Thermal seams in a coupler. Why are expansion joints needed in concrete screeds? Expansion joints in concrete

A common option for floors of buildings, structures and coatings in industrial premises with intense mechanical stress is a concrete floor. The material from which these structural elements are made is subject to shrinkage and has a low resistance to deformation, as a result of which cracks occur. In order to avoid repeated repairs, artificial cuts are created in, for example, an expansion joint in the walls of a building, roofs, bridges.

What are they needed for?

The concrete floor appears to be a strong and durable base. However, under the influence of temperature fluctuations, shrinkage processes, air humidity, operational loads, soil sedimentation, its integrity is lost - it begins to crack.

To betray some degree of elasticity of this building structure, expansion joints in concrete floors. SNiP2.03.13-88 and its Manual contain information on the requirements for the design and installation of floors, indicating the need for a break device in the screed, underlying layer or coating, which provides a relative displacement of disparate sections.

Main functions:

Minimization of sudden deformations, through division monolithic slab for a certain number of cards.
The ability to avoid costly repairs with the replacement of the rough and main coating.
Increasing resistance to dynamic loads.
Ensuring the durability of the structural basis.

Main types: insulating seam

In concrete floors, depending on its purpose, it is divided into three types: insulating, structural and shrinkage.

Insulating cuts are made at the junction of the structural elements of the room. That is, they are an intermediate seam between walls, columns and floors. This makes it possible to avoid cracks during shrinkage of concrete in the places where horizontal and vertical elements rooms. If we neglect their arrangement, then the screed, when dried and reduced in volume with a rigid adhesion to the wall, for example, is most likely to crack.

An insulating joint is created along walls, columns and in places where the concrete floor borders with others. Moreover, a seam is cut near the columns not parallel to the faces of the columnar element, but in such a way that a straight cut falls on the corner of the column.

The considered type of seam is filled capable of allowing horizontal and vertical movement of the screed relative to the foundation, columns and walls. The thickness of the joint depends on the linear expansion of the screed and is about 13 mm.

Main types: shrink seam

If the insulating joints prevent deformation of the monolithic concrete floor at the points of contact with the walls, then shrinkage cuts are necessary to prevent random cracking of the concrete over the entire surface. That is to prevent damage caused by shrinkage of the material. As the concrete dries from top to bottom, tension appears inside it, created by the hardening of the top layer.

The device of expansion joints in concrete floors of this type occurs along the axes of the columns, where the cuts are joined to the corners of the joints along the perimeter. Cards, that is, parts of a monolithic floor, limited on all sides by shrinkage seams, should be square, L-shaped and elongated rectangular shapes should be avoided. The work is carried out both during the laying of concrete with the help of forming rails, and by cutting the seams after the screed has dried.

The probability of cracking is directly proportional to the size of the cards. How less area floor, limited by shrinkage joints, so the likelihood of cracking is minimal. The sharp corners of the screed are also subject to deformation, therefore, in order to avoid concrete ruptures in such places, it is also necessary to cut shrinkage-type seams.

Main types: construction seam

Such protection of monolithic floors is created when it occurs at work. The exceptions are rooms with a small area of pouring and continuous supply of concrete. An expansion joint in concrete floors of a structural type is cut at the joints of the screed, made in different time. The shape of the end of such a connection is created according to the "thorn-groove" type. Features of structural protection:

The seam is arranged at a distance of 1.5 m parallel to other types of deformation demarcations.
It is created only if concrete is laid at different times of the day.
The shape of the ends should be made according to the "thorn-groove" type.
For a screed thickness of up to 20 cm, a 30-degree cone is made on the wooden side protrusions. Metal cones are allowed.
Tapered seams protect the monolithic floor from minor horizontal movements.

Expansion joints in concrete floors of industrial buildings

Increased wear resistance requirements are imposed on floors laid in factories, warehouses and other facilities. industrial use. This is due to the appearance of influence of different intensity mechanical impact(motion Vehicle, pedestrians, impact from falling solid objects) and possible spillage of liquid on the floor.

Usually, design feature floor is a screed and coating. But under the screed there is an underlying layer, which in a rigid design is laid out of concrete. A seam is cut in it in mutually perpendicular directions through 6-12 m, with a depth of 40 mm, with at least 1/3 of the thickness of the underlying layer (SNiP 2.03.13-88). A prerequisite is the coincidence of the expansion joint of the floor with similar protective gaps in the building.

