Expansion joint in a brick building. Differences between expansion and “cold” joints Construction of settlement and expansion joints
To prevent deformations in structures, they are divided into compartments (along their length) by vertical gaps - expansion joints. The need for such seams is determined external conditions and geometric design parameters.
With any chosen dressing system, the construction of the wall begins with laying the corners. It is important to arrange the dressing of seams in the corners not only in such a way that the selected dressing pattern in the outer versts of both intersecting walls is observed, but also in such a way that the dressing is performed with maximum overlap of the seams.
According to their purpose, expansion joints can be temperature or sedimentary. The location of expansion joints must be indicated in the project.
Sedimentary seams
Settlement seams are installed to prevent uneven settlement of the structure along its length. These seams divide the building or structure into compartments along the entire height of the structures: from the base of the foundation to the cornice. A foundation divided into compartments by a sedimentary seam is called a split foundation. The structure of the sedimentary joint in the masonry of the foundation and wall looks different (Fig. 34).
Figure 34. Construction of a sedimentary seam in brickwork: a) foundation (plan); b) wall (plan); c) longitudinal section along the foundation and wall; 1 – foundation laying; 2 – wall masonry; 3 – sedimentary seam; 4 – tongue and groove; 5 – gap under the tongue for settlement
The seam must be perpendicular to the wall or foundation. At the seam, the bricks are not tied to each other; instead, a gasket is made of hydrocarbons. insulating material in two to three layers (tar paper, roofing felt, fiberglass, etc.). The seam in the foundation is made straight, in the wall - with a tongue (a protrusion on one side of the seam and a depression on the other side). The thickness of the tongue is usually half a brick, less often – a quarter of a brick. A gap of 1-2 bricks (rows) of masonry is left above the edge of the foundation under the tongue to prevent pressure from the tongue on the foundation masonry in case of uneven settlement. All joints between the foundation masonry and the wall masonry must be sealed to protect the wall from moisture penetration from the foundation.
If the foundation is made of a different material (for example, reinforced concrete), the principles of the sedimentary joint do not change.
The thickness of the sedimentary joint in the brickwork should be 10–20 mm, so the arrangement of the joints does not affect the change in the length of the building (it simply replaces part of the vertical joints of the masonry).
WITH outside walls, sedimentary seams are sealed with tarred tow, silicone sealant or a special seal. Moreover, the first option (with tarred tow) is ineffective, so if possible, you should choose another option. On the outside of the foundation they arrange clay castle or another waterproofing option.
The need to install sedimentary joints arises in several cases.
1. Adjacency new wall to the old one. In this case, the seam can be made without a tongue and groove, since cutting a groove in old wall- a labor-intensive task.
2. The adjoining of one part of the building to another: for example, when a veranda or porch is adjacent to the main part of the building, and the foundation for an extension can be built with less material consumption (smaller cross-section). In this case, the settlement of the porch and the main part of the building will be different, and in the absence of a settlement seam, cracks and other deformations of the masonry may occur.
3. Construction on soils with uneven settlement. This property of the soil base can be judged by the buildings existing on the site, the surface of the earth without cultivation (you can see a pronounced settlement of the soil from it), or geological surveys. If it is not possible to determine the condition of the soil using the last option, resort to the first two. It is important to remember that cracks in buildings can be caused not only by uneven settlement of the soil foundation, but also by errors made in the design (incorrect calculation of the foundation, lack of settlement joints in a long wall, etc.). However, if buildings nearby have cracks, it is better to provide settlement joints in it in any case when constructing a new structure.
Expansion joints
Temperature (temperature-shrinkage) joints protect a building or structure from deformations (cracks, ruptures of masonry, distortions, shifts of masonry at seams) associated with changes in air temperature and the structures themselves. At low temperatures masonry tends to shrink and expand in hot weather. So, for every 10 m of length brick construction when the temperature changes from 20 °C to –20 °C, it shrinks in size by 5 mm. In addition, temperature differences can occur in different parts of the building.
