How to make reinforcement correctly - Metals and their processing

Reinforcement frame for the foundation - technological features of the work

An important structure of each object is the foundation, the arrangement of which is given close attention. Subject to certain rules for performing work, quality, long operational period, and reliability of the structure as a whole are guaranteed.

In each type of base, a reinforcement cage is installed for the foundation. A concrete base that does not have a metal frame does not have the required level of strength.

Concrete absorbs only compressive loads, while steel rods compensate for tensile and deformation forces, thereby ensuring the integrity of the foundation.

Reinforcement technology

Preliminary preparation is carried out, during which:

calculate the load effects of the object and the foundation base on the soil composition;
choose the most suitable fittings, taking into account calculation data and financial capabilities;
a construction site is being prepared, a foundation trench with a sand cushion at the bottom is being installed.

The reinforcement cage for a strip foundation is arranged as follows.

First of all, the formwork structure is exposed, the internal surfaces of which are covered with roofing felt material or parchment. Steel rods of the required length and cross-section of 1 cm are driven into the soil. Smooth reinforcement can be used. The installation step is forty to sixty centimeters.

A stand is placed along the bottom of the trench, on which rods are laid out horizontally in several rows, connecting them longitudinally with jumpers and tying them with wire.

When erecting a frame base, you must strictly maintain the permitted distances to the foundation surfaces. Make sure that the concrete solution covers the ends of the reinforcement with a margin to protect it from corrosion.

Reinforcement schemes

When building a house on your own, you don’t have to carry out complex calculations for limit states in order to determine the cross-section of the reinforcement and the overall need for material. It is permitted to use information from the Manual on the Design of Concrete Structures. Using the available data, the general cross-section of the longitudinal elements of the reinforced frame for the foundation is specified:

if the side of the tape does not exceed three meters, reinforcement 10 mm in diameter is taken in an amount of 0.1% of the cross-section of the base;
in the case when the length of one side is more than indicated above, then the rods are taken in the same quantity, but their diameter is 12 mm or more.

Reinforcement, the cross-section of which exceeds 4 cm, is not allowed for the construction of the frame.

The placement of longitudinal rods is shown in the table:

Conditions	Minimum installation step
Bottom frame in one or two rows	Not less than 2.5 cm, rod diameter – maximum
Top frame for one or two rows	Likewise, at least 3 cm
Bottom reinforcement with more than two rows	Likewise, at least 5 cm
When performing compaction with vibrators	All previous conditions are met, the step in some places is not less than 6 cm.

In cases where it is necessary to lay a lot of metal rods, they are allowed to be arranged in bundles, maintaining a distance taking into account the entire cross-section.

Horizontal transverse clamp

Such rods are assigned structurally and do not depend on the cross-section. The load effect of the object is taken into account. The minimum cross-section parameters of the transverse rod are 6 mm.

The rods are installed in increments equal to twenty diameters of the working rods. For example, if the cross-section of the longitudinal element is 1.4 cm, the horizontal rods are set at intervals of 28 cm. To simplify the task, this figure is rounded to 30 cm.

The length of the rods in the reinforcement frame for a strip foundation is determined by a similar parameter of the strip and the required concrete layer to create protection.

Vertical clamp

The size of the reinforcement in diameter is determined by the height of the foundation base. If it does not exceed 80 cm, then choose rods with a cross-section of 0.6 cm. In other cases, from 0.8 cm, subject to the condition that it will not be less than 0.25 of the diameter of the working rods.

If the construction of a large structure is planned, the rods in the frame should be laid with a certain margin and pitch similar to transverse reinforcement. The length of the steel rods is determined taking into account the height of the foundation, from which the thickness of the protective layers is subtracted.

Gusset

When performing rigid installation with an overlap and using a “claw,” the free ends of the rods, directed in one direction, are bent at ninety degrees and connected to perpendicularly located elements.

The bent “foot” should have an overlap length equal to thirty to fifty times the diameter of the rod. The clamps are installed in increments of 3/8 from the height parameter of the reinforced concrete base.

The reliability of the connection of the working reinforcement is achieved by L-shaped clamps applied to the rods with an overlap equal to fifty times the diameter of the longitudinal rod. The interval between the fastening clamps is 0.75 of the height of the foundation wall.

They use additional elements that look like the letter “P”. A pair of such clamps are installed at each corner, the length of which corresponds to fifty diameters of the longitudinal rod. At the overlap point of such a clamp, an additional frame of vertical and transverse rods is mounted.

Obtuse angle reinforcement

Performed with overlap. The outer rods are bent to the desired angle, and the inner ones are joined with an overlap, the length of which starts from fifty rod diameters. A vertical clamp is installed at the bend point of the outer element.

Joining walls

The frame rods are bent, and the length of the section should not be less than 50 sections. Each of the abutment rods is connected to the outer rod of the wall, located perpendicularly. The connection area differs in the installation step of the clamps at 0.375 from the height of the foundation strip.

If clamps in the shape of the letter “G” are used, then the rods are bent so that both sides correspond to the length of five dozen rod diameters. The first side is fixed with the reinforcement of the adjacent wall, the second is connected to the external working element of the tape, which fits perpendicularly. The interval between clamps is halved in relation to the total length of the tape.

When installing clamps “P”, the connection is made to the outer rod using a “claw”. An additional indicator of reliability is created by a rod curved in the letter P, its length corresponding to two dimensions of the width of the foundation base.

Selection of fittings

To construct a reliable frame for a foundation made of reinforcement, it is necessary to select the right material.

If you need to reinforce the base for a one- or two-story house, or build another light structure, metal reinforcement with a cross-section of 1.0 - 2.4 cm is suitable.

A material with a thicker cross-section will cost much more, and its strength indicator will still not be used. But tying the foundation frame with less thick reinforcement may not withstand the created load.

The right solution is to use special reinforcement bars with corrugation. They provide excellent adhesion to concrete and guarantee a high level of strength and reliability. An analogue with a smooth surface will cost you a little less, but is not suitable for use due to poor adhesion. An exception is considered to be transverse connections, since they are subject to less load.

If there is a homogeneous soil composition under the foundation, it is permissible to make a reinforced frame for a strip foundation from rods with a diameter of 1.0 - 1.4 cm. In case of heterogeneity of the soil, the load force on the foundation increases, and it is more correct to purchase rods with a diameter varying in within 1.6 – 2.4 cm.

Naturally, thicker metal rods are quite expensive. But if you make a frame for the foundation from reinforcement with your own hands, then, most likely, the volumes are not so large, and there will not be a large overpayment. But the finished base will be reliable and durable.

When making independent calculations and choosing metal fittings, there is a possibility of errors that can result in breakdowns in the future. It will be better if you order the preparation of the project and all calculations to specialists.

How to knit a frame correctly

So, how to properly make a reinforcement cage for a foundation?

The design drawings are studied in advance, since the operational life of the structure depends on the reliability of the foundation.

To avoid mistakes, it is recommended to follow certain rules while working:

minimum overlap - from five centimeters;
in corner areas, rods located perpendicularly are connected to each other. Blocks that are not connected to each other are prohibited from being used. An excellent option is corners prepared from bent reinforcement. This frame design is considered to be of higher quality. True, certain equipment will be required to bend rods whose cross-section exceeds fourteen millimeters;
if the connections are made with binding wire, they must differ in density. Using a special hook, the wire should be tightened until it stops, leaving no free spaces between the clamps and reinforcing bars. Be sure to check the clamp for mobility. If it is easy to move it by hand, it is necessary to perform an additional ligament;

the spacing between the reinforcing bars must correspond to the design drawings;
the reinforcement frame for a slab or other foundation in the formwork structure is installed evenly, the metal must be surrounded on all sides by a concrete solution that protects against corrosion;
The reinforcement is bent cold, without preheating, so as not to reduce the strength of the metal.