A distinctive feature of the structure of the sexes in industrial buildings is the creation of a top layer of concrete. Depending on the intensity of mechanical action, coatings are designed different thickness. With a thickness of 50 mm or more, a deformation joint in concrete floors (SNiP "Floors" clause 8.2.7) is created in the transverse and longitudinal direction with the repetition of elements every 3-6 m. less than 40 mm or a third of the coating thickness.

Requirements for creating deformation floor protection

Concrete must be cut with a cutter after two days of hardening. The depth of cuts according to the norms is 1/3 of the concrete thickness. In the underlying layer, it is allowed to use slats treated with anti-adhesion compounds in places of alleged gaps before pouring concrete, which are removed after the material has hardened and as a result protective seams are obtained.

The lower parts of columns and walls to the height of the future thickness of the coating should be pasted over with rolled waterproofing materials or foamed sheet polyethylene. In those places where the project provides for expansion joints in concrete floors. Cutting technology begins with marking with chalk and a ruler of artificial breaks.

A test joint serves as an indicator of timely cutting: if the grains of the aggregate do not fall out of the concrete, but are cut by the cutter's blade, then the time for creating expansion joints is chosen correctly.

Seam processing

The normal functioning of the seam is achieved by sealing it. Sealing expansion joints in concrete floors is carried out using the following materials:

A waterstop is a profiled tape made of rubber, polyethylene or PVC, which is laid when pouring a concrete screed;
A sealing cord made of foamed polyester is placed in the slot and retains its elasticity during temperature changes, ensuring the safe movement of the concrete pavement;
Acrylic, polyurethane, latex mastic;
Deformation profile, consisting of rubber and metal guides. It can be built-in or overhead.

Before sealing working surface gaps must be cleaned and purged compressed air(compressor). Also, to increase the service life of concrete floors, it is desirable to strengthen upper layer topping or polyurethane material.

Creation conditions

An expansion joint in concrete floors (monolithic) becomes mandatory under the following conditions:

Screed, total area above 40 m2.
Complex floor configuration.
Operation of the floor covering at elevated temperatures.
Rib length (one is enough) floor structure more than 8 m.

Expansion joints in concrete floors: norms

In conclusion, the requirements for the installation of protective gaps in concrete floors according to the norms are given.

The underlying layer should have deformation cuts perpendicular to each other with a step of 6 to 12 meters. The seam is 4 cm deep and is one third of the thickness of the concrete pavement or sub-base.

With a concrete coating thickness of 50 mm or more, a deformation joint is created in the transverse and longitudinal directions with a repetition every 3-6 m. These cuts must coincide with the seams of the floor slabs, the axes of the columns, and the expansion gaps in the underlying layer. The cutting width is 3-5 mm.

The cut is carried out two days after the concrete is laid. Protective cuts are sealed with special cords and sealants.

Any building structures, regardless of what material they are made of (brick, monolithic reinforced concrete or building panels) change their geometric dimensions when the temperature changes. When the temperature drops, they shrink, and when they rise, naturally, they expand. This can lead to the appearance of cracks and significantly reduce the strength and durability of both individual elements (for example, cement-sand screeds, foundation blind area, and so on), and the entire building as a whole. To prevent these negative phenomena, an expansion joint serves, which must be equipped in appropriate places (according to regulatory building documents).

Vertical temperature-shrinkage joints of buildings

In buildings of great length, as well as buildings with different amount floors in separate sections of SNiP-th, the mandatory arrangement of vertical deformation gaps is provided:

Temperature - to prevent the formation of cracks due to changes in the geometric dimensions of the structural elements of the building due to temperature changes (average daily and average annual) and shrinkage of concrete. Such seams are brought to the level of the foundation.
Sedimentary joints that prevent the formation of cracks that may form due to uneven settlement of the foundation caused by unequal loads on its individual parts. These seams completely divide the structure into separate sections, including the foundation.

The designs of both types of seams are the same. To equip the gap, two paired transverse walls are erected, which are filled with heat-insulating material, and then waterproofed (to prevent precipitation from entering). The width of the seam must strictly comply with the design of the building (but be at least 20 mm).

Pitch of temperature-shrinkable joints for frameless large-panel buildings is normalized by SNiP and depends on the materials used in the manufacture of panels (concrete compressive strength class, grade of mortar and diameter of longitudinal load-bearing reinforcement), the distance between the transverse walls and the annual difference in average daily temperatures for a particular region. For example, for Petrozavodsk (annual temperature difference is 60°C), temperature gaps must be located at a distance of 75÷125 m.

