The foundation of any building is continuously subjected to stress; it is influenced by the weight of the structure, the climate and the processes occurring in the soil. If the base has a defect, it will cause a gradual destruction of the structure. The only way to strengthen the structure, make it as strong as possible, is the reinforcement of the foundation. The labor of generations of builders has shaped the techniques and rules of how to knit reinforcement for the foundation in order to get a reliable base.
Prepared reinforcement cage
The foundation of the strip foundation is concrete. This material was widely used as a basis for the erection of buildings in ancient Rome. And only 200 years ago, it was guessed to increase its strength with the help of a steel bar frame. The new building material, reinforced concrete, combined the advantageous characteristics of metal and concrete and made possible the construction of impressive structures. The process of placing the metal frame in concrete was called reinforcement.
When a country house is being designed, it is often the ribbon foundation that is chosen as the basis for it. The preparation of the tape base (as well as any other) takes 25-30% of the construction cost; the reason for its demand is in a successful combination of qualities:
Uncomplicated in design.
Suitable for projects with basements (as opposed to pile-screw analog) and heavy floors (reinforced concrete, monolithic).
Does not need to use special equipment.
Tape foundations in formwork
Despite its widespread use, tape the foundation also has limitations in use:
It is beneficial only on dry and stony soils.
Poorly suited for a device on problematic (wet heaving, peaty) soil; it will have to be poured to a greater depth, which is unprofitable.
The shape of the strip footing is determined by the layout; it has a closed form, is laid along the entire perimeter of the house, under the supporting walls and internal partitions.
The foundation is created in order to withstand the load of the structure; it copes best with a uniformly applied pressure force. But in practice, the load too often turns out to be uneven and internal stresses arise in the foundation. The reason can be either ground changes or project miscalculations (unequal weight of individual parts of the structure).
Design errors will definitely become noticeable
Concrete has excellent axial compression resistance and weak resistance stretching. Reinforcing rods have natural plasticity and compensate for the lack of concrete. The latter, in turn, protects the metal from corrosion.
During operation, concrete (which resists compression) and metal (tensile) is able to most effectively resist multidirectional loads, protecting the structure from destruction. Correctly carried out reinforcement not only increases the strength, but also is a means of saving: it allows to reduce the cost of concrete (to reduce the massiveness of the foundation).
Tape foundations are laid with a margin of safety; It must be resistant to external factors (mechanical and climatic). How to knit reinforcement for strip foundations correctly is described in the provisions of SNiP 52-01-2003, which contain detailed requirements for construction and materials. A number of requirements are put forward to reinforcement:
The placement of the reinforcement cage should not impede the correct technological casting of concrete.
The valve is installed with the specified design step.
Calculation of the pitch of the clamps when reinforcing the angle
At the intersections of the frame, floating (movable) connections of the rods are not allowed for any connection method.
It is necessary to create a protective anti-corrosion layer for the structure.
Replacement of the type of support rods is allowed if the calculated bearing capacity remains the same.
On our site you can find contacts of construction companies that offer the service of repair and design of the foundation. Directly to communicate with representatives, you can visit the exhibition of houses "Low-rise Country".
As the reinforcement cage increases the stability of the structure, taking on a significant part of the load, its quality becomes of fundamental importance. The frame is formed from interconnecting reinforcing rods.For tying the frame, various are used:
Manufacturers offer reinforcement, which can be divided by:
Material production. Steel reinforcement - a classic, time-tested option; divided into 6 classes of strength, it can be bent and welded. Composite fittings contain carbon, basalt, glass or aramid fibers. It is lighter, cheaper, does not corrode, does not bend and is not subject to welding.
The armature with a periodic profile has improved performance
Profile. Reinforcement with a smooth profile is more often used as connecting bridges. The armature with a periodic profile has a relief surface, which improves adhesion to concrete.
Tying of fittings for strip foundations, the scheme of which can be changed, is made using:
Knitting wire. Reliable and common connection technology using a node. There are different patterns of mating.
Threaded and crimp sleeves (at mechanical joints).
Metal Clips. Reinforcement elements are connected without knot tying.
Plastic clips and clips (clamps). Plastic products provide easy and quick installation, resistant to corrosion. Their use is not approved by all professionals.
Composite reinforcement rods fastened with a
It can be interesting! In the article on the following link read about pouring the foundation.
Rebar mating for strip foundations is considered more practical than welding: strength in knots does not decrease, a qualified welder is not needed, work takes place directly in the formwork (or near). The spatial framework of the reinforcement can be assembled manually (which is not easy to do with gloved hands) or with a tool. For mating use:
Knitting gun. The fastest way. Pistol inconvenient to use in remote places; besides, he spends a lot of wire. Its main drawback is the price. Models of leading manufacturers cost about 30,000 rubles. , the Chinese gun is enough for 1 foundation.
