An owner planning to build a house must have at least some performance where to start construction.
And most importantly, necessary know where and how to start.
Capital buildings must stand on durable a foundation that can last for decades and withstand all loads.
What is reinforcement and why is it needed?
Reinforcement- This is the laying of strong steel rods along the foundation strip. Concrete stone has great performance strength in compression, but under tensile loads it is not as strong.
Various soil structures and building features can cause uneven loads, which leads to various deformations, including ruptures.
As a result of ruptures, the foundation may become covered cracks. And any of them can lead to the destruction of the house.
To strengthen the structure and compensate for this shortcoming, it is necessary reinforce strip foundation. Steel reinforcement, which is placed inside the concrete, helps eliminate its stretching, making it durable and sustainable to temperature changes and heavy weight.
What fittings should I use?
For the frame the following are usually used types of fittings:
- rods made of steel A-III, the diameter of which 1,0-1,6 cm and length is about 600 cm;
- clamps, whose diameter 0,5 -1 cm, they are made from auxiliary fittings Vr-I;
- vertical rod-pins diameter 1 cm.
Auxiliary fittings must be used Necessarily, if the foundation is concreted with a height of more than 15 see Vertical rods are designed to connect the vertical parts of its structure and uniform distribution of loads along the entire foundation of the building.
Reinforcement calculation
When calculating the reinforcement of a strip foundation, the following parameters are taken into account:
on reinforcement frame links;The maximum load occurs at longitudinal parts frame. Because optimal An option would be to use ribbed pins for frame reinforcement. Thanks to this, the most will be achieved quality adhesion to concrete.
The laying of the frame is carried out taking into account the difference in soil indicators. The larger it is, the thicker Reinforcement bars must be used in the frame.
Steel rods laid along the perimeter of the foundation should be located at a distance of more than 50 mm from the top edge of the base, formwork and bottom. Reinforcement placed in concrete must receive corrosion protection.
The distance between the rods is determined, for example, like this. Let the width of the foundation be 0,4 m, then distance between the rods located lengthwise there should be equals:
- 1-3 dm vertically depending on depth and load;
- 3 dm horizontally.
Smooth rods that can withstand lighter loads are used for vertical and transverse frame elements. Place them at a distance 1-3 dm from each other. Sometimes it is possible to place the rods at a distance of up to 5 dm.
Important! According to building rules, the strip foundation frame must be made in width 2 times less than the height. After all the calculations have been made, installation work can begin.
How to make a reinforcement cage?
Exist standard technological operations for reinforcing such a foundation, which involve laying four rods laid horizontally: two- at the top edge; two- at the bottom. The rods are connected to each other with clamps.
It should be noted that protruding reinforcing bars adhere better to the concrete. That is why it is best to cut slightly longer than the foundation.
Installation includes the following Steps:
- under the foundation trench, and then broken bricks in layers 1-1,5 dm;
- Slicing And location frame rods in longitudinal and transverse directions;
- Installation reinforcement at corners;
After the formwork is installed, the supporting reinforcement rods are installed. They are located along the entire length of the trench. Right You can check whether the rods are installed using a plumb line.
The layer of broken brick at the bottom of the façade trench is intended for the so-called cushion. Sand-lime brick for this purpose unacceptable.
The transverse reinforcement can be bent so that it seems to go along the trench. A pipe is put on the rods, and with its help the rods are bent like this necessary.
Harness necessary to ensure that the foundation reinforcement is accurate and high quality. It reliably fixes the location of the fittings. In practice, plastic clamps, welding or knitting wire are used for this purpose.
Most reliable is the fixation of reinforcement with tying wire.
After the reinforcement has been made, it is necessary to pour the foundation concrete. You can find out what concrete to use for these purposes from ours.
Reinforcement scheme
Its various options can be found on the Internet. Sometimes even everything necessary calculations
Fittings
This is a traditional material for creating the frame of foundation structures. It is used in strip foundations, pile foundations, column foundations and prefabricated reinforced concrete foundations. Class AI reinforcement is used to create a reinforcement frame in the foundations for “light” houses: frame, wooden, less often for houses made of foam concrete and aerated concrete, and other lightweight structures. This is due to the fact that AI has a circular cross-section in cross-section and a smooth surface. Because of this, its adhesion to concrete decreases. The diameter of the reinforcement used is 6 mm and above. Calculated at the house design stage.
