Purpose of expansion joints, types of expansion joints: for bridges, between buildings, in industrial buildings, between walls subtitles

An expansion joint is a technological cut in a concrete floor that reduces the acting forces on the coatings and nearby architectural structures. The technical parameters of expansion joints are specified in the design documentation of buildings and structures. Depending on the functions performed, expansion joints are divided into several types.

Expansion joints in concrete floors

Table. Types of expansion joints.

Insulation joints are installed around foundations and columns, as well as along walls in order to prevent the transfer of deformations from the house structures to the floor screed

Expansion joint

Expansion joints are widely used in many industrial areas. We are talking about high-rise construction, construction of bridge structures and other industries. They represent a very important object element, and choosing the required type of dilatation structure will vary depending on:

• the magnitude of static and thermohydrometric changes;
• the magnitude of a certain transport load and the required level of travel comfort during operation;
• from the conditions of detention.

The purpose of the expansion joint is to reduce the load on individual parts of structures in places of expected deformations that can occur due to fluctuations in air temperature, as well as seismic phenomena, unexpected and uneven sedimentation of the soil and other influences that can cause their own loads that reduce the load-bearing properties of structures. In visual terms, this is a cut in the body of the building; it divides the building into several blocks, giving these a certain elasticity to the structure. To ensure waterproofing, the cut is filled with suitable material. These can be various sealants, waterstops or putties.

Why is sealing needed?

In rooms with increased requirements for water resistance, seams are sealed, since excess moisture promotes peeling of coatings. The activation of this process increases in the presence of high temperatures.

Sealing helps prevent exposure to water and other aggressive substances, as well as clogging of the joint space. When choosing a sealant, the operating conditions and loads to which concrete pavements are subjected must be taken into account.

Main types of sealants :

• mastics (polybutylene);
• hot and cold curing thermoplastics (bitumen, butyl rubber);
• thermosets (vinyl acetate, polyurethane, polysulfide);
• silicones.

For example, most floor coverings in industrial plants must be easy to clean and at the same time withstand heavy loads. Sealants for such floors must be both flexible and hard enough to prevent chipping.

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Installing an expansion joint is the prerogative of experienced builders, so such a responsible task should be entrusted exclusively to qualified specialists. The construction team must have adequate equipment for proper installation of the expansion joint - the longevity of the entire structure depends on this. It is necessary to provide for all types of work, including installation, welding, carpentry, reinforcing, geodetic, and concrete laying. The technology for installing an expansion joint must comply with accepted specially developed recommendations.

The maintenance of expansion joints in general does not present any difficulties, but requires periodic inspections. Special control must be carried out in the spring, when pieces of ice, metal, wood, stone and other debris can get into the dilation space - this can serve as an obstacle to the normal functioning of the seam. In winter, care should be taken when using snow removal equipment, since its actions can damage the expansion joint. If a malfunction is detected, contact the manufacturer immediately.

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, and soil settlement, its integrity is lost - it begins to crack.

To impart some degree of elasticity to this building structure, expansion joints are created in the concrete floors. SNiP2.03.13-88 and its Manual contain information on the requirements for the design and installation of floors, indicating the need to create a gap in the screed, underlying layer or coating, which ensures the relative displacement of isolated sections.

• Minimizing sudden deformations by dividing a monolithic slab into a certain number of cards.
• The ability to avoid expensive repairs with the replacement of rough and base coatings.
• Increased resistance to dynamic loads.
• Ensuring the durability of the structural basis.

Purpose of expansion joints

Since hydraulic structures made of reinforced concrete or concrete (for example, dams, shipping buildings, hydroelectric power stations, bridges) are of considerable size, they undergo force impacts of various origins. They depend on many factors, such as the type of base, production conditions and others. Ultimately, thermal shrinkage and sedimentary deformations may occur, risking the appearance of cracks of various sizes in the body of the structure.

In order to ensure the safety of the solidity of the structure to the maximum extent, the following measures are applied:

• rational cutting of buildings with temporary and permanent joints depending on both geological and climatic conditions
• creation and maintenance of normal temperature conditions during the construction of buildings, as well as during further operation. The problem is solved by using low-shrinkage and low-heat grades of cement, its rational use, pipe cooling, thermal insulation of concrete surfaces
• increasing the level of homogeneity of concrete, achieving its adequate tensile strength, strength for reinforcement in places where cracks may occur and axial tension

At what point do the main deformations of concrete buildings occur? Why are expansion joints needed in this case? Changes in the building body can occur during construction under high temperature stress - a consequence of the exotherm of hardening concrete and fluctuations in air temperature. In addition, at this moment concrete shrinkage occurs. During the construction period, expansion joints can reduce excessive loads and prevent further changes that could be fatal to the structure. The buildings seem to be cut along their length into separate sectional blocks. Expansion joints serve to ensure high-quality functioning of each section, and also eliminate the possibility of forces occurring between adjacent blocks.

