Reinforcement of the holes of the tape grillage. What technology is used for reinforcement of pile foundation grillages? Calculation of piles. Example

We performed all the preparatory work and installed the formwork for the pile-grillage foundation. In the same part, we want to tell you and show you our work on the installation, assembly and binding of corner fittings and grillage piles into a single structure.

To begin with, let us recall what a grillage is. it top part pile foundation, which distributes the load from the walls of the building to the piles. The grillage combines stand-alone structures into a single structure, therefore, the reinforcement of the grillage is a very important and responsible process that must be approached wisely.

So, today our work began with the installation of the previously manufactured elements of the grillage reinforcement cage. They had to be lifted onto the exposed formwork. It turned out that this was not as easy as expected. Individual elements were over 11 meters. All parts of the frame had to fit into each other in such a way that they could then be correctly connected.

After thinking a bit about how to do everything more conveniently, we went along the following path. First of all, we pulled out all the formwork screeds, and to be precise, the previously installed studs. With their help, having set the pins around the entire perimeter of the formwork, we made a convenient base for the frame. Then, starting from the large elements and moving down to the smaller ones, we carefully set the entire frame onto the formwork. Of course, it will be very difficult for one to cope, so it is better to think about assistants in advance.

After installation, we cut off excess reinforcement that went beyond the formwork and with the most ordinary brush removed all the dirt and rust, which, unfortunately, appeared on our frame due to the whims of the weather, namely, prolonged rainy days.

After all these manipulations, we moved on to the most important thing - knot tying or, in other words, creating rigidity of the connection nodes. When making a grillage, special attention should be paid to them, since the strength of the entire structure depends on them.

To knit the knots of the common grillage frame, as before, we needed:

- chopped knitting wire 1.2x400mm (price 145 rubles per package, 1 kg)

- a screwdriver with a homemade crochet hook inserted into it (bent reinforcement, diameter 6 mm)

- pliers for hard-to-reach places.

In one of our articles, we have already told you how to knit reinforcement correctly, so we invite you to refresh your memory and watch this video or, if not relevant, go further.

And then we want to pay attention to the knitting of the grillage knots, namely the corners and intersections. Recall that the entire construction of a house with our own hands is carried out on the basis of ours. So we work strictly according to it, however, sometimes, to calm our conscience, we make our own additions, which will in no way affect the overall structure.

So, we were offered 2 reinforcement knitting schemes.

The first diagram in the photo below represents typical nodes for reinforcing corners and crossings of a grillage using a reinforcing P-part.

The second scheme, also shown in the photo below, represents typical nodes for reinforcing corners and intersections of a grillage using a reinforcing G-piece.

The second method turned out to be closer to us, and we decided to use this particular option for knitting reinforcement.

For each corner of the grillage, we needed 6 L-shaped corners from the reinforcement. For each intersection, we need 4 bent reinforcement. According to our project, the minimum length of the reinforcement from the fold should be 48 cm in each direction, and accordingly the total length should be at least 96 cm.

About the corners. At the beginning of the work, we realized that it is better to insert the L-parts inside the frame, and then knit. To do this, it was first necessary to push the longitudinal reinforcement apart, insert the G-parts in the required amount, move it, and then tie it with a knitting wire and a screwdriver.

Thus, the corners and intersections of the grillage were reinforced. After that, we lowered the frame down into the formwork, starting from the middle and going to the outer sides of the frame, and continued working. It was necessary to partially return the pins for the formwork screed to their places, since, according to our idea, the entire frame was hanging on the top row of pins.

After that, we needed to reinforce the place for the future brick mine. Reinforcement of the broadening for the chimney shaft and ventilation was additionally made with meshes in the upper and lower positions from reinforcement with a diameter of 12 mm with a pitch of 200x200 mm. How we got it can be seen in the photo below.

After knitting the corners, we completed the process by placing all the studs in place.

In the course of work, we encountered the following nuances. Firstly, our piles, unfortunately, are not ideally located in all places due to the fact that while drilling in the ground we came across a lot of unpleasant foreign bodies, due to which we had to shift the location of the piles. Thus, we now have places where the piles are close enough to the formwork and there was simply no place to install the grillage frame. In these places, we cut the reinforcement and tied it using U-shaped parts with elongated ends of at least 50 cm in different directions. Below in the photo you can see how it looks in reality.

In one place, the pile left us quite strongly due to the floor slab in the ground, but since we got 36 bored piles for the whole house, which, in the opinion of the majority, is considered more than enough, we did not worry too much. At the same time, all the piles for the bearing walls were in perfect order, which could not but rejoice.

Then our initiative followed. This was exactly the moment when we acted for the benefit of our conscience and nervous system \u003d) We decided, in addition to all the universal binding of the frame, which had already been done, to strengthen the corners and reinforcement bundles sticking out of the piles with our grillage.

How we increased the rigidity of the grillage corners. To create rigidity, we added 4 reinforcing corners with sides of 40 cm, 4 pieces, which can be seen in the photo below, to the corner knitting structure. We connected the corners with the reinforcement sticking out of the piles and the grillage frame. Grabbed in about 3 places. We also used 1 corner to fasten the outer part of the grillage corner. This can also be seen in the photo below.

The situation was identical with all the piles. We knitted all 36 piles to the grillage using similar corners. We tried not to spare the knitting wire, as this is another reason to calm our conscience and be confident in the reliability of our grillage.

In the ways listed above, we have given greater strength to our structure, which is responsible for the reliability of the entire future home. We hope that our advice will help you in the construction site, and our video will provide answers to the remaining questions.

By the way, do not forget about what you need to put on after the complete manufacture of the frame. This important little thing can save you from many unpleasant moments, to which we have dedicated one of our articles.

And finally, about the most important thing. How much is a do-it-yourself grillage frame? We answer. According to our calculations, the price of our monolithic grillage frame was approximately 18,000 rubles. An excellent combination of the best price and quality that you are sure of.

And, of course, if you are interested in our DIY home construction, subscribe to our YouTube channel and read our blog.

P.S. The final part of the article about the grillage can be read.

Best wishes,

Yana and Zhenya Shigorev.

A grillage is a device that evenly distributes the load of a house on pillars or foundation piles.

There are 3 most popular types of grillage: tape, slab and pile. Reinforcement of the grillage must be carried out exactly according to the project, which must be drawn up in advance. In it, a preliminary calculation and analysis of the foundation of the future house should be made. Because, neglecting these data, you can make a mistake in the foundation, which will lead to undesirable and irreversible consequences.

The process of reinforcing slab and monolithic grillage

Reinforcement scheme of the glass part of the grillage: 1 - transverse reinforcement mesh; 2 - space frame; 3 - indirect reinforcement meshes.

When reinforcing a monolithic grillage is done, it is imperative to lay 2 layers of horizontal meshes, and make a protective layer between them. Reinforcement bars must be installed at a distance (step) of 200 mm. The joints themselves cannot be welded, because their heating leads to a loss of strength of the metal. Therefore, for reinforcement connections, it is necessary to use knitting wire, which is tied with special hooks. The reinforcement cage should be made spatial; for this, "vertical distances" are used, which are made from cut pieces of reinforcement. These segments are not made very long, so that the resulting connection has a sufficient margin of safety and stability.

The vertical outlet from the foundation piles must be connected to the horizontal rods. This is also done with a knitting wire. Reinforcement can be considered complete only when all the rods are laid in the formwork, and they will not sag anywhere under pressure on them. After that, it is necessary to check the protective layer in the lower sections of the joints.