AT monolithic structures and buildings built by the prefabricated-monolithic method, the pitch of the transverse temperature-shrinkage joints (according to SNiP) varies from 40 to 80 m (depending on design features building). The arrangement of such seams not only increases the reliability of the building structure, but also allows you to gradually cast individual sections of the building.

On a note! In individual construction, the arrangement of such gaps is used extremely rarely, since the length of the wall of a private house usually does not exceed 40 m.

In brick houses, the seams are arranged in a similar way to panel or monolithic buildings.

AT reinforced concrete structures buildings, the dimensions of the floors, as well as the dimensions of other elements, may vary depending on temperature differences. Therefore, when installing them, it is necessary to arrange expansion joints.

Materials for their manufacture, dimensions, places and laying technology are indicated in advance in project documentation for the construction of the building.

Sometimes such seams are structurally made sliding. To ensure sliding in those places where the floor slab rests on bearing structures, two layers of galvanized roofing iron are laid under it.

Expansion joints in concrete floors and cement-sand screeds

When pouring cement-sand screed or the arrangement of a concrete floor, it is necessary to isolate all building structures (walls, columns, doorways, and so on) from contact with the poured mortar throughout the entire thickness. This gap performs three functions simultaneously:

At the stage of pouring and setting the solution works as a shrinkable seam. A heavy wet mortar compresses it, with the gradual drying of the concrete mixture, the dimensions of the poured canvas decrease, and the gap-filling material expands and compensates for the shrinkage of the mixture.
It prevents the transfer of loads from building structures concrete pavement and vice versa. The screed does not press on the walls. The structural strength of the building does not change. The structures themselves do not transfer loads to the screed, and it does not crack during operation.
With temperature differences (and they necessarily occur even in heated rooms), this seam compensates for changes in volume concrete mass, which prevents its cracking and increases the service life.

To arrange such gaps, a special damper tape is usually used, the width of which is slightly larger than the height of the screed. After the solution has hardened, its excess is cut off with a construction knife. When shrink joints are arranged in concrete floors (in case the finishing flooring not provided), the polypropylene tape is partially removed and the groove is waterproofed using special sealants.

In rooms of a large area (or when the length of one of the walls exceeds 6 m), according to SNiP, it is necessary to cut longitudinal and transverse temperature-shrinkage joints with a depth of ⅓ of the thickness of the fill. The expansion joint in concrete is produced using special equipment (gasoline or electric joint cutter with diamond discs). The step of such seams should not be more than 6 m.

Attention! When pouring with a solution of underfloor heating elements, shrink joints are arranged to the full depth of the screed.

Expansion joints in foundation blind areas and concrete paths

The blind areas of the foundations, designed to protect the base of the house from the harmful effects of precipitation, are also subject to destruction due to significant temperature changes during the year. To avoid this, equip the seams that compensate for the expansion and contraction of concrete. Such gaps are made at the stage of construction of the blind area formwork. In the formwork along the entire perimeter, transverse boards (20 mm thick) are fixed in increments of 1.5 ÷ 2.5 m. When the mortar sets a little, the boards are removed, and after the final drying of the blind area, the grooves are filled with damping material and waterproofed.

All of the above applies to the arrangement concrete paths on the street or parking spaces near own house. However, the step of deformation gaps can be increased up to 3÷5 m.

Materials for arranging seams

The same requirements apply to materials intended for arranging seams (regardless of type and size). They should be resilient, elastic, easily compressible and quickly recover their shape after compression.

It is designed to prevent cracking of the screed during its drying and to compensate for loads from building structures (walls, columns, and so on). Wide selection dimensions (thickness: 3 ÷ 35 mm; width: 27 ÷ 250 mm) of this material allows you to equip almost any screed and concrete floors.

A popular and easy-to-use material for filling deformation gaps is polyethylene foam cord. There are two varieties of it on the construction market:

continuous sealing cord Ø=6÷80 mm,
in the form of a tube Ø=30÷120 mm.

The diameter of the cord should exceed the width of the seam by ¼÷½. The cord is installed in the groove in a compressed state and fill ⅔÷¾ of the free volume. For example, for sealing grooves 4 mm wide cut in a screed, a cord Ø = 6 mm is suitable.

Sealants and mastics

To seal the seams, various sealants are used:

polyurethane;
acrylic;
silicone.

They are both one-component (ready-to-use) and two-component (they are prepared by mixing two constituent parts immediately before use). If the seam is small, then it is enough to fill it with sealant; if the gap width is significant, then this material is applied over the laid polyethylene foam cord (or other damping material).