Nuances of performing work

We know how to knit a frame from reinforcement for a foundation. Now let's study some of the features that will have to be encountered in performing this type of work. Having certain secrets, you can easily cope with the task and even minimize the consumption of building materials.

Here are a few basic rules:

it is necessary to reinforce the entire area of the foundation;
it is forbidden to expose the reinforcing edges, otherwise the metal will begin to undergo destruction;
points where metal rods are connected. Connecting using a welding machine is strictly prohibited;
The reinforcement frame is formed from several types of material. Longitudinal elements can be twelve millimeters in diameter and have a corrugated surface. For transverse and vertical rods, it is allowed to use smooth reinforcement and take a smaller diameter;

when deciding on the choice of steel material, clarify the expected load effects on the concrete base, study the structural structure of the soil, climatic features of the region;
the frame base is prepared initially on the surface, then lowered into the formwork structure on supports.

In the absence of technical capabilities to calculate the zones most likely to deform, it is recommended to install three longitudinal rows of steel rods over the entire area of the foundation structure, connecting them with knitting wire.

If you do not have sufficient experience in carrying out such work, you should not try to do it yourself. Seek help from specialists or find an experienced assistant.

Conclusion

If you think about it, there is nothing complicated about arranging a metal frame for a foundation. You should correctly determine the need for material, purchase high-quality fittings, and stock up on the necessary tools.

Source: https://betonov.com/fundament/stroitelstvo/armaturnyj-karkas-dlya-fundamenta.html

Why do you need to reinforce the foundation?

Strip foundation is one of the most common types of foundation for a house. During its construction, great importance is paid to the reinforcement of the formwork. Reinforcement allows you to increase the strength of the base and its tensile strength. This article will help you figure out and understand what kind of reinforcement is needed for a strip foundation and what details you pay attention to so that it lasts for many years.

After choosing the type of foundation, many are concerned with the question of what the concrete should be, its composition and optimal proportions in order to produce a high-quality foundation pour. The builder must also pay attention to:

number of floors of the future house;
weight of the building;
soil type;
groundwater level and soil freezing.

Concrete for foundation

Great importance is paid to the quality of the concrete solution. Any brand of concrete consists of four components:

Cement . The main component of concrete, which is best purchased from trusted construction stores. Cement has a shelf life, so it is not recommended to buy it in reserve. For pouring strip foundations, cement or Portland cement M400 is often chosen.
Sand . Experts recommend using sand that contains both large and small particles. It is best to choose river sand with a small admixture of quarry sand. The sand fraction for the foundation is 2 – 2.5 mm.
Crushed stone . When constructing small buildings, granite crushed stone of medium fraction from 20 to 40 mm is used.
Water . Clean drinking water must be used. Water with a high content of salts and sulfates will reduce the quality of the concrete solution.

If there is a need to increase the properties of concrete, plasticizers are often added. Such chemical additives can affect the hardening, strength and fluidity of the mass. The ratio of plasticizers in concrete mortar is 0.2-0.3%.

Requirements for fittings

To understand the importance of installing reinforcement, you need to understand what reinforcement is.
It is designed to increase the strength and reliability of the foundation. During operation, the base is subject to loads:

from the building itself;
during ground movement;
from frost heaving.

Foundation reinforcement

Due to these loads, the upper part of the base experiences a compressive load, and the lower part experiences a tensile load. It is in these parts that builders always install reinforcement, which takes on part of these loads. When choosing reinforcement for the foundation, pay attention to:

rod diameter;
corrosion resistance;
the need for welding;
resistance to negative temperatures.

Specialized stores offer reinforcing bars with a diameter of 5 to 32 mm with a ribbed and regular smooth surface.
Ribbed ones create better adhesion to concrete, so they are used as the main elements. Smooth reinforcement serves as an additional element and is installed in areas not subject to tension.

To reinforce the foundation, you need ribbed reinforcement with a diameter of 8-16 mm and smooth reinforcement with a diameter of 6 mm.

In the construction of foundations, ribbed reinforcement of class A3 (A400) is most often used. When purchasing, you can see different markings of the elements. The letter “K” in the marking means that the rods are coated with a special anti-corrosion compound, and the letter “C” means that the rods can be welded.

To reinforce the foundation you need ribbed reinforcement with a diameter of 8-16 mm

Reinforcement requirements

To carry out high-quality and reliable reinforcement of the foundation, you must adhere to some rules:

Make purchases of rods in specialized stores that can provide quality certificates for products.
The interlocking rods should not be deformed during pouring with concrete mixture.
To connect reinforcing elements, it is better to use the manual knitting method instead of welding the rods.
In addition, construction documents and standards for reinforced concrete structures describe the permissible distances between reinforcing bars:

no more than 40 cm for longitudinal rods;
no more than 30 cm for cross rods;
not less than 25 cm for elements located vertically.

According to experts, the diameter of the reinforcement for a strip foundation should be:

for light houses on stable soil, a diameter of 8 mm is suitable;
for loose and heaving soils and heavy buildings from 12 mm.

Requirements for foundation reinforcement

When calculating the required diameter of the reinforcement, the width and depth of the strip foundation are used. If the width of the foundation reaches 50 cm and its depth 100 cm, then the cross-sectional area of the foundation strip will be:

50 cm X 100 cm = 5000 cm2.

According to regulatory documents, the cross-sectional area of the reinforcement must be no less than 0.01% of the base, which means:

5000 cm2 X 0.01% = 5 cm2.

The result obtained is found in a special table for calculating the diameter of reinforcing bars. It turns out that for the foundation of a house with this width and depth you can use:

6 rods with a diameter of 10 mm;
8 rods with a diameter of 9 mm;
3 rods with a diameter of 14 mm.
It is worth considering that if the length of the foundation is more than 3 meters, then 12 mm is the minimum permissible diameter for use.

The amount of reinforcement is calculated independently depending on the reinforcement scheme.

Calculation of the quantity and diameter of reinforcement

Some reinforce the base with four rods, others use six. The reinforcement of the corners also differs. Some people use L-shaped clamps, perhaps also U-shaped patterns and various variations.

To find out the number of longitudinal elements, when calculating, the perimeter of the house is calculated, and the indicators of the walls, which are located above the foundation strips, are added to it. The resulting number is multiplied by the planned number of longitudinal rods located at the same width of the tape.

Rules for reinforcing strip foundations

Reinforcing bars differ not only in class and appearance, they also differ in their purpose:

Working longitudinal (horizontal)

Rods that are located along the base and take the main load from compression and tension factors. To increase the strength of the foundation, they are installed in the lower and upper parts of the tape. The diameter of the lower reinforcement elements must be greater than the diameter of the upper rods.

Transverse mounting

It is installed to connect individual upper or lower working rods together. Ensures the integrity of working elements and distributes the load between them.

Scheme of typical strip foundation reinforcement

It is installed vertically and connects the upper and lower longitudinal reinforcement. Proper reinforcement of a strip foundation uses all these types of rods. Only together will they ensure the integrity of the reinforcement structure and evenly distribute the load.

How to properly reinforce the foundation?

The distance between the rods and the surface of the foundation should be 5 cm. The main load is taken by the horizontal rods, the transverse ones only connect the frame into a single whole. The bottom layer of rods is placed on special stands.

Great importance is paid to the reinforcement of corners.
In these places, the rods are not simply connected, but separate curved L- or U-shaped clamps are used for this. At the corners, the rods are installed more often and denser than at the base itself. The reinforcement of a pile-strip foundation is no different from the reinforcement of a conventional strip foundation.

The main mistakes in foundation reinforcement:

reinforcement of corners not with clamps, but with the usual crossing of rods;
location of the rods in the middle of the foundation;

Vertical foundation reinforcement

when there are only two bent rods in the corners of the foundation;
uneven arrangement of reinforcement throughout the base.