After making sure of the reliability of the structure, you can begin the process of its concreting.

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The process of reinforcing the band grillage

Reinforcement technology is practically no different and is similar to plate reinforcement. The differences will lie in the formwork installed, because it will significantly limit the work area. Within the limits of the formwork itself, it is imperative to withstand layers of protection from all sides. It is also necessary to produce with the help of knitting wire.The rods must be overlapped. The size of the overlaps should be equal to or slightly larger than the 50 bar diameters used.

To make the right reinforcement, remember that the rods that will be laid in a horizontal position should not sag. At the moment when concrete pouring occurs, the rods must necessarily occupy the position specified in the project. The vertical rods must be correctly positioned in the strip foundation, because they will provide rigidity to the rods. Therefore, their presence in the strip foundation is mandatory.

The main difference between slab and tape grillages is that in the first option, all the heads are connected at once. With the tape version, only adjacent structures are connected with a grillage.

If you are reinforcing a grillage with a pile foundation, then this can be done from different materials... The material from which the piles are made is mainly concrete. The reinforcement process is a fairly simple matter. For the pile foundation, it is necessary to prepare reinforcing rods, the diameter of which should be 1.0-1.5 cm. In order for the piles, the height of which can be 2 meters, to be tied together, the reinforcement should be placed at a distance of 45-55 cm from each other. The frame made of reinforcement for the pile foundation must be made so that the protrusions of the vertical rods are 15-20 cm. It will be necessary to tie it to them.

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Features of work production

The main problem that arises during the construction and calculation of the foundation is in the choice of the cross-section of the grillage itself. It is imperative to take into account the fact that an air gap must be made under the tape grillage, the size of which must be at least 15 cm. Very often during construction, there may be a desire to combine the slab and tape structure. This can lead to sad consequences in the future, namely: when the soil freezes in winter, the foundation tape will rise, and the slabs will prevent this. Which will lead to the rupture of the supports, and this will cause further destruction of the entire foundation, and then the destruction of the house.

To determine the size of the cross, you first need to make a house project: determine the thickness of the walls being erected, with the type of the structure itself (number of storeys). You need to find out the slope of the construction site and the type of soil. If a strip foundation is to be used, it must match the thickness of the wall of the house itself. In this case, it is necessary to take into account the insulation of the wall and its decoration. If there is a slope at the construction site, then you must immediately take into account that the strip foundation will have different heights along its entire length.

If the slope of the construction site is very large, then the grillage can be made of a stepped structure. In this case, the support rods must be deepened at least 20-25 cm. The support must be inserted into it by 5-7 cm. When choosing the height of the steps, it is imperative to determine the thickness of the wall masonry. The steps should not depend on the location of the supports themselves, their location should be free. When the construction of the wall is carried out at the very place of the step, it is imperative to lay the rods in order to exclude the appearance of cracks. The location of this reinforcement should be in the same plane with the structure and only in the place of the steps.

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Calculation of the reinforcement of the slab foundation

To calculate the amount of reinforcement, you need to be guided by the type and shape of the foundation. They can be determined based on the load on the foundation and the bearing capacity of the soil. As an example, it can be done for a house, the size of which is 6x10 m and has 2 internal walls.

Bars that have a ribbed surface will be used. Fittings of class A3 meet these requirements. took a diameter of 10 mm. It must be remembered that the thicker the rods, the stronger the foundation will be. The thickness of the reinforcing bar must be selected taking into account the mass of the house and the type of soil on which it is located. If the soil on which the future structure will be located is rather dense and its bearing capacity is high, then the deformation of the foundation will be less. When building a panel, frame or light wooden house, where there will be soil that will have a good bearing capacity, it will be possible to use rods with a diameter of 10 mm. If a slab foundation and soil with a weak bearing capacity are used, then in this case it is necessary to use reinforcement with a diameter of 14-16 mm. The step of the frame mesh from the reinforcement is made 20 cm (0.2 m). The calculation of the quantity will look like this:

((10 / 0.2) +1) \u003d 51 pcs. rods of 10 m.

((6 / 0.2) +1) \u003d 31 pcs. rods of 6 m.

51 + 31 \u003d 82 pcs. rods.

Since the foundation is slab, it uses 2 reinforced belts: lower and upper. You need to double the number of rods in it. It turns out 164 rods, of which 102 pieces. length 10 m and 62 pcs. 6 m long. The result is:

102 * 10 \u003d 1020 m.

62 * 6 \u003d 372 mm.

1020 + 372 \u003d 1392 m.

The bottom grid of rods must be connected together. Connections are made at the intersection of transverse and longitudinal rods. The number of connections is calculated:

51 * 31 \u003d 1581 connections.

If using a plate 200 mm thick. And the distance of the slab surface to the frame is 50 mm, then 200 - 50 - 50 \u003d 100 mm or 0.1 m.

1581 * 0.1 \u003d 158, m.

158.1 + 1392 \u003d 1550.1 m. Is the required number of rods for the slab foundation.

The knitting wire is calculated:

51 * 31 * 2 \u003d 3162 connections.

You need to connect it with a double folded knitting wire. The length of a piece of wire is 15 cm. Multiplied by 2, it turns out to be 30 cm. The number of ties at the joints is multiplied by the number of joints and you get 6324 pcs.

6324 * 0.3 \u003d 1897.2 m of wire.

Quite often, a house under construction is erected on a pile type of foundation, in this case, the reinforcement of a grillage of a pile type of foundation becomes relevant.

The type of pile foundation is simply necessary in the case when construction work is carried out on weak and heaving soils, there are large differences in soil height at the construction site or there is groundwater.

In addition, a pile foundation is the only solution if the construction of a house is planned in permafrost regions, as well as in many other cases.

In general, piles are used for these purposes, differing from each other both in the method of immersion in the ground and in the material used for their manufacture.

What unites them is that it is the grillage that connects them into a single solid and durable structure.

In turn, to give strength to the grillage itself, it is imperative to reinforce it, having previously made a drawing and calculating all the expected loads during the subsequent operation of a private house.

The main features of the grillage

Immediately before proceeding to the arrangement of the grillage itself, and, accordingly, to its reinforcement, it is necessary to decide on the type of pile foundation and the number of piles themselves.

Their minimum number can be from four pieces on the basis that each corner will have its own pile.

It is on such a foundation of the pile type that the grillage itself will subsequently be laid. It can be in the form of a single solid plate or tape type.

In general, the main purpose of the foundation grillage is to interconnect all parts of the pile-type foundation into a single whole for even distribution of the load.

In the case when concrete beams are used as a grillage, it resembles a tape-type foundation, but the difference is that the grillage tape is never buried in the ground.

This is primarily due to the fact that in severe frosts, the soil tends to bulge, and this, in turn, can lead to a violation of the integrity of the grillage itself, both of a tape type and a solid slab.

The device for the foundation grillage can be different.

So, it can be made of durable concrete and have a reinforcing cage, it can also be prefabricated from various elements manufactured at the factory, and combined.

It is possible to connect the piles with various elements of the grillage itself using ordinary welding, as well as monolithic sections.

When equipping the foundation for a pile-type house, a variety of materials can be used for the grillage.

If a tape-type foundation is assumed, then the grillage can be made of metal channels or I-beams.