Depending on the service life, expansion joints are divided into structural, permanent or temporary (construction). Permanent seams include temperature cuts in structures with a rock foundation. Temporary shrinkage joints are created to reduce temperature and other stresses; thanks to them, the structure is cut into individual columns and concreting blocks.

What materials are used to seal temperature-shrinkable seams?

To protect joints in concrete floors from debris, moisture and destruction, they must be filled with CEMMIX sealants:

1. Adhesive sealant for seams CEMMIX;
2. Heavy-duty roofing adhesive-sealant;
3. Facade adhesive-sealant CEMMIX.

To construct temperature-shrinkable seams, inventory (ready-to-use) profiled tapes, metal profiles with plastic or rubber inserts, and sealing strips made of foamed polymer can be used.

The most modern and reliable solution is the use of CEMMIX polyurethane sealants.

Concrete floors are subject to significant loads, and the filling material must have certain characteristics: be elastic, strong, durable, waterproof, and not afraid of temperature changes. It is also important that it be easy to use. Polyurethane sealants meet all these requirements: Cemmix Heavy-Duty Roofing Adhesive-Sealant, CEMMIX Facade Adhesive-Sealant and Cemmix Seam-Adhesive.

They have the following characteristics:

1. high adhesion to different types of building materials;
2. strength, elasticity, durability;
3. no foaming or shrinkage;
4. vibration absorption;
5. rapid setting under the influence of atmospheric humidity;
6. resistance to ultraviolet radiation, temperature changes, precipitation, exposure to aggressive compounds that may be present in precipitation (salts, acids);
7. corrosion resistance;
8. possibility of use at different temperatures;
9. no need to prime surfaces before applying sealant;
10. resistance to the formation of fungus, mold, mosses, lichens;
11. no odor, safe for humans.

Cemmix's heavy-duty roofing adhesive-sealant is paintable, and Cemmix Seam-Adhesive Sealant and CEMMIX Façade Adhesive-Sealant are available in several shades, so a seam-filling solution can be not only durable and reliable, but also aesthetically pleasing.

Important!

CEMMIX joint sealants are designed to fill joints up to 20 mm wide.

It should be added that Cemmix polyurethane sealants are one-component, that is, they are supplied ready-to-use, easy to apply and easy to clean from surfaces before polymerization.

Step-by-step instructions for filling seams with polyurethane sealant:

1. After laying the concrete, 28 days must pass.
2. The surface is cleaned of any contaminants, in winter - from frost, ice using metal brushes or power tools, then blown with compressed air and, if necessary, degreased with acetone.
3. If necessary, the surface is primed.
4. At the mouth of the seams, a separating material is placed that does not have adhesion to the sealant, for example, a cord made of closed-cell polyethylene foam. This is done for two purposes. The separating material prevents the formation of a third contact surface for the sealant, which is a prerequisite for its durability and strength, and also regulates the depth of filling the seam with sealant (it should not exceed the width of the seam). Round materials are used, the diameter of which is 20% larger than the width of the joint to ensure a dense filling.
5. The surfaces around the seams are protected with masking tape.
6. The sealant is applied using a construction gun in a smooth motion in one direction only and at the same time leveled with a spatula dipped in soapy water. Within 10 minutes you can adjust the application and remove excess.
7. Within 24 hours after applying the sealant, the seams are not subjected to stress.

What mistakes should be avoided when filling shrinkage joints:

1. The joints must be cut on time, usually about 12 hours after the concrete is laid. First, make a test cut. If the filler grains do not fall out, but are cut, then the seams can be cut.
2. The interval between joints depends on the properties of the concrete.
3. Triangular and sharp-angled areas should be avoided.

What to do if cracks do appear:

1. If cracks appear within 1–2 hours after laying the concrete, you can get rid of them by repeated vibration treatment.
2. Cracks that appear after the concrete has set are treated with cement repair compounds.
3. Cracks that appear in concrete can be filled with polyurethane sealant.
4. If there are a lot of cracks, the best solution is to remove the screed and refill it, taking into account the errors.

