What is formwork in private construction? Formwork is the basis of monolithic construction

What is formwork?

Regardless of the features of the building being erected, designers and builders are interested in ensuring the strength and stability of the structure. The course of industrial and civil construction has its own characteristics depending on the purpose of the building. But there is something that unites full complex measures for the construction of construction objects - formwork. What is the formwork, the installation of which is carried out on initial stage contemporary construction works? Why is it difficult to imagine construction without it?

Consider in the presented material the purpose, requirements, features, types of formwork.

Purpose

According to the terminology used in construction, the formwork is a temporarily erected box-shaped structure made of metal, wood or other materials, assembled for the purpose of pouring concrete. After reaching concrete composition strength characteristics, the frame is dismantled.

Pouring a monolithic foundation necessarily involves the assembly of formwork

The structure is a set of panel elements combined into a prefabricated frame using special fasteners. The formwork performs the following tasks:

• attaches concrete structures required configuration;
• maintains the required dimensions;
• saves the spatial position of the elements;
• reproduces, if necessary, the structure of the surface.

Shuttering panels are in contact with the concrete mass, perceive the forces acting on the surface from the side of the mixture.

Requirements

Set of prefabricated formwork elements - load-bearing part building structure with special requirements:

• Accurate provision of the configuration of the poured concrete mass.
• Increased strength characteristics, providing a maximum resource of use, resistance to the effects of builders moving along it and other variable loads.
• Resistance to surface deformations arising under the influence of concrete pressure.
• Accelerated assembly rates, low labor intensity of dismantling, which are the criteria for manufacturability.
• The tightness of the shield surface, which makes it difficult for the composition to leak during concreting.
• Possibility of manufacturing from materials used in construction.

Compliance specified requirements prefabricated structure provides high quality concrete mass, positively affects its service life.

Formwork is a building term meaning a box-shaped structure, a set of elements and parts designed to give the required shape to monolithic concrete or reinforced concrete structures.

Varieties

The classification of formwork of various types is carried out depending on the following factors:

• functional purpose, which determines the structural elements, the type of structures for which the panel structure is intended;
• the possibility of dismantling the formwork system in order to reuse panel elements;
• used for the manufacture of the material that determines the technical characteristics, the amount of costs for the purchase and installation;
• design features construction object, characterizing the spatial arrangement of the formed surface, its configuration.

Let us consider in more detail the features of each factor.

Scope of use

The scope of the formwork structure varies depending on the purpose of the structural elements that are used for the following purposes:

• Construction of monolithic objects.
• Construction of the foundations of structures.
• Construction of walls and partitions.
• Arrangement of floors between floors of buildings.
• Floor structures in tunnels, mines.
• Column concreting.
• Formation of elevator shafts.

The most used element of the formwork system in the long list of modular formwork can be considered boards with a height of approximately 3 thousand mm

Possibility of dismantling

The main feature that divides formwork systems into two subspecies is the possibility of dismantling, which is represented by the following varieties:

• dismantled, removable structure, removed for the purpose of reuse after the concrete composition reaches strength characteristics sufficient for operation. It consists of a group of panel elements connected with locking locks;
• stationary formwork of a non-removable type, which cannot be reused due to the fact that the system after pouring is an integral element of the concrete structure.

Varieties of materials used

Modern formwork- is not wooden shields, as in the past, but varied technical devices from many materials. How to choose for yourself suitable option- the question is rather complicated. Need to get familiar with the diversity existing species and the difference between them. Which of the proposed structures is suitable is decided based on the funds allocated for construction, the specifics and type of structure, and the method of its construction.

What is formwork in construction?