Before starting work, it is better to familiarize yourself with the rules of knitting reinforcement. For this process, a knitting wire and a hook are purchased. This wire bends well, and its average diameter reaches 1.2-1.3 mm. You can purchase a hook at a hardware store or make it yourself. For knitting, rods 5-6 meters long are used. The knitting technology for all foundations is the same, and if the diameter of the rods is more than 25 mm, then the rods are connected by welding.

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You can knit the reinforcement in a place convenient for work, then place it in the formwork, and then install clamps at the corners of the base. To make knitting more convenient, do not use too long pieces of wire. Bite off 20 cm of metal thread and fold it in half. The overlap of the reinforcing bars when tying reaches 2 cm.

Knitting reinforcement using a special device

In addition to conventional hooks, the construction market offers many additional devices and tools to not only speed up the process of knitting reinforcement, but to do it reliably and firmly:

Gun for tying reinforcement

Significantly reduces the time wasted tying rods. Additional expenses will be required for the tool, but it will provide more reliable tightening of the wire. In the gun, the wire is located in a special drum, which is easy to replace. However, it weighs 2-3 kg and not all builders are comfortable working with it.

Gun for tying reinforcement KW-0041

Specialized tools that significantly reduce the assembly time of the reinforcement cage for the foundation. Tying the rods can be done using ordinary pliers. Some home builders use a screwdriver into which a bent nail is inserted.

Tying reinforcement is an important step when pouring a strip foundation, and it is better not to skimp on quality tools.

How to knit reinforced mesh in a trench

It is more difficult to knit a reinforcement cage in a trench than in a free area. It is better to think through the connection diagram of the elements in advance, so as not to waste time redoing the work in the future. Purchase reinforcement clamps from a specialized store. They will place the mesh above the formwork and ensure uniform application of the concrete solution to all reinforcement.

It is impossible for one person to work in a trench; an assistant is needed for such work. First, vertical rods are driven into the trench, and horizontal working reinforcement is attached to them. Finally, they begin to strengthen the corners of the base.

Welding fittings for reinforcement

Welding reinforcing elements is faster than knitting rods, however, it significantly reduces the strength of the metal frame. After welding, the rods become more fragile, which affects the quality of the strip base. If a heavy building of several floors is being erected, and the area has problematic soil, it is better to abandon this method of connecting reinforcing bars.

To weld reinforcement, you must purchase special rods of class A500 and additional marking “C”. Welding of reinforcement can occur in different ways:

contact;
bathroom;
butt;
contact-point.
If the reinforcement is welded by contact, it is very important to control the current strength, which determines the quality of the seam.

Practical advice

The reinforcement of brick walls is laid on the mortar between the brick layers. The work process starts from the very bottom. Particular attention is paid to door and window openings, as cracks often occur in them. Individual reinforcement elements can be connected with tying wire.

“How to reinforce aerated concrete blocks?”

Reinforcement of aerated concrete is made with reinforcing mesh. To position the reinforcement, make grooves in the blocks using a fence cutter. The ditches are cleared of debris and reinforcement tied with a special hook is laid. After laying the reinforcement, the grooves are filled with cement mortar.

Proper corner reinforcement should protect the foundation from cracks and ensure that the foundation resists tensile and compressive forces. The rigidity of the connection is ensured by both knitting and welding.

High-quality strength of the corner base is created by U- and L-shaped clamps.

Source: https://pobetony.expert/armirovanie/armirovanie-fundamenta

How to knit reinforcement for beginners: methods, norms and rules, frame for the foundation

There are only two ways to attach reinforcement to a frame: electric welding and knitting. We will not open a debate about which one is preferable. Let’s just say that knitting does not reduce the strength of the working rods.

Any welding weakens the metal because it creates local stresses in it. This negatively affects the reliability of the entire structure.

Compared to welding, knitting work is more labor-intensive.

Despite this, in private construction with its small volumes it is better to choose them. Especially when it comes to such critical structures as foundations and floor slabs.

articles:

In this article we will tell novice builders how to knit reinforcement correctly. Let's look at the tools, materials and technologies used for this work. We hope that the information received will help you confidently handle metal, assembling strong and reliable frames.

Methods of knitting reinforcement

There are two ways to fix reinforcing bars: manual and automated.

The manual method uses four types of tools:

Pliers;
Hook (simple and reversible);
Screwdriver with attachment.

Using pliers is not very convenient. Therefore, they are rarely used and only for assembling small frames. Crochet is used more often. This simple device, with some skill, helps to quickly connect steel rods.

There is an improved modification of the simple hook (reversible). Its basis is a screw that rotates when the handle is pulled back.

By combining a hook with a screwdriver, home craftsmen have created another convenient device for fixing steel rods in a frame.

Automated knitting is performed with a so-called pistol. This is a rather complex and expensive device used at large facilities. Its performance is such that tying one knot occurs in 1 second.

The device is equipped with a compartment in which a spool of wire is installed. The working body of the gun delivers it to the fittings and ties it into a knot.

Crochet technology

There is nothing complicated in this operation. After doing it several times, you will quickly get used to it.

The essence of the method is as follows: the intersection of the rods is covered with steel wire folded in half. The crochet hook is inserted into the loop and the other free end is grabbed with it. After this, the tool is rotated until it is tightened. The ends of the wire are bent inside the frame.

The craftsmen know one little secret that guarantees tight contact: after not tightening the loop a little, you need to pull it towards yourself and only then tighten it to the end.

Scheme for knitting reinforcement using a hook

Working with a screwdriver is not fundamentally different from crocheting. The advantage is higher speed and less labor intensity. When using a screwdriver, do not forget to set the rotation speed of its chuck to minimum.

You should not knit reinforcement with an electric drill. The large inertia of this tool does not allow you to accurately determine the moment of completion of tightening.

Methods for connecting steel rods and the main types of nodes are shown in the diagram below.

Materials

To assemble the frame, special annealed wire is used. It is durable, but at the same time quite soft. This allows you to tighten the knots without the risk of tearing it. The recommended diameter of this material depends on the cross-section of the reinforcing bars and ranges from 1.0 to 1.4 mm.

Cheap wire comes without coating and is called black. It is more resistant to corrosion and has a protective layer of zinc.

Knitting wire is produced in two versions: in coils and measured (in segments). Working with a skein is more difficult because it has to be cut into pieces by hand. The measuring material can be used immediately. Wire with loops at the ends is especially convenient.

Norms and rules for performing work

Guidelines for the design and manufacture of reinforcement cages are contained in two regulatory documents. GOST 10922-2012 specifies technical conditions for knitted and welded connections of reinforced concrete structures. The set of rules SP 52-101-2003 regulates the requirements for the design of frames.

Based on these standards, standard patterns for tying reinforcement under a strip foundation, dimensions of overlaps, diameters of the reinforcement used and other rules for the execution of work have been developed.

When joining rods on straight and corner sections, the length of the overlaps is important. SNiP sets this parameter depending on the diameter of the working fittings (in millimeters):

300 mm for rods with a diameter of 10 mm;
380 for 12 mm;
480 for 16 mm;
580 for 18 mm;
680 for 22 mm;
760 for 25 mm.

Knitting the strip foundation frame

The estimated number of longitudinal rods (diameter 12-18 mm) are placed at the bottom of the trench on supports (bosses) 4-5 cm thick. The distance between them depends on the size of the foundation and can range from 5 to 20 cm. If the standard length of one steel rod (6 meters) is not enough for the entire “ribbon,” then several rods are used. They are connected to each other, observing the regulatory overlap.

Supports for reinforcement cage

Clamps made of smooth or corrugated steel with a diameter of 8-10 mm are attached vertically to the working rods. According to building codes, the pitch of the clamps must be at least 3/8 of the height of the foundation (20-50 cm).

Having installed the clamps, the upper chord of the working reinforcement is attached to them with wire, observing the design distance between the rods.