Proper installation of temperature-shrinkage joints prevents the appearance of chaotic cracks and destruction of the concrete floor screed. It involves cutting the seams and filling them with a strong, flexible, and durable material to resist fracture. Cemmix polyurethane sealants - Heavy-duty roofing adhesive-sealant, CEMMIX Facade adhesive-sealant and Seam sealant adhesive - are modern high-tech materials that are the optimal choice in this case. You can buy Heavy-Duty Roofing Adhesive-Sealant, CEMMIX Facade Adhesive-Sealant and Adhesive-Sealant for Seams wholesale from the manufacturer and in Leroy Merlin stores.

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Types of expansion joints

There are a number of types of expansion joints. Traditionally, they are classified according to the nature and nature of the factors causing deformation in structures. Here they are:

• Temperature
• Sedimentary
• Antiseismic
• Shrinkage
• Structural
• Insulating

The most common types are temperature and sedimentary expansion joints. They are used in the vast majority of constructions of various structures. Expansion joints compensate for changes in the body of buildings that occur due to changes in ambient temperature. The ground part of the building is more susceptible to this, so cuts are made from the ground level to the roof, thereby not affecting the fundamental part. This type of seam cuts the building into blocks, thus ensuring the possibility of linear movements without negative (destructive) consequences.

Sedimentary expansion joints compensate for changes due to uneven various types of structural loads on the ground. This occurs due to differences in the number of floors or large differences in the mass of ground structures.

The anti-seismic type of expansion joints is provided for the construction of buildings in seismic zones. The arrangement of such sections makes it possible to divide the building into separate blocks, which are independent objects. This precaution allows you to effectively counteract seismic loads.

In monolithic construction, shrinkage joints are widely used. As concrete hardens, a decrease in monolithic structures is observed, namely in volume, but at the same time excess internal tension is formed in the concrete structure. This type of expansion joint helps prevent the appearance of cracks in the walls of the structure as a result of exposure to such stress. When the wall shrinkage process is completed, the expansion joint is tightly sealed.

Insulation joints are installed along columns, walls, and around the foundation for equipment in order to protect the floor screed from possible transfer of deformation resulting from the building structure.

Construction joints act as shrinkage joints; they involve small horizontal movements, but in no case vertical ones. It would also be good if the construction seam corresponded to the shrinkage seam.

It should be noted that the design of the expansion joint must correspond to the plan of the developed project - we are talking about strict compliance with all specified parameters.

TechLib SPB UVT

External walls, and together with the remaining structures of the building, if necessary and depending on the specifics of the building solution, natural-climatic and engineering-geological conditions of construction, are cut through expansion joints of various types:

• temperature,
• sedimentary,
• seismic.

An expansion joint is used to reduce the loads on various structural elements in places of possible deformations that occur during seismic phenomena, temperature fluctuations, uneven soil settlement, as well as other influences that can cause their own loads that reduce the load-bearing capacity of the structure.

This is a cut in the structure of a building that divides the structure into separate blocks, thereby imparting a degree of elasticity to the structure. For sealing, it is filled with elastic insulating material.

Expansion joints are used depending on the purpose. These are temperature, antiseismic, sedimentary and shrinkage. Expansion joints divide the building into compartments, from ground level to the roof inclusive. This does not affect the foundation, which is located below ground level, where it experiences less temperature fluctuations, and therefore is not subject to significant deformation.

Some parts of the building may have different number of floors. Then the foundation soils, which are located under different parts of the building, perceive different loads. This can lead to cracks in the walls of the building, as well as in other structures.

Also, the uneven settlement of soils at the base of a structure can be influenced by differences in the composition and structure of the base within the building area. This can cause sedimentary cracks to appear even in a building of the same number of storeys, over a considerable length.

To avoid dangerous deformations, sedimentary seams are made. They differ in that when cutting a building along its entire height, the foundation is also included. Sometimes, if necessary, different types of seams are used. They can be combined into temperature-sediment joints.

In buildings constructed in earthquake-prone areas, anti-seismic joints are used. Their peculiarity is that they divide the building into compartments, which from a structural point of view are independent stable volumes.

Shrinkage joints are made in walls built from various types of monolithic concrete. As concrete hardens, monolithic walls decrease in volume. The seams themselves prevent the occurrence of cracks, which reduce the load-bearing capacity of the walls.

Expansion joint - designed to reduce loads on structural elements in places of possible deformations that occur when air temperature fluctuates, seismic phenomena, uneven soil settlement and other influences that can cause dangerous self-loads that reduce the load-bearing capacity of structures. It is a kind of cut in the structure of a building, dividing the structure into separate blocks and, thereby, giving the structure a certain degree of elasticity. For sealing purposes, it is filled with elastic insulating material.

Depending on the purpose, the following expansion joints are used: temperature, sedimentary, anti-seismic and shrinkage.