Class AIII fittings are made of alloyed and high-quality steel with increased strength characteristics. It is ribbed in cross section. The surface pattern can be of several types: ring, crescent or mixed. Reinforcement with a ring profile is designed for massive structures due to its high adhesion to concrete. Reinforcement with a crescent pattern can be used in structures subject to tensile loads. For tensile loads, reinforcement with a larger diameter is used.
The diameter of the reinforcement is calculated at the design stage. For “light” houses with relatively low weight, reinforcement with a diameter of 8-10 mm, or mounting 6 mm, is allowed. In houses with heavy walls, reinforcement with a diameter of 12-14 mm is used to reinforce the foundations.
Non-carbon steel reinforcement can be welded when preparing the foundation frame. Welding of carbon steel reinforcement is not recommended. The weld area will be fragile. It is better to knit the reinforcement with tying wire.
The fittings are produced in coils and in the form of rods. Reinforcement with a diameter of 6-10 mm is supplied in coils. Large diameter fittings are supplied in rods. Standard rod lengths: 6 m, 9 m, 11.7 m. The maximum diameter of the manufactured reinforcement is 32 mm.
Composite reinforcement
Its main advantage is its significant corrosion resistance and inertness to any aggressive environment. Such characteristics make it possible to reduce the diameter of the reinforcement when reinforcing foundations without reducing the strength of the structure as a whole. The use of reinforcement will make it possible to reduce the protective layers of concrete. The calculated and expected durability is assumed to be about 75 years. Based on materials, composite reinforcement is divided into: glass, basalt, and Kevlar.
The advantages of composite reinforcement: strength is 1.5 times higher than steel, is not subject to corrosion and is 3.0-3.5 times lighter than steel. It has dielectric properties and is radiotransparent. Frost-resistant. The coefficient of thermal expansion (CTE) of composite reinforcement is equal to the CTE of concrete. With a lot of advantages, there is one technical drawback - low heat resistance.
Composite reinforcement is more expensive than conventional reinforcement. But there will be an article of savings on the diameter of the reinforcement used. To reduce costs, you can use a rubble concrete foundation, when coarse aggregate is added when pouring concrete: broken brick and rubble stone (savage), crushed stone and gravel.
Fiber concrete
A material that is gaining popularity when pouring foundations is reinforced concrete. The properties of concrete depend on the type of fibers. Fiber-reinforced concrete is used for pouring strip foundations and for complex reinforcement to improve the quality of the foundation.
To reinforce concrete, different types of fiber are added. Fiber is a waste product from the production of nails and cutting of steel wire for steel fiber. Basalt fiber is made from basalt fibers. Similarly, glass fiber and polymer fibers, in particular polypropylene, can be added to concrete. Textiles are added.
Adding fiber increases impact resistance by a fantastic 500% and abrasion resistance by 50%. In this case, 900 grams of propylene fiber per 1 cubic meter will be sufficient. m of concrete, or 20-50 kg of steel fiber per 1 cubic meter. m.
These additives are designed to perform the function of reinforcement in concrete, increasing crack resistance and resistance to deformation. Such qualities as frost resistance and water resistance are improved. Adding fiber to concrete lightens the weight of structures made from it. Along with fibers of various natures, binders and modifying additives are added to fiber-reinforced concrete. All together gives concrete completely new properties, which can significantly reduce construction time and save material consumption.
The foundation is the part of the building that is located below and takes the main loads, transferring them to the soil layers. There are several methods for making a concrete base. Builders choose one method or another depending on the characteristics of the soil, the mass of the structure and other factors. Thus, when constructing low-rise buildings, strip foundations are most often laid. It is important that the concrete base of the building is strong and durable. To strengthen it, experts resort to. It is important to take into account that different types of concrete foundations require the use of different screeds and reinforcement methods.
Benefits of foundation reinforcement
Installing reinforcement helps make concrete higher quality and stronger. Consequently, a building that stands on such a foundation will be stable and durable. The use of a screed is necessary so that over time the base is not exposed to various factors. The screed helps strengthen the structure.