At corners and junctions, clamps are placed more often (1/2 step), and the working reinforcement is bent, connecting to the rods of the intersecting section of the “ribbon”.

The length of the bend must be at least 50 diameters of the working reinforcement.

Making a reinforcement cage in a trench is labor-intensive and inconvenient work. That's why experienced builders use this simple device.

Having laid the longitudinal whips on wooden stands, clamps and the lower belt of the working rods are tied to them. The finished structure is transferred and placed in a trench.

Assembly of the reinforcement frame of a monolithic slab is simpler than that of a strip foundation. The design here consists of two flat meshes. The lower rods are laid perpendicularly with a given pitch and connected to each other. Then, at the points of their intersections, stands made of steel rods are placed and the upper mesh is screwed to them.

Stand for mounting the upper frame of a monolithic slab

In recent years, fiberglass reinforcement has begun to be used to assemble frames.

You can knit it in several ways:

annealed steel wire;
plastic zip ties;
plastic clips.

Approximate prices

The cost of tying reinforcement, as estimators say, “sits” in the total price of 1m3 of reinforced concrete. In square or linear meters it is calculated individually for each type of structure. In this case, it is necessary to take into account various parameters (the width and height of the grillage, the thickness of the slab, the cross-section of the reinforcement, the level of complexity of the frame, etc.).

For approximate calculations, builders use prices in rubles per 1 ton of metal used. Today in 2017 it averages from 20 thousand rubles.

Source: https://greensector.ru/stroitelstvo-i-remont/kak-vyazat-armaturu-dlya-nachinayushhikh-sposoby-normy-i-pravila-karkas-pod-fundament.html

How to lay foundation reinforcement - proven methods

To strengthen the foundation of residential buildings and industrial buildings, special steel frames made of reinforcement are used. It is necessary to know how to lay foundation reinforcement to make the foundation durable.

The house should not only be beautiful, warm and cozy, but also durable and reliable. The strength characteristics and load-bearing capacity of the house will depend 60 percent on the foundation. Therefore, it is very important to build a high-quality foundation at the initial stage of construction.

In this article we will look at all the features and nuances regarding the installation of reinforcement, and also analyze the correct reinforcement technology.

Why is the reinforcement procedure performed?

Concrete is used to construct the base. Even the highest quality concrete mixture is not able to withstand loads of different directions (compression, bending, tension). If a building is built on unstable soil, it may sag, which will lead to uneven distribution of the load and subsequent deformation. In order to increase the strength characteristics of concrete, a reinforcement procedure is performed.

Reinforced concrete becomes more monolithic, which allows the load to be evenly distributed over the entire surface. Under the influence of moisture and other destructive factors, concrete begins to crack and crumble. The reinforcement will resist this destruction.

When constructing houses and small industrial buildings, the strip type of foundation is often used. It has a number of advantages:

Easy to install. For installation you will not need specialized equipment and additional construction equipment;
Fast construction time;
Economic benefit. The material is relatively inexpensive and not much is required;
High levels of strength, reliability and durability. Subject to installation technology and high-quality materials, a foundation of this type can last more than a hundred years.

Features and nuances that should be taken into account when reinforcing

The installation procedure is quite simple, but there are still a number of features and nuances that should definitely be taken into account.

The fittings must be selected based on preliminary calculations. This takes into account: the size of the house, its number of storeys, soil type and environmental conditions. You need to choose high-quality material with a rod thickness of at least 1.2 centimeters. Particular attention should be paid to the corner connection of the rods. It is in these places that there will be a large load, and they must meet all the necessary reliability indicators.

The steel rods are connected to each other by viscous bonding. At corners and joints, the rods should overlap with a sufficient margin so that the rods intersect. The rods around the entire perimeter should be well tensioned. The presence of sagging is unacceptable according to technological standards. To increase the strength of the reinforcement frame, vertical supports for the racks are made at a certain distance (approximately 50 centimeters).

Nuances to consider:

Depending on the size and load, the frame may have several layers. Each layer must contain at least three rods;
It is recommended to use building materials with special markings A-Sh;
The material is usually measured in tons, so you will need to take measurements first and calculate the amount needed.

Selection of the necessary material and tools

For a high-quality reinforcement procedure, you will need the following materials and tools:

Metal fittings of appropriate thickness. The number of rods is determined at the design stage. It is imperative to have a 5-10 percent reserve;
Wire for making jumpers, which are located along the entire perimeter of the base at a certain distance from each other (no more than 70 centimeters);
Connecting wire for tying reinforcement. It is thin and is designed to connect rods in the required places;
A special hook for knitting or a knitting gun. These are the necessary tools with which you will tie the rods. Using a knitting gun is much faster and more convenient;
If the frame must have high rigidity, then the reinforcement must be welded. In this case, you will need a welding machine and all the necessary equipment for welding.

The main materials for installation should not have visible defects (cracks, chips, etc.). If you use rods and wire without zinc coating, it will need to be pre-treated with a protective layer.

Recommended reading:

What reinforcement should be chosen when laying the foundation of a private house

Simple and proven methods of tying reinforcement for the foundation of a house

How to lay reinforcement for the foundation - the correct diagram

In a strip-type base, the reinforcing elements should be arranged in a rectangle in the longitudinal section. This arrangement allows the acting loads from different sides to be evenly distributed throughout the entire structure and not create stressed areas. The reinforcement procedure is carried out if the height of the foundation does not exceed 65 centimeters.

The impact on the foundation of the house comes both from above (load of walls, floors, roof, etc.) and from below (soil movement, heaving in winter). In order to compensate for the impact of these forces, the upper and lower chords are made of steel rods. If the depth of the foundation is more than one meter, then three reinforcing belts are laid.

Working fittings must be located in a strictly designated place. In this position it is secured using rods of smaller diameter. These rods are called structural and perform only a reinforcing function for working reinforcement. To facilitate the knitting process, you can use additional clamps. Thanks to the clamps, the metal structure becomes stronger and more rigid.

How to lay foundation reinforcement

The first step is to install the formwork. If the width of the tape allows, then the reinforcing frame is assembled directly in the prepared pit. Longitudinal type rods are lowered onto the prepared and compacted bottom.

They rise by 5-6 centimeters and they should be approximately the same distance from the walls of the formwork. To do this, support supports of a certain width are placed. Pieces of brick can be used as supports.

The lower belt is fixed in certain places using a knitting wire.

If you are using an already formed rectangular frame, then simply tie the upper reinforcing belt to it. If you use cut reinforcement to form a frame, you will need to install and tie vertical posts. After this, the next layer of longitudinal reinforcement is tied to them.

There is another way to lay reinforcement. This method allows you to make a more rigid and durable frame, but in this case there will be an increased consumption of materials.

Initially, it is necessary to install vertical racks. They are driven into the ground. First of all, the racks are installed in the corners around the entire perimeter, as well as in the places where the horizontal rods will be connected. The diameter of the stand must be at least 20 millimeters. The posts are driven in at a short distance from the formwork walls (3-5 millimeters). The depth of the racks can reach two meters, and on unstable soils it can be even more.

Next, vertical posts are installed along the entire perimeter of the base with a certain pitch (no more than 300 millimeters). Now the lower belt is tied, if necessary we make horizontal jumpers. We tie the top belt using a knitting wire. It should be 5 centimeters below the concrete mixture. After this, we tie the horizontal jumpers.

It is much more convenient and faster to install using pre-formed steel frames. To do this, the rods are bent to a rectangular shape. This form must have certain geometric dimensions. Each subsequent bent rectangle must be of the same geometric dimensions. Minimal deviations are allowed. After this, all the elements of the belt are connected to each other and installed in a trench with prepared formwork.

How to correctly calculate the required amount of material

Before starting the procedure for laying reinforcement, it is necessary to accurately calculate the required amount of material. Calculations are made based on the area of the future house, as well as the height of the base. These calculations are performed by specialists at the preliminary design stage.