Expansion joints divide the building into compartments from ground level to the roof inclusive, without affecting the foundation, which, being below ground level, experiences temperature fluctuations to a lesser extent and, therefore, is not subject to significant deformations. The distance between expansion joints is taken depending on the material of the walls and the estimated winter temperature of the construction area.

Individual parts of the building may have different heights. In this case, the foundation soils located directly under different parts of the building will bear different loads. Uneven soil deformation can lead to cracks in walls and other building structures. Another reason for uneven settlement of the foundation soils may be differences in the composition and structure of the foundation within the building area. Then, in buildings of considerable length, even with the same number of storeys, sedimentary cracks may appear. To avoid the occurrence of dangerous deformations in buildings, sedimentary joints are installed. These seams, unlike temperature seams, cut buildings along their entire height, including foundations.

If it is necessary to use expansion joints of different types in one building, they are combined, if possible, in the form of so-called temperature-sedimentation joints.

Anti-seismic joints are used in buildings constructed in areas prone to earthquakes. They cut the building into compartments, which from a structural point of view should represent independent stable volumes. Along the lines of anti-seismic seams, double walls or double rows of load-bearing racks are placed, which are part of the load-bearing frame system of the corresponding compartment.

Shrinkage joints are made in walls built from various types of monolithic concrete. Monolithic walls decrease in volume as concrete hardens. Shrinkage joints prevent the occurrence of cracks that reduce the load-bearing capacity of the walls. During the hardening process of monolithic walls, the width of the shrinkage joints increases; Once the shrinkage of the walls is complete, the seams are tightly sealed.

To organize and waterproof expansion joints, various materials are used: - sealants - putties - waterstops

An expansion joint is a vertical gap filled with elastic material that divides the walls of a building. Its purpose is to prevent the appearance of cracks from temperature changes and uneven settlement of the building.

Temperature-shrinkage joints are installed to avoid the formation of cracks and distortions in the walls caused by the concentration of forces from the effects of variable air temperatures and shrinkage of materials (masonry, concrete). Such seams cut only the ground part of the building.

To avoid the appearance of cracks caused by shrinkage deformations in walls made of monolithic concrete and concrete stones, as well as unseasoned sand-lime brick (up to three months old), it is recommended to lay structural reinforcement with a total cross-section of 2— 4 cm2 per floor.

The seams in walls connected to metal or reinforced concrete structures must coincide with the seams in the structures.

Maximum permissible distances (in m) between expansion joints in the walls of heated buildings

The distances indicated in the table are subject to reduction: for walls of closed unheated buildings - by 30%, for open stone structures - by 50%

With changes in temperature, reinforced concrete structures are deformed: they are shortened or lengthened, and due to concrete shrinkage they are shortened. When the foundation settles unevenly in the vertical direction, parts of the structures are mutually displaced.

Reinforced concrete structures, as a rule, are statically indeterminate systems, in which, with temperature changes, the development of shrinkage deformations and uneven settlement of foundations, additional forces arise that can cause the formation of cracks. To reduce this kind of effort in long buildings, temperature-shrinkage and settlement joints are necessary.

In the coverings and floors of buildings, the distance between the seams depends on the flexibility of the columns and the pliability of the joints; in monolithic structures this distance should be less than in prefabricated ones. When installing rolling supports, thermal stresses can be completely avoided.

In addition, the distance between expansion joints depends on the temperature difference; therefore, in heated buildings these distances, regardless of all other factors, are smaller.

Temperature-shrinkage seams cut through structures from the roof to the foundations, and settlement seams completely separate one part of the structure from another. A temperature-shrinkage joint can be formed by installing paired columns on a common foundation. Settlement joints are provided in places where there is a sharp difference in the height of buildings, where newly erected buildings adjoin old ones when constructing buildings or structures on soils of different composition, and in other cases when uneven settlement of foundations is possible.

Sedimentary seams are also formed by the arrangement of paired columns, but installed on separate foundations.

The distances between temperature-shrinkage joints in concrete and reinforced concrete structures of low buildings can be taken structurally, without calculation.

Settlement joints are used to divide the building lengthwise into parts in order to prevent the destruction of structures in the event of possible uneven settlement of individual parts. Sedimentary seams run from the eaves of the building to the base of the foundation; the location of the seams is indicated in the project. The seams in the walls are made in the form of tongue and groove, usually 1/2 brick thick, with two layers of roofing felt; and in foundations - without tongue and groove. A gap of 1-2 bricks is left above the top edge of the foundation under the tongue and groove of the wall, so that when settling the tongue and groove does not rest against the foundation masonry. Otherwise, the masonry may collapse in this place. Sedimentary seams in foundations and walls are caulked with tarred tow.