A variety of mastics (bituminous, bitumen-polymer, raw rubber-based compositions or epoxy with additives to impart elasticity) are used mainly for sealing external expansion gaps. They are applied over the damping material laid in the groove.

Special profiles

AT modern construction expansion joints in concrete are successfully closed using special expansion profiles. These products are available in a wide variety of configurations (depending on application and joint width). For their manufacture, metal, plastic, rubber are used, or several materials are combined in one device. Some models of this category must be installed already in the process of pouring the solution. Others can be installed in the groove after the final hardening of the base. Manufacturers (both foreign and domestic) have developed a wide range of the lineup fixtures for both outdoor and indoor use. High price profiles is compensated by the fact that this method of sealing the gaps does not require their subsequent waterproofing.

In custody

Proper arrangement of temperature, expansion, expansion and settlement joints significantly increases the strength and durability of any building; parking spaces or garden paths with concrete pavement. Using high quality materials for their manufacture, they will last without repair long years.

Cement-sand and concrete screeds withstand compressive loads well, but in the event of another type of load in concrete slab cracks may occur. If pressure is applied to concrete that exceeds its strength characteristics, it does not deform, as, for example, plastic or other plastic materials, but crack. Cracking can also occur under the influence of internal stresses in concrete, which cause shrinkage during hardening and temperature changes.

Cracks in the concrete screed can appear as a result of loads on the floor that exceed the strength of concrete.

To protect the floor from such damage and control those places where cracks appear, cutting is carried out.

They are of three types:

insulating;
shrinkage;
structural.

For cutting in concrete, you will need the following tools:

Compact floor saws are used for cutting in concrete floors.

seam cutters;
rope for marking;
wide range;
mechanical brush or sandblaster.

You will also need:

insulating material;
sealant;
metal cones (for structural);
special slats (for shrink).

insulating

The structure of the building during its operation is subjected to various deformations. Their main reasons include:

the impact of the external environment;
temperature changes;
soil movement;
operation of equipment inside the workshop, etc.

To prevent the transfer of deformations from the walls and foundation to the concrete floor, insulating is performed in places where the concrete screed is in contact with the floor and other building structures. B tends to shrink, so if the screed with a fixed object has a strong bond, it is likely to crack.

Insulating ones are made in places where the floor comes into contact with the building structures, i.e. along the walls and around the columns. The shape around the column is square (a) or round (b), without insulating joints the screed will crack (c).

Insulating is done around all the columns in the building and along the walls. If there is a screed that borders on another base, it must be done around the entire foundation. Around the columns they can be round or square. AT last version the seam must be rotated relative to the section of the column by 45 ° and made directly opposite its corner. If, however, equipment will move through the insulating one, then in this case it is better to make the screed thicker by about 25%, and then, having completed it with a wedge, reduce the thickness to the original one with a slope of no more than 1:10.

Material installation

When pouring the screed, a formwork is made around the columns along the line. After the concrete has set, insulating material is laid instead of the formwork.

Filling is carried out with the help of insulating materials, which must not collapse under the action of elastic deformations. When calculating the thickness, the coefficient of linear expansion of the screed is taken into account. Usually it is 13 mm. Most often, insulating ones are filled with sealant or prepared fiber, while it is important that the material for insulation does not protrude onto the surface of the screed. It is impossible for the screed concrete to come into contact with the concrete of other structures in the building, because the insulating one will not perform its functions, and cracking may occur at the point of contact.

Shrink

Shrinkage joints are cut along the column axes, end-to-end with the corners of the insulating joints around the columns.

Shrinkage is cut along the axes of the columns and joined with the corners of the seams that run along the perimeter of the columns. The distance to the column should be equal to 2-3 times the thickness of the screed. The floor maps formed by shrinkage joints should be square, while avoiding elongated or L-shaped. Shrinkage must be made straight and preferably without branches. In driveways and aisles, they should be located at a distance equal to the width of the screed. If the tracks are wider than 360 cm, it is necessary to make a longitudinal seam in their center.

Layout of insulating and shrinkage joints in concrete floors.

It is important to consider that if the card small sizes, then the probability of cracking will also be minimal. Shrinkage must also be done at the outer corners, otherwise cracks may come from them. If the screed section has a very sharp angle, there is a good chance that it will crack. Therefore, it is desirable to avoid such angles. But if this option is not possible, it is important to make sure that the substrate is well compacted, and in those places where there is a high probability of cracking, cut shrinkage seams.