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For example, the area of the house is 36 square meters, the installation step is about 50 centimeters, the average width of the base (no more than 30 centimeters). In this case, in order to lay one reinforcing layer, you will need about 30 meters of rods of the appropriate diameter. Accordingly, if there are 4 layers, then 120 meters of metal rods will be needed.

In order for the reinforcement to be of high quality, you need to know how to lay reinforcement for the foundation. The strength and durability of the future building will depend on this. Be sure to follow the correct installation technology and select high-quality material.

Source: http://blog.kpmtrade.ru/sortovoj-prokat/kak-ukladyvat-armaturu-dlya-fundamenta/

Foundation reinforcement from A to Z on the advice of experienced builders

Proper foundation reinforcement can increase the strength of your building by 245%, increase its resistance to mechanical stress by more than 150%, eliminate possible subsidence and reduce brittleness of edges. Do you still think that rebar jointing is a waste of money?

Important rules for tying reinforcement and basic SNiP

Before you start embroidering your future foundation with reinforcement or wire, you need to roughly calculate the load on it in order to decide what cross-section of rod you will need. You don’t need to know exactly, since they always take it with a reserve.

For example, when building a temporary metal structure with a wall weight of up to 400 kg/1 m2, you can use reinforcement with a diameter of 8 millimeters. When building a cinder block garage with walls up to 3 meters in height, a rod with a cross-section of 12 millimeters is used.

If you are building a two-story cottage, then you will have to embroider it with more serious metal - a diameter of 14-18 millimeters.

Of course, you can give this project to experienced specialists for calculations, who will save money and select the minimum acceptable value, but if a few thousand rubles do not play a big role, take it with a reserve. Often there is a desire to complete a floor with an attic or make a multi-level heavy roof - the foundation must be prepared for such a “turn of events.” There are several SNiPs that regulate the manufacture of this design. Let's take a closer look at them.

SNiP 7.3.4 states that the minimum distance between two vertical rods should be no less than the cross-section of the reinforcement itself, and preferably 2-3 times larger. The maximum value is not indicated, since it is selected individually for each project and depends on the masonry method, the presence of a sealant, the brand of cement, the quality of the aggregate and other factors.
SNiP 7.3.6. The distance between two parallel longitudinal rods should be no more than 40 centimeters. The greater the load on the base, the shorter this distance will be. The minimum distance for a strip foundation is 10 centimeters with a reinforcement diameter of 14 mm.
SNiP 7.3.7 regulates the spacing of transverse reinforcement. The value should be no more than half the working height of the section, but in no case should it exceed 30 centimeters.

By adhering to these SNiPs, you will get reinforcement according to “book standards”. But there are several rules that were developed specifically by builders to facilitate the process of establishing a foundation. These recommendations are time-tested and will significantly improve the physical and mechanical properties of your structure, as well as save a little on the purchase of materials.

You cannot weld fittings together. Heating the metal significantly worsens its properties , but there is no need for strong connections there at all - they are held in place by the concrete, not the metal that you will fuse for hours.
The reinforcement is subject to corrosion, so you need to deepen it on all sides into concrete so that it lasts for decades. On the sides, the metal should “go” into the concrete by at least 8 centimeters, from below by 10, from above by 10.
You cannot make cross joints at the corners; the rods should not intersect perpendicularly; it is better to take and bend the metal into the required shape so that the next joint is no closer than 100 centimeters from the corner. They always bear the heaviest load, and a connection on a short section of the site will not provide the required strength.
The corners should be additionally reinforced with crossbars and verticals. Very often, people simply do cross-stitching, believing that the mass will, for some reason, rest on the rod itself. But such a knitting of reinforcement for the base is simply unacceptable, because you will end up with 2 separate blocks that will not have any connection with each other. The sense of this action is exactly 0.0%. U-shaped and L-shaped reinforcements are needed at the corners and at the first crossbars from them.

We have discussed the basic rules of how to make high-quality foundation reinforcement, the diagram for which is located below . Now you can move on to the phased construction of this structure and analyze all the nuances in more detail.

Step-by-step instructions on how to make a reinforcement cage for a foundation with your own hands

Preparing the pit and jointing is a responsible process. Reinforcement plays one of the most important roles here. In order to do everything correctly, the structure was as strong and connected as possible, everything must be done according to the following instructions.

>Step 1: Set up the formwork.

Before knitting reinforcement for the foundation, you need to prepare a place for it. First, we dig a hole of the required size, mainly 40 centimeters wide (for a house) and 90 centimeters deep, depending on the weight of the future structure and the characteristics of the soil. Next, we install 50x50 mm wooden beams in the corners, to which we nail longitudinal boards. We raise the foundation and move it smoothly into the base.

Important: even if you have an almost flat hole below ground level, you still need to install the formwork from boards, and from even planks. This is done to ensure that the reinforcing elements are at the same distance from the outside of the concrete - this is an important point that must be taken into account. The formwork is fixed on the outside with earth or sand and water, and on the inside with wooden spacers (the length must be the same).

>Step 2: Install vertical supports for the metal frames.

The first step is to set the verticals to which the horizontal reinforcing belts will be attached, and then the crossbars. Let's assume that the foundation will have 4 corners - the simplest design. Then in each corner you need to retreat 6 centimeters from the inner and outer walls, then mark the place and hammer in a rod, align it plumb.

>Step 3: Screw on the horizontal frame.

As a rule, these are 2 parallel straight lines, which are wound with ordinary knitting wire. Important: you cannot weld them to verticals and cross members, as high temperature will significantly worsen their physical and mechanical properties.

>Step 4: Screw on the cross members.

This can be done manually or using special knitting guns, which will greatly simplify the work. The pitch of the crossbars should be at least 40 centimeters, preferably 60-65 cm. Remember that a very dense mesh does not guarantee high strength. We only need to give the concrete flexibility and eliminate the risk of subsidence.

>Step 5: Strengthen.

First of all, we strengthen the corners with L-shaped and U-shaped elements, make oblique spacers between the lower trim and the upper parallel elements. The sides can be supplemented with obliques between the parallels, and longitudinal branches can be installed from the upper corner of one edge to the lower corner of the other edge.

Pouring concrete onto the frame

We have just figured out how to reinforce the foundation, now we will look at how to pour concrete correctly so as not to damage the integrity and increase the strength of the structure. The first step is to make a good base. To do this, pour 5 centimeters of broken brick or cinder block under the first strapping belt. Next, fill it with liquid solution so that it penetrates well into all the cracks and ensures maximum strength of the sole.

Important: you cannot fill the foundation and plinth in “waves,” especially at the junction of the reinforcement - the crack will go along this line. If you need to perform the operation in 2 times, then it is better to make the “break” in the middle of the foundation. For example, if its height is 150 centimeters, then at the level of 75 cm you can take a break. Next, you need to fill everything with a monolithic layer, and that’s the only way.

The metal is poured at least 8-10 centimeters so that it is not near the edge, otherwise the foundation will fall apart under an average load. This will not affect the overall strength, but the base will lose its appearance - the edges will crumble.

Source: https://grounde.ru/sxema-armirovanie-fundamenta.html

Strip foundation reinforcement: meaning and features. How to reinforce the foundation? | "Build a bathhouse Ru"

The foundation is constantly subject to various influences: soil movement, the weight of the house, frost. Such actions lead to deformation and destruction of the base, and if it deteriorates, then the bathhouse itself will not last long.

In order for the building to serve for many years, it is important that the strip foundation is done correctly. One of the stages of foundation installation is reinforcement.

Let's take a closer look at what reinforcement is, why it is needed, and how to properly knit reinforcement for a strip foundation.

Strip foundation reinforcement: what is it and why is it needed?