To prevent surface groundwater from penetrating into the basement through the sedimentary joint, a clay castle is installed on its outside or other measures provided for by the project are applied. Expansion joints protect buildings from cracks due to temperature deformations.

Sedimentary joints are installed at the junctions of building sections:

• located on heterogeneous soils;
• attached to existing buildings;
• with a difference in height exceeding 10 m;
• in all cases where uneven settlement of the foundation can be expected.

Settlement and expansion joints in brick walls should be made in the form of a tongue and groove with a groove size for walls 1.5 and 2 bricks thick - 13 x 14 cm, and for thicker walls 13 x 27 cm. In rubble masonry of basement walls and foundations, the seams can be arranged end-to-end.

When installing expansion joints in the covering, it is best to tear the roofing carpet. Rolled rubber can be used as a vapor barrier membrane in the construction of an expansion joint.

In cases where the expansion joint is installed in watershed areas, and the movement of water flow along the seam is impossible, or the slopes on the roof are more than 15%, then it is permissible to use a simplified construction of the expansion joint. The deformations of the building are compensated by the upper mineral wool insulation.

In roofs with a corrugated sheet base, it is necessary to secure the main layers of roofing material at the edges of the expansion joint.

A temperature expansion joint with walls made of lightweight concrete or piece materials can be installed in roofs with a concrete base or reinforced concrete slabs.

The wall of the expansion joint is installed on the supporting structures. The edge of the TDS wall should be 300 mm higher than the surface of the roofing carpet. The seam between the walls must be at least 30 mm.

A metal expansion joint installed in a temperature expansion joint cannot serve as a vapor barrier. It is necessary to lay additional layers of vapor barrier material on the compensator.

Temperature joints are installed in long walls to prevent cracks from appearing due to temperature changes. Such a seam cuts the structures only from the ground part, to the foundations, because foundations being in the ground do not experience temperature effects. The distance between these seams ranges from 20 to 200 m and depends on the material of the walls and the area of ​​construction. The smallest seam width is 20 mm.

The sedimentary seam cuts the building to its entire height - from the ridge to the base of the foundation. Such a seam is placed depending on several factors:

• when the difference in building heights is not less than 10 m;
• if the soils used as a foundation have different bearing capacities;
• during the construction of buildings with different construction periods.

The smallest joint width is 20 mm

A seismic seam is installed in buildings that are built in seismic areas.

Scheme of placement and design of expansion joints: a – facade of the building; b – expansion or sedimentation seam with groove and tongue; c – temperature or sedimentation joint in a quarter; d – expansion joint with compensator; 1 – expansion joint; 2 – sedimentary seam; 3 – wall; 4 – foundation; 5 – insulation; 6 – compensator; 7 – roll insulation.

The designs of expansion joints must ensure the possibility of moving the ends of the spans without overstressing and damage to the elements of the seam, the riding clothes, the canvas and the spans; must be water- and dirt-proof (prevent the ingress of water and dirt onto the ends of the beams and support platforms); operable in specified temperature ranges; have reliable anchoring in the span of the structure; prevent the penetration of moisture onto the roadway slab and under the edging (have reliable waterproofing).

The material of construction of expansion joints must withstand wear, abrasion and abrasion, the effects of ice, snow, sand; should be relatively immune to the effects of sunlight, oil products, and salts.

In general, expansion joints should be located:

• between the foundation and wall masonry using bitumen roll materials;
• between warm and cold walls;
• when the wall thickness changes;
• in unreinforced walls more than 6 m long (longitudinal reinforcement of walls makes it possible to increase the distance between expansion joints);
• when crossing long load-bearing walls;
• at junctions with columns or structures made of other materials;
• in places where there is a sharp change in the height of the wall.

Sealing expansion joints

Expansion joints are sealed with mineral wool or polyethylene foam. On the room side, the seams are sealed with elastic, vapor-tight materials, on the outside - with weather-resistant sealants or flashings. The facing material should not overlap the expansion joint.

The dimensions of temperature blocks are taken depending on the type and design of buildings. The largest distances (m) between expansion joints in frame buildings that can be allowed without a verification calculation.

In addition to temperature deformations, a building can give uneven settlement if it is located on heterogeneous soils or in the case of sharply different operating loads along the length of the building. In this case, to avoid sedimentary deformations, sedimentary seams . In this case, the foundations are made independent, and in the above-ground part of the building the sedimentary seam is combined with a temperature seam or with an abutment seam (the abutment of buildings of different heights, an old building to a new one). Expansion joints are installed in walls and coverings in order to allow mutual displacement of adjacent parts of the building in both horizontal and vertical directions without compromising the thermal resistance of the joint and its waterproofing properties.