Expansion joints divide the building into compartments along the entire height of the walls, not including the foundation. That is, unlike sedimentary joints, the foundation is not separated by expansion joints. The construction of an expansion joint in a brick wall is similar to that of a sedimentary one: in the form of a tongue and groove with a layer of insulating material and sealing with sealant on the outside of the wall. The sealant for sealing expansion joints must be designed for all temperatures possible during the operation of the building or structure.
The thickness of the expansion joint in the brickwork should be 10–20 mm. If masonry is carried out at an air temperature of 10 °C or higher, the thickness of the seam can be reduced.
The need to install expansion joints arises when brick walls are long and when there are significant differences in air temperature between winter and summer periods of the year. Building codes and rules ( SNiP II-22-81 “Stone and reinforced stone structures”) establish the maximum permissible distances between expansion joints in brick walls. These distances depend on the average outside temperature of the coldest five-day period of the year, the type of brick and brand of mortar. In the most difficult climatic conditions the maximum permissible distance between expansion joints in heated buildings in masonry made of ceramic bricks is 50 m, in masonry from sand-lime brick– 35 m. Since the walls of individual buildings rarely reach such a length, expansion joints in them are practically not suitable. For unheated closed buildings maximum length walls without expansion joints can be: in masonry made of ceramic bricks - 35 m, in masonry made of sand-lime bricks - 24.5 m. For unheated open buildings (for example, brick fences) these standard values are respectively 30 m and 21 m.
Buildings of considerable length may be subject to deformation. The reason for this is fluctuations in air temperature, uneven settlement of the foundation soil, seismic phenomena and other reasons. As a result of deformations, cracks appear in the walls, reducing the strength of buildings. To prevent this, it is planned to install expansion joints, which are gaps that cut buildings vertically into separate sections. Depending on their purpose, seams are divided into temperature, shrinkage, sedimentary and anti-seismic.
Expansion joints. Changes in outside air temperatures in different periods year leads to an increase in the length of the walls due to heating in the summer and a reduction in length during cooling in the winter. Despite the insignificance of the changes, if the building is longer, cracks may form in its walls. Expansion joints that cut buildings into compartments from ground level to the eaves do not affect the foundation, which is below ground level and does not experience significant temperature fluctuations. The distances between expansion joints are taken in accordance with SNiP design standards, depending on climatic conditions and wall material, and these intervals between joints largely depend on the range of fluctuations in outside temperature.
Rice. 1. Expansion joints in the walls: a and b - made of brick; c - from brick blocks; g - from reinforced concrete panels; 1 - tarred tow; 2 - compensator made of galvanized roofing steel; 3 - antiseptic wooden plugs; 4 - wire mesh; b - plaster
Shrinkage joints are installed in walls constructed from different types concrete, which, when hardening, have varying degrees of reduction in volume. The process of general shrinkage of the material leads to the appearance of cracks. To protect against them, shrink joints are installed, the width of which during the hardening process monolithic walls increases. After the walls have finished shrinking, the seams are tightly sealed.
Sedimentary seams. In buildings with different number of storeys, foundation soils located directly under the building segment with increased amount floors, will accommodate large narrow spaces. The soil deformation in this part will be the greatest, which will lead to uneven deformation of the soil under the entire building and can cause cracks in the walls. Another reason for uneven soil settlement is the difference in its structure. The appearance of sedimentary cracks in this case is possible in extended buildings and with the same number of storeys.
Settlement joints, unlike temperature joints, cut the building wall structures along their entire height, including the foundations. They are made at the boundaries of areas that have different geological structure soils, different loads on the ground (and if their difference is more than 10 m, the installation of joints is considered mandatory) and different order of construction, as well as in places where new walls adjoin old ones, when uneven settlement of individual sections of the building is possible.
Distances between seams in buildings made using various materials, are given in the normative data.
Sedimentary joints can simultaneously perform the functions of expansion joints, since they have the same appearance in plan. In the walls they are made in the form of tongue and groove, the dimensions and design of which are indicated in the project. Examples constructive solutions expansion joints are shown in Fig. 1. For better separation of masonry sections, roofing felt or tarred tow is placed in the seam, and for better protection from blowing - compensator made of galvanized roofing steel. The seams of the masonry must necessarily coincide with the seams of the floors and other structures located in this vertical. In frame buildings, expansion joints must cut the frame and structures resting on it (ceilings, coverings, etc.) into separate sections.