Formwork in modern construction acting auxiliary structures. The types of formwork systems used differ in form, material, purpose. Industrial formwork is an economical system of monolithic housing construction, which significantly increases the manufacturability of construction, speeds up the production process and increases the quality of construction. It reduces the cost of the process due to repeated use. The most demanded products of this class are structural modifications of Framax-Doka, PEPY, Utinor, Goliath, IBE and others.

formwork- a set of elements and details that give the necessary shape concrete mix. They hold the reinforcement, preventing it from moving during pouring, and retain the structure until the mortar has completely hardened. Modern formwork systems meet high requirements strength, since they must withstand heavy loads of poured concrete, its aggressive thermal and chemical effects.

Formwork: classification, structures, applications

The basic principle of classifying building formwork is the method of use. Devices are divided into two main groups:

• fixed remains at the installation site, becoming part of the structure and performing additional function(insulation, insulation, cladding);
• removable is disassembled after the concrete hardens for reuse.

Formwork is used to create:

• straight as well as curved walls;
• columns of many shapes;
• mines;
• floors;
• flyovers;
• foundation.

Sometimes formwork is used in non-monolithic structures, when it is not possible to arrange the entire foundation in blocks and partially fill is used or when a reinforcing belt is installed to reinforce the structure to break. Also, with a pile or columnar foundation, a harness is created with its help.

What is a removable formwork: its device and varieties

The collapsible design creates any geometry of monolithic structures made of concrete or reinforced concrete. Removable formwork systems are different designs and appointments.

1. Frame, consisting of frame shields, supports, bolts and fasteners. It happens small-panel, large-panel, block. This system is most suitable for the construction of small buildings.
2. Beam includes I-beams, crossbars, slabs, steel fasteners, props.
3. Tunnel - these are half-sections of vertical and horizontal panels for walls and ceilings. Mounted with a crane.

For the production of formwork, different materials are used.

1. Wood in the form of boards and timber. Laminated plywood also belongs to this group. They are cheap, readily available, and able to create almost any shape. The disadvantages are low strength and the ability to deform.
2. Steel. She's different high strength, rigidity, resistance to heavy loads, long service life.
3. Aluminum. Its main advantage is its lightness, which reduces the complexity during transportation and installation. It is resistant to aggressive environments, but subject to deformation.
4. Plastic. It is light and durable, does not require lubrication, cheap, but less durable than the rest.

Formwork in private construction, most often, consists of wooden structures. They are made of boards or plywood, fastened with bars, which rest against the props. Downed shields should be slightly wider than the foundation being built. They are installed along the trench, fastened together at the corners and along the top of the walls. Opposite each connection, a peg is driven in and a spacer is placed.

Types of fixed formwork, their features

Fixed formwork consists of panels or blocks that are combined into one structure, which is a formwork for reinforced monolithic concrete. The main advantage of such formwork is the reduction of construction time due to the connection technological processes. After the concrete has hardened, it becomes part of the wall structure.

There are several types fixed formwork: decorative, blocks with voids, according to the Plastbau-3 technology, armored panel, wood concrete, glass-magnesite.

It is produced from foamed polystyrene, polystyrene concrete, wood concrete, glass-magnesium sheet. Also apply asbestos-cement pipes and slabs metal sheets and grids.

Formwork production

In the production of formwork, the main thing is to maintain the dimensions and make the structure durable. It must retain its shape until the concrete hardens. To make it easier to remove the formwork, it is necessary to treat it with impregnations or cover it with a film before concreting. The formwork is removed after one and a half to two weeks, depending on the weather.

Mounting technology is quite difficult process so it's best to turn to professionals to get excellent result. Contact specialized firms by phone for advice or submit an application for work.

Formwork is a structure consisting of many parts. Their immediate purpose is the creation of monolithic blocks. Therefore, if you are going to build a house, then the part of the foundation that will be above the ground requires formwork. Let's figure out what it is, what types exist and how to make high-quality formwork for the foundation with your own hands. Believe me, anyone who shows due diligence can cope with this.