However, even despite the fact that the calculation of such a strip type of foundation shows its high reliability, in economic terms it is not profitable and will be quite expensive.

In this case, the most preferable will be the grillage, arranged in the form of a monolithic concrete structure, in which the corresponding reinforcement is made.

Calculation of a foundation with a grillage

In order to make the correct calculation of a foundation of this type, first of all, it is necessary to determine as accurately as possible the composition of the soil at the construction site, especially at the depth at which it is planned to equip the foundation itself.

This is necessary primarily in order to calculate the length of the piles, to plan their structure, as well as the distance between the piles separately.

The calculation of the bearing capacity of the future pile is also carried out.

When calculating a pile foundation with a grillage, it is also necessary to determine the expected loads that the house will exert directly on the piles themselves, as well as on the ground.

To get a calculation total weight of the future structure, it is necessary to add together not only its weight, but also the weight of the roof and floors.

Natural loads are also taken into account, such as, for example, snow, the mass of people in the house, various equipment and furniture.

All subsequent calculations are made taking into account the total area of \u200b\u200bthe entire house.

In most cases, a foundation with a grillage is equipped for those buildings whose area will be at least three hundred square meters.

As a rule, the necessary calculation is carried out by specialists, since there are many different subtleties and nuances.

After the necessary calculation of the foundation of the house has been made, on the basis of which the number of piles, the distance between them and the depth of their installation are determined, an appropriate diagram and drawing should be drawn up.

It should be noted that screw piles are more profitable economically and they can be equipped without the involvement of special equipment.

When carrying out work on the construction of the foundation for a house with a grillage, reinforcement of the structure must be made, both for the tape type and for a solid monolithic slab.

Grillage reinforcement

In any case, the pile-type foundation must be reinforced without fail. The piles themselves are reinforced primarily in order to give them the appropriate strength.

In turn, the grillage is reinforced to maximize its bearing capacity.

The part of the reinforcement that will protrude from the pile structure will be used as a connecting element between the pile itself and the grillage.

The fastening itself, as a rule, is carried out by welding.

To carry out the reinforcement, it is necessary to use a previously drawn up drawing, in addition, the reinforcement diagram should be in front of your eyes and directly.

It should be remembered that those elements of the grillage, on which the appropriate reinforcement will not be made, simply will not withstand the loads during the construction of walls and floors of the house.

In the case when tape grillages are mounted, the reinforcing cage itself should be made from two separate belts.

They must be rigidly connected to each other using vertical metal rods with a cross-sectional diameter of up to eight millimeters.

This diameter is chosen in view of the fact that these metal rods are practically not subject to stress, but are mainly intended to give the frame an appropriate shape.

A prerequisite is that each belt must consist of at least two rods.

The belts are tied together with the help of rods located in a horizontal position and tied with an ordinary knitting wire.

In the production of reinforcing cages for foundations with a grillage at industrial enterprises, welding machines are used for fastening transverse joints.

However, directly transverse circles or squares with longitudinal rods are connected exclusively by knitting.

If a warping device is supposed to be in the form of a solid monolithic slab, then the reinforcement scheme remains exactly the same as in strip-type foundations.

In this case, the upper frame of the frame is made in the form of a mesh of reinforcement with a cross-sectional diameter of 10 to 14 millimeters, and reinforcement with a smaller diameter is used to arrange vertical rods.

The cost of the foundation itself is mainly influenced by the amount of concrete and reinforcement used for its arrangement.

In addition, the price includes lumber, which is necessary for the construction of the formwork. Depending on their design, the grillages can be high or low.

However, regardless of the type of structure chosen, the principle of grillage reinforcement remains unchanged.

In the event that a base of a ruined type is assumed, its lower part should be flush with the ground.

In some cases, it may drop a few centimeters lower.

It is necessary to arrange trenches between the piles, in which appropriate pillows are made from carefully compacted sand and rubble.

This reinforcement cage must be rigidly connected to the pile heads and not reach the walls of the installed formwork by about five centimeters.

Only after this is the foundation itself poured with concrete. It should be noted that such a grillage is possible only if the house is being built on non-porous soil.

In all other cases, it is necessary to equip high grillages, while special attention should also be paid to the reinforcement of the entire structure.

A pile-type foundation is used as a reliable foundation for the construction of buildings. The base on the supporting elements is necessary for the construction of facilities on problem soils. The pile foundation is the optimal solution in many situations, including if the structure is being erected on permafrost or weak soil with closely located aquifers, as well as in the presence of significant differences in height at the construction site. Reinforcement of the grillage of the pile foundation allows to ensure the strength of the base, to form a reliable base for the building being erected.

The grillage is a critical, horizontally located part of the load-bearing frame, connecting the supporting columns into a single contour. It ensures the verticality of the posts, prevents them from moving. Ensuring the strength characteristics of the supporting structure is achieved by strengthening with steel reinforcement. To strengthen the support contour, a drawing is required; it is required to perform calculations of the expected forces acting on the base during the operation of the structure.

Pile foundation - a universal base for the construction of brick, wood, aerated concrete and foam concrete low-rise buildings

Let's consider how the grillage foundation is strengthened. Let us dwell on the features of the main stages of work, the professional implementation of which will ensure the reliability of the base being built.

What is a grillage?

For those who do not know the construction terminology, we inform you that the grillage is an important part of the pile foundation, connecting the pile heads into a single power circuit.

Exist different kinds grillages used in pile foundations:

• tape type, representing a monolithic concrete tape. It is located along the perimeter of the supports sequentially located under the load-bearing capital walls;
• slab structure, in the form of a monolithic slab, the dimensions of which correspond to the contour of the base of the structure and cover all the supports.

The grillage is a strip structure that connects free-standing piles to each other

Depending on the features of the grillage foundation, it can be manufactured in the following versions:

• One-piece version. Manufacturing is carried out by pouring concrete mortar into a previously prepared formwork. The formation of a monolithic base occurs after the concrete mixture has hardened.
• Composite. The base is a prefabricated surface from industrially produced reinforced concrete products, connected during installation with support columns, as well as with each other.

Regardless of the design features, the grillage forms a supporting surface intended for the construction of the walls of the building. The strapping of the columns located in the ground ensures high rigidity of the spatial system and resistance to the effect of acting forces.

Reinforcement of the pile grillage base allows you to strengthen the monolithic base with steel bars, which contribute to the integrity of the structure and increase durability.

Design features

To form a strip foundation located on the piles, grillages are made at different heights in relation to the zero mark. Depending on the location of the contour relative to the ground level, the following types are distinguished:

• high, the lower mark of which exceeds the ground level by 10 cm or more. Constructed for light buildings located on all types of soil. On problem soils, its device is especially important. The structure needs serious reinforcement with reinforcement, which is associated with the presence of cavities under the concrete monolith located above the soil surface;

It is in the case of monolithic installation pile grillage, which is used when arranging houses made of heavy materials, it is necessary to reinforce the strapping

• ground version, made on gravel-sand bedding without burying into the soil. Its peculiarity is the lack of free space between the concrete monolith and the ground. Installation is carried out on non-problematic soils. When the soil is susceptible to frost heaving, cracks may form and the hardened concrete mass may separate from the support columns;
• shallow-buried type, formed by burying the lower part into the soil on a previously prepared sand and gravel bed. The design of such a base resembles the device of a strip foundation, the base of which rests on piles. The formation of a buried foundation is associated with significant costs and is used for the construction of massive buildings located on soils characterized by a low bearing capacity.