Knitting the reinforcement frame
Knitting reinforced mesh at each corner of a concrete structure requires special care. The rods are bent, and the overlaps are hidden in cement walls. To determine how strong the reinforced tie for the base screed is, you can stand directly on the frame. A properly made structure will support the weight of the worker and will not deform. The reinforcement bars should be placed as follows:
- Before knitting and pouring concrete, you need to calculate the load of concrete on the base. This value will allow you to determine the consumption of building materials (diameter and volume of rods for reinforcement).
- During the manufacture of the frame, special attention should be paid to the possible maximum load that will be exerted on the base due to soil deformation.
- To make concrete stronger, the reinforcement should be placed in concrete mortar to a depth of five centimeters.
Types of reinforcing mesh for foundations
On the modern building materials market there are four main types of reinforced mesh, which are used for screeding and other work:
- Working. When working with foundations, builders use this product to counteract the stretching and pressure that occurs under loads from both the outside and the inside.
- Distribution. With its help, you can secure the rods of the working reinforcing mesh - this will contribute to the correct distribution of loads.
- Assembly room. Such reinforcement is used when installing frames in the desired position. After filling the foundation with concrete, the reinforcement can be dismantled.
- Clamps. They are used to create frames and carry some loads. Clamps are similar to distribution reinforcing mesh.
In addition, the fittings can be smooth or corrugated. The use of a corrugated frame makes it possible to increase the conjugation of concrete and reinforcing screed.
Reinforcement rules
Installation is a complex process, the correct execution of which will determine the strength of the foundation. Before reinforcing and laying the concrete base, it is necessary to calculate all loads. Calculations will allow you to choose the right type of reinforcing mesh. To do this, you should contact a specialist.
However, there are general tips and recommendations for screeding the foundation. When performing work, it is important to take into account that when constructing low-rise buildings, the frame is fastened with wire, and not a welding machine, since welding changes the properties of the metal rods at the seams, which negatively affects the reinforcing mesh. In addition, the frame must be located in the base structure of the building (distance - at least five centimeters from the surface). The corners are reinforced using bent rods. The mesh must be cleaned of rust and debris, as they reduce the contact of the frame with the concrete mixture.
Reinforcement of a monolithic strip foundation
To strengthen the strip base of the building, it is necessary to install wood formwork. A reinforcing mesh is driven into the soil, the length of which should be equal to . The reinforcement should be placed at a distance of fifty millimeters from the wooden formwork. It is necessary to install supports for reinforcement one hundred millimeters high in the pit. You can purchase them at a specialty store or use bricks. Then jumpers must be secured to the pins, and the intersection area must be secured with wire.
Reinforcement of a slab foundation
Reinforcement of slabs involves the use of a reinforcing steel frame, which is located inside the concrete. First you will need to dig a pit, checking the dimensions using a special level. Under the base, which includes gravel and sand. Then the pillow is waterproofed and laid on the slabs. After all the necessary work has been carried out (laying the cushion, waterproofing), you can begin installing the reinforcement frame.
First you need to create two reinforcing meshes (the diameter of each cell is twenty by twenty centimeters) from rods. When the grids are ready, one of them is placed on the bottom layer of waterproofing material, the other a few centimeters from the surface of the slab. To reinforce such products, formwork is installed around the entire perimeter of the tile. It must exactly follow the outline of the building. The frame is attached to posts standing in a vertical position on the outside of the base. The walls of the shields are covered with cardboard, which can be used to retain liquid in the cement mixture. Then the solution, poured into wooden formwork, is carefully compacted.
The strip type of foundation is used when a heavy building is being built. That is, only heavy wall material is used in its construction. Such materials include bricks, cinder blocks, concrete and more.
Depending on the size of the building, a trench is dug under the foundation.
If we take the view of a private house. On average, its width is about 50 centimeters and no more than one and a half meters deep. Next, the formwork is installed, and the entire form is filled with concrete.
But, in order to avoid cracking of the foundation base during soil shrinkage, before pouring the concrete solution into the formwork, the foundation base must be reinforced.
The question suggests itself. What fittings are used for this? When choosing the type of material to use in the foundation, as reinforcement, you should take into account the type of foundation itself, the strength and height of the future building.
