materials and also have several floors must have a solid foundation that will withstand all existing loads and will not move on the ground, despite all its features. In this case, the characteristics of the soil, the depth of freezing, the presence of floats and the general composition of the soil are taken into account.

Based on this, there are two types of monolithic foundation:

• tiled, created from special concrete slabs, which are also used as flooring;
• monolithic, created from concrete and metal reinforcement of the required diameter.

Both types of foundations have a similar feature, which is that they have slabs at their base, which are made of reinforced mesh (interconnected metal reinforcement of the required diameter) and concrete. This gives the foundation strength, since concrete protects the metal from corrosion and melting, and it, in turn, gives the concrete rigidity and does not allow it to crack under the influence of various loads.

Foundation slabs and floors can have the following varieties:

• corrugated surface on both sides or on one side;
• smooth surface.

This feature affects the scope of their application. The corrugated surface has good adhesion, so such slabs are ideal for foundations, as they adhere well to the ground. Smooth slabs are most suitable for various floors inside the house, and are not recommended for use in the ground.

It's no secret that the use of ready-made reinforced concrete slabs increases the cost of construction several times, since you need to pay for the finished product. And if you do it yourself, you can save some money. Therefore, we will talk about making a foundation with your own hands.

What materials will be needed to create a monolithic foundation?

Tying the reinforcement of a monolithic slab

If you create a monolithic foundation with your own hands, it will consist of two main components: iron and concrete. If everything is clear with metal, the following materials will be used:

• fittings, preferably with a diameter of 10 millimeters;
• metal rod with a diameter of 6 - 10 millimeters;
• knitting steel wire with a diameter of 1.2 millimeters.

It is immediately necessary to make a reservation that the wire will be used to tie the reinforcement and rods together to create a frame. It is better not to use welding, since in the places where it is used, the metal loses its properties and quickly collapses under the influence of water, which will remain in the concrete solution for some time. When asked which wire is best to choose, you can definitely say - only steel.

Now you can move on to the next element, concrete. It will be made from the following materials:

• sand (river or quarry);
• cement, preferably grade M 300 or 400;
• crushed stone of the middle fraction to give the foundation a relief surface.

Having figured out what is needed to create a good monolithic foundation, you can move on to other work.

Preparing to create a monolithic foundation

Creating a metal frame from reinforcement

This process can be divided into two stages.

1. This is digging a pit. This needs to be given close attention. First of all, you need to correctly calculate its perimeter. In order for everything to be done according to the standard, you need to have an idea of ​​the size of the entire house and the total weight of the structure. The dimensions can be found from the finished drawing, and the weight can be calculated using a construction reference book. Its depth will depend on the general data. The characteristics of the soil should also be taken into account. Freezing depth, presence of heaving and hard soil layers.
2. This is the creation of a metal frame from reinforcement of the required diameter, directly in the pit, or next to it. This will be discussed below.

How to correctly calculate the amount of reinforcement, wire and steel rods

Before you begin to correctly calculate the amount of reinforcement, its diameter, and other related materials, you need to have an idea of ​​the mesh and the correct frame.

The metal frame (mesh) that goes under the monolithic base has certain requirements, which are as follows:

• it must be double-sided, that is, consist of a lower and an upper layer, which should be located at a distance of no more than 2-5 centimeters from the edges of the sides of the concrete base;
• its edges should also be at a distance of 5 centimeters from the concrete monolithic slab.

Now you can proceed to calculating the required amount of reinforcement that needs to be tied.

As a basis, you can take the dimensions of the house as 8 x 8 meters. The reinforcing mesh should have a pitch of 200 millimeters. In this case, the correct calculation will occur according to the following formula:

• first you need to determine how much reinforcement will be needed for laying - 8 meters (perimeter side)/0.2 meters + 1 reinforcing rod = 41 pieces, and to obtain a mesh, such rods must be laid perpendicular to each other;
• the next calculation is the total quantity, that is, 41 pieces x 2 and you get 82 pieces of metal fittings.

This calculation allows you to calculate the amount of reinforcing material on one side, and, as you know, there are two of them, so 82 will need to be multiplied by the number 2 and you get 164 pieces of reinforcing pins. Now you can calculate the total number of reinforcing pins required.

It may be recalled that its diameter is 10 millimeters and the standard length is 6 meters. Thus, if 164 is multiplied by 6, it turns out that for a house with a perimeter of 8 x 8 meters you will need 984 linear meters of reinforcement with a diameter of 10 millimeters.

Here you can immediately estimate the total cost.

It is important to know that for a monolithic floor there will also be similar miscalculations.

Now you can proceed to calculating the number of rods. As mentioned above, having a diameter of 6-10 millimeters. We can immediately remind you that they are also suitable for monolithic ceilings inside a building.

The connection points between the two sides, where the rods and reinforcement will be connected, will be in the amount of 1681 pieces (41x41), it follows that a metal rod with a diameter of 10 millimeters will need 0.1 millimeter x 1681 = 168.1 meters. The total quantity of this element is: 984+168.1=1152.1 meters. That is, you can calculate the cost of the rod that will be needed for the layout.

It should be noted right away that the calculation includes a rod with a diameter of 10 millimeters.

Well, now you can take up the wire that will be used for knitting. Its calculation will be based on the following considerations. There will be 3362 knitting points on both sides of the mesh. This calculation is taken from the fact that there are 1681 knitting points on one side, and 3362 on both sides (1681+1681). As stated above, the wire for knitting should be steel.

To make the binding strong, it is better to bend the wire in half and then tie it.

This method can also be used for the manufacture of monolithic floors. They are no different from the foundation, but in the production of floor slabs, it is better to use small fractions of crushed stone, or even cement-sand mortar, so that the surface is smooth.

In order to create a monolithic reinforced concrete foundation for a house, you must first calculate its area and height, and then start determining the amount of material that will be used to make it. It's simple.

I purchased reinforcement D-14 millimeters for a slab foundation 8400*9450 (solid without ribs), I want to make a grid with a cell of 200 by 200 millimeters. How to correctly calculate the amount of reinforcement consumption and with what step to knit the reinforcement for a monolithic slab and how to lay out the reinforcement rods, including at the corners? And what is better to boil or knit with weave?