Pile-type foundations are mainly formed for light structures. That is why the grillage foundation is quite common, the basis of which is a hanging tape made of concrete reinforced with steel reinforcement. With a base height of up to 40 cm, its width depends on the type, size of the material used for the construction of walls, and is 30-40 cm.

About the expediency of reinforcement

The need to strengthen the base of the building with steel reinforcement is associated with the characteristics of the concrete. The material has increased resistance to compressive forces, but is susceptible to bending moments and stretching, which cause damage to the integrity and deformation of the base.

Note that the foundations are subject to reinforcement, in which two types of piles are used - driven and bored.

Reinforcement of the pile grillage structure allows you to prevent the likelihood of destruction, increase the stability, service life of the building being built The reinforcement cage located inside the concrete mass absorbs tensile loads and bending forces, ensuring the stability of the base being erected.

Regardless of the design of the piles used, located inside the soil, the support columns are also reinforced with reinforcement. The steel bars located in the piles are connected to a common structure with the reinforcement cage of the supporting surface.

Reinforcement of the pile foundation grillage allows:

• Prevent the destruction of the monolithic mass as a result of soil reaction.
• Significantly increase the strength of the base, taking the load from the mass of the structure.
• To prevent shrinkage of the structure caused by the low strength characteristics of the base.

Strengthening the grillage foundation avoids negative phenomena.

Reinforcement specifics

Reinforcement of the pile foundation grillage is carried out with a pre-fabricated volumetric frame, consisting of two tiers of rods, united into a single structure using steel lintels.

Reinforcement of the tape grillage is carried out by means of a spatial reinforcement cage, consisting of two longitudinal reinforcement belts

For the longitudinal belts of the frame, corrugated rods are used, produced by the hot-rolled method, which corresponds to the class of reinforcement A3. Depending on the load perceived by the base, the diameter of the rods is 12-16 mm.

Connecting elements located in the vertical and horizontal planes can be combined into a common power loop:

• separate corrugated steel rods of rectilinear shape, the diameter of which corresponds to the range of longitudinal reinforcement;
• steel clamps of rectangular configuration, made of smooth bars of class A2 with a cross section of up to 10 mm. Despite the increased complexity of manufacturing and installation, rectangular jumpers provide reliability and durability of the reinforcement structure.

When strengthening the strip foundation placed on the piles, adhere to the following recommendations:

• Use at least 4 rods located in the upper and lower tier of the frame of the tape contour, providing an interval between the elements of 10-15 cm.
• Observe the distance by installing jumpers in the longitudinal belt equal to 15-25 cm.
• Provide a step of vertically located frame jumpers - 30-40 cm.

Reinforcement of the grillage begins after the completion of all the previous stages of the arrangement of the pile foundation - the installation of piles, their trimming and the arrangement of the formwork

The need for a protective layer between the metal structure of the frame and the concrete surface of the grillage is due to the following factors:

• the need for the correct distribution of the existing forces by the metal structure of the frame;
• susceptibility of reinforcing bars to corrosive processes arising from moisture penetrating into concrete.

Compliance with a fixed distance from the reinforcement to the formwork while providing a protective layer is achieved by using supports made of plastic.

Calculation method

To determine the need for reinforcement that allows the reinforcement of the pile foundation grillage, it is necessary to develop a drawing in advance. The documentation contains the following information:

• Dimensions of the structure.
• Number of reinforcement belts.
• Rebar profile.
• Diameter of the used rods.
• Distance between jumpers.

Scheme of the correct reinforcement of the corners and abutments of the grillage

Knowing the overall dimensions of the grillage foundation, it is easy to calculate the length of the steel bars of the reinforcement in the upper and lower chords, as well as the dimensions of the lintels.

Summing up the obtained values, we obtain the total length of each standard size of the used reinforcement. Knowing the footage and the mass of one running meter of a certain bar, it is not difficult to determine the need for reinforcing bars, expressed in kilograms.

If the connection of the elements is not planned to be carried out using electric welding, you will need a wire for knitting. Having a drawing that provides information on the number of connection points, you can calculate the required amount of knitting wire. Considering that about 30 centimeters are needed to securely fix two perpendicularly spaced rods, the total wire requirement is determined by multiplying the number of connections by the length of the material.

Making calculations is not difficult. The main thing is to pre-develop a drawing of reinforcement.

Grillage strengthening technology

If the installation of reinforced piles has been completed and the formwork has been mounted, then you can proceed to the formation of the reinforcing cage. Please note that the frame is fixed to the reinforcement protruding from the concrete piles to the height of the formwork. Fastening of steel rods can be done by welding, as well as using knitting wire.

The work execution algorithm is as follows:

• fix horizontally located longitudinal bars at a distance of 5 cm from the bottom of the formwork;
• place and secure the perpendicular rods of the lower belt;
• install clamps of rectangular section or vertically located rods for securing the bars of the upper tier;
• fasten the longitudinal rods of the upper belt;
• perform corner reinforcement of the grillage by installing curved rods in the corners of the structure.

Reinforce the corners securely with reinforcement, since in these places the frame absorbs significant forces.

Conclusion

Reinforcement of the pile foundation grillage with steel reinforcement makes it possible to form a reliable base that ensures the stability of the structure being erected. The work is not difficult to do on your own, having previously developed a drawing, according to which the grillage of the pile foundation is reinforced.

Reinforcement of the pile foundation grillage: drawing, technology, calculation

How to reinforce the pile-grillage foundation? Correct calculation method. Features of the technology for strengthening the grillage. Drawings and diagrams of grillage reinforcement.

In the field of individual construction, when using a pile foundation, a monolithic reinforced concrete grillage is the most popular option, since even with significant sizes it can always be made on its own.

The materials used for this can be delivered to the construction site by conventional trucks or even light vehicles without the use of special platforms or cranes.

However, the installation of a monolithic grillage is more complicated than a prefabricated one, and the main difficulty lies in the correct reinforcement of the pile grillage.

You can often hear about the similarity of the grillage device and the usual strip foundation, but this statement is only partially true. Indeed, in its appearance and function, the grillage is very similar to a tape base, however, the operating conditions of these structures are significantly different:

• if for a strip foundation the occurrence of a bending moment in a vertical plane is more likely a phenomenon out of the ordinary, then for grillages, which are beams laid on piles, this is the norm. The span located between the supports takes the weight of parts of the building and other loads, while being, as it were, suspended in the air, which causes deflection;
• another difference is that the load on the strip foundation is less predictable. The underlying soil under various parts of the base may "float" or swell. This causes multidirectional deflections, in which both the upper and lower parts of the cross section can be stretched. And the stretched zone, which occurs during the deflection of a reinforced concrete element, is, as you know, exactly the zone in which the reinforcement should be located. Thus, a conventional strip foundation has to be reinforced in the same way both at the top and at the bottom.

In the case of the grillage, the impact from the soil is completely excluded, therefore, the stresses that arise in it are quite predictable: in the spans between the piles, the lower part of the cross section is always stretched, in the areas supported by the piles - the upper one.

This also determines the scheme of reinforcement of the pile foundation grillage. The lower belt of the reinforcing cage in the areas between the piles is made more powerful, and at the points of support on the piles, the upper belt is strengthened.

Selection of materials for the reinforcing cage and determination of its parameters

The diameter of the reinforcement used and the parameters of the frame are selected on the basis of a calculation that takes into account permanent and temporary loads.