Foundation reinforcement is a method of increasing the load-bearing capacity of a structure by installing a frame. When building a bathhouse, you need to take into account all the requirements that the foundation must meet, specified in SNiP. Reinforcement of the strip foundation is necessary to increase the service life of the foundation and the entire structure as a whole.

The basis of the strip foundation is concrete. As is known, such a material is non-plastic, i.e., when stretched, it can easily crack. The metal frame is characterized by higher stability and reliability; when reinforced, it takes part of the load upon itself, thereby preventing stretching and reducing the risk of destruction of the foundation; tying reinforcement for a strip foundation is necessary.

What material is best to make a reinforcement cage for a strip foundation?

Progress does not stand still; new building materials are constantly appearing. If previously the knitting of reinforcement was strictly made of metal, today you can see plastic reinforcement, fiberglass options and composite parts. So what is the best way to knit reinforcement? Let's look at the materials in more detail.

Despite the emergence of new and more modern materials, time-tested metal fittings remain popular. Its service life is about 50 years. The fittings are distinguished by their high weight, strength and reliability. Its main disadvantage is that it begins to rust when exposed to moisture.

To make the binding of reinforcement for the foundation, hot-rolled construction reinforcement of a periodic profile, mechanically strengthened or heat-treated, is suitable.

When choosing reinforcement, you need to take into account the value of the yield strength. For the installation of longitudinal rows bearing the main load, rods of class A400 (AIII) are suitable; it is permissible to use materials of a higher class. But keep in mind that they will cost more.

It is important that the profile is ribbed, because it adheres better to concrete and evenly transfers the load.

For lintels, smooth reinforcement of class A1 is suitable; this will help reduce the cost of the foundation, while it will have sufficient strength.

For a strip foundation, reinforcement with a diameter of 6-12 mm is suitable.

If the side of the tape is less than 3 m, then it is permissible to use rods of at least 10 mm for horizontal clamps, if more than 3 m, then at least 12 mm. For vertical clamps with a foundation height of less than 80 cm, reinforcement with a diameter of 6 mm or more is suitable, for more than 80 cm - from 8 mm.

Fiberglass reinforcement is 2 times stronger and 9 times lighter than metal. An important advantage of this material is that, unlike metal, it is not subject to corrosion. Fiberglass reinforcement has a service life of about 70 years. Moreover, its price is cheaper than the metal version.

You need to choose the material for reinforcement carefully. If the reinforcement is of poor quality, then cracks may appear on the foundation, which will gradually expand, and as a result, the structure will serve you much less than it could.

You can knit a frame from reinforcement yourself or buy ready-made reinforcement mesh.

The second option will be more expensive, but the question of how to knit the reinforcement frame will not bother you, since these concerns will be taken on by specialists. In addition, the advantage of the finished mesh is that the rods are firmly connected to each other in the factory. This ensures that the frame will not fall apart over time, as can happen with a homemade one.

In addition, in this case it will be easier to reinforce the foundation: you just need to lay the frame in two parallel layers.

Why is the bathhouse floor cold? How to fix it?

How to properly reinforce a strip foundation with your own hands?

Strong and properly connected reinforcement retains its shape perfectly when pouring concrete for the foundation. But in order for the structure to be of high quality and reliable, you need to know how to properly knit reinforcement for the foundation and choose the right materials.

According to the rules, any reinforcement must be protected from external factors; for this, it is poured with concrete. Moreover, it is necessary that the upper part of the frame is buried in concrete by 5 cm, and the lower part by 7 cm.

If you want to know how to properly reinforce a foundation, then do not forget to study SNiP, where everything is described in detail. In particular, in accordance with SNiP, the total area of the frame must be at least 0.1% of the cross-sectional area of the foundation.

Tension zones can appear in both the upper and lower parts of the foundation, so reinforcement should be done on both sides.

If you are making a shallow foundation, then the step between the horizontal bars during reinforcement should be 30 cm.

Strip foundation reinforcement scheme

First, preparatory work is carried out to clean the area. Next you need to prepare the trench.

The pattern of tying reinforcement for a strip foundation begins with the installation of formwork.

Do-it-yourself foundation reinforcement is carried out according to the following scheme:

Metal rods are driven in an amount equal to the depth of the base, at a distance of 5 cm from the formwork. 40-60 cm should be left between the rods.
Stands are installed at the bottom, 2-3 threads of the bottom row of reinforcement are placed on them. Different materials are used as stands, for example, bricks or stones are suitable. Thanks to them, the reinforcement is located higher, and after pouring concrete it will be protected from all sides.
The rows of reinforcement are attached to the perpendicularly installed pins with jumpers.
The joints are strengthened by welding or tying with wire.

After you have made the reinforcement frame, you need to prepare holes for ventilation and pour concrete.

Foundation reinforcement schemes may be different. When choosing, you need to take into account the size of the foundation, its load-bearing capacity and personal preferences.

The best option is a foundation with a square or rectangular frame, since in this case a strong frame is obtained.

It is recommended to make the frame in such a way that its width is half the height. This will help improve the reliability of the design.

How to properly reinforce a strip foundation? You can knit the structure in the trench, as described above, or first prepare the reinforcement cage and then lower it into the trench.

The difference between these schemes for tying reinforcement for the foundation is that in the second case everything can be done independently, but if you mount the frame directly in a trench, you will need the help of another person.

How to reinforce a strip foundation? To make a bundle or weld?

Horizontal and vertical rods must form a single structure. They can be connected in two ways: by tying or welding.

The disadvantage of welding is that such a procedure deteriorates the physical properties of the metal, it becomes more brittle, so this method is rarely used.

If you still decide to fasten the rods by welding, then try to reduce the number of seams.

Another option is a bunch. It requires a soft and thin wire with a diameter of 0.5 mm and a length of about 30 cm. It should be folded in half and placed at the junction of the rods, and a hook should be threaded into the resulting loop. Next, twist it to form a knot.

Do not twist the wire too much, it may break!

How to knit reinforcement? Methods

Tying reinforcement for the foundation can be done manually or using tools. If you are not a professional builder and are building a bathhouse for yourself, then there is no need to buy special tools - this will be a waste of time. You can do the job just fine manually.

Methods of tying reinforcement:

This is the simplest method that does not require special skills. You need to take a wire with a diameter of 12 mm, cut it into pieces 1.8-2 m long, and bend it in half. Next, you need to fasten the elements with wire in such a way that there are free ends 0.3-0.5 m long. After that, you need to hold the free ends with one hand, and with the other, insert the hook into the loop with rotational movements and twist the wire with both hands.

Knitting with reinforcement clips.

Paper clips can be purchased at the store. This mounting option is suitable for hard-to-reach places. To tie reinforcement under a strip foundation, you need to fix a paper clip along the diameter on one rod, and press the adjacent reinforcement with the other end. The advantage of this type of fastening is that the reinforcement process is faster than other methods.

This method is relevant in the case of tying reinforcement at the junction of foundation walls and for lengthening the reinforcement cage. The length of the overlap should be approximately 30 times the diameter of the reinforcement. Moreover, the reinforcement must be installed so as not to touch the formwork. This is necessary to protect it from moisture, high and low temperatures.

All these methods have in common that the first loop must be placed along the spiral grooves so that the fastener holds better.

Reinforcement of strip foundation corners

The corner of the reinforced concrete foundation is subject to stronger pressure compared to the walls; it is the most vulnerable point in the entire structure. If the reinforcement of the corners of the walls is done incorrectly, this will lead to cracks, which will cause the foundation to quickly collapse.

Some people believe that it is enough to lay the rods at right angles, but this opinion is wrong. This design does not allow making a single rigid frame, so the base will not last long.

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How to reinforce the foundation in the corners? It is best to use bent L- or U-shaped rods. They strengthen the joints in the corners of the foundation. It is also necessary to reduce the step for tying the rods by 2 times.