Features of structural protection

In practice, the process rarely fills the screed without long breaks. This option is possible in a room with a small area and if concrete mix supplied continuously. Most often, pouring is carried out with technological interruptions, so the laid concrete hardens and acquires a certain strength. In places where concrete, laid at different times, is in contact with each other, it is advisable to cut structural.

Scheme of the device "thorn in the groove".

These seams are made in those places where the day's concrete laying was completed. It is advisable to perform them at a distance of at least 1.5 m from other species that are located in parallel. For the structural shape of the edge of the screed, it is made according to the “thorn in the groove” technology. When the side protrusions are made of wood, then for a screed having a thickness of 12-20 cm, a 30 ° cone is sufficient. Metal cones are also quite often used, which are installed according to the manufacturer's instructions.

cutting technology

All cut seams must be clean and straight. The worker who performs this procedure must know optimal depth cuts, their sequence and be able to prevent rapid wear of the blade in the case of using very hard aggregate in concrete. The seams must be done when the concrete has become stronger, so as not to damage it with a blade, but before random cracks can appear in it. Slicing in concrete floor starts no earlier than 24 hours, but no later than 72 hours after completion finishing.

Expansion joints are cut to a depth of 1/3 of the screed thickness, which allows creating a “weak” zone in the screed.

The location of each seam is usually marked with chalk on a stretched rope. A guideline for cutting is a special ruler or a board with a width of at least 4 cm. During the cutting process, spare equipment should always be available, it will come in handy if the main one fails.

If there is a risk of premature cracking of concrete, for example in hot weather, it is necessary to cut every third or fourth seam before cutting the intermediate ones. They are performed in the same sequence in which concrete is laid. Their depth should be equal to 1/3 of the thickness of the screed. This creates a zone of slack in it, and when concrete shrinks, it cracks in this place. The edges of the crack that has appeared have a rough structure, which excludes the possibility of their vertical displacement - as a result, the crack does not become too wide.

More recently, an easy dry cutting method has been invented, which is performed immediately after the concrete has been finished. If you use a long handle during work, it is possible to cut up to 10 m even without moving along the floor surface. For cutting long seams, a worker in special boots with a smooth sole can move along the screed and use a 2 m handle. This type is cut to a depth of no more than 2-3 cm.

Sealing

The expansion joints are filled with a sealant, and then a sealant is applied.

To facilitate the cleaning process and provide support when various loads the seam needs sealing. Sealing allows you to effectively protect against moisture, aggressive environments and clogging. The type of sealant is selected depending on the operating conditions and the strength of the loads. For example, if the floors will need to be washed frequently or heavy trucks will move over them, then a sealant that is sufficiently hard and elastic is best suited.

In industrial premises, the joints must be filled with an appropriate material that is able to support the joint and withstand heavy loads. The material is applied not earlier than 28 days after laying the screed. The seam must be cleaned of contaminants before sealing by blowing it with compressed air and using a mechanical brush or sandblaster. If a processor is used for this purpose, you must first make sure that it does not leave an oil film in the seam.

Summing up, we can conclude that in order to obtain a durable concrete floor that is resistant to pedestrian, transport and other loads, as well as temperature extremes and corrosion, it is necessary to apply quality materials, accurately perform the necessary technological operations, correctly cut expansion joints and care for concrete floors.

Cement-sand floor screed - a product that is not capable of plastic deformation.

Under the influence of internal stresses that occur during hardening or temperature changes, the screed is prone to cracking.

In order to avoid cracking of the floor and to control the appearance of cracks, it is necessary to make expansion joints.

The seams used for semi-dry screeds are divided into 2 categories:

Seams

Insulating joints must be made at the junction of the floor to the walls, columns and foundations for equipment.

An insulating joint allows you to "untie" the floor from existing structures, which makes it possible to harden and shrink the screed, regardless of the elements of the building.

The appearance of a crack passing through the middle of the room or in the middle between the wall and the column, the wall and the foundation for the equipment is due to the lack of an insulating joint.

Figure 1 shows typical cases of such cracks.

The main material for the device of such seams is polyethylene foam with a thickness of 8-10 mm.

Before starting concreting, it is necessary to cut the insulating material into strips with a width exceeding the expected screed thickness by 100-150 mm.

The insulating material is fixed masking tape to building elements.

After finishing work on the installation of a cement-sand floor screed, the excess insulating material is cut off by the level of the floor surface.

Shrink seams

The hardening of the cement-sand screed is associated with uneven shrinkage: top part shrinks faster than the bottom. The edges of the tie "raise" above the center. The resulting internal stresses lead to the formation of cracks.