The calculation of the reinforcement of the pile foundation grillage should be performed by an experienced civil engineer who is well versed in the topic of reinforced concrete structures.

Typical solutions

In practice, in individual construction, the following rules are followed:

• in the stretched zones of the grillage, several longitudinal reinforcement bars of class AIII with a diameter of 20 mm or more are laid;
• reinforcement with a diameter of 8 - 15 mm is placed in the compressed belt. The pitch between the bars of the longitudinal reinforcement, also called working, is 80 - 100 mm.
• For the perception of transverse tensile forces, as well as for combining longitudinal reinforcement into a single frame, transverse bars are attached to it - smooth reinforcement of class AI with a diameter of 6 to 8 mm. The distance between them should not be less than 250 mm, but usually it is taken equal to 3/8 of the height of the grillage section.

If the height of the grillage exceeds 150 mm, vertical rods are installed in the reinforcement cage, the step of which corresponds to the step of the transverse reinforcement.

Most often, instead of individual longitudinal and transverse rods, clamps are used - parts made of reinforcement in the form of a closed rectangle or an inverted letter "P".

Reinforcement of the abutment zones of the grillage tapes

Where the grillage ribbons form an L-shaped or T-shaped intersection, it is not enough to simply fasten the intersecting rods of the working reinforcement.

Here, rods bent at right angles are placed, each part of which fits into one of the adjoining tapes and enters into it at least 40 diameters.

Clamps in these areas are installed twice as often.

Manufacturing jobs

Reinforcement of the pile foundation grillage is performed immediately after the construction of the formwork. An obligatory element of the latter should be transverse jumpers in the upper part, to which, in the end, the reinforcing cage will be suspended.

Work on the installation of reinforcement in the future grillage can be divided into several operations.

The device of the lower belt of the reinforcing cage

At the bottom of the formwork, special plastic bosses are laid on top of the waterproofing, on which the lower belt of the reinforcing cage will then be located.

If the bosses are not available, they can be replaced with brick fragments or wooden blocks 40 - 50 mm high:

• the height of all shims must be the same so that the reinforcement rods take a strictly horizontal position;
• the spacing between the bosses or elements used as an alternative depends on the diameter of the working reinforcement: it must be such that the bars do not bend;
• on the bosses with an equal pitch, it is necessary to lay the working reinforcement of the lower chord. The distance from the outer rods to the side surfaces of the formwork should be 30 - 40 mm.

When constructing the frame, the contractor must be guided by the requirements of the documents describing the reinforcement of the grillage of the pile foundation: the design drawing with all the necessary instructions is given in the construction project.

If the grillage tape has a considerable length, each thread of the working belt is recruited from several reinforcing rods connected with an overlap of 1 m.

Bars of transverse reinforcement or clamps are attached to the lower chord, combining transverse and vertical reinforcement.

Upper belt device

The working reinforcement of the upper chord is suspended from the lintels of the formwork, which were mentioned at the beginning of the section. The length of the suspensions should be such that after the grillage is poured over the reinforcement, a protective layer of concrete 30 to 40 mm thick is formed.

The rods of the upper chord are connected with transverse and vertical reinforcement or with clamps, if any.

Then both working chords should be tied to the reinforcement protruding from the piles. The reinforcing frame can be considered ready.

Reinforcement knitting methods

The most common fastening method is tying the reinforcement with a special wire. Electric welding is used very rarely and only for fittings marked with the letter "C".

It is not allowed to weld ordinary fittings, since due to exposure to high temperatures, it becomes weaker.

For knitting of reinforcement, only annealed round wire with a diameter of 1 mm is used. Unbaked wire is less ductile, therefore it bends poorly and breaks easily.

The fastest way to knit fittings is with a special pistol equipped with a battery. But its acquisition is advisable only for large volumes of work, moreover, it is not very convenient when knitting reinforcement in hard-to-reach places.

Reinforcement of the pile - grillage foundation for a private house is mainly carried out using another tool - a special hook. Professionals prefer homemade crochet hooks, but purchased hooks are also suitable for one-time work.

On the market you can find both conventional and screw hooks, also called semi-automatic.

The latter make it possible to knit reinforcement a little faster, but due to their design, after tightening the knot, they leave too long free ends of the wire, which often protrude from the concrete and begin to rust.

The simplest and most common types of knots are the so-called "loop" and "two loops". The first is used for overlapping reinforcement, the second for butt joints. In practice, the loop is often used not only for overlap joints, but also for corner joints.

At the final stage of the installation of the reinforcing cage, you should remove the bosses on which the working reinforcement of the lower belt was installed. After that, the entire frame will be suspended on a wire twisted around the upper formwork lintels. Now you can start pouring concrete.

Video about the reinforcement of the pile foundation grillage

Pile foundation - a universal foundation for the construction of brick (about reinforcement brickwork - read separately), wooden, aerated concrete (about the reinforcement of aerated concrete - read separately) and foam concrete low-rise buildings in any soil conditions. Such bases are also used for other structures (for example, fences, columns). The strength and reliability of the pile foundation directly depends on the grillage, the reinforcement technology of which we will talk about in this article.

Grillage reinforcement

You will learn why it is necessary to reinforce the pile-grillage foundation, what materials are used for this, and how the process itself is performed. Diagrams and drawings will be given explaining all the nuances of reinforcing a monolithic grillage.

What functions does the grillage perform and why do you need its reinforcement?

The grillage is a strip structure (we read separately about how a conventional strip foundation is reinforced), connecting the free-standing piles to each other. Due to the strapping of the supports, additional spatial rigidity and resistance to tipping loads are obtained. Also, the grillage acts as a supporting surface on which the walls of the building are erected.

See also: What is reinforcement anchoring and why is it necessary?

There are several types of strapping according to the material of manufacture - steel (from a channel or I-beam), wooden (from a bar) and reinforced concrete. It is in the case of the installation of a monolithic pile grillage, which is used in the arrangement of houses from heavy materials, that it is necessary to reinforce the strapping.

The need to strengthen the monolithic grillage with reinforcement is due to the fact that concrete as a material has a high resistance to compressive loads, but at the same time it has a weak resistance to bending and tensile loads, which can cause its deformation.

Diagram of the pile-grillage foundation

The reinforcement cage placed inside the monolithic grillage absorbs the above loads, preventing the risk of its destruction, which significantly increases the reliability and durability of the structure. Reinforcement is necessary not only when installing a pile-grillage foundation, but also in a columnar base, which has a similar configuration.

See also: what kind of mesh is the reinforcement of the floor screed?

Note that the foundations are subject to reinforcement, in which two types of piles are used - driven and bored. Driven piles are prefabricated structures that, upon completion of installation, are cut with a special hydraulic pile cutter using a pile driver.

After trimming, the reinforcement is exposed on the end part of the pile, which is subsequently connected to the frame of the monolithic grillage. When installing bored supports, their reinforcement cage is made so that reinforcement protrusions with a height of 30-40 cm are above the concrete body of the pile.
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What and how to reinforce?

The reinforcement of the tape grillage is carried out by means of a spatial reinforcement cage, consisting of two longitudinal reinforcement belts (upper and lower), connected by horizontal and vertical bridges.

Longitudinal belts are made of rods of A3 class (hot-rolled corrugated profile), the diameter of which is 13-16 mm. It is possible to use fiberglass reinforcement, which is confirmed by reviews on the successful operation of such pile-grillage foundations in specialized forums.