The construction of joints in these cases can be carried out by a combination of paired columns, and if the expansion joint is sedimentary or sedimentary and temperature, it is also made in the foundation.
Rice. 77. Transition from the sedimentary seam of the foundation to the sedimentary seam of the wall: a - plan according to AB (wall seam); b - plan for VG (foundation seam); c - section along DE; 1 - foundation; 2 - wall; 3 - wall seam; 4 - foundation seam; 5 - tongue and groove; 6 - clearance for draft
The thickness of the seams between the walls is from 10 to 20 mm. A smaller thickness is possible at outdoor temperatures of +10° and above. If the outlines of the sedimentary seams of the foundations and walls do not match, horizontal gaps for settlement are left under the sheet piles of the walls (Fig. 2).
Penetration of surface and groundwater into the basement through sedimentary joints is prevented by a device clay castle, walkways and other techniques in accordance with the project. Anti-seismic joints separate adjacent compartments along the entire height of the buildings, which ensures the independence and stability of their volumes. Temperature and sedimentary joints are also used as anti-seismic joints.
The width of the anti-seismic joint is determined in accordance with the height of the buildings. For buildings up to 5 m, it is taken to be at least 3 cm; for every subsequent 5 m of height, the size increases by 2 cm, which ensures free mutual displacement of the walls separated by a seam.
In buildings with load-bearing walls anti-seismic seams are formed by placing paired walls, and with load-bearing columns- installation of paired frames. An anti-seismic joint can also be made by combining a wall and frames. The height of the building within the compartment is made the same.
The need for such seams is determined by external conditions and geometric parameters of the structure.
With any chosen dressing system, the construction of the wall begins with laying the corners. It is important to arrange the dressing of seams in the corners not only in such a way that the selected dressing pattern in the outer versts of both intersecting walls is observed, but also in such a way that the dressing is performed with maximum overlap of the seams.
According to their purpose, expansion joints can be temperature or sedimentary. The location of expansion joints must be indicated in the project.
Sedimentary seams
Settlement seams are installed to prevent uneven settlement of the structure along its length. These seams divide the building or structure into compartments along the entire height of the structures: from the base of the foundation to the cornice. A foundation divided into compartments by a sedimentary seam is called a split foundation. The structure of the sedimentary joint in the masonry of the foundation and the wall looks different.
The seam must be perpendicular to the wall or foundation. At the seam, the bricks are not tied together; instead, they are arranged waterproofing material in two or three layers. The seam in the foundation is made straight, in the wall - with a tongue (a protrusion on one side of the seam and a depression on the other side). The thickness of the tongue is usually half a brick, less often - a quarter of a brick. Above the edge of the foundation under the tongue and groove, a gap of 1-2 bricks (rows) of masonry is made to prevent pressure from the tongue and groove on the foundation masonry in case of uneven settlement. All joints between the foundation masonry and the wall masonry must be sealed to protect the wall from moisture penetration from the foundation.
If the foundation is made of a different material, the principles of constructing a sedimentary seam do not change.
The thickness of the sedimentary joint in the brickwork should be 10-20 mm, so the arrangement of the joints does not affect the change in the length of the building (it simply replaces part of the vertical joints of the masonry).
On the outside of the walls, sedimentary seams are sealed with tarred tow, silicone sealant or a special sealant. Moreover, the first option (with tarred tow) is ineffective, so if possible, you should choose another option.
The need to install sedimentary joints arises in several cases.
- Joining the new wall to the old one. In this case, the seam can be made without a tongue and groove, since cutting a groove in an old wall is a labor-intensive task.
- The adjoining of one part of the building to another: for example, when a veranda or porch is adjacent to the main part of the building, and the foundation for the extension can be built with less consumption of materials (smaller cross-section). In this case, the settlement of the porch and the main part of the building will be different, and in the absence of a settlement seam, cracks and other deformations of the masonry may occur.