Arranging a shrink seam, we show the screed in which place it is necessary to crack. Shrink joints are made to avoid cracking in unpredictable screed areas by creating straight planes along which we shoot internal stress screeds.

The best way to organize shrinkage joints is to cut the concrete screed 1/3 of its thickness after 24-72 hours after laying.

Before 24 hours, it is not recommended to cut the seam due to the inevitable destruction of the cut edge in such cases, and after 72 hours, cutting the seam becomes practically meaningless due to the fact that shrinkage processes have already led to the formation of microcracks in the thickness of the screed, and the cut will have practically no effect on the location and nature of the cracks that have appeared.

Sawing or cutting shrinkage seams is carried out with special equipment - a seam cutter (seam cutter), using a diamond-coated disc. The width of the disc should be within 3-4 mm, diameter 300-450 mm.

Shrinkage seams are cut along the axes of the columns and joined with the tops of the rhombus from the seams that the column bypasses (Figure No. 2).

Bypassing the column "diamond" is necessary to prevent the formation of cracks coming from the corners of the column, which has a square or rectangular shape. When bypassing the column with a "rhombus" of shrinkage joints, it is necessary to monitor the depth of cut at the vertices of the rhombus, since due to the fact that the disk has round shape, it is not always possible to saw through a section close to the top to the required depth. In such cases, it is allowed to bring the cut from the wall or other column directly through the top of the "rhombus" to the current column.

To obtain an even cut under the shrinkage seam, a chopping (dyeing) thread is used. This allows you to accurately mark the lines of the connecting axis of the columns. The importance of hitting strictly in this line is due to the fact that otherwise a beautifully arranged seam will not help to avoid the appearance of a crack that will pass exactly along the line of the axes of the columns (see Figure No. 3).

It is necessary to cut shrinkage seams with “cards” of square or rectangular shape, but with a ratio of the larger side to the smaller side no more than 1.5.
The total area of the map should not exceed 40 square meters. m. Shrinkage seams should be straight and not have branches.

Filling of shrinkage joints is carried out after at least 3 weeks from the moment of laying the screed.

This is due to the fact that only after 28 days the moisture content of the concrete W corresponds to the conditions for applying the sealant, namely W Before filling, the joint must be cleaned of dirt and dust by blowing it with compressed air.

The main part of the cut (except for 10 mm in the upper part) is filled with foamed polyethylene (vilatherm) round section with a diameter of 3-5% greater than the width of the disk used for slotting.

The remaining 10 mm are filled with sealant with a hardness of 40-50 Shore units.

Adhering to the edges of the cut, the sealant allows the screed to move both horizontally and vertically, and the specified hardness will not allow the sealant to deform under the action of almost any load on the surface of the concrete floor.

Expansion joints in the blind area of the house

The foundation is the main structure of the whole house, and the time that the house will last depends on the level of its quality. When installing any foundation, it is important to arrange expansion joints in the blind area as correctly as possible.

An expansion joint is a specially made section that acts as a protection and allows the foundation to endure fluctuations in temperature and soil. The expansion joint is a popular construction technique in seismically active areas, and the tape base needs protection most of all.

All expansion joints that exist in construction can be divided into several categories:

The selection of a specific type of seam is carried out with an eye to the land type and climate features of a particular region, as well as the nuances of the underlying layer.

The nuances of the right creation

It is desirable that the number of seams be calculated by an experienced surveyor. To correctly make a seam that will protect the foundation from deformation, you must follow some rules. So, the height of the seam should be equal to the height of the foundation, and the distance between each of the seams can be determined just based on the calculations. But in general, there are average standards for the location of seams, for houses that are made of wooden materials, the step of the seams will be 0.6 meters, and for buildings whose walls are made of brick - 0.15 meters.

expansion joints in the blind area

The structure of the building is also important. For example, if the house has an extension, then expansion joints will also need to be created along the corner boundaries, which should have an average width of 10-12 cm. with the help of tarred tow, and the base belt type will require separate thermal insulation and waterproofing.

When creating a blind area, wooden slats are used, which must later be filled with bitumen. The seam located between the blind area and the base of the house will not be needed if the base already has insulation from moisture and cold.

The above tips can be called universal and suitable for all types of expansion joints. Following them will help to make a strong and durable foundation that will last for decades.