Source: https://postroifundament.ru/kak-vyazat-armaturu-dlya-monolitnoy-plityi.html

How to knit reinforcement for a monolithic slab?

There are two types of monolithic foundation:

• slab, created from special concrete slabs, which are also used as floors;
• monolithic, created from concrete and metal reinforcement of the required diameter.

Both types of foundations have a similar feature, which is that they have slabs at their base, which are made of reinforced mesh (interconnected metal reinforcement of the required diameter) and concrete.

This gives the foundation strength, since concrete protects the metal from corrosion, and it, in turn, gives the concrete rigidity and prevents it from cracking under the influence of various loads.

Foundation and floor slabs may have:

• corrugated surface on both sides or one;
• smooth surface.

This feature affects the scope of their application. The corrugated surface has good adhesion, and therefore such slabs are ideal for foundations, as they adhere well to the ground. Smooth slabs are most suitable for various floors inside the house and they are not recommended for use in the ground.

It's no secret that the use of ready-made reinforced concrete slabs increases the cost of construction several times, since you have to pay for a finished product. And if you do it yourself, you can save some money. Therefore, we will talk specifically about making a foundation with your own hands.

Secrets of knitting reinforcement for slab foundations

During operation, compressive and tensile forces are observed in a monolithic foundation slab. If concrete easily copes with the former on its own, then to compensate for the stretching it is necessary to use reinforcement.

This structural material increases the tensile strength of the slab base by 10 times.

Moreover, the rods must be knitted correctly, in accordance with the standards SP 52-101, according to the reinforcement scheme, the mesh must be laid in two layers with a minimum vertical distance of 10 cm, a protective layer of 3 cm.

Rules for reinforcing a slab foundation

The basic requirements for a monolithic slab are given in 52-101-2003. They contain recommendations on the location and knitting of reinforcing mesh, and what supports to use to provide a lower protective layer. The use of rods with flaking rust is not allowed.

The periodic cross-section rods provide high adhesion, and the binding wire is more reliable than plastic clamps. However, reinforcement should begin in stages: choosing a rational scheme, calculating the cross-section of the rods, fixing the frames in space using special elements.

Reinforcement schemes

The recommendations of SP 63.13330 for reinforced concrete structures have a special section on the manufacture of main load-bearing structures (10.4). In particular, the following requirements are specified for a slab foundation:

• the reinforcement is laid in two directions (mesh with a maximum cell size of 30 x 30 cm), connected by wire knitting or welding;
• the meshes are placed as close as possible to the top and bottom edges, taking into account a protective layer of 3 cm;
• Using U-shaped clamps, the mesh rods are tied together at the ends;
• in places where monolithic walls and columns are installed, vertical rods are released or anchored with hooks to strengthen the slab;
• under load-bearing walls, the cell pitch decreases compared to the rest of the slab;
• It is allowed to discharge the mesh cell in the central part to the minimum permissible percentage of reinforcement (0.3%).

The grids can be positioned correctly taking into account the lateral protective layers (minimum 4 cm between the rod and the formwork), the location of the communication input nodes (relevant for non-buried slabs).

In practice, for low-rise cottages the following scheme is used:

• mesh of 6 mm wire in the top layer;
• similar mesh in the bottom layer;
• reinforcement of USHP ribs or a smooth slab (thickness 30 cm or more) with frames around the perimeter of 10 - 14 mm periodic cross-section rods.

This is due to the absence of heaving forces when using a warm blind area, ring drainage around the foundation, replacing soil with non-metallic materials to a depth of 40 cm. The recommended cell size in the discharged part is no more than 1.5 of the slab thickness, under walls 10 x 10 - 20 x 20 cm In the absence of a footing, the lower protective layer increases to 5 - 7 cm.

Openings

In non-buried slabs it is impossible to do without openings in the monolithic structure for the entry of utility systems. This issue is very poorly described in the specialized literature. An individual developer should refer to the design guidelines for reinforced concrete buildings:

• cutting holes in welded mesh with bending the rods upward;
• edging of openings larger than 30 cm with rods 10 - 14 mm diagonally located to the mesh cells;
• There is no need to reinforce the perimeter of holes smaller than 15 cm.

In deep slabs there are no communication entry nodes by default. To increase the maintainability of engineering systems, sewerage and water supply are run through the basement walls.

Plate/tape interface

It is possible to correctly install reinforcement bars in the formwork of a buried slab foundation with a basement, taking into account the following conditions:

• walls on a recessed slab are prohibited from being placed close to its edges; the minimum perimeter offset is equal to the thickness of the foundation strip (from 10 to 40 cm);
• The anchoring scheme for the interface between the tape and the monolithic basement wall has several options.

Reinforcement outlets in the slab under the walls.

For example, a U-shaped clamp can be extended upward from the slab, the distance between the rods of which corresponds to the size of the tape frame, in order to subsequently connect these two structures. In addition, you can tie rods bent at right angles to the lower and upper mesh of the slab and extend them 40 - 60 cm outwards in the same way as the previous option.

If the project does not have a rigid connection between the tape and the wall with a deep slab, in these places the mesh is reinforced with U-shaped clamps to avoid pushing through.

What reinforcement is needed for a slab foundation

Any rod used in the foundation frame must comply with the requirements of GOST 5781 of 1982. However, reinforcement, like most structural materials, has a classification:

• AIII – corresponds to the A400 marking, has a variable cross-section, popularly called “corrugated”;
• AII – corresponds to the current class A300, the cross-section is periodic, discharged;
• AI – new A240 marking, smooth profile.

For the foundation, reinforcement A400 (AIII) is used, it has a crescent-shaped profile.

Rods of class A500C (for welded mesh, frames) or A500 are more expensive and are rarely used by individual builders. They are made from alloy steels, in contrast to conventional reinforcement of the first three classes, for which 32G2Rps, 25G2S or 35GS steels are used.

We recommend: What reinforcement is needed for the foundation.