- Construction on soils with uneven settlement. This property of the soil foundation can be judged by the existing buildings on the site, the surface of the earth without cultivation (you can see a pronounced settlement of the soil from it) or geological surveys. If it is not possible to determine the condition of the soil using the last option, they resort to the first two. It is important to remember that cracks in buildings can be caused not only by uneven settlement of the soil foundation, but also by errors made in the design (incorrect calculation of the foundation, lack of settlement joints in a long wall, etc.). However, if buildings nearby have cracks, it is better to provide settlement joints in it in any case when constructing a new structure.
Expansion joints
Temperature (temperature-shrinkage) joints protect a building or structure from deformations (cracks, ruptures of masonry, distortions, shifts of masonry at seams) associated with changes in air temperature and the structures themselves. At low temperatures, masonry tends to shrink, and in hot weather it tends to expand. Thus, for every 10 m of length, a brick structure decreases in size by 5 mm when the temperature changes from 20 °C to -20 °C. In addition, temperature differences can occur in different parts of the building.
Expansion joints divide the building into compartments along the entire height of the walls, not including the foundation. That is, unlike sedimentary joints, the foundation is not separated by expansion joints. The construction of an expansion joint in a brick wall is similar to that of a sedimentary one: in the form of a tongue and groove with a layer of insulating material and sealing with sealant on the outside of the wall. The sealant for sealing expansion joints must be designed for all temperatures possible during the operation of the building or structure.
The thickness of the expansion joint in the brickwork should be 10-20 mm. If the masonry is carried out at an air temperature of 10 ° C or higher, the thickness of the seam can be reduced.
The need to install expansion joints arises when brick walls are long and when there are significant differences in air temperature between the winter and summer periods of the year. Building codes and regulations establish the maximum permissible distances between expansion joints in brick walls. In the most difficult climatic conditions, the maximum distance between expansion joints in heated buildings in ceramic brick masonry is 50 m, in sand-lime brick masonry - 35 m. Since the walls of individual buildings rarely reach such a length, expansion joints in them are practically not suitable. For unheated closed buildings, the maximum length of the wall without expansion joints can be: in masonry made of ceramic bricks - 35 m, in masonry made of sand-lime bricks - 24.5 m. For unheated open buildings (for example, brick fences), these standard values are respectively equal to 30 m and 21 m.
If it is necessary to install both settlement and temperature-shrinkage joints in a building, they are combined and a universal-purpose expansion joint (or several joints) is installed, with cutting of structures along the entire height.
Problem:
Very often, Customers are faced with the question of initializing the type of seam in building structure through which water flows. Indeed, this issue is very serious and requires certain construction knowledge.
I propose to take a closer look at deformation sedimentary and temperature (“cold”) seams and understand the difference between them.
What is an expansion joint?
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 bearing capacity designs. 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.
What is a temperature “cold” seam?
The “cold” concreting joint is the weakest point concrete structure, which is formed as a result technological features production monolithic works. That is, during the construction of a building, a monolithic foundation slab is first poured, and then the walls are supported on it. In the same way on finished walls support monolithic ceiling. We consider seams from the point of view of probable leaks, and here it is necessary to mention that there are many technologies for waterproofing such seams.
What are the dangers of seam leaks?
Leaks in expansion joints are not dangerous - there are no important structural elements in such joints, but leaks in “cold” joints are cause for concern, since they contain load-bearing reinforcement that is subject to corrosion. Reducing the diameter of the reinforcement by tenths of a millimeter has a very serious impact on the load-bearing capacity. Consequently, “cold” concreting joints require repair and strengthening through injection work.
How to fix leaks?
Practice shows that at the construction stage, work to seal the seams is either not carried out (not counting the polystyrene foam installed) or is carried out extremely poorly! Already at the stage of preparing the object for delivery, widespread leaks of seams appear, which will not allow the construction project to be handed over to the State. commissions!
In such situations, the most EFFECTIVE, FAST and CHEAP method– INJECTION WATERPROOFING from SK LLC “Vertical”
Is it possible to perform injection waterproofing yourself?