An effective option is to bend the corners and overlap them using clamps at a distance of 7 cm from the corner.

L-shaped rods are the most reliable option for connecting foundation corners. They need to be laid out so that one end of the rod goes towards one wall, and the other end towards the other. L-shaped rods ensure solidity and high strength of the foundation.

How to knit reinforcement for a foundation? Watch the features of knitting corners in this video:

Reinforcement of the foundation increases the cost of the foundation and the entire building as a whole. But thanks to it, you get a strong foundation that will extend the service life of the bathhouse. If you decide to make a strip foundation, then reinforcement is, of course, a mandatory stage in the construction of the foundation. It’s better to spend more on the foundation once than to build a bathhouse again later - as they say, “the miser pays twice.”

Source: https://PostroitBanju.ru/fundament-bani/armirovanie-lentochnogo-fundamenta-znachenie-i-osobennosti-kak-armirovat-fundament.html

The process of reinforcing a strip foundation with your own hands

Technical concrete can withstand strong mechanical stress, but requires additional strengthening. To ensure high-quality load-bearing capacity, the strip foundation is reinforced, which enhances the efficiency and durability of the work performed. It is also performed in slab structures, piles and pillars, although there is no such need.

Operating rules

First, you need to prepare a reinforced frame that will strengthen the base in case of deformation or uneven masonry. Such actions create bending loads, which are impossible to get rid of without reinforcement. While working, you need to follow some rules:

the granularity of the aggregate in the concrete should be such that the material does not get stuck between the rods in case of frequent placement;
when making frames, their elements are overlapped, and the porosity of the surface must be observed; even for clamps and connecting parts, the use of smooth reinforcement is not recommended;
It is mandatory to have a 5 cm thick layer of concrete to help protect the surface from rust and corrosion.

Metal reinforced frames are tied together; welding corner elements is not allowed, as they may not withstand the load. Builders do not recommend using welding, as it can damage the section. For work, use the layout of class A400 rods.

Bunch of elements

In the process of installing a frame made of reinforcement for a strip foundation, the method of linking elements is used . It protects against metal burn-through and increases strength. You can use either a special hook or a knitting machine. The second device significantly speeds up the procedure, while the first is better used for laying small volumes.

For connection, reflected wire is used, which allows you to correctly and reliably fix and lay all the frame parts. It creates strong knots. Other materials are not suitable for this.

Knitting pattern

To properly reinforce a strip foundation, you need to overlap the elements. To carry out the correct tying at an angle, you need to do this at the junction of one wall to another or between two perpendicular elements. You can use the paw method, the length of which should be at least 35 dm.

Multiple parts may be used. The number of legs per corner can be from 2 to 5 depending on the location of the reinforcement elements. The rod used resembles a poker, which connects the frame of one wall with the elements of another. Here the reinforcement parts must be welded to ensure good reliability.

L-shaped clamps can be used. The principle of fastening here is similar to a poker, but instead of a foot, an L-shaped element is used, the length of one side of which is greater than that of the working fittings. Such elements can be used for both horizontal and vertical mounting. The choice of reinforcement size depends on the load the monolithic foundation will withstand.

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You can also use U-shaped elements. For one corner, two parts are used, the length of which is the same and is about 50 diameters of the reinforcement. One of the clamps is welded to two parallel and one perpendicular element.

Builders will help you calculate how many pieces of reinforcement will be needed for a certain type of foundation. As for the placement of horizontal jumpers between elements, they are calculated per step.

Expert advice

To calculate what kind of reinforcement is needed for a strip foundation, you should pay attention to the type of building and its dimensions. When purchasing metal, the overlap that will occur when connecting several elements is taken into account, so it must be purchased with a reserve.

To properly reinforce the foundation, at obtuse angles you need to select a straight element and bend it to the desired size. Also, for reinforcement, an additional part is attached, which compacts the texture.

The most common errors during operation include:

connecting elements at right angles;
lack of any connection between different elements;
using longitudinal rods as a bunch of crosshairs.

There is no need to repeat these mistakes during the work process, as they will affect the quality. For high-quality binding, you need to move along the base of the foundation, installing horizontal jumpers for the elements. They must be parallel to each other.

Using a crochet hook

Although a knitting machine is often used in work, it is intended to perform a large volume of work. A crochet hook is a simpler material that is used to connect elements.

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To simplify the workflow, you need to make templates . To do this, you will need wooden blocks 30-50 cm wide. Holes are made in the wood that will repeat the rods in the frame. Pieces of knitting wire are laid out in them and after that the necessary rods are fixed. A crochet hook is used when connecting crosshair elements for overlapping knitting. After this, the wire can be tightened tighter.

The connection is made in several places along the entire length. The wire is placed so that it is in depth, then folded in half and laid under the joint. After this, use a hook to pull a loop and rotate it, twisting the wire. Upon completion of work, the tool is carefully removed.

If you use a knitting machine, the knitting process will noticeably speed up and you will be able to create a reinforced frame faster, but for small buildings its use is not practical. It is also better to avoid welding elements, since in the process parts of the fastening are burned and metal erosion may begin.

It is better to consult a professional about what kind of reinforcement is used for a strip foundation. If you do not have experience in calculating the number of metal rods for the foundation, it is also better to turn to builders for help. The reinforcement should be purchased with a margin for overlap during the fastening process.

The preparation of the frame and its installation are carried out immediately before pouring the foundation. If you carry out the work following the recommendations of specialists, you can achieve a high-quality result and build a reliable foundation for your future home. A strip foundation is considered the best option for reinforcement inserts, although such reinforcement can also be tried in other types of foundation.

Source: https://betonli.ru/armirovaniu-lentochnogo-fundamenta/

Reinforcement of strip foundation corners – Piles Mania

Reinforcing the corners of a strip foundation requires knowledge of some nuances. This is the collection point, the place that takes on the maximum stress on the reinforcement structure.

If the design is incorrect (wrong connection, breaks), there is a serious risk that the reinforcement, instead of being a rigid frame taking on the load, will turn into a set of disparate parts. The result is cracks and delamination of concrete in the corners of the building.

It is necessary to consider in detail how to properly reinforce corners in a strip foundation of a reinforced concrete structure.

Types of angles

The reinforcement pattern depends on the type of corner. The easiest to bandage is an obtuse angle, the most difficult is an acute angle. What are the angles:

Direct ones are the most common. They can be L-shaped or T-shaped, the latter are also called T-shaped junctions (examples are below in the diagrams).
Dumb.
Arbitrary (bay windows).

An obtuse turned angle from 160° will not require much effort - just study the diagrams below (here are the simplest ones), and correctly lay the reinforcement, drawing lines from the outside to the inside, as if creating a connection between them, doubling the frequency of crossbars compared to the rest the length of the foundation, and then perform a high-quality dressing. An angle of 90-160° will require additional vertical rods. Sharp corners have their own specifics, but they are not discussed here. They are extremely rare in private low-rise construction.

Variety of corner connections

It is necessary to reinforce corners for two main reasons: these are potential stress points. They need to be strengthened, otherwise there is a risk of seeing cracks in the edge areas of the building over time.

The purpose of the reinforcing belt is to impart rigidity and strength to the frame. It is she who takes on a significant share of the loads falling on the concrete mass.

The corner is a weak point in any foundation (except slab).

General rules for reinforcement

For work, you must use the standards given in SNiP 52-01-2003.

The collection indicates the required minimum reinforcement per foundation area (0.1% per foundation cross-sectional area, which is determined by a simple formula: multiply the width by the height) - the number and thickness of the rods depends on this calculation.