Due to the complexity of calculations and the small dimensions of buildings in low-rise construction, a simplified scheme is recommended. Two grids at a distance of 10 cm vertically with at least identical cells. If the developer wants to save on pouring the slab, the calculation should be ordered from specialists who will calculate the minimum required reinforcement, use thin reinforcement in the center of the foundation, strengthen the perimeter, and the places where the internal walls pass.

If the foundation dimensions are more than 3 m on any side of the slab, it is recommended to use rods of at least 12 mm. To determine the minimum possible cross-section, the following method is used:

• calculation of the slab cross-section - length multiplied by thickness (for example, 6 m x 0.3 m);
• calculation of the minimum allowable cross-sectional area of ​​the rod - the previous figure is divided by the minimum percentage of reinforcement (0.3% for concrete B20, 0.15% for grade B22.5, 0.1% for grade B15), for this example 1.8 m²/0 .15 = 27 cm²;
• calculation of the reinforcement area in each row - the result obtained is divided in half (in the example 27/2 = 13.5 cm²);
• determination of the minimum permissible cross-section of a rod depending on the mesh pitch (13.5 cm² / 31 rods every 20 cm for a slab 6 m long = 0.42 cm²;

GOST 5781 contains a table of assortments with reinforcement sections of different diameters. For example, for rod diameters 14 mm, 12 mm, 10 mm, this value will be 1.54 cm², 1.13 cm², 0.785 cm², respectively. Thus, even 10 mm reinforcement provides twice the reinforcement percentage compared to the minimum. Mating is done in the building spot after laying out in rows.

Template for laying reinforcement.

Then it is necessary to correctly calculate the total number of rolled metal products of each diameter. The rods are sold in 11.7 m lengths, the overlap for longitudinal anchoring is 40 - 60 cm. The length of the workpiece for each U-shaped clamp is equal to 5 dimensions of the slab thickness, their number coincides with the total number of longitudinal and transverse rods in one mesh. You can convert the length into kilograms using tables from the same GOST, but each construction market has similar conversion tables.

The upper mesh is laid on supports; the most popular in private construction are:

• spider - a U-shaped clamp with legs curved in opposite directions;
• the supporting frame is a lattice curved at a right angle.

The length of each of them is calculated individually, taking into account 2 pieces/m².

The spider is made of reinforcement with a diameter of 8 mm; such elements must be made in advance for laying the upper mesh.

Laying reinforcement in a slab foundation

A typical TTK map for installing reinforcement in the formwork of a foundation slab provides for the following sequence of actions:

• control of formwork - linear dimensions, compliance with the axes of the walls;
• the first row of the lower mesh - polymer clamps for the lower protective layer are placed on the concrete base, longitudinal rods are laid out in their nests (increased in length with an overlap of 40 cm if necessary);
• second row - ladders are laid on the rods, shifted as needed, transverse rods are laid out sequentially with the design grid spacing;
• knitting - at the intersection points, the reinforcement is tied (less often welded);
• stands - have several names (spider, frog, table, supporting frame), designs, tied to the lower grid in a checkerboard pattern;
• upper grid - made in a similar way or large format cards tied in the building spot are placed;
• knitting U-shaped clamps along the ends of the slab;
• under load-bearing walls, the grid spacing is reduced by 1.5-2 times.

Longitudinal overlap of at least 50 reinforcement diameters.

Depending on the design of the foundation slab (smooth, with a strip, side walls), at the last stage vertical rods are installed to connect with the structures that will be concreted on its surface. These are L-shaped or U-shaped clamps with design dimensions. When bending rods yourself, it is prohibited to use metal heating to avoid changing the structure. All elements of the slab foundation must be bent using jigs, clips or manual pipe benders.

The slab is reinforced at the ends with U-shaped clamps.

To provide a lateral protective layer, plastic supports of various shapes can be used. This is necessary to prevent accidental shifting of the frame while laying concrete and workers walking along the ladders.

Knitting of reinforcement is done in several ways:

• hand hook - standard twist;
• mechanized hook – has a spiral handle, doubles the knitting productivity;
• a gun for tying reinforcement - is expensive, more often used by professional teams on large volumes.

A special plastic cup provides a protective layer.

Experts often soak the reinforcement to increase adhesion to concrete. The SP standards only prohibit flaking rust; there is no information about fresh corrosion. For example, in ACI-318 this point is specifically highlighted; rusty reinforcement is allowed inside concrete.

This guide covers the key points of reinforcing slab foundations. This will allow the individual developer to implement the project independently to reduce the construction budget.

Source: https://GidFundament.ru/plitnyj/kak-pravilno-vyazat-armaturu-dlya-monolitnoj-plity.html

Reinforcement of a monolithic slab: calculation and tying of reinforcement

Reinforcing a monolithic slab is a complex and responsible task. The structural element absorbs serious bending loads that concrete cannot cope with. For this reason, when pouring, reinforcement cages are installed, which strengthen the slab and prevent it from collapsing under load.

How to properly reinforce a structure? When performing a task, you need to follow several rules. When building a private house, they usually do not develop a detailed detailed design and do not make complex calculations. Due to the small loads, I believe that it is enough to comply with the minimum requirements that are presented in the regulatory documents. Also, experienced builders can lay reinforcement following the example of already made objects.

The slab in a building can be of two types:

In general, the reinforcement of the floor slab and the foundation slab does not have critical differences. But it is important to know that in the first case, rods of larger diameter will be required. This is due to the fact that under the foundation element there is an elastic foundation - the earth, which takes on part of the load. But the reinforcement scheme for the floor slab does not require additional reinforcement.

Foundation slab reinforcement

In this case, the reinforcement in the foundation is placed unevenly. It is necessary to strengthen the structure in places of greatest compression. If the thickness of the element does not exceed 150 mm, then the reinforcement for a monolithic foundation slab is performed with one mesh. This happens when building small structures. Thin slabs are also used under the porch.

For a residential building, the foundation thickness is usually 200-300 mm. The exact value depends on the characteristics of the soil and the mass of the building. In this case, the reinforcing mesh is laid in two layers one above the other. When installing frames, it is necessary to maintain a protective layer of concrete. It helps prevent metal corrosion. When constructing foundations, the size of the protective layer is taken to be 40 mm.