Slight differences in the types of seams determine the area in which they are used, and the peculiarity of their work will depend on this. So, a seismic seam will be appropriate in areas with increased risk of earthquakes. It will take on the load in the event of ground vibrations and will not allow the building to deform. If the seam needs to be placed between the extension and the main building, then the foundations of these two structures must be separated by a layer of foam, styroform, or use armoflex with a thickness of 2 cm.

Expansion joints in the blind area are used mainly in regions where the air temperature varies greatly throughout the year. In order to smooth out soil shifts as much as possible after temperature changes, the foundation area is divided into sectors using wooden slats. Similar types of seams are used when installing in buildings that do not have heating.

Seams of shrinkage-deformation type are made between the base blocks and the concrete poured from above. The reason for such measures can be called the peculiarity of concrete, which shrinks when water evaporates.

Installation of a sedimentary protective seam can be found when laying the foundation for a house with many floors. This makes it possible to redirect the entire load as evenly as possible and remove the risk of damage. Installation of expansion joints is carried out using different profiles. Professional craftsmen simply choose the most preferred profile and create an expansion joint from it in the blind area.

Seam filling

If the seam is not arranged correctly, it may collapse. It is important to use only high-quality sealants, the elasticity of which is just right for sealing such joints. Sealants are made from polymers, which give the necessary properties to the product.

The most popular sealant for filling the expansion joint cavity is the polyurethane type, which gives greater endurance and provides long term services of insulated structures. The price of such a material will be higher than other sealants, but its properties are much higher.

Sealing expansion joints

Preparation for sealing consists in cleaning the seam from various pollution. The seam processed in this way will be of high quality and will last a long time. Polyurethane sealants except high level elasticity are well bonded to the surface, they are also heat-resistant and can tolerate temperature fluctuations of -100- +100 degrees.

Joint insulation

The entire structure of the house under construction is divided into separate sections drawing - nodes in which expansion joints in the blind area will be placed. An unconditional condition for the creation of such seams is their protection from water, especially if there is a basement or basement.

When choosing a waterproofing agent, one should be guided by the size of the seam, the possibility of deformation, pressure on it and the maximum load, as well as the nature of the effect on the seam, also important nuance will be the water pressure.

During the design of the seam protection against water, the most the best option there will be a self-made loop that will collect moisture. You also need to make moisture-collecting pads by placing them directly in the concrete. After the seams have been protected from excessive moisture, be sure to examine all points of contact for leaks. Made in accordance with the rules and regulations, the expansion joint in the blind area will make the foundation of the house durable, which is especially important on unstable lands. At the stage of designing houses and other construction projects in seismically active regions, the creation of expansion joints is one of the most important sections of design documents. The correctness of the arrangement, sealing and protection of the seams from water is directly correlated with the indicator of the strength of the foundation of the house.

Deformation seam in the blind area

The expansion joint in the blind area is important structural element. It will prevent premature destruction of concrete.

Why and how expansion joints are made in concrete: an overview of technology, types of joints and a step-by-step scheme of work

Because today the price of all building materials is constantly increasing, you need to think about how to do it for real quality constructions so that later you do not have to constantly correct defects.

All kinds of concrete structures- for example, floors and blind areas around the building. If the floors are done incorrectly, they will simply crack, and this will automatically lead to deformation of the finished floor covering.

Photo showing temperature lines in the structure of a concrete floor

As for the blind area, it is, in fact, responsible for the integrity and normal condition of the foundation tape. If cracks appear in the blind area, then water will penetrate there, which in turn will fall into the structure of the foundation. And this is already fraught with serious consequences.

To minimize the risk of cracking, an expansion joint is arranged in concrete according to SNIP - with its presence, deformation is unlikely.

In fact, these are kind of cuts in the concrete structure, thanks to which the concrete does not crack during temperature changes - as it seems to have room to expand.

Correctly made blind area

In fact, there is a whole classification of protective lines - and there are not only temperature ones. Let's consider what they generally are, and then, using the example of installing floors and blind areas, we will figure out how expansion joints are arranged in reinforced concrete structures.

Types of seams in concrete

After the entire mass has solidified, the shrinkage incision is closed.

Such is the classification.

Please note that the installation of expansion joints in concrete implies their mandatory processing - these are not voids. As a rule, such cuts are sealed either with sealants, or with special profiles or elastic inserts. If this is not done, then it worsens significantly visual appearance and, of course, the thermal insulation qualities of the structure are lost.

Filling the deformation line with a special profile

Now we can move on to how exactly such temperature protection is done.