Formwork and its types

We have already figured out that in order for the foundation to be strong and have a certain structural appearance, it is necessary to build a formwork. And now I would like to talk about its types. Currently, there are only two of them: removable and non-removable. Various types formwork systems are presented, for example, in the company "KRAMOS" - http://www.kramos.ru/opalubka/. Regardless of the type, formwork must perform several simple, but at the same time very important tasks, the main of which is to perceive and retain specific pressures from concrete, while not changing its shape. It is unacceptable for the concrete mixture to flow through the structure, in addition, the formwork must be simply and quickly constructed. Let's take a closer look at its types and determine the advantages and disadvantages of each of them.

Fixed and removable formwork

It can be understood from the name that after installation, the structure becomes an integral part of the foundation of the building. This kind of formwork is a structure made from improvised materials. They are easy and quick to install. The material used is chipboard, fiberboard or In some cases it makes sense to use expanded polystyrene. We will talk about this a little later. There are similar solutions, for example, columnar foundation from metal or Their diameter ranges from 150-200 millimeters. The obvious advantage is durability. This is especially true in cases where a columnar foundation and reinforced concrete slabs are used. In addition, such formwork means that there is no additional earthwork, as well as the need to install auxiliary supports and struts. As for removable structures, there is nothing special to talk about. After pouring the foundation and its formation, the formwork is dismantled, and boards or plywood can be used in any other business.

Metal structures: advantages and disadvantages

One of the most expensive materials that can be used to make formwork is iron. Most often, sheets with a thickness of several millimeters are used, which is quite enough to absorb the forces from the foundation. At once it would be desirable to tell about advantages of such decision. Firstly, it is the ability to bend the steel sheet the way you want. Thanks to this, it is possible to adapt to the desired shape of the foundation. Secondly, this is the most best waterproofing, which you can think of for your foundation. Another important point- it is possible to weld the reinforcement of the foundation to the frame. From this, the strength of the structure increases several times. But for this you need to use a monolithic or strip foundation. As for the shortcomings, it is only one - the cost.

Fixed formwork made of expanded polystyrene and reinforced concrete products

First of all, I would like to say about reinforced concrete products. This solution is slightly cheaper than using steel sheets, but the price of concrete plates not so small, so the costs will be noticeable. However, due to the possibility of changing the thickness of the reinforced concrete, you can reduce the consumption of concrete for the foundation, therefore, save a little. But here the problem is this: firstly, the plates are very heavy, and secondly, it is necessary to use additional spacers, since the products are not monolithic. As for such material as expanded polystyrene, it is used as formwork not so long ago, but has already gained great popularity because of its practicality. The main advantages are ease of assembly. The blocks are quite simply attached to the reinforcement, and are held together by metal brackets. This solution is good because, thanks to the unique design of monolithic blocks, the foundation is obtained not only perfectly even, but also of high quality (good thermal and waterproofing).

What to use under the strip foundation?

strip foundation up to today is considered one of the most relevant methods of obtaining the foundation for a future building. The principle here is extremely simple. There is sand cushion, a prepared screed is poured onto it and a framework of reinforcement is formed. Only after this is carried out. But which formwork is better to use? Almost any solution is suitable here, for example, a structure made of polystyrene foam, metal, reinforced concrete products, etc. In some cases, you can not use anything at all, just dig a trench. But it is strongly not recommended to do so, as the consequences are possible, and the most unpredictable. According to statistics, most often the tape formwork is wooden. This is largely due to the low price of its manufacture, and the installation itself is quite fast.

Classic wooden formwork

Despite the fact that today there are newer and more unique in their technical specifications materials, most prefer wooden structures. This is due to many factors. First, it's the price. Today it is possible to rent the formwork, and return it back in a month. But even if you just buy boards, you are unlikely to lose anything, because they can be used in the future. For example, you can put the floor in the same house. Another important parameter, because of which it is worth giving preference to this particular material - practicality. If something sticks out somewhere or, conversely, a piece of the product is missing, then this is very simply solved with a saw or a hammer with nails. For example, formwork plywood is used on floors. It is not only inexpensive, but also very reliable.