Connecting vertical and horizontal bridges can be made in two versions - in the form of separate bars welded to the longitudinal belts of the reinforcement (the diagram shows the configuration). In this case, it is necessary to use rods of the same standard size as when arranging a longitudinal belt.

Drawing of the connection of belts with separate jumpers

Also, the frame can be connected with jumpers from the reinforcement curved into the clamps (the diagram below). This approach uses smooth rods of class A2 (diameter 8-10 mm). Bent clamps are laborious to install, but due to the smaller number of welded seams they are more reliable and durable. Fiberglass reinforcement, which cannot be bent, is not used to create clamps.

Drawing of the connection of belts with clamps

According to the provisions SNiP No. 2.03.01 "Manual for the design and arrangement of pile-grillage foundations", when installing the reinforcement cage, the following step must be observed between the constituent elements:

• the number of rods in the longitudinal belts is at least 4, the distance between them is up to 10 cm;
• the step between the transverse crosspieces of the longitudinal belt is 20-30 cm;
• the step between the vertical connecting jumpers - up to 40 cm;
• protective concrete layer - at least 5 cm.

The protective layer is the distance between the outer contours of the reinforcement cage and the walls of the concrete body of the monolithic grillage. If the protective layer does not have the required thickness, two problems will arise - the frame will not be able to correctly redistribute the loads acting on the grillage and the reinforcement will be excessively susceptible to corrosion under the influence of moisture penetrating into the concrete micropores.

Plastic stand for fittings

To make a protective layer along the bottom edge of the grillage, special plastic mushroom stands are used, which raise the reinforcement above the formwork. The use of pieces of brick for these purposes is not allowed.
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As an example, we give the calculation of the number of reinforcement for a monolithic grillage with a perimeter of 8 * 6 m.We use the conditional dimensions of the strapping 40 * 40 cm.The reinforcement frame for such a strapping will consist of two longitudinal belts of 3 rods A3 with a diameter of 14 mm in each (the pitch between the rods is 10 cm , 5 cm on each side eats away the protective layer of concrete). The belts are connected by jumpers made of reinforcement A1 with a diameter of 11 mm, located in increments of 20 cm.

The calculation is performed according to the following algorithm:

1. Determine the total length of the rods in the upper longitudinal belt. To do this: a) determine the perimeter of the grillage: 8 + 8 + 6 + 6 \u003d 30 m; b) we calculate the length of 3 rods: 3 * 30 \u003d 90 m; c) we calculate the length of reinforcement A3 for both belts: 90 * 2 \u003d 180 m.
2. To connect the rods of the longitudinal belt, we need jumpers 30 cm long, which will be located with a step of 20 cm.Calculate their number for both grillage contours: 2 * (30 / 0.2) \u003d 300 pcs, after which we calculate the total length of the transverse jumpers: 300 * 0.3 \u003d 100 m.
3. It remains to calculate the length of the vertical bridges connecting the upper and lower contours of the frame to each other. But since in the example a rectangular grillage is calculated, their number and length will be identical to the transverse lintels. If a grillage of a rectangular configuration is used, the calculation is performed according to the formula specified in paragraph 2.

As a result, the calculation showed us that the grillage reinforcement requires 180 m of A3 class reinforcement and 200 m (100 + 100) of A2 rods with a diameter of 11 mm. You may also need to calculate the tying wire if you do not plan to use a weld splice. It is carried out taking into account the fact that one connection takes about 40 cm of material: we determine the number of connections: 4 * (30 / 0.2) \u003d 600 pcs; and calculate the material consumption - 600 * 0.4 \u003d 240 m.
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Features of grillage reinforcement (video)

Monolithic grillage reinforcement technology

Reinforcement of the grillage begins after the completion of all the previous stages of the arrangement of the pile foundation - the installation of piles, their trimming and the arrangement of the formwork. You must have a ready-made formwork, inside of which the reinforced frames of the piles protrude to a height equal to the cross-section of the strapping.

Formwork and piles before starting reinforcement

When assembling the frame, the reinforcement can be knitted with each other using a wire, or the rods can be connected by welding. There is no significant difference in the method of joining - it is often argued that the welded frame, due to the lack of elasticity, is less resistant to deformations than a connected viscous structure, however, in industrial multi-storey construction, the frames of pile-grillage foundations are always welded, so these fears are groundless. In addition, welding is a more practical and quicker way to implement.

See also: how stairs are reinforced, and should it be done?

Reinforcement of the grillage - step by step instructions:

The assembly of the reinforcement cage in straight sections of the grillage is quite simple to perform. Difficulties arise when reinforcing the corners, which must be additionally reinforced, since this part of the frame experiences maximum loads.

Scheme of the correct reinforcement of the corners and abutments of the grillage

The corners and places of abutment of the inner walls of the strapping to the outer cannot be reinforced with overlapping reinforcement... In these areas, it is necessary to lay solid rods bent in a L or U-shaped configuration. A diagram of the correct reinforcement of the corners of the pile grillage is shown in the image.

Related articles:

Reinforced concrete monolithic structures are one of the prerequisites for the strength, reliability and durability of an object. Reinforced concrete means that the concrete is reinforced with a special frame, tied or welded from reinforcing bars. You should learn how to properly knit reinforcement for the foundation before reinforcing concrete in your personal plot, building a house, garage or other durable objects.

Rebar knitting options

The basics of properly tying reinforcement

Basically, in individual construction, a reinforcing frame is used when laying a strip foundation. The tape base is a monolithic structure made of concrete and a reinforced cage inside, in which the frame takes on tensile loads and lateral ground shifts. Due to the multidirectional loads on the reinforcing cage, it is important to correctly make its calculations, as well as find out the parameters of a house or other building that uses reinforcement in the structure, the number of building materials and their characteristics.

In order to tie a reinforcing belt with your own hands for any type of foundation in which it can be used, you need to be able to tie the transverse and longitudinal joints of the rods in the correct way. Welding is very often not recommended for the assembly of the reinforcing cage due to a too rigid connection, which, under sufficiently strong loads, can burst and weaken the entire structure. Therefore, you should use a special factory or homemade hook, plus know the basic layouts of reinforcing bars in concrete.

Reinforcement parameters when calculating the frame for a strip foundation

Knitting steel wire must be soft or annealed, and in order to correctly crochet the reinforcement, it is necessary to study the requirements for knitting wire, which are regulated in GOST 3282.

Professional builders categorically deny knitting of metal reinforcement with plastic clamps, which are allowed to knit fiberglass reinforcement, since the mass of concrete pouring into the formwork displaces the knitting points along with the mortar. Slab concrete foundations are a separate topic, and reinforcing frames are allowed to be welded in them. There are ready-made industrial reinforcement mesh welded from rods. But such a frame is much more expensive than a home-made one, in addition, the end joints need to be additionally reinforced with U-shaped clamps in place, which makes the welded frame even more expensive. Therefore, for the foundation of a private or country house, it is easier to knit the reinforcement cage by hand using a coil of soft wire, a special crochet hook, and instructions for use.