Reinforcement diameter

Before knitting reinforcement for the foundation, you will need to select its cross-section. The working rods in the slab are arranged perpendicularly in both directions. Vertical clamps are used to connect the top and bottom rows. The total cross-section of all rods in one direction must be at least 0.3% of the cross-sectional area of ​​the slab in the same direction.

Reinforcement example

If the side of the foundation does not exceed 3 m, then the minimum permissible diameter of the working rods is set to 10 mm. In all other cases it is 12 mm. The maximum permissible cross-section is 40 mm. In practice, rods from 12 to 16 mm are most often used.

Before purchasing materials, it is recommended to calculate the mass of the required reinforcement for each diameter. Approximately 5% is added to the resulting value for unaccounted expenses.

Laying metal along the main width

Reinforcement schemes for a monolithic foundation slab along the main width assume constant cell dimensions. The pitch of the rods is assumed to be the same regardless of their location in the slab and direction. Usually it is in the range of 200-400 mm.

The heavier the building, the more often the monolithic slab is reinforced. For a brick house, it is recommended to set a distance of 200 mm; for a wooden or frame house, you can take a larger step value.

It is important to remember that the distance between parallel rods cannot exceed the thickness of the foundation by more than one and a half times.

Source: https://DomZastroika.ru/foundation/vypolnenie-pravilnogo-armirovaniya-monolitnoj-zhb-plity.html

How to properly knit reinforcement for a monolithic slab?

Monolithic slabs, having the necessary strength, have positively proven themselves as a reliable foundation for various buildings. Manufacturing technology allows the use of fittings of different brands.

The operational characteristics of the foundation depend on the thickness of the slab base and the reliability of the load-bearing frame. The reinforcing mesh for the slab is a critical design for which a steel rod with a diameter of 10-14 mm and annealed wire are used.

To ensure the durability of the base, it is important to understand how to properly knit the reinforcing mesh.

There is a fundamental difference between concrete and reinforced concrete slabs used in the construction industry. The latter are able to withstand significant loads by strengthening the concrete mass with the help of a reinforcement grid.

The slab foundation is an important element of the building, consisting of the following components:

• sand-crushed stone cushion damping soil reaction;
• branded concrete made according to a standard recipe;
• power grid, for the manufacture of which you can take reinforcing bars.

The reliability and durability of the foundation is determined by the quality of the slab, the upper part of which has to bear the weight of the structure, and the lower part has to compensate for the reaction of the soil.

For a monolithic slab, tying reinforcement is much simpler than for a strip foundation

A power grid made of steel reinforcement located inside a concrete mass performs a number of serious tasks:

• provides a margin of safety for the foundation;
• prevents destruction of the slab and the formation of cracks;
• absorbs compressive loads and bending moments.

A solid slab is a floating foundation that ensures the integrity of the structure during soil movements. The design ensures the stability of buildings on problematic soils, provided that the reinforcement grid elements are correctly knitted and high-quality concrete is used. When performing knitting work, one should be guided by the requirements of the state standard, as well as building codes and regulations governing the specifics of knitting.

Let us dwell in more detail on the requirements for the reinforcement grid and the nuances of knitting:

• for the manufacture of gratings, ribbed rods are used, which provide increased adhesion of the elements;
• form two tiers of power grids connected to each other by vertical rods with a concrete thickness of 15 cm or more;
• perform single-layer reinforcement with a grid with square cells ranging in size from 20x20 cm to 40x40 cm with a slab thickness of less than 15 cm;
• For rigid connection of reinforcement frame elements, annealed wire intended for knitting reinforcement is used.

When answering the question about the features of correct tying of reinforcing elements intended to strengthen a monolithic foundation, experts recommend using the following tying methods:

Knitting reinforcement begins with the purchase of metal, the amount of which must first be calculated with the minimum possible margin

• manual, providing reliable fixation at minimal cost. To connect the rods, it is necessary to make significant efforts when performing work with wire cutters or using a crochet hook;
• semi-automatic, allowing you to perform an increased volume of work through the use of a special reversing device. The rotation of the hook occurs as a result of the reciprocating movement of the body;
• automatic, designed for accelerated tying of reinforcement at large industrial facilities. The use of a special knitting gun or a screwdriver with an attachment ensures increased work efficiency.

The choice of knitting tool is carried out individually depending on the volume of work performed:

• for a one-time assembly of a reinforcement grid, a crochet hook or reversible device is suitable;
• When producing reinforcement cages on an industrial scale, an automatic gun should be used.

When performing work, a number of rules must be observed:

• to ensure a strong connection of the rods, correctly use a binding wire with a cross-sectional diameter of 0.8-1.4 mm;
• the connection of individual rods should be made with wire in the areas of their mutual intersection;
• when twisting the wire, force should be applied to ensure rigid fixation of the reinforcing bars

The technology for manufacturing gratings using the bonding method is superior to the method of welding reinforcement, which causes local overheating and significantly reduces strength.

The reinforcement itself is laid and knitted along the footing, which is then connected into a common frame

Novice developers do not always have the correct idea of ​​what kind of reinforcement is needed for a monolithic slab. When planning to assemble a reinforcement grid, you should familiarize yourself with the requirements of the state standard.

He classifies reinforcing bars as follows:

• rods marked A1, which in accordance with the previous classification were designated A240, are distinguished by a smooth surface;
• rods of class A2, corresponding to the former marking A300, have minor changes in the profile in the cross section;
• reinforcement with index A3 (“corrugated”), which was previously classified as A400, is distinguished by a profile of variable cross-section.

To ensure reliable fixation of the rods, reinforcement with corrugations should be used. The diameter of the reinforcing bars in the cross section is selected in the range from 1 to 1.4 cm in accordance with a previously developed sketch. The drawing of the reinforcing lattice and all necessary calculations should be entrusted to specialists who will take into account all the loads on the slab and provide for strengthening problem areas taking into account the percentage of reinforcement for specific brand of concrete.