We make formwork with our own hands

All work takes place in several stages. Let's start with the very first one. We need to do all the ground work. After calculating the load on the structure, get down to business. It is recommended to leave approximately 1-2 centimeters of space between the formwork and the foundation. It is needed for more easy installation. In the future, the void is covered with earth. The trench must be covered with sand (sand cushion). Next comes which is necessary to reduce the loss of material during pouring. If it is planned to reinforce the structure with rods, then they must be driven into the ground at this stage. At the second stage, we will erect the formwork. To begin with, we customize all the elements, and only then we proceed directly to the construction.

Marking, strengthening and installation

First you need to do markup. After that, where the corners of the formwork should be, we hammer in small pegs (wooden). They are needed directly for fastening the structure. Further, according to pre-calculated dimensions, shields are selected. Here monolithic formwork more preferable, as it is easier to install due to design features. The shield is attached to the stakes with nails, screws and self-tapping screws. So, in fact, the frame is formed. But that is not all. With a significant length of the formwork or large volumes poured concrete, it is necessary to strengthen the structure. This is done with the help of spacers, which are placed in increments of 70-90 centimeters. There is another solution: to tighten the structure with studs, but in this case, the further use of the shield in the household will be difficult, since there will be holes in the boards. During installation, you need to carefully monitor the verticality of the structure, for which you need to use building level. All cracks must be sealed. Almost any improvised means will do for this. If the distance between two formwork elements is more than 4 mm, then this is an obvious concrete leak.

How to make a calculation?

Before the formwork of the house is erected, it must be calculated. This is done to determine the decisive parameters. As an example, consider the most common wooden formwork. So, a standard board has a length of 6 meters, a thickness of 25 millimeters and a width of 100-150 mm. The perimeter of the foundation must be divided by 6, that is, by the length of the board, and the height by the width. The results obtained must be multiplied, and you will get the finished number. On average for one cubic meter takes about 42 boards 100 mm wide. Based on this, you will have to spend approximately 5-6 thousand rubles per cubic meter. To all this, it is necessary to add the price of a beam for spacers and structural reinforcement. All together it will cost about 10,000 rubles. For example, it must be calculated by a specialist. This is where the foundation plan comes into play. If there are many complex nodes, then the cost will be approximately the same as when buying steel sheets. In addition to all of the above, you must not forget to take into account the cost Supplies: nails, screws, fittings, spacers, etc.

Need to get rounded shapes? Not a problem

In some cases, rounding is simply indispensable, and this is an obvious fact. A metal shield or a wooden non-inventory board can be used as a material. If you want to build a column, the first thing you need to do is create L-shape from mounting brackets. Don't forget to fasten them together. But everything becomes much more complicated if it is necessary to get not a square, but round shape. It is best to use boards here. It is necessary to recruit them according to the principle of a barrel. The fact is that the formwork of the columns must withstand large specific loads, so it is recommended to make a fixed structure. To do this, after every 50-80 centimeters, it is necessary to use screeds and pegs to strengthen. In some cases it makes sense to search already finished frame. If you are lucky, you will find a suitable diameter and you can save a lot, not only money, but also nerves.

What other materials are suitable?

Of course, not only the board can be used, but in some cases this is the only correct solution. If you need to build formwork of low strength, but rounded, use plastic. Perfect solution for the construction of a gazebo, but no more. The material bends well, especially if it is slightly heated. But, again, the strength here is minimal. For example, plywood for formwork is also a good solution, but all this is good if it is additionally reinforced with a board. Its strength is slightly higher than that of plastic, but still for serious purposes it is far from the best. The best decision. As for metal sheets, they can be used almost everywhere. But the formwork of metal slabs hardly makes sense. The loads here are small, and the volume of the foundation too. But the cost of the sheet will unpleasantly surprise you. If you do take metal sheets, use them for columns or where a very strong material is required.