When constructing longitudinal expansion joints or height differences between parallel spans on paired columns, paired modular coordination axles with an insert between them should be provided. Depending on the size of the anchorage of the columns in each of the adjacent spans, the dimensions of the inserts between the paired coordination axes along the lines of expansion joints in buildings with spans of the same height and with coverings along the rafter beams (trusses) are taken equal to 500, 750, 1000 mm.

The size of the insert between the longitudinal coordination axes along the line of difference in heights of parallel spans in buildings with roofing on rafter beams (trusses) must be a multiple of 50 mm:

• binding to the coordination axes of the faces of the columns facing the direction of the drop;
• the thickness of the wall made of panels and a gap of 30 m between its internal plane and the edge of the high-span columns;
• a gap of at least 50 mm between the outer plane of the wall and the edge of the low-span columns.

In this case, the size of the insert must be at least 300 mm. The dimensions of the inserts at the junction of mutually perpendicular spans (lower longitudinal to higher transverse) range from 300 to 900 mm. If there is a longitudinal seam between spans that are adjacent to a perpendicular span, this seam is extended into the perpendicular span, where it will be a transverse seam. In this case, the insertion between the coordination axes in the longitudinal and transverse seams is equal to 500, 750 and 1000 mm, and each of the paired columns along the line of the transverse seam must be shifted from the nearest axis by 500 mm. If coating structures are supported on external walls, then the internal plane of the wall is shifted inward from the coordination axis by 150 (130) mm.

Columns are tied to the middle longitudinal and transverse coordination axes of multi-story buildings so that the geometric axes of the columns' sections coincide with the coordination axes, with the exception of columns along the lines of expansion joints. In the case of tying columns and external walls made of panels to the extreme longitudinal coordination axes of buildings, the outer edge of the columns (depending on the frame design) is shifted outward from the coordination axis by 200 mm or aligned with this axis, and a gap of 30 is provided between the inner plane of the wall and the edges of the columns mm. Along the line of transverse expansion joints of buildings with floors made of prefabricated ribbed or smooth hollow-core slabs, paired coordination axes are provided with an insert between them measuring 1000 mm, and the geometric axes of paired columns are combined with the coordination axes.

In the case of an extension of multi-story buildings to one-story buildings, it is not allowed to mutually mix the coordination axes perpendicular to the extension line and common to both parts of the interconnected building. The dimensions of the insert between the parallel extreme coordination axes along the extension line of buildings are determined taking into account the use of standard wall panels - elongated regular or additional ones.

If there are double walls at expansion joints, double modular alignment axes are used, the distance between which is taken to be equal to the sum of the distances from each axis to the corresponding wall face with the addition of the seam size.

Read on topic:

• Expansion joints of buildings
• Expansion joints of structures

Bridge expansion joints

Designers of bridge structures, first of all, advocate the excellent versatility of expansion joints and their design, which would allow one or another system of joints to be used practically without changes on any type of bridge structures (dimensions, diagrams, bridge deck, materials for manufacturing spans, etc.) .

If we talk about expansion joints installed in road bridges, the following criteria should be taken into account:

• Waterproof
• Durability and reliability of operation
• The amount of operating costs (it should be minimal)
• Small values ​​of reactive forces that are transmitted to supporting structures
• Possibility of uniform distribution of gaps in the spaces of suture elements over wide temperature ranges
• Moving bridge spans in all possible planes and directions
• Noise emissions in different directions when vehicles move
• Simplicity and ease of installation

How to make expansion joints in a blind area?

To divide the monolithic structure of the slab into separate blocks (cards), first a waterproofing layer is laid on a base prepared from crushed stone and sand, then an electric-welded anti-shrinkage reinforcing mesh. Dividing partitions are placed and secured on it. Expansion seam options:

1. It is possible to lay a layer of roofing felt, glass, plastic, polymer film, wood between the foundation and the blind area, and across the plinth strip, to prevent the materials from adhering.
2. Another method is to cut expansion joints with a machine using a diamond or abrasive wheel.

Design features of the blind area

Of all the types of arranging a blind area, the most reliable and easiest way to make it is to use concrete. For this:

1. The first step is to draw the boundaries defining the perimeter of the structure.
2. Remove the soil using the bayonet of a shovel.
3. Compact and level the bottom of the trench.
4. Use roofing felt to waterproof with an overlap of 15-20 cm.
5. Pour in crushed stone and sand and compact again with a tamper.