For reinforcement, ribbed reinforcement with a diameter of 12-16 mm is used, which provides better adhesion

How to tie reinforcement for a monolithic slab in compliance with technology

Depending on the knitting method used, the sequence of actions for knitting frame elements changes. Let's consider the order of operations when performing manual knitting.

It provides the following actions:

1. Cutting wire blanks 0.15-0.2 m long.
2. Bending the tie wire in the center of the workpiece.
3. Placement diagonally in the rod joining unit.
4. Thread the crochet hook into the formed loop.
5. Pulling the wire ends into a loop using a hook.
6. Rotate the working tool in the loop to the required tightening force.

When performing work manually, it is important to control the tightening force. Increased effort when working with the tool leads to wire breakage.

Performing knitting operations using a reversible device requires a different algorithm:

1. Inserting the hook of the device into the loop.
2. Axial movement of the handle toward you.
3. Return the handle to its initial position.
4. Repeated rotation of the hook by pulling the handle.

When using an automatic tying gun, there is no need to cut wire blanks. The wire located on the working drum is fed automatically, which allows you to perform knitting work at an accelerated pace.

Knitting is considered the best method of connecting rods

Preparation for tying rods for a monolithic slab foundation

When preparing to knit reinforcing bars with your own hands, you should perform the following preparatory measures:

1. Calculate the magnitude of the forces that will act on the foundation. This is a difficult task, the solution of which is advisable to entrust to professionals.
2. Select the brand of reinforcing wire and determine the cross-sectional size of the rods. The maximum permissible angle of their bending depends on the class and diameter of the rods.
3. Determine the amount of wire to assemble the frame, and also calculate the need for reinforcement. When determining the need, you should be guided by the mating pattern.
4. Decide on the method of performing knitting operations. You should prepare the appropriate tool, as well as the wire for knitting, in a timely manner.

Before starting work, a drawing or working sketch of the reinforcement cage should be developed.

How to lay the reinforcing mesh for the slab

When laying reinforcement, it is important to ensure a constant distance from the reinforcement grid to the concrete surface, equal to 3-5 cm. This will prevent corrosive destruction of the reinforcement frame due to capillary ingress of moisture. To ensure a guaranteed thickness of the protective layer, special fixing elements made of plastic or metal stands are used.

At the intersection of the rods, the strapping is carried out

Procedure for laying reinforcement:

1. Check the dimensions of the formwork.
2. Place the lower grille elements on the clamps.
3. Lay transverse reinforcement.
4. Tie the lower level mesh lattice together.
5. Attach vertical rods to the bottom mesh.
6. Knit the top mesh in the same way as the bottom mesh.

If the length of the reinforcing bars is insufficient, join the bars with an overlap of 40 times the diameter of their cross-section. So for reinforcing bars with a diameter of 10 mm, the amount of overlap will be 40x10 mm = 400 mm.

When independently performing work on assembling a reinforcement grid, novice developers often have a question about how to knit reinforcement for a monolithic slab. The technology for assembling a reinforcement grid for a monolithic type foundation is simple.

The general procedure involves performing the following operations:

1. Determining the need for reinforcement.
2. Acquisition of material in the required quantity.
3. Cutting of reinforcement blanks.
4. Making stands.
5. Installation of longitudinal rods of the lower tier.
6. Fastening the cross bars to the bottom mesh.
7. Installation of reinforcement posts.
8. Attaching top-level elements to supports.

Bonding is necessary only at the time of pouring; inside the concrete structure after it hardens, it does not bear any load

When performing work, you should pay attention to a number of points:

• ensuring a minimum protective layer;
• placement of radius pads in corner areas;
• maintaining a constant step when laying reinforcement;
• connection of rods with an overlap of 0.4-0.65 m depending on their diameter;
• ensuring rigid fixation of the connected reinforcement.

Depending on the total number of areas where bars are joined, the method of performing the work is determined.

How to knit reinforcement - process features and tools

Regardless of the knitting method and the tool used, the process of fixing the rods involves:

1. Coverage of the rod connection area with tying wire.
2. Forming a loop around steel bars.
3. Tightening the wire assembly using a hand or special tool.

The hand tightening tool options are as follows:

• round nose pliers;
• wire cutters;
• homemade hook;
• manual reversible device;
• purchased hook for tying reinforcement.

Semi-automatic and automatic tools will allow you to speed up the work:

• industrial gun for fixing rods;
• electric drill with a special attachment.

When performing work with any type of tool, it is important to control the tightening force.

When carrying out concreting work on a slab, you should pay attention to a number of factors:

1. use of high-quality concrete;
2. continuous supply of working solution;
3. removal of air inclusions;
4. compaction of the concrete mass.

For the normal course of the hydration process, constant humidity must be maintained in the concrete. To do this, the surface is covered with polyethylene and periodically moistened with water. After hardening, the formwork is dismantled.

Let's sum it up

The strength characteristics of the foundation slab depend on the quality of assembly of the reinforcement frame and proper concreting. When doing the work yourself, you should figure out how to tie the reinforcement for a monolithic slab. It is important to use high-quality materials and decide on the knitting method. Consulting professionals will help you avoid mistakes.

Source: https://pobetony.expert/armirovanie/vyazka-armatury-monolitnoj-plity

How to knit reinforcement for a monolithic slab correctly

Any concrete structure, especially one used as part of a foundation, needs an internal reinforcement cage.

The reinforcement inside a monolithic structure turns ordinary concrete into reinforced concrete. The advantages of reinforced concrete over conventional concrete are obvious. It is much stronger, more stable, less likely to crack, and works well in bending. And these are just its main advantages, well-known and hotly discussed. But there are also more subtle moments.

Knitting reinforcement with a gun

Be that as it may, when pouring the same monolithic reinforced concrete foundation slab, the frame itself, which we intend to install in the foundation formwork in the future, must be correctly assembled and fastened. To assemble it, it is necessary to knit the reinforcement together. How, as a rule, to knit metal or fiberglass reinforcement for the foundation will be discussed in this article.

Purpose and features

What is ordinary reinforcement knitting and why is it needed at all? As you already know, any reinforced concrete structure consists of concrete itself and a metal reinforcement frame.

Inside a slab, strip or column, the technology always involves the installation of a kind of load-bearing skeleton, which gives the future structure the necessary characteristics.