A few important points

So we have considered how to make formwork, as well as what materials are best suited for the implementation of a particular purpose. As you can see, there is nothing complicated here, the main thing is to observe a few important rules. Firstly, it is worth paying enough attention to the strength of the structure, and secondly, we must not forget about the verticality of the structure, since this has great importance. For example, when creating formwork for columns in order to make the structure more even, it makes sense to bury the boards a little into the ground. So you will give strength and avoid distortion during pouring of concrete. If you are not working with outer walls, then it is not necessary to use metal sheets, it is simply irrational. Most often, slab formwork is created from plywood or boards, it is really profitable and expedient.

Conclusion

Now you know what formwork is. This is something that any building construction cannot do without. Despite the fact that there is a huge selection of materials, the principle of construction remains the same.

Well, that's all that can be said about how to make various materials. If you are going to live in this house, then be careful at all stages. You probably don’t want to “enjoy” a crooked wall or damp corners later due to the fact that the verticality was not observed, or the wrong material was used.

formwork- this is a rigid counterform of a given geometry, designed to absorb the load from freshly laid concrete. Manufacturability of the formwork involves its quick assembly on site from pre-prepared elements, dismantling after use with minimal losses and preparation for reuse.

Formwork types:

1. By the number of times of use: stationary(disposable) and inventory(reusable);

2. mobile and immovable;

3. By material: made of wood, plywood, plastic, metal, reinforced cement, metal-plastic, fabric, concrete, pneumatic deck (for domes and vaults)

4. by design and technological features:

- collapsible- is the most versatile. Used for concreting walls, columns, ceilings, foundations, etc. After a set of concrete of a given strength, it is disassembled, cleaned and reused

-climbing- for concreting towers of circular cross section - used in the construction of structures high altitude having a variable cross section.

- sliding- structures with a constant horizontal section (plan). (Construction of residential buildings, hotels, stiffening cores).

- tunnel - used for the construction of structures extended in terms of

the form of arches, tunnels, as well as multi-storey buildings with transverse bearing walls.

- self-elevating- designed for high-rise structures with an arbitrary plan shape;

- inflatable - formwork is mainly used for shells of double curvature, i.e. forms, the manufacture of which from flat sheet elements is extremely expensive and time consuming.

- fixed-remain in the structure and serve as its cladding. They are made of reinforced concrete slabs, reinforced cement, plastic or asbestos-cement sheets. e.g. foundation

- hanging - for concreting beams

11. Collapsible and climbing formwork.

Collapsible going from finished elements: shields, boxes, inventory racks. After a set of concrete of a given strength, it is disassembled, cleaned and reused.

Wooden collapsible op. used for concreting partitions, beams, foundations, columns, floor slabs.

Widespread use in construction received metal formwork design. TsNIIOM TP from unified shields. Shields of 10 types, sizes, made of metal corners, channels and sheet steel 2 mm thick.

-Climbing- used in the construction of buildings of greater height with a variable cross section. The outer part of such a formwork is assembled from rectangular and trapezoidal panels, and the inner part is made of rectangular panels with the installation of spacer rods that ensure the rigidity of the inner formwork. With the help of special devices, the formwork is lifted up as it is concreting, fixed, then the lift shaft is increased.

12. Sliding and tunnel formwork.

sliding Construction of residential buildings, hotels, stiffening cores, etc.

It has an inner and outer shell h = 1.2m, Alpha is fastened around the perimeter with rigid frames. A flooring is attached to the frames, which is a workplace for concreting and jacks of hydraulic, pneumatic or electric action for formwork lifting.

Unlike other types, the sliding formwork does not come off the concrete surface, but as the concrete is concreted and hardened, it slides up with the help of jacks.

Formwork is a collection of parts and elements, it is needed in order to give strength monolithic buildings from concrete and reinforced concrete. After building mixture hardens, in most cases it is removed, however, there are also fixed structures that become part of the building structure being erected.

The formwork must be strong and reliable, so its construction should be taken very seriously.