Expansion joints are created using tape made of vinyl or blocks inside the formwork. After this, the first layer of concrete (5 cm) is poured, and a reinforcing mesh is laid on top of it after the mortar has set. The top layer is poured to form a slope from the wall. If the groundwater runs high, then the formwork needs to be buried 40-50 cm and a drainage pipe should be laid to the bottom.

Why do you need a damping seam, and how to make it correctly?

Recently, to create anti-sediment and temperature cuts, a damper tape has been used, which compensates for linear deformations of reinforced concrete or mortar. Under the influence of heat, the cement screed expands by 0.5 mm/m. Due to this, it puts pressure on the wall of the building, and the resulting additional load leads to the formation of cracks, bulges and chips in the screed. The damping seam provided by the tape differs in that:

• compensates for voltages over a wide range;
• has good thermal insulation;
• it can be easily hidden due to the external surface finishing.

Expansion joints of small and medium bridges:

In span structures of small and medium-sized bridge structures, expansion joints of filled and closed types are used when moving the ends of span structures up to 10-10-20 mm, respectively.

Based on the type, the following classification of expansion joints in bridges is obvious:

Open type. This type of seam involves an unfillable gap between the composite structures.

Closed type. In this case, the distance between the adjacent structures is closed by the roadway - a coating laid without the necessary gap.

Filled type. In closed joints, on the contrary, the coating is laid with a gap, because of this, the edges of the gap, as well as the filling itself, are clearly visible from the roadway.

Overlapping type. In the case of a covered expansion joint, the gap between the connecting structures is blocked by some element at the upper level of the roadway.

In addition to the type characteristic, expansion joints of bridge structures are divided into groups according to their location in the roadway:

• under the tramway
• in the curb
• between sidewalks
• on the sidewalks

This is the standard classification of bridge expansion joints. There are also secondary, more detailed divisions of seams, but all of them must be subordinate to the main grouping.

Judging by the experience of operating bridges in Western Europe, it is obvious that the service life of a bridge structure (any) depends almost one hundred percent on the strength and quality of expansion joints.

What it is?

An expansion joint in brickwork is a special gap around the perimeter of the structure, which divides the wall into separate compartments, which gives the building elasticity. It is made in order to prevent cracks in the building structure when building materials expand and contract under the influence of temperature changes, as well as for additional protection of walls from deformation during shrinkage of the house. The size of the gap depends on the type of masonry and the ambient temperature at different times of the year, taking into account the climatic conditions of the region. In multi-storey buildings, the expansion joint is:

• Vertical. It runs along the height of the entire house, with the exception of the foundation, and is 20–40 mm wide.
• Horizontal. It is done at the level of all ceilings with a width of 30 mm.

The contact of the expansion joint in the brickwork with the foundation of the building is unacceptable.

Expansion joint between buildings

What are the types of expansion joints between buildings? Experts classify them according to a number of characteristics. This may be the type of structure being serviced, the location (device), for example, expansion joints in the walls of the building, in the floors, in the roof. In addition, it is worth considering the openness and closedness of their location (indoors and outdoors, outdoors). A lot has already been said about the generally accepted classification (the most important, covering all the most characteristic signs of expansion joints). It was adopted on the basis of the deformations that it is intended to combat. From this point of view, the expansion joint between buildings can be temperature, sedimentary, shrinkage, seismic, or insulating. Depending on the current circumstances and conditions, different types of expansion joints are used between buildings. However, you should know that all of them must correspond to the initially specified parameters.

Even at the building design stage, specialists determine the location and size of expansion joints. This occurs taking into account all expected loads causing deformation of the structure.

When constructing an expansion joint, it is necessary to understand that it is not just a cut in the floor, wall or roof. With all this, it must be correctly designed from a constructive point of view. This requirement is due to the fact that during the operation of structures, expansion joints take on enormous loads. If the load-bearing capacity of the seam is exceeded, there is a risk of cracks. This, by the way, is a fairly well-known phenomenon, and special profiles made of metal can prevent it. Their purpose is expansion joints - profiles seal them and provide structural reinforcement.

The seam between buildings serves as a kind of connection between two structures that are close to each other, but have different foundations. As a result, the difference in the weight load of the structures may have a negative impact, and both structures may develop unwanted cracks. To avoid this, a rigid connection with reinforcement is used. In this case, it is necessary to make sure that both foundations have already settled properly and are sufficiently resistant to the upcoming loads. The construction of the expansion joint is carried out in strict accordance with generally accepted procedures.

Regulatory Requirements

Preparatory work, installation of screeds, calculation of the number of expansion joints in floors are regulated by building codes and regulations. A technological map is drawn up for work producers, which takes into account:

• purpose of the premises;
• concrete grade and material and thickness of the underlying layer;
• calculated static and dynamic loads.