Mainly:
- Mounting fittings:
- Structural or distribution type reinforcement, which is most often used as additional reinforcement. The main function of this type of reinforcement is to increase rigidity;
- Working fittings;
- Longitudinal view of reinforcement, which is used to increase resistance;
- Transverse type of reinforcement, which is more designed to neutralize the total load.
What diameter of reinforcement is needed for a strip foundation
Among all types of fittings, there is an average indicator by which the diameter of the required fittings is determined. In addition, when making your choice, pay attention to the appearance of the fittings.
It may have a smooth surface, or it may have a ribbed surface. Reinforcement with a ribbed top is considered more durable than smooth reinforcement. Due to the unique surface, that is, due to the ribs, this type of reinforcement has the property of better adhesion to concrete mortar.
With smooth sides, reinforcement is used mainly as a structural element, that is, as a skeleton for the foundation.
If the future building is an individual structure, then in this case, for reinforcement it is best to use metal rods 8-16 mm in diameter. However, their size depends on the size of the building itself.
The type of reinforcement described above is established using several methods. In this case, the first type of installation of reinforcement is carried out manually by knitting in advance of the installation of the formwork. This means that the prepared rods need to be tied together using soft wire.
Thus, the resulting frame is installed inside the formwork and filled with concrete mortar. An additional belt is installed to strengthen the foundation. If the builder is not a professional, the process of tying the reinforcement itself is long and painstaking.
Such fastening can be replaced by welding. Despite the fact that welding shortens the bonding process, the strength of such a foundation is lower.
It is safe to weld a reinforcement frame only if a foundation with such a frame is needed for a non-residential premises.
The strip foundation is reinforced in two encircling rows. The first row of the belt is laid at the very bottom of the formwork, and the second row is placed on top. In this case, only rods with a diameter of 10-14 mm should be used. Remember, the heavier the building itself, the larger the diameter of the reinforcement should be.
At the base of the frame, be sure to use reinforcement with a ribbed surface; you can already supplement the skeleton of the frame with smooth rods.
In this case, the diameter of the smooth rods must be at least 8 mm, taking into account the fact that they are located at a distance of 50 centimeters from each other.
In this case, metal products are tied together to create something in the form of a cage.
If everything is done correctly, during shrinkage and under the influence of the external environment, the foundation will not lose its power, but will only become stronger and stronger every year.
Due to the fact that a strip foundation is less susceptible to bending than, for example, a slab foundation, reinforcement is used for reinforcement with a diameter of 10 to 12 mm and very rarely a diameter of 14 mm.
For reinforcement, two belts are used:
- Longitudinal rods - they are laid at a distance of 5 cm from the surface of the foundation in its lower and upper parts. They are the ones who take on the load on the foundation. Therefore, in this case it is necessary to use ribbed reinforcement.
- Vertical and transverse rods - they do not carry much load, so they are made of smooth reinforcement
For example, if the width of the foundation is 40 cm, then four longitudinal rods will be enough, two should be at the top and two at the bottom.
Let's give an example.
The length of the foundation for a house is 6 by 10 m with two internal walls:
6 + 10 + 6 + 10 + 6 + 10=48 meters.
If the width of the foundation is 60 centimeters with reinforcement of 6 longitudinal ribbed rods, then their length will be 48 * 6 = 288 meters.
When creating a frame for this type of foundation, you can use 4 reinforcement bars, which are connected to each other into a frame having a diameter of 6 to 8 mm. In this case, the distance between thick rods should be 30 cm.
Such a foundation will turn out to be long and not very wide, and there may be a complete absence of transverse ones. And horizontal rods will be needed to create a frame.
Reinforcing the corners of the foundation is very important.
In order for the frame to be strong, the rods must be connected with a cage, while placing the rows at an angle of 90 degrees.
An excellent way to join is by crocheting with a special wire.
How to knit reinforcement for a strip foundation
The binding of the reinforcement itself is performed as follows:
- Take a wire and cut a piece of wire equal to 30 centimeters
- Then folded in half
- Next, you need to wrap a piece of wire around the joint of the rods diagonally
- The next step is to insert the crochet hook into the loop.
- Now place the loose ends of the wire into the hook.
- The last stage is to turn the hook clockwise until good security is achieved.