But how to make an armored belt or reinforcement cage for aerated concrete? Very simple. It is necessary to tie together many reinforcing bars. They communicate according to a certain system. The work uses a special scheme for applying rods. The scheme specifies what brand of fittings should be used, in what quantity and where it should be placed.

Knitting reinforcement allows you to fasten individual rods into a strong, solid frame.

A properly connected frame is capable of completing the task and does not break under external pressure. Obviously, all work on installing the frame is done manually.

And this is where the problems begin. Knitting reinforcement is only possible by hand, but imagine that you need to knit a frame for a foundation slab with dimensions of 10x10 meters.

The frame for this slab will consist of hundreds of large, heavy reinforcing bars, tied together at each node by countless turns of wire. But slabs with similar dimensions are the foundation for a small one-story building, but nothing more.

But what if you need to work with the structure of a buried strip foundation? The strip foundation strip can only be up to 2 meters in height, and the total length of the strip foundation, if we consider the same one-story house with dimensions of 10x10 meters, will be equal to hundreds of meters.

As you can see, the amount of work here is simply colossal. It is not surprising that builders are looking for ways to simplify and speed up the work process in every possible way, without compromising the quality of the final result.

Knitting equipment

Knitting reinforcement for the foundation is carried out using special consumables.

For work use:

• wire;
• reinforcement clamps;
• reinforcing couplings.

Wire is the most popular option at all times. The wire used is hardened, it is not afraid of temperature changes, it bends easily, but does not break.

Hand knitting of reinforcement with wire

This is a very important point, because tying reinforcement involves twisting the wire dozens of times. The thickness of the knitting reinforcing wire is approximately one millimeter. If the wire is thinner, then you can work with it only in extreme cases.

You cannot tie the wire in half. It's not practical. The task and property of the wire is flexibility. Double knitting does not give it the necessary flexibility, and therefore, the quality of fixation.

If we knit plastic reinforcement, then by reducing its weight, we can use thinner wire, but only in limited quantities.

The use of clamps is not very common. Reinforcing clamps are the same wire, but slightly modified. It is, so to speak, adapted for direct tying, giving the builder the opportunity to fasten two rods together faster.

However, the time savings are not so significant, but the difference in price is noticeable. An experienced monolithicist or frame knitter will be able to handle the wire in the same amount of time. Therefore, knitting clamps are used much less frequently.

Reinforcing couplings are even less common. Their scope of application is the construction of strip or columnar foundations for industrial buildings. In domestic construction, the use of couplings is impractical due to their extremely strong connection and, as a consequence, high price.

Another thing is industrial construction, where the main task is strength, and money is a secondary resource.

Work tool

As we have already noted, the reinforcement needs to be tied in huge quantities. The frame for even a small strip foundation will pull hundreds and even thousands of reinforcement units. What can we say about the designs of large strip foundations, slab foundations, etc.

It is obvious that builders have been looking, are looking and will continue to look for better ways to speed up work. And the easiest way is to use the right tool .

Tools for tying reinforcement vary. Starting from homemade to professional devices, expensive and extremely effective.

In work they use:

1. Hook for tying reinforcement (manual or mechanical).
2. Gun for tying reinforcement.

A hook for tying reinforcement is a favorite tool of any professional. The knitting of the first reinforcement cages began with it.

This tool is extremely simple and extremely effective. It can be simple, that is, manual, or complex.

Hook for tying reinforcement, regular

A hand tool in the form of a hook is a simple device consisting of a handle and a curved metal rod. The design of its device is very similar to a screwdriver, only its shaft is not straight, but curved in one or several places.

Advanced hooks, that is, mechanical ones, are a more productive tool. They work on special springs. Use a hook to hook the wire, then pull the handle. The coil spring inside the handle is tensioned, and when released, it collapses back, making several turns.

The number of turns is regulated by the number of pulls on the hook handle, as well as their strength and speed.

Using a pistol

A gun for tying reinforcement is a tool of a different order. This is a completely autonomous electrical device designed for assembling frames on an industrial scale.

Using it, tying reinforcement is easy and simple. Even a child can cope with such work if he has a pistol. Its operation scheme consists of pulling a pre-installed wire around the installation site of the device.

The gun is simply applied to the connection point and the button is pressed. The mechanism itself tightens the rods with a coil of loaded wire.

Guns can be loaded with different wires, including plastic ones. This is why they are most often used on advanced construction sites, where the bulk of the reinforcement cages consists of plastic or polyurethane reinforcement.

The only downside of the pistol is its price. Professional tools have always been expensive, and a mounting gun is no exception. The cost of a high-quality model from well-known manufacturers starts from $300-400.

Knitting technology

The technology of tying reinforcement is very simple and is described in a few sentences. For example, let’s take the knitting of a frame for a strip foundation structure.

For a strip foundation, it is important to create a high multi-level structure from reinforcement bars.

First we fold the first level and tie it together with wire. Tightening is carried out at each structural node. Any place where rebar intersects with other rebar, wire must be used.

Tightening is easy. We tie a knot in one or two coils of wire, then we hook the two edges of the wire and wrap it around its axis several times, forming a kind of spiral. The spiral is bent around the nearest reinforcement and the job is done.

Then we apply the next level and tighten it again. And we continue like this until we complete the structure.

Source: https://betfundament.com/kak-pravilno-vyazat-armaturu-dlya-monolitnoy-plity/

Secrets of knitting reinforcement for slab foundations - Piles Mania

The strength of the foundation depends on many factors, but a huge role in the reliability and durability of the foundation is played by: well-chosen reinforcement, the quality of the concrete and the correct knitting of the reinforcing frame.

Even the most powerful reinforcement will not cope with the loads if the knitting is carried out with violations of the technological process.

Preparing reinforcement and choosing a tying method

First of all, the entire structure must be fastened at least 50% of all crosses, but the more connections, the more reliable the structure as a whole (see Calculation of reinforcement for a strip foundation).

Before you begin assembling the frame, you should prepare the reinforcement, cut it to size, and clean it of rust, oil stains and dirt.