It is possible, but on one condition: that you already have extensive experience working with polymer compounds. It is also necessary to take into account a very complex and often very lengthy stage preparatory work, where it is necessary to apply the most non-standard technical solutions that... Another feature is the ability to work with vacuum pump, since the thing is extremely expensive and requires periodic complex Maintenance, up to its complete disassembly and reassembly.
Based on all of the above, it remains to conclude that it is most convenient and cheapest for Customers to contact a specialized company for injection waterproofing, such as "Vertical".
! Most effective solution the problem of leakage of expansion joints is injection waterproofing!
The main advantage of injection waterproofing is guaranteed positive result, which can be observed already in the first minutes after completion of injection waterproofing work.
MAIN ADVANTAGES OF INJECTION WATERPROOFING JOINTS:
High speed of work - a team of 4 specialists per shift can perform waterproofing up to 10 m.p. expansion joint
There is no need for preparatory work that requires approval from government agencies or owners of neighboring buildings - all work is carried out from the side of the premises (from the basement)
Low cost of the work package, since there is no expensive preparation stage
There is no seasonal factor, since work can be performed by local heating of the structure
Stages of work:
1. Main stages of work - SEALING THE EXPANSION JOINT
1) Visual inspection, local opening of the seam, checking and clarification of accepted technical solutions
2) Clearing the expansion joint
3) Placement of the Vilaterm cord in the designed position
4) Installation of injection packers - MC-Injekt
5) Preparing the injection gel for use MC-Injekt GL95 TX
6) Supply of injection gel MC-Injekt GL95 TX with a two-component pneumatic pump (for example, MC-I 700)
2. Main stages of work - SEALING THE "COLD" SEAM
1) Visual inspection, local opening of the seam, verification and clarification of the adopted technical solutions
2) Sealing the expansion joint
3) Installation of injection packers - MC-Injekt
5) Preparation of injection material for use - MC-Injekt 2300, MC-Injekt 2300Top or MC-Injekt2700 *
6) Supply of injection material with a pneumatic pump (for example, MS-I 510 or MS-I 700)
7) Quality control of work performed
* the type of material used is determined depending on the type of seam leakage.
Important! Carrying out injection waterproofing work requires extensive experience in this area and does not forgive mistakes, since the cost of equipment and injection materials quite high.
Any structural element the structure in the process of its work in the structure carries a certain power load. Moreover, it is not always associated with seismic vibrations or the weight of the building as such. The problem of construction physics itself is already long time represents uneven expansion different materials when heated and their narrowing when cooling.
Eg:
The thermal expansion coefficients of metal and wood differ several times. This justifies mechanical destruction wooden beams located in the cold under-roof space, which are secured using conventional studs and fittings without thermal break. To solve this and some other problems, expansion joints are used in general construction practice.
Below we present full list problems when this element “works” and helps maintain the structural integrity of the entire building:
- seismic activity of the earth's crust;
- soil settlement, rise of groundwater;
- force deformations;
- sudden change in ambient temperature.
Depending on the nature of the problem being solved, all expansion joints are divided into temperature, shrinkage, seismic and sedimentary.
Temperature expansion joint
Structurally expansion joint is a section that divides the entire structure into sections. The size of the sections and the direction of division - vertical or horizontal - is determined design solution and power calculation of static and dynamic loads.
To seal the cuts and reduce the level of heat loss through expansion joints, they are filled with an elastic heat insulator, most often these are special rubberized materials. Thanks to this separation, the structural elasticity of the entire building increases and the thermal expansion of its individual elements does not have a destructive effect on other materials.
As a rule, a temperature expansion joint runs from the roof to the very foundation of the house, dividing it into sections. It makes no sense to divide the foundation itself, since it is located below the depth of soil freezing and does not experience this negative impact like the rest of the building. The spacing of expansion joints will be influenced by the type of used building materials And geographical location object that determines the average winter temperature.