Calculations, including for angles, are made at the design stage, although this stage in private construction is often neglected, doing everything on the fly. The first available iron rods are used for the foundation, which is a serious mistake. If everything is done correctly, you should decide in advance:

With the type of reinforcement (class, section, d=12 mm is often used for low-rise buildings). Longitudinal elements are made with ribbed rods, crossbars and verticals are made with thinner smooth rods.
How many belts? Their number is from 1 to 3. Two – for shallow and medium-depth foundations, 3 – for deep ones. According to SNiP, if the height of the frame is less than 80 cm, then the minimum diameter of the rod is 6 mm, if more - 8 mm.

Calculation example: the trench has a depth of 80 cm, a width of 60 cm. Sectional area = 80 * 60 = 4800. Minimum reinforcement: 4800 * 0.1 = 480. Hence, the minimum area of the rod is 4.8 cm2.

The intersections of the rods along the main length of the foundation are connected with wire in 20 cm sections, using hooks or a tying gun. You can use pliers, a screwdriver or special paper clips.

Knitting, including for reinforcing corners of the foundation, is a simple but painstaking operation. There are techniques that will make this work faster. The easiest time-saving option: knitting with a gun. It is carried out 5 times faster than when using pliers.

How to determine the distance between the longitudinal lines of the reinforcing belt and the pitch between the transverse rods? According to SNiP 52-01-2003, the distance from one longitudinal line to another is within 25-40 cm. The distance between the crossbars is ½ the height of the working section, but not more than 30 cm.

Hand knitting is preferable to welding. It can be carried out with metal wire, clamps (usually up to 40 mm) or other types of connections. The diameter of the wire is an individual value, usually no more than 1.2 mm.

Anchoring during dressing

The choice of anchorage depends on the type of reinforcement and the site of the structure. Bending of reinforcement is carried out using a vice or a special machine. All types of reinforcement anchorage and their specific application in corners:

The least desirable in corner joints is straight. Only for periodic profile reinforcement. This is a simple overlapping of rods and ligation. But if the dressing is done efficiently, then it is acceptable for small buildings. It is important to achieve complete rigidity of the structure; if shifts are obvious when pouring concrete, then the reinforcement was laid poorly.
Foot - the end of the rod is bent in the form of a right angle.
Hook – bend 180°. Thus, the end is adjacent to the main part of the rod.
Loop - the rod is folded in half, the loop is located in the corner.
Welding of crossbars.
Additionally, a washer or a steel angle is used.

The last two methods are suitable only for reinforcement suitable for welding, and direct anchoring and claw are only suitable for rods of different diameters.

Types of reinforcement anchorage

Incorrect corner reinforcement

Possible mistakes made when reinforcing corners are as follows:

The reinforcement is simply crossed in the corners and fixed with knitting wire. This scheme is quite common, although it is an extremely serious mistake.
Bent reinforcement in corners without anchoring.

According to SP 50-101-2004, monolithic and prefabricated monolithic foundations are a rigidly connected system of cross strips. If there is a break at the bends (and this is the only way to classify the connection with a simple crosshair), there will be no rigid connection.

According to SP 52-101-2003 clause 8.3.26, methods for connecting reinforcement in corners and overlapping areas are:

Lap without welding: grooved rods with straight ends; rods with straight ends, but there are welding or cross rods; there are bends at the ends (hooks, loops, tabs).
Welded.
Mechanical (fastening with couplings).

Reinforcement options

The correct diagrams for a reinforced monolithic strip foundation are illustrated below. The main point to consider is the anchoring of the reinforcement. Different bond strengths are formed for individual wall zones in the corner.

The rods running along the outside are tied together, vertical reinforcement is installed, and on the inside the rods intersect freely.

In the corner, transverse rods are 2 times more frequent than along the main length of the foundation strip (half of three-quarters of the height of the section of the foundation strip, but not more than 25 cm).

Reinforcement is given precisely along the outer corner, and not along the inner one. You can add a rod along the inside line of the corner, but it will not work.

U-shaped installation

At least 5 reinforcements are used (highlighted in yellow in the photo above) in each direction, in total a minimum of 10 p-elements will be required. Anchoring with such a U-shaped installation is not necessary.

How to make a U-shaped installation in a T-shaped corner? For each step, a U-shaped element is added, at least 5, they go towards the adjacent wall.

But other options (with anchoring) are also possible; one of them can be seen in the diagram below:

Corner reinforcement rules:

Additional transverse and vertical rods are required.
The corner rod is bent as follows: one end goes into one wall, the other into the other, to a depth of no less than 40 diameters of the reinforcement.
If the rod is too short, then L-shaped profiles are added.
Reinforcement with L- and U-shaped profiles is necessary throughout the entire height.
The distance between the clamps is halved compared to the rest of the structure.

Reinforcing the corners of a strip foundation: how to do it correctly
Reinforcing the corners of a strip foundation requires knowledge of some nuances. This is the collection point, the place that takes the stress on the structure.

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How to tie reinforcement for a strip foundation

The foundation is the basis of the entire structure, the guarantor of its durability and strength. Strip foundation reinforcement, drawings and diagrams must be prepared and calculated in advance.

The need for reinforcement

The foundation is a monolithic reinforced concrete structure. Concrete itself is a material that can withstand significant loads only in compression. To increase the tensile and bending strength of the foundation, it is necessary to make a metal frame. Moreover, strength indicators increase only due to the arrangement of working longitudinal rods.

Therefore, thick profiled rods with a diameter of 10÷14 mm are used as them. Transverse elements are designed to create the spatial geometry of the foundation; they do not allow the longitudinal bars to move when pouring concrete mortar, and keep them in the right place.

For these purposes, you can use smooth or profiled rods with a diameter of 6÷9 mm.

Requirements of regulatory documents for reinforcement materials

You can learn how to properly reinforce a strip foundation by reading the regulatory documents. The requirements that must be observed when reinforcing a monolithic strip reinforced concrete foundation are set out in SNiP (No. 52-01-2003).

Types of steel rods recommended for reinforcement:

hot-rolled smooth or profiled (Ø=3÷80 mm);
thermomechanically strengthened profiled (Ø=6÷40 mm);
cold-rolled profiled or smooth (Ø=3÷12 mm).

Important! Compared to smooth ones, profiled rods have better adhesion to concrete: this can significantly increase the reliability of the structure.

Requirements for the arrangement of rods in the reinforced frame for a strip foundation:

the distance between the longitudinal rods should be no more than 0.4 m;
the pitch of the transverse fixing elements should be no more than 0.5 m.

The minimum relative content of working longitudinal rods in a reinforced concrete element must be at least 0.1%.

For tying elements of reinforced concrete structures, only special baked steel wire (Ø=0.8÷1.2 mm) should be used.

Example of calculation of foundation reinforcement

Let's try to calculate how much materials will be needed to arrange the reinforcement of a specific strip foundation with drawings. Let's say we are building a small country house with overall (external) dimensions of 5x8 m from building blocks (0.4 m wide).

The nature of the soil on our site allows us to make the height of the strip 0.9 m, its width 0.4 m, which corresponds to the width of the building material of the walls.

In the reinforcement cage for the strip foundation we will use longitudinal working rods with a diameter of 12 mm and □-shaped transverse clamps made from rods with a diameter of 8 mm.

Reinforcement of a shallow strip foundation:

The photo shows that the distance between the working longitudinal rods (0.4 m) and the pitch of the □-shaped transverse clamps (0.5 m) were chosen in accordance with the requirements of regulatory documents.

We check the relative content of longitudinal working rods in our reinforced concrete structure. To do this, we will use the following terms and notations:

h – foundation height (900 mm);
w – foundation width (400 mm);
Sₒ – cross-sectional area of the foundation;
Sₐ – total cross-sectional area of longitudinal rods (6 pieces);
r is the radius of the longitudinal rod (6 mm), which is equal to d/2, where d is the diameter of the rod (in our case d=12 mm);
D – relative content of working rods in the “body” of the foundation.

Source: https://zamesbetona.ru/armirovanie/armirovanie-lentochnogo-fundamenta-chertezhi.html