Rebar Tying Hook

When knitting a frame for a foundation, operations are performed in the following order:

1. A piece of knitting wire 20-25 cm long is used for tying reinforcing rods Ø 8-16 mm. A segment of this length must be cut off from the bay;
2. The segment is bent in half in the center, brought under the intersection of the rods diagonally;
3. The sharp end of the crochet hook needs to be threaded into the loop, which turned out when the piece of wire was folded;
4. The clamp, which turned out from a piece of wire, should be pulled tight;
5. the free end of the clamp is applied to the working end of the crochet hook;
6. now we knit two intersections together: when you rotate the hook 3-5 turns, you get a strong, but flexible twist;
7. After removing the knitting hook from the loop, the remaining free ends of the wire clamp must be bent inside the reinforcement cage.

Important: If reinforcement Ø 25 mm or more is used for the aromatic cage, the intersections of the rods must be welded, not tied. Connected joints can break during operation of the finished reinforced foundation under the weight of concrete and building.

Ready reinforcement cage

Common mistakes when knitting a reinforcing frame that do not need to be repeated:

1. Straight bar segments at the corners of the frame are connected by the overlap method;
2. The reinforcing frame is installed not on pads, but on the vertical rods of the frame;
3. In the context of a concrete tape, the reinforcing binder and reinforcing material is less than 0.1% of the total volume of concrete;
4. There is no protective layer on the sides of the formwork, due to which the rods can come into contact with the formwork material.

The corner intersections of the frame rods in the strip foundation cannot be simply tied and left in the form of an overlap of the rods. The connection of the rods is done according to specially designed anchoring schemes for such cases, one of which is presented below:

Anchorage schemes for frame corners

Reinforcement of the concrete foundation must take into account some of the features of the strip structure:

1. The reinforced frame for the concrete tape can be tied both in the ground and in the finished formwork. For this, reinforcing bars, metal clamps and anchors are used;
2. The deep-seated foundation is reinforced before installing the panel formwork - this option is preferable due to the fact that the heavy frame does not have to be lowered into the trench and deform it;
3. The reinforced frame must be reinforced with U-shaped or L-shaped anchors at the corners of the structure;
4. To ensure the protection of the frame from below with concrete, props 5-7 cm in size are used, which are called glasses;
5. Elongation of short longitudinal bars occurs with an overlap, the overlap should be ≥ 20 bar diameters, or ≤ 25 cm;
6. It is impossible to place the reinforcement cage on stones, bricks or pieces of reinforcing rods - only iron, plastic or concrete linings should be used;
7. Overlapping reinforcement joints must be spaced apart - in one section, more than half of the total section of the longitudinal rods should not be connected.

Important! Clamps in the reinforcement cage are used to create and hold the geometry of the structure. Therefore, the diameter of the long horizontal rods should be 6 for a length ≤ 0.8 m and 8 mm for a rod length ≥ 80 cm.

Reinforcement of a tape with L-shaped and U-shaped reinforcements

Reinforcement of a slab floating foundation should take into account some design features and not repeat common mistakes:

1. The rods at the corners of the upper and lower levels should be connected with U-shaped clamps;
2. You cannot use one reinforcing mesh instead of two frames - the lower frame takes on tensile loads from the weight of the house, and loads from heaving forces are applied to the upper layer of the frame. One reinforcement mesh is allowed with a concrete slab thickness ≤ 15 cm;
3. Non-compliance with the provision of concrete protective layers for the frame from above and below. Concrete layers should be ≥ 5-7 cm thick;
4. The mesh size of the reinforcing mesh should be ≤ 40 cm, the optimal mesh size is taken at 20 cm.

To assemble the concrete slab reinforcing frame, the upper belt of the mesh is fixed using such bracket-bending devices as "tables", "conductors", "pawns", "frogs", "clubs", "spiders", and other supporting elements with extended rods, which rest against the design of the lower belt.

Brackets for reinforcing frames and meshes

Bending of reinforcing bars should not be carried out using gas welding. The rods are bent on special bending mills or clips, in which you can set the required radius.

Near the bearing walls, the foundation should be reinforced with additional rods, since the dimensions of the mesh cells near the walls are half the size of the others. If slabs with stiffeners are used for the base, then the reinforcement cage is used the same as for the strip foundation or grillage.

Bending machine

Grillage reinforcement

Due to the fact that the grillage is like a foundation strip, many craftsmen make mistakes in reinforcing it. Tensile loads from the weight of the house are applied to the concrete tape in the area of \u200b\u200bthe sole, the upper part of the foundation is under stress from the seasonal heaving of the soil. The grillage never experiences loads from heaving forces, since it rises above the soil and has an air gap or a layer of expanded polystyrene, which crumples during deformation. Only vertical bending forces are applied to the grillage in the areas where the supports are pinched.

Important: In the grillage, the reinforcing frame is necessarily reinforced with longitudinal reinforcement connected with steel clamps. Strengthening is carried out for the upper columns, piles or pillars, as well as for the lower armored belt.

Reinforcement of grillage for piles

The section of the reinforcing frame is of different types:

1. If the formwork is tubular, then the frame can be tied round or square;
2. For a columnar foundation in prefabricated panel formwork, round or square clamps are used to knit vertical reinforcement rods;
3. One support must have at least four longitudinal bars.

Pile reinforcement

The bottom of the piles does not need to be reinforced. The pile head at a distance of 1 meter from the bottom must be reinforced and poured with concrete. Vertical rods of reinforcement are bent at an angle of 900 with subsequent tying to the grillage.

Pile reinforcement

Homemade reinforcing frame is made only on twists of soft knitting wire. Ready-made reinforcing cages for floating, slab, pile and columnar foundations are fastened using electric welding. It is forbidden to use gas welding, as the reinforcement rods become soft in the heating places.

Using the recommendations above, you can tie the reinforcement cage or mesh yourself - on the ground or in the formwork. Each type of foundation has its own structural differences that affect the thickness of the protective concrete layer, and the most difficult operation during reinforcement is anchoring the corners of the base, strengthening the stretching and squeezing areas.

The arrangement of foundations for any building is a very responsible and important stage from which the main construction work begins. It is recommended to manufacture foundations in strict accordance with the design documentation.

For monolithic structures, a rather important part of the work is the reinforcement of the grillage. The strength of the entire structure largely depends on the quality of the connected reinforcement. You can make the reinforcement yourself, having previously familiarized yourself with the technology of this type of work.

What is a grillage

A grillage is a monolithic element of the base of a building that connects free-standing pillars or piles into a single system. It is manufactured in the form of a strip foundation on which the supporting and external enclosing structures of the building are installed. The tape evenly distributes the loads over the entire base of the building, which in turn transfers them to the ground.

Grillage device diagram

The grillage can be made not only in the form of a monolithic strip foundation. It is also made from wood, metal and reinforced concrete products located between the columnar supporting structures... Such a device in the form of beams is used much less often than a monolithic one.

Distinguish between hanging and recessed structures

Depending on the height of the grillage foundation relative to the ground level, there are hanging and recessed versions of the device. When building a buried grillage, a monolithic version is selected. If hanging, then the base of the grillage can be arranged from horizontal beams.

The monolithic grillage is based on concrete and reinforcement. Reinforcement takes most of the time when constructing this type of foundation. When carrying out work on the reinforcement of the strip foundation, it is necessary to be guided by building codes and regulations 52-01-2003.

The grillage must serve as a reliable support and protect the structure from moisture. The pile-grillage foundation is suitable for the construction of buildings with no more than three floors.

Monolithic grillage device

To make a monolithic grillage foundation, you will need to complete several stages of work.