When designing buildings and structures, expansion joints are tried to be located in the axes of the building. They must coincide with the joints of reinforced concrete floor slabs or expansion joints in floors according to the design.

They have to:

• Be mutually perpendicular;
• The thickness and depth of the seams must correspond to the design documentation;
• Grooves must be cut within the prescribed time frame;
• There must be a distance between the grooves specified in the project;
• The grooves must be sealed with special polymer compounds.

Expansion joint between walls

As you know, walls are the most important element in the structure of a structure. They perform a load-bearing function, taking on all falling loads. This is the weight of the roof, floor slabs, and other elements. It follows from this that the reliability and durability of a building largely depends on the strength of the expansion joint between the walls. Moreover, the comfortable operation of interior spaces also depends on the walls (load-bearing structures), which perform the important function of fencing from the outside world.

You should know that the thicker the wall material, the higher the requirements are placed on the expansion joints installed in them. Despite the fact that externally the walls appear monolithic, in reality they have to endure various types of loads. The causes of deformation may be:

• air temperature changes
• the soil under the structure may settle unevenly
• vibration and seismic loads and much more

If cracks form in load-bearing walls, this can threaten the integrity of the entire building. Based on the foregoing, expansion joints are the only way to prevent changes in the body of structures that could become fatal.

In order for the expansion joint in the walls to function correctly, it is necessary, first of all, to carry out the design work correctly. Thus, the calculation of actions must be carried out at the building design stage.

The main criterion for the successful operation of an expansion joint is the correctly calculated number of compartments into which it is planned to cut the building to successfully compensate for stresses. According to the established quantity, the distance that must be taken into account between the seams is also determined.

Profiles for expansion joints

To fill them, materials are used that have sufficient tightness, ductility, elasticity and insulating properties. Special putties, sealants, elastic bands, and waterstops are used as fillers for seams. First of all, filling the seam is a necessary measure in multi-story buildings.

Types of profiles are classified based on the purpose of the seam. There are:

• Temperature;
• Shrink;
• Seismic;
• Sedimentary.

Depending on the tasks assigned to the expansion joint, the profiles can be:

• insulating;
• invoices;
• lining;
• waterproof;
• thermally expanding;
• parapet.

What is an expansion joint used for?

Let's consider the key purposes of its use:

1. Def. jointing is necessary in order to effectively separate tiled surfaces from structural elements: walls, columns, plinths. Thus, deformation profiles for tiles ensure the ability of the surface to have slight mobility in any direction. An equally important function of the seam is to enhance sound and heat insulation.
2. The seam is used to divide large areas covered with tiles into sections (their number depends on the construction site and operating conditions). The separation seam provides compensation and absorption of stress generated as a result of changes in linear parameters or other types of deformation processes (for example, mechanical or thermohygrometric). Thanks to the seam, monolithic structures are reliably protected from critical structural tension.
3. Separating joints interrupt the tiled surface. In areas of flexible joints, temperature, shrinkage and construction seams can be duplicated. The presence of special breaks that provide sufficient mobility of the base increases the overall reliability and stability of the structure.

Proper arrangement of separation joints is a measure necessary to effectively control the level of stress generated in the structure of lined surfaces. Their presence serves as a strong guarantee of the durability of the structure. The most important requirement for seams is that they extend across the entire cladding/base layer and must be connected to structural seams.

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As a rule, in walls with a load-bearing function, expansion joints have an interval of approximately 20 meters. If we are talking about partitions, then a distance of 30 meters is allowed. In this case, builders are required to take into account areas of concentration of internal stresses. The distance is determined by the type of expected expansion joints, which in turn depend on the factors causing changes in the body of the structure.

In addition, at the initial stage of design in the walls of structures, the width of the cut for expansion joints is taken into account with special care. This parameter has important functional significance, as it determines the amount of expected transverse displacement of the building’s structural elements. You should also think about ways to seal expansion joints in advance.

Reinforcement

The risk of cracks in masonry can be reduced by reinforcing it. Reinforcement also allows you to increase the distances between expansion joints. The reinforcement is either located in horizontal joints or provided in the form of reinforcing belts. The need for reinforcement and the location of the reinforcement is determined by the designer.

Be sure to reinforce:

• long walls for which it is necessary to provide resistance to lateral loads (wind);
• parts of the wall with increased load;
• the first row of blocks on the foundation;
• Bottom seam of window openings (at least 900 mm on both sides of the opening);
• supporting surfaces of lintels (900 mm).

Since bauroc blocks are laid on a thin glue joint, we recommend using the following as reinforcement for the joints:

• A-III fittings with a diameter of 8 mm
• Murfor fittings