In addition, you can use electric hooks for knitting or use a screwdriver with a special attachment.
The strip foundation is a strip of reinforced concrete that runs along the entire perimeter of the building under the external load-bearing walls, as well as under the structural partitions located inside.
A notable feature of a monolithic strip foundation may be the identity of the cross-sectional shape of each of its fragments. The main advantage of this type of foundation is the ease of its production when compared with pile or slab foundations.
The main material for the production of a monolithic strip foundation is considered to be concrete, created from sand, cement and water mixed in a known proportion. Since hardened concrete cannot boast of the necessary strength and resistance to the influence of various causes (mechanical loads, moisture, temperature changes, etc.), there is a need to specially strengthen its structure.
Ready strip monolithic foundation
In order to solve this issue, it is successfully used concrete reinforcement– adding metal products to its internal structure, which, due to their own plasticity, add the required hardness to the finished product.
Methods for reinforcing strip foundations
The strip foundation is regularly subjected to various loads. This happens due to soil shifts. Soil vibrations occur as a result of the influence of various forces on it, the most common of which is considered to be the force of soil heaving. In order for the foundation to successfully resist such forces, it is recommended to reinforce it. Reinforcement blocks the formation of cracks or other flaws in the foundation.
Correct reinforcement of the tape and the corner part of the foundation
Main frame made of reinforcement
The reinforcement scheme for a strip foundation is quite trivial, but in order to make this scheme it is advisable to know a few points. First you need to know that several types of reinforcement are used to prepare the reinforcement frame. Longitudinal reinforcement is usually a ribbed rod with a diameter of 12 mm. Vertical and transverse rods are usually smooth, their diameter is smaller than that of longitudinal ones.
Example of strip foundation reinforcement
The reinforced frame for the strip foundation is assembled in advance and installed in the finished form into the formwork. Since it is impossible to determine where the greatest deformations will be, it is best to make three levels of longitudinally directed reinforcement. If it’s shallow, then 2 is enough. Smooth rods are used to form racks on which longitudinal ribbed rods will be mounted.
First of all, it is advisable to assemble the racks. It is best to assemble them on a pre-made template. Then a rod of suitable size is cut, formed on a template and tied with wire for knitting. A special crochet hook is used for knitting. It can be purchased at one of the construction supermarkets.
When the required number of reinforcement frame racks has been prepared, these racks should be connected to each other in 3 longitudinal belts, using a ribbed rod with a diameter of 12 mm. They are also connected using wire. The distance between the posts should be approximately 300 mm. Since the width of the foundation strip is usually less than 400 mm, the width of the reinforcement cage will also be 300 mm. The distances between the frame and the formwork located at the top, both below and on both sides should be 50 mm.
We reinforce the corner part of the foundation
When reinforcing the foundation strip, it is also worth paying special attention to the reinforcement of the corners. It is realized using bent rods. One end of the rod is bent into one wall, and the other end into the other wall. The transfer of rods to another wall must be more than 40 diameters of the reinforcement. If the rod is not enough to prepare a bend for another wall, then the torn rods at the corner are connected with an L-shaped rod. You also need to pay attention to the fact that in the corners the distance between the posts of the reinforcement frame should be half as much as in the strip frame.
High-quality reinforcement of the foundation strip
To summarize, it is advisable to note that it is easy. However, it will take a lot of time and work. In addition, there is no need to be greedy with the reinforcement frame. It significantly increases the stability of the building’s support and in the future you will not have to worry about the reliability of the foundation.
Video on reinforcing a strip foundation
A brief and very clear video instruction on reinforcing a strip foundation and its construction.
Where does reinforcement begin?
Before starting the production of a reinforced strip foundation, it is recommended to carry out preparatory calculations of the actual load on the foundation. Next, in full accordance with the obtained value, the required reinforcement is selected according to the required cross-section (for example, reinforcement with a diameter of less than 12 mm is perfectly used when reinforcing a strip foundation for the construction of a garage or frame building and is absolutely inapplicable for implementation in the foundation of a brick building).
Steel bars used for foundation reinforcement
Since the stability of the strip foundation fully influences the final stability of the entire house, it is advisable to entrust the calculation of the diameter of the required reinforcement to professionals, who will also know the most appropriate step for installing the reinforcement. The next fundamental parameter of a strip foundation - depth - is determined from the results of studying the soil.