1. Installation of formwork.
2. Reinforcement of the grillage.
3. Concreting.
4. Stripping.
5. Waterproofing tape.

Formwork installation

The formwork must be installed strictly at an angle of 90 degrees

The grillage foundation is made hanging or buried in the ground. The formwork design directly depends on its shape.

Regardless of the design, the side walls of the formwork must be assembled in a strictly vertical level, and the angles must correspond to 90 °, unless another design is provided for by the project.

When making a tape in the ground, you can use soil instead of formwork, as a support for the future foundation. Above ground level, formwork is usually assembled from boards or plywood. It is knocked together or pulled together in such a way that the concrete does not squeeze out the boards and does not spread during the laying process. The part of the foundation that protrudes above the ground will be fenced with such a structure.

If a hanging version of the grillage device is chosen, then it is necessary to provide a high-quality base in the formwork. It needs to be calculated based on the load that it must withstand. The load is determined by the mass of concrete and reinforcement. It is also necessary to take into account the mechanical effects on the structure from vibration of concrete in the process of pouring it.

The side walls of the formwork must be firmly assembled. For this, transverse ties, spacers, tubes with pins and other materials can be used to ensure the reliability of the structure.

Poor-quality formwork can lead to disruption of the concrete placement process. This is unacceptable in construction, but often happens due to negligence in this part of the work.

Grillage reinforcement

Reinforcement of the structure

Reinforcement of the grillage of a pile or columnar foundation is one of the most critical stages of the foundation for a building.

Periodic metal reinforcement is used as the main material for the reinforcement of foundations. IN recent times they began to replace it with composite fiberglass. It should be noted that fiberglass reinforcement is not suitable for hanging structures. It is good where there is support on the ground.

Reinforcement is welded into beams

The reinforcement is bound or welded in some cases into frames, the so-called beams. There are several types of beams. The type of reinforcement, and hence the type of beams, is determined at the design stage.

For self-construction, when there is no project, and there is no way to contact specialists, there is an option to use the online reinforcement calculator. It is advisable to find several such online programs and make calculations in each, so that, by comparing the data, determine the error in the calculations. Having calculated the reinforcement according to the entered parameters of the foundation, you can start work.

Reinforcement of a monolithic grillage in the most common form consists of straight longitudinal and transverse rods, which are interconnected by knitting wire or welding. In order to correctly make the connection of the structure, clamps and U-shaped products are made from reinforcement. They are the connecting elements in the reinforcement cage nodes.

To find out how to correctly manufacture reinforcing cages and their assemblies, you need to familiarize yourself with the guidelines for designing concrete and reinforced concrete structures from heavy concrete (without prestressing).

Reinforcement of pile-grillage foundations is impossible without connecting the reinforcement of the piles to the grillage frame. When arranging a pile field at the stage of reinforcement, vertical rods are made with allowances in height. When installing the reinforcing cage of the strip foundation, the rods released from the piles are bent at the desired horizontal level and connected to the main frame. Thus, structural integrity is achieved. For all the details on pouring the pile-grillage foundation, see this video:

Do not heat metal fittings in order to bend them. For bending, you must use special devices or a pipe bending machine.

Concreting tape

It is necessary to pour concrete into the formwork without interruption to get a high-quality monolith

The grillage foundation is poured with concrete at a time without interruption in the work until their complete completion. It is strictly forbidden to make gaps along the length of the foundation. The only permitted action is to break the height of the grillage. After pouring a 150-200 mm layer over the entire volume of the tape, a break is made in the work.

Before continuing construction work, you must wait until the concrete has reached the minimum permissible strength. Then you need to clean off the top layer, the so-called concrete milk, and only then continue concreting the tape.

It is important to carry out work so that there are no pores in the concrete mass. The concrete is required to fill the entire space in the formwork. There should not be a single air pocket inside the grillage.

Stripping

It is important not to remove the formwork ahead of time

You can neglect this process once and make it ahead of time in order to incur losses that will significantly affect the construction budget.

If the formwork is prematurely removed, the foundation may crack, which will leave almost no options other than dismantling it. In this case, a new foundation will be required, respectively, construction costs will increase significantly.

Concrete gains strength depending on its grade and ambient temperature. The ideal temperature is 20 ° C, in such conditions concrete of the M200-300 grades will gain 100% strength in 28 days.

Data on concrete strength gain are presented in the table.

Concrete grade	Curing time, days	-3 ° C	0 ° C	+ 5 ° C	+ 10 ° C	+ 20 ° C	+ 30 ° C
	1	3	5	9	12	23	35
	2	6	12	19	25	40	55
M200-300 on Portland cement M-400 and M-500	3	8	18	27	37	50	65
	5	12	28	38	50	65	80
	7	15	35	48	58	75	90
	14	20	50	62	72	90	100
	28	25	65	77	85	100	-

The table shows that at low temperatures it is advisable to use concrete with additives for a quick set of strength. This slightly increases its cost, but also significantly speeds up the construction process.

It is allowed to make stripping when concrete gains strength not less than 50%.

Waterproofing tape

With a hanging grillage, you can use a coating waterproofing. In the recessed version, it is possible to lay the roll waterproofing into the ground before pouring the concrete and, after removing the formwork of the upper part, completely close the foundation with it. For more information on waterproofing grillage structures, see this video:

It is important to protect the substrate from moisture. If the foundation absorbs water, then in winter at subzero temperatures during the expansion of the freezing water, microcracks will form in it. This must be avoided.

Reinforcement errors and how to avoid them

Do not reinforce the corners by crossing the reinforcement

There are a number of mistakes associated with reinforcement that inexperienced builders make in order to save money or simply because of ignorance of building codes and regulations. Below are the most frequently recurring ones.

1. A decrease in the diameter of a bored pile, according to some builders, should be accompanied by a decrease in the number of vertical reinforcement rods, to which the grillage frame should subsequently be attached. Reducing the allowance for vertical bars.
2. Reinforcement of corner sections by crossing straight reinforcement rods. Many do this so as not to complicate the knitting of the frame.
3. Failure to comply with the step of installing jumpers when reinforcing the grillage. Skipping required connections. This often happens in order to save money.
4. Deviation of the reinforcement cage from the central axis. This will lead to an uneven bearing capacity of the base, which often happens due to trivial negligence. All the intricacies of reinforcing the pile foundation, see this video:

The solutions to the above errors are given below.

1. The pile diameter should not be less than 300 mm, and the number of vertical rods should be less than 4, the reinforcement allowance for the grillage should be at least 0.5 m.
2. For the correct connection of the nodes of the beams, it is necessary to make bent U- and L-shaped parts with which you want to connect the corner elements.
3. When installing the reinforcing cage, a pitch of 200 to 400 mm between the jumpers must be observed. The exact step size is determined at the design stage.
4. It is required to make all measurements using building levels so that the frame is aligned with respect to the central axis.

Reinforcement is a significant part of the construction process. Everything is important and the quality of materials, and the experience of builders, and the availability of working documentation.

Failure to comply with the rules of reinforcement can lead to the most serious consequences. This stage of construction is one of the most critical.

During construction work, any mistake leads to a decrease in the life of the building without the need for repair. This is at its best. At worst, even at the stage of construction of the building, it undergoes reconstruction.

To achieve the maximum service life, it is required to comply with building codes and regulations, not allowing deviations from the project. Construction combines a set of measures that must be followed to achieve the desired result. If possible, it is better to entrust such work to professionals.