Formwork types are different, in order to select the desired type, you must first determine the nature of the structures or structures being concreted, taking into account the ratio of their geometric dimensions, work production technologies and climatic conditions. Before erecting such a structure, it is imperative to make formwork drawings (this is a very important process), it should be noted that such work as a formwork drawing must be done by specialists. You will also need certain tools:

• building level;
• screwdriver;
• a hammer;
• wood saw;
• plumb;
• mount;
• square.

Formwork types are classified according to functional purpose, it depends on what kind of structures that are concreted:

• the design can be one that is designed for vertical surfaces, while taking into account the walls;
• for horizontal and inclined surfaces, a variant is used that is mainly suitable for floors;
• in order to concrete walls and ceilings;
• in order to concrete individual rooms and apartments;
• for curved surfaces (in this regard, the pneumatic view is mainly used).

Depending on what material is used, structures can be wooden, wood-metal, metal, reinforced concrete, reinforced cement. In addition, there are types of formwork that are made of rubberized and synthetic fabrics. Concerning wooden structures, then they have gained great popularity, because they are built very quickly and without much difficulty, and it is also cheap. Structures made of aluminum have also gained great popularity, they differ in that they weigh less than steel ones, so they are much easier to transport and install. For fixed structures, a material such as polystyrene is most often used.

Collapsible small-panel formwork

This type consists of small elements, their area can reach up to 3 m², and their weight can reach 50 kg. Its scheme is such that it can be disassembled and assembled manually. Large blocks and panels are assembled from the elements, they can be mounted and dismantled without disassembling by a crane into their constituent elements. Its scheme is unified, it can be used for different monolithic structures, while the dimensions can be constant, variable and repetitive. Its use is expedient mainly in order to concrete non-standardized structures of small volume.

Back to index

Large-panel formwork

This type is made from large shields and different elements connections. Its shields carry all technological loads, it is not necessary to install additional load-bearing and supporting elements. Its scheme is such that it is used to concrete extended walls, tunnels and ceilings. As for the size of the panels, it is equal to the size of the structure that is being concreted: for walls - the height and width of the room, for floors - the length and width of the floor.

If floors are concreted large area, then it is necessary to lay and compact the concrete in one shift, while the overlap is divided into cards. As for the size of the map, they are set technological regulations, and on the boundaries is set metal grid, maximum thickness which is 4 mm, cells 10 by 10 mm. This is done to ensure sufficient grip with subsequent cards.

The large-panel type will be used mainly for buildings in which monolithic walls and partitions, prefabricated ceilings. Collapsible large-panel formwork is needed to concrete structures of variable cross-section.

Back to index

block formwork

The types of formwork are different, it should be noted the volumetric-adjustable type, which is needed in order to build 3 or 4 walls at the same time along the contour of the building cell, its scheme is such that overlaps are not required for this. It is mounted from separate blocks, where there are gaps that are equal to the thickness of the walls being built. If the building has external and internal walls monolithic, and prefabricated floors, it is better to choose combined option. For the outer surfaces of the walls, a large-panel type is used, for internal surfaces and walls - vertically moved, block and retrieved types.

As for block forms, they are closed spatial blocks, which can be rigid and one-piece, cone-shaped, sliding and detachable. Such block forms are mainly used for concreting closed structures of relatively small volume. They are used for both vertical and horizontal surfaces. They can be used for solid wall elements, elevator shafts, freestanding foundations, columns, etc.

Back to index

Volumetric adjustable type

This view consists of sections and is a horizontally extractable block of large dimensions, it is designed to simultaneously concrete walls and ceilings. When stripping the formwork, the sections must be moved inward, rolled out to the opening, in order to then be removed by a crane. Such formwork is used in order to concrete transverse, load-bearing walls and monolithic floors civil and residential buildings.

This type of longitudinally moved formwork is used in buildings with longitudinal load-bearing walls and ceilings made of monolithic reinforced concrete. If a building with a simple plan configuration, large areas floors, facades with flat surfaces, it is better to make volumetrically adjustable formwork: tunnel, vertical and horizontally movable type.