Methods and technologies
The initial operation of producing a strip foundation is the installation of removable wood formwork. Since wood is a material that absorbs water well, to prevent this, glassine is used, mounted to the formwork with a stapler. The bottom of the trench made for the strip foundation is covered with a layer of broken bricks approximately 50 mm thick. It will become the basis for the reinforcement frame.
Pouring strip foundation with cement
One of the main criteria for the correct reinforcement of a strip foundation independently is strict adherence to the distance from the internal iron structures to the external surface. It cannot be less than 50 mm. The implementation of these rules will make it possible to make a foundation of such a structure that all reinforcement components will be placed inside the concrete.
This will ensure that the criteria necessary to give the foundation the expected strength and increase its durability will be met.
The technology for the production of reinforcement implies a specialized structure for its installation, the type and quality of which really determine the characteristics of the final object (foundation). The form of reinforcement is almost always a metal frame, the rods of which are placed at a distance (step) from each other strictly described in the project. This parameter depends on the desired foundation depth and is in the range of 100 - 250 mm.
This is what the reinforcement frame of the foundation looks like
Limits are also imposed on the volume of the reinforcement cage cell - its length is taken to be 400 mm and its width is 300 mm. The depth of such a cell is determined by standards for high-rise buildings, when the load on the foundation exceeds the average values, and is 750 mm. However, in the case of building a country house, the parameter of the depth of the reinforcement cage cell does not play a special role.
The methods of fastening reinforcing rods to each other are also affected by stability and safety restrictions. It is not advisable to make such connections by welding, since with all this, the physical parameters of the metal change at the point of the weld - its thickness decreases. The best solution in this case would be to use a wire connection. With all this, it does not hurt to ensure the integrity of the rods (without intermediate connections), which has a positive effect on the strength and stability of the reinforcement frame. One of the methods of increasing the strength of a strip foundation would be to install ventilation holes (more than 3) in the basement area of the foundation. In addition, the depreciation coefficient of the foundation also increases and the formation of rottenness is blocked.
Formation of reinforcement frame
The process of producing a reinforcement frame begins with the installation of reinforcing bars along the perimeter of the foundation by driving them into the ground. Next, the lower and upper chords are tied along these rods, and in order to achieve the required rigidity, absolutely the entire height must be filled, and it is advisable to install the reinforcement along with the installation of the formwork. To perform the tying, a knitting wire and a special hook are used. The finished frame will have the necessary strength and stability to avoid distortion of its shape during concrete pouring.
Unless otherwise specified in the project, reinforcement is carried out using standard methods: vertically in pairs (step 300 mm) or horizontally in pairs (step 2000 mm). When implementing the horizontal type of reinforcement, an indispensable condition will be the use of vertically laid rods at the lintel connections. The quantity, diameter, length and precise placement of each rod is recorded in the project. In the absence of information of this kind, the frame is implemented with 2 rows of vertical reinforcement. They are fastened in horizontal rows, the number of which is determined by the depth of the foundation.
For the production of concrete mixture, high-quality concrete grade M200 is used.
Video on DIY reinforcement technology
Who else but the French knows how to carry out proper reinforcement? Modern European technology is demonstrated using the example of a strip foundation.
Final processing
It is advisable to provide the finished foundation with the required protection from water. For this, after the final hardening of the concrete, which will take about 7 days, the outer plane of the foundation is covered with bitumen mastic, onto which a waterproofing material (roofing felt, cellophane, etc.) is glued.
Ready-made reinforcement frame for the base of a wooden house
In addition, it is advisable to treat the soil touching the foundation with a polymer mixture of a binder type. Finally, the layers of the foundation cavities are filled with sand. Any layer is properly compacted and filled with water.
Nuances
Higher quality reinforcement of a strip foundation comes out when adjacent reinforcement bars are placed in a perpendicular order (“in a cage”). To create a strong bundle of rods, annealed iron wire and knitting guns are used.
The lining of bricks, which serves as the basis for the reinforcement frame, preventing its interaction with the ground, can be replaced with special eraser holders. However, the introduction of broken bricks is many times more effective and profitable.