Let us remind you what reinforcement to use for the foundation:

• For longitudinal reinforcement of a strip foundation, ribbed reinforcement is used, transverse reinforcement is performed with smooth reinforcement.
• For a slab foundation, only reinforcement with a periodic cross-section is required.
• For columnar and pile foundations, vertical rods must be ribbed.

For more details, see here: What reinforcement to use for a strip foundation

Ribs - notches increase the adhesion area of ​​the reinforcement to the concrete.

After the preparatory work is completed, you need to choose the method of tying the reinforcement:

• The rods can be connected using special plastic clamps; this method assumes that the frame will not be walked on; concrete should be poured with special precautions so as not to damage the geometry of the frame.
• For fastening composite reinforcement, special connecting elements of various configurations are provided, which are easily attached and firmly hold all components of the structure.
• Very often, welding is used to make a reinforcing frame. If the reinforcement has a diameter of up to 24 mm, then spot welding of the joints is suitable; rods with a larger diameter are secured by arc welding (see Diameter of reinforcement for strip foundations). This method significantly speeds up the assembly process, but resistance welding significantly reduces the strength of the hardened rods. The joints become vulnerable to loads.
• Connecting reinforcement using tying wire is the most labor-intensive, but also the most reliable method of fastening a structure. For this, a special wire with a diameter of 0.8 - 1.2 mm is used, which is sold in rolls. It should be cut into pieces of 20 - 30 cm, and for twisting, prepare a special hook or pliers. The wire is folded in 2 layers, the joints are wrapped, then the hook is inserted into the loop, and the ends of the wire are twisted together several turns. This process can be greatly facilitated by using a special gun.

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DIY knitting technique

After the pit, trench or well has been dug and all preparatory work has been completed:

• Drainage.
• Summing up communications.
• Waterproofing.
• Sand and crushed stone cushion.

You can begin assembling the reinforcing frame.

If everything is very clear with the reinforcement of pillars, first a frame is made, and then it is lowered into a prepared well or hole, then a strip or slab foundation is made in several stages and requires some knowledge. As a rule, in private construction, the installation of a metal structure is carried out before or simultaneously with the installation of formwork. The reinforcement is tied directly in the trench.

1. Support reinforcement is driven into the ground at the corners and along the perimeter, and the verticality of the rods is checked using plumb lines.
2. Bricks, special plastic stands or rubble stones are laid at the bottom along the entire length; this measure allows for the necessary clearance for the concrete pad. The bricks should be laid at such a distance from each other to prevent sagging of the reinforcement. White sand-lime bricks cannot be used. Instead, sometimes metal pins or beams are driven in around the perimeter, but the aggressive soil environment and corrosion destroy such supports over time, and this leads to a weakening of the foundation as a whole. In addition, if the soil is weak, the pins become loose and make tying the reinforcement more difficult.
3. The reinforcement of the lower longitudinal layer is laid on the stone base. It is recommended to bend it at the corners onto the adjacent wall, at least 25 cm. The rods are attached to each other and to the supports. The horizontality of the layer must be checked.
4. Then, an upper longitudinal layer is placed on the supports, which is fixed with vertical and horizontal transverse reinforcement. The optimal width of the cells between the rods is 150-400 mm. Smooth reinforcement is bent for structural strength. It is recommended to check the levelness of the frame as often as possible.

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instructions

Foundation, how to knit reinforcement

The transverse reinforcement can not be cut into separate pieces, but bent into something like rectangles with rounded corners. To do this, smooth reinforcement is cut, the size is equal to the perimeter of the frame. Then a channel is taken and a piece equal to the sides of the cell is cut off.

Grooves are cut in the channel to secure the rod. Then a pipe is put on the rod, thus creating a homemade lever that helps bend the reinforcement.

This method allows you to produce a rectangle with relatively equal edges, which significantly increases the chances and makes it easier to create the correct frame geometry.

Tying reinforcement for the foundation frame is a labor-intensive process and requires repeated and careful checking of the vertical and horizontal lines, so it is recommended to clearly fine-tune the process before fixing the rod, removing rust from it, and, if necessary, straightening it with a sledgehammer. The wire should be twisted tightly, but not tightly, so as not to break.

The subsequent use of a submersible vibrator for compacting concrete imposes additional responsibility on the quality of the binding of the reinforcing frame; try to use only high-quality materials and fasten as many crosses as possible.

After the installation of the reinforcement frame is completed, it is necessary to remove soil and other contaminants from it, this will extend the life of not only the foundation, but also the entire structure.

Source: https://svaimania.ru/uteplenie/sekrety-vyazki-armatury-dlya-plitnogo-fundamenta.html

How to knit reinforcement for a foundation slab

The construction of private houses using standard building materials (brick, concrete floor slabs) requires the installation of a reliable monolithic foundation. To do this, you can turn to professionals, spending a significant amount of money, or you can make such a foundation yourself, which this publication will help you with.

Technology of knitting reinforcement of a monolithic slab

For a monolithic slab, tying reinforcement is much simpler than for a strip foundation. The meshes are created from rods on the construction site; to work you need an angle grinder with a metal disc, a tying device or a cordless tool.

Technology for manufacturing reinforcing mesh for a foundation slab

Knitting reinforcement begins with the purchase of metal, the amount of which must first be calculated with the minimum possible margin. For the reinforced belt of the slab, it is necessary to take into account the following factors:

• protective layer at the bottom - with a footing 4 cm, without a concrete screed 7 cm
• protective layer on top, at the ends - 4 cm
• joints when extending rods are spaced apart with a minimum offset of 60 – 90 cm for a diameter of 10 – 16 mm, respectively
• the overlap of rods in straight sections (splicing) is 40 – 65 cm for 10 – 16 mm corrugation, respectively
• Unlike strip foundations, there is no need to bend the reinforcement at the corners; the rods are butted end-to-end (the spacing is at least two diameters)

To create the lower protective layer, exclusively concrete or polymer pads are used. It is forbidden to lift the mesh with pieces of reinforcement, pipes, or lay crushed stone or brick.