In statically indeterminate systems of reinforced concrete buildings and structures, in addition to the forces from external loads additional forces arise as a result of temperature changes and concrete shrinkage. In order to limit the magnitude of these forces, temperature-shrinkage seams are installed, the distances between which are determined by calculation.
The calculation may not be done for structures of the 3rd category of crack resistance at design low temperatures outside air above minus 40° C, if the distances between expansion joints do not exceed the required values given in the SNiP table. In any case, the distances between the seams must be no more than:
150 m for heated buildings made of prefabricated structures;
90 m - for heated buildings made of prefabricated monolithic and monolithic structures.
For unheated buildings and structures, the indicated values must be reduced by at least 20%. To prevent additional forces from occurring in case of uneven foundation settlements (sections of different heights, complex ground conditions etc.) provision is made for the installation of sedimentary joints.
It should be noted that sedimentary seams cut through the structure to the base, and temperature-shrinkage seams only to the top of the foundations. At the same time, sedimentary seams also play the role of temperature-shrinkage seams.
Schemes of expansion joints
The width of the temperature-shrinkable seam is usually 2...3 cm, it is specified by calculation depending on the length of the temperature block and the temperature difference.
Key points in the temperature calculation problem
Expert opinion.
Uncertainty with the rigidity characteristics of the base in the horizontal direction - for example, given the rate at which the thermal load is applied, a fair amount of rheology may occur. Friction on the soil will be different in different areas of the foundation depending on the pressure on the soil in these areas. Local damage to waterproofing - can it happen and should it be taken into account? What about local zones of plasticity in soils? Well, the plus I mentioned backfilling. Variation of the rigidity characteristics of the base in the horizontal direction can repeatedly change the forces from temperature loads. With piles it is even more difficult.
Nonlinearity of reinforced concrete, its rather “long-term” rigidity characteristics - what will be the change in the deformation diagram of reinforced concrete at a loading rate that is characteristic of temperature loads? I am already silent about all the other subtleties of modeling the nonlinear properties of reinforced concrete - at a minimum, it is necessary to model with solids in order to take into account the reduction, including the shear stiffness of all elements, especially massive ones, which are concentrators.
Uncertainty with the temperature loads themselves. In reinforced concrete, even without these loads, numerous cracks will open, and even more so taking into account the temperature. And not only the rigidity of the frame will decrease, but also the loads themselves, because the area of the elements itself decreases (due to the formation of cracks), which is not taken into account by the methods known to me.
Thus, I believe that a full-fledged temperature calculation of reinforced concrete frames is currently a guess, and the only thing you need to trust is design experience, reflected in particular in the recommended distances between temperature blocks.
Settlement expansion joint
Second important application expansion joints is compensation for uneven pressure on the ground during the construction of buildings of varying number of storeys. In this case, the higher part of the building (and, accordingly, heavier) will press on the ground with greater force than the lower part. As a result, cracks can form in the walls and foundation of the building. A similar problem can arise from soil settlement within the area under the foundation of a building.
To prevent cracking of the walls in these cases, sedimentary expansion joints are used, which, unlike the previous type, divide not only the building itself, but also its foundation. Often in the same building there is a need to use seams various types. Combined expansion joints are called temperature-sedimentary joints.
Antiseismic expansion joints
As their name suggests, such seams are used in buildings located in seismic zones of the Earth. The essence of these seams is to divide the entire building into “cubes” - compartments that are themselves stable containers. Such a “cube” should be limited by expansion joints on all sides, along all edges. Only in this case will the anti-seismic seam work.
Along the anti-seismic seams, double walls or double rows of support columns are installed, which form the basis load-bearing structure each individual compartment.
Shrinkage expansion joint
Shrinkage expansion joints are used in monolithic concrete frames, since concrete, when hardening, tends to slightly decrease in volume due to the evaporation of water. The shrinkage seam prevents the occurrence of cracks that impair the bearing capacity of the monolithic frame.
The point of such a seam is that it expands more and more, parallel to the hardening of the monolithic frame. After hardening is complete, the resulting expansion joint is completely caulked. To impart hermetic resistance to shrinkage and any other expansion joints, special sealants and waterstops are used.