Installation of expansion joints

As already mentioned, we will get acquainted with the technology using the example of concrete floors and blind areas around the perimeter of the building. Why these structures? Because in most cases they are made with their own hands and with characteristic mistakes (see also the article “Grid for concrete - types and applications”).

And the errors just lie in the fact that there is no protective temperature line.

Screed without protective cuts

Before starting, a few words about the features of these structures, in which cases they need to be protected by such technology.

In addition, incisions must also be made along the perimeter of the columns (if any) at the points of contact with the floor.

Please note that the installation of expansion joints in concrete is also carried out in the walls. And even if they are not made of a monolith, but also of ordinary bricks or blocks.

Now you can proceed directly to work. Brief Instructions for pouring the floor and the blind area, in which the main attention will be paid to the arrangement of seams.

This element of the house is done like this:

How to make expansion joints in the blind area?

Design features of the blind area
Why do I need a damping seam and how to do it correctly?
When should expansion joints be placed?

The main purpose of the blind area is to protect the base of the house from moisture and temperature extremes. The arrangement of this important strip around the building should not be neglected: it will prevent premature obsolescence of concrete and other building materials from which the foundation and basement are made.

The blind area of the house protects the foundation from deformation and prevents penetration surface water and drains to its base.

Expansion joints in the blind area are designed to prevent cracking due to seasonal soil movements.

They are necessary only when pouring a cast concrete strip, since the blind area from finished slabs or blocks is able to independently compensate for frost heaving of the soil.

Design features of the blind area

The device is a typical blind area.

if the groundwater level is high or the soil is predominantly clayey, a device is recommended drainage system along the perimeter of the building;
the purpose of the protective concrete tape is to drain water from the building, therefore a slope of the strip is necessary from the foundation to its outer edge;
if the climate is predominantly cold, then it is recommended to perform insulation. This can be done with polyurethane foam or foam;
for any blind area, it is necessary to have a waterproofing layer, which is carried out with roofing material in 1-2 layers with a mandatory overlap of sheets by 15-20 cm. It is laid on a pre-leveled and compacted bottom of the trench;
any protective tape along the perimeter of the building consists of 2 layers: underlying and facing;
if fulfilled concrete blind area, then on waterproofing material a layer of crushed stone 10-15 cm thick is poured and compacted. Next, either a heater or a reinforcing mesh is laid, after which concrete is poured;
if it is decided to make a protective strip with a facing layer of paving slabs, then only sand is used, which is poured in layers, spilled with water and compacted;

Why do I need a damping seam and how to do it correctly?

The scheme of the expansion joint.

Practice has shown that any solid plinth tape made without expansion joints collapses after the first winter. Therefore, every 2-2.5 m, when installing the underlying layer, the installation of damping joints is provided. The first of them is located at the junction of the blind area itself and the wall of the house, its basement. It will protect its lining from destruction during seasonal soil movements. The remaining seams, after a certain distance, are placed across the tape, perpendicular to the wall of the building. The width of each of them is 1-2 cm. They will allow the concrete to narrow and expand under the influence of temperatures. environment without causing damage to either the building or the blind area itself.

Use as an expansion joint wooden blocks, pre-treated by mining or tarred. You can also use modern water-repellent impregnations. The thickness of the boards (bars) should be 15-20 mm. Such a seam is not afraid of either moisture or cold. For the damping effect, special vinyl tapes which will also prevent cracking of the concrete. Standard Width tapes 1-1.5 cm. The installation step depends on the width of the protective strip being constructed. The larger it is, the more often the laying of bars or tape is required.

When should expansion joints be placed?

marking is made and the soil is removed on the bayonet of the shovel;
the bottom of the trench is leveled and compacted;
if possible, the waterproofing layer is made using clay. If it is not there, then roofing material is laid;
then they arrange an underlying layer of sand and gravel, each of which is carefully leveled and compacted;
after which the formwork is mounted (for a concrete tape) or curbs are installed (for a blind area from paving slabs);
in the formwork, a material is placed that is intended to act as expansion joints: bars or vinyl tape;
the first layer of concrete is poured;
on it, after this layer hardens, a reinforcing mesh is installed;
further pouring with concrete is carried out, taking into account the necessary slope towards the outer edge of the blind area;

A practical owner will certainly make sure that his household looks fresh and sound for many years. That is why it is so important to consider all technological nuances, which include the laying of damping seams, during the construction of the blind area.

Expansion joints in the blind area: how to make them correctly?

Expansion joints in the blind area are an important structural element. It will prevent premature destruction of concrete from soil movements and create maximum conditions for the durability of the protective strip.

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