Professional tool - a gun for knitting fittings
Knitting Hook. Looks like a bent and turned nail with a handle instead of a cap. It is often used as a nozzle, clamping in the screwdriver cartridge. The industry produces screw hooks - effective at work, but slowing down the process of mating (leave long tails).
Folk remedies. If the amount of work is small and the tool is not stocked, use pliers or make a hook from a suitable nail. Quality results can not be obtained using a homemade product; This approach will invariably affect the strength of the structure.
On the reinforcement of the shallow-strip strip foundations in the video:
The cores that make up the structure differ in their purpose:
Working reinforcement. So called longitudinal horizontal bars placed along the strip of the foundation.
Clamps. They are divided into horizontal and vertical transverse, linking the frame into a single unit.
The reinforcement cage of the foundation in private construction often has parameters:
Armature. Metallic or composite, section 11-14 mm (for a small farm building), with a periodic profile and section 12-18 mm (for reinforcement of tape-type foundations).
Example of how to knit reinforcement for the foundation with transverse clamps
It can be interesting! In the article on the following link read about the foundation for a wooden house.
Horizontal elements. The rods are stacked with an overlap and are connected with vertical elements. In a shallow-deeper foundation, 2 layers are made (from 2 to 4 rods in each), in a deep-seated - 3. The distance between the rods does not exceed 30-40 cm.
Vertical elements (connecting and supporting the upper and lower layer) are placed in 40-90 cm.The load on the vertical elements is small, so rods with a cross section of 6-11 mm can be used for them.
Corrosion protection. The reinforcement cage must be completely submerged in concrete; it should be separated from the formwork by 6-8 cm. When organizing the foundation for a private house, the reinforcement rods in most cases are connected using a crochet hook.
About how to knit reinforcement correctly on the video:
The amount of material (in meters) is calculated based on:
Foundation parameters (length, width, depth)
Reinforcement schemes (number of layers and longitudinal rods in width)
Most often, the material for reinforcement is realized not in linear meters, but in kilograms. For the transfer of values, there are special tables. Plastic fittings are often sold in running meters.
Tape foundation reinforcement scheme
Correct Binding of reinforcement for strip foundations, optimal in many respects, is a combination of rods of reinforcing cage "cell". In this case, the rows are fixed with wire (or other selected method) at an angle of 90 °. The knitting scheme consists of several sequential operations:
A fragment of 25-30 cm in length is cut from a skein of knitting wire (for rods of 8-16 mm in section).
The wire is bent in half and brought under the overlap of the rods, placing diagonally.
A hook is hooked on a loop (the place where the wire is folded), the opposite end of the wire is cut around the intersection of the rods and placed over the hook.
By rotating the hook around the upper end of the wire, a twist of 3-4 turns is created.
The hook is removed, the ends of the wire unbent inside the structure.
About the intricacies of reinforcement in the video:
Angles of tape the foundation can not be reinforced with a simple overlap of the rods; This is considered a gross violation of technology. For the reinforcement of corners and connecting adjacent linear elements with them, bent rods are used, the corner fragment is reinforced with L-shaped or U-shaped anchors.
Bars laid at the corners of a building without a bend, at right angles, are unable to create a rigid structure. Such parts of the foundation are likely to be destroyed in the future.
Angle reinforcement requires adherence to technology
The framework for the future foundation is calculated and mounted on the basis of the size of the trench, from the working reinforcement and auxiliary wire. Its parameters are calculated in advance, taking into account the expected load; it is convenient to assemble the construction on a long workbench. Installation of valves takes place in stages:
Vertical elements (clamps) are assembled. Vertical arrangement of the rods is checked with a plumb line.
The lower horizontal belt is mounted. The lower belt works to deflect the foundation down. It is attached with knitting wire to the vertical clamps.
The upper horizontal belt is mounted. His task is to resist bending the foundation strip upwards.
Corner elements are mounted. They need to pay special attention because they bind the sides of the foundation. Additional rigidity is provided by additional vertical racks, which are laid twice as often.
Formwork is being prepared for the foundation.
Installation of the linear fragment of the reinforcing frame
The prepared reinforcement cage is being laid. In the process of laying, pipes are laid between the bars of the reinforcement (systems of engineering communications and ventilation will subsequently be laid through them).
Concrete is poured. Filling is performed in several stages, with each layer being leveled (manually or by vibroplatform). This technology ensures uniform distribution of the concrete mix.
Waterproofing of the foundation is carried out. After the concrete has dried, the foundation tape is coated with bitumen mastic or roofing material. Such an operation is an important measure to preserve the foundation.
If the frame is going into a trench, into the ground, with respect to the calculated distances, first the rods are driven in. They fix transverse lintels, the lower and upper reinforcing belt.
It may be interesting! In the article on the following link read about the brick for the foundation of the foundation.
The laying of the foundation is a crucial stage of construction, determining the strength of the supporting structure and the whole house.In order for the foundation to work properly and for many years not give cause for concern, the work is best entrusted to professionals.