Calculation of the amount of reinforcement

The reinforcement is knitted according to a standard pattern; calculating the number of rods is quite easy:

• standard length of reinforcing bars 6 m
• 0.4 – 0.6 m overlap in joints
• minus 8 cm for each rod for a protective layer of concrete
• cell 15 x 15 cm or 20 x 20 cm
• as the thickness of the slab increases, the cell decreases, the rods become thicker

It is more difficult to take into account the configuration of Z-shaped tables made of 6 - 8 mm reinforcement to support the upper chord. The upper U-shaped part usually measures 20 x 40 x 20 cm for a 30 cm slab. The support legs are about 40 cm on each side. One table requires 1.6 m of smooth reinforcement, their quantity is calculated depending on the project.

Thus, the number of rods is determined by the formula:

wall length/cell + 1, for example for a 7 m wall 7/0.2 + 1 = 36 pieces

Then it remains to take into account that there are two armored belts in the design, with overlaps when connecting. In principle, there can be no problems with converting lengths into kilograms - every construction market has a conversion table. You can also buy knitting wire there, knowing the number of joints and the length of the piece for each of them (30 cm - twice 15 cm).

The most popular wire is 1.2 - 1.4 mm for 8 - 12 mm rods, respectively. Thicker wire is more difficult to form into a knot; the twists stick out above the upper reinforced belt, reducing the protective layer of concrete. Thin wire rod is easier to work with, but it can break when the torque increases. The margin recommended by experts is 15%, both for reinforcing bars and wire. For smooth fittings from which the tables will be bent, a 10% margin is sufficient.

Bar cutting

It is more convenient to cut the reinforcement using a template. Separately, longitudinal pieces of two meshes and transverse rods of structures are cut. For large formwork dimensions, pieces are cut out for extension, taking into account a 60 cm overlap, and screwed with wire to the long elements of the slab.

The most economical is cutting with abrasive equipment. An angle grinder with a metal disc can easily cope with fittings of any diameter. In addition, this is the most affordable power tool for an individual builder. At the same stage, it is easiest to clean the fittings from possible rust. This will be much more difficult to do later.

Making stands

To support the upper mesh of reinforcement, stands - tables are needed. They are bent taking into account the thickness of the slab and reinforcement. For example, for a 40 cm monolithic structure, the calculation looks like:

• slab thickness – two protective layers – thickness of the upper and lower mesh rods (4 overlapping rods)
• 40 cm – (4 cm+4 cm) – (4 x 1 cm) = 28 cm

Then you need to make a table, calculate the bending radius or calculate it experimentally. First, the U-shaped structure is bent, then the legs are bent in opposite directions. The table acquires spatial rigidity and a large supporting surface.

Installation of the lower mesh

The best option for fixing reinforcement bars to each other is knitting with annealed wire. Depending on the budget and volume, work can be carried out using several tools:

• hook - comfortable handle, time-tested configuration of the working part
• knitting gun – fully automates the process, just bring it to the overlap of the rods and press start
• mechanical device - has spiral grooves, converts vertically applied force into mechanical rotation of the working body

To reinforce one large-format slab, individual developers can use a screwdriver with a regular hook, partially mechanizing the process, and avoiding the cost of purchasing a professional binding gun. In this case, the handle will have to be cut off so that the hook can be inserted into the quick-release chuck.

When working with a conventional mechanical hook, the wire is wound manually by the operator. The cordless gun does everything on its own; the purchase budget is 40 thousand rubles for the most budget models. Therefore, a mechanical tool is more often used, costing 500 - 700 rubles, or a regular hook, which is even cheaper.

The technology for knitting a mesh of reinforcing bars is as follows:

• layout of reinforcement along one wall every 15 - 20 cm depending on the cell size
• laying out the rods on top of them with a similar step
• knitting overlapping joints with special wire

A piece of 30 cm wire is bent in half, the resulting structure is additionally bent in half and placed under the joint where the rods intersect diagonally. The hook tip is inserted into the loop, the free side goes around the rod. By rotating (usually clockwise), the wire is tightened at the junction of the reinforcing bars, giving the spatial structure the necessary strength.

In the manual method, the tightening force is controlled by a wire tensioner. If a mechanical device is used, the torsional moment is more difficult to determine (usually a visual assessment). When using a screwdriver, you can set the required tightening force (21 - 9 positions in different models). The cordless rebar tying gun also has torque adjustments.

Installing the top chord

Before laying the upper chord of reinforcement, it is necessary to place tables on the lower grid. They are installed according to the following scheme:

• the support legs rest on two rows of rods
• the top shelf is parallel to the bars of the covering mesh or located diagonally
• the legs are connected with wire to two adjacent rows of rods
• the top shelf is fixed with wire in at least two places to the top mesh

In practice, the tables are tied to the bottom mesh, standing on concrete, polymer pads, with paws every two rows. They are joined to the top mesh after it is leveled in accordance with the protective layer. The reinforcement should not protrude from the formwork above the design level of the slab.

All metal elements must be cleaned of rust, otherwise corrosion of the reinforcement will continue inside the concrete. It “eats” approximately 0.01 mm per year, so in a few years the thickness of the armored belt will decrease significantly. The slab will no longer be able to properly absorb loads, which threatens not only cracks in the masonry walls, but also the collapse of the load-bearing frame.

The main mistake of an individual developer is the use of ready-made reinforcement mesh or pre-connected 6 m rods on a convenient site in the building area. When producing reinforcement cards industrially, manufacturers often use welding, which is dangerous due to the weakening of the metal near the welded joints and the occurrence of corrosion at the joints.

When making your own meshes 6 x 6 m (standard length of rolled metal), this size is often not enough for the slab. The grids are overlapped, but there is no spacing in adjacent rows; the slab in this area is weakened by default. The only correct way is to build up the rods locally with an overlap of at least 60 diameters in adjacent rows.

If the specified technologies for knitting reinforced belts for a monolithic foundation slab are followed, the maximum possible service life of a reinforced concrete structure can be achieved. Any violation will automatically lead to a decrease in quality, which is very dangerous for slab foundations that have zero repairability.

Source: http://fundamentdomov.ru/vyazka-armatury-monolitnoj-plity/