Paper tape.
The paper tape is sold in rolls 52 mm wide, 50.76 m or 153 m long. Of those brands that are heard, you can name Sheetrock, Knauf, NextBuild.
The paper tape is made of special extra strong paper reinforced with fiberglass in the longitudinal and transverse directions. Its surface is slightly rough for better adhesion to the putty. The tape has a slight depression in the center, which makes it easy to use for finishing inner corners... The paper tape effectively resists stretching and creasing.
The disadvantages of paper tape include the installation process, which is somewhat more laborious than the serpyanka, and (with insufficient qualifications of the worker) the tendency to form air bubbles with a small amount of putty under the tape (more on this below). To avoid bubbles, it is better to use a tape with microperforation, which reduces the likelihood of bubbles and at the same time does not affect the strength characteristics of the tape.
Serpyanka is self-adhesive.
Serpyanka is sold in rolls 45 and 50 mm wide, 20, 45 and 90 m long. It is usually used for finishing joints of plasterboard sheets with a thinned edge, as well as for sealing cracks and small holes. There are so many trade marks, which are distinguished by their tensile strength. The nets are also divided into two types: self-adhesive and non-self-adhesive. The latter is less expensive, but more laborious (requires fastening with paper clips).
One important detail: when using self-adhesive tape, the started roll must always be stored in plastic wrap to prevent the adhesive layer from drying out.
Fiberglass tape, unlike paper tape, for obvious reasons is not recommended for reinforcing inner corners.
Now let's look at how to work with each type of tape.
The method of sealing joints using a serpyanka.
Longitudinal joints of drywall with a thinned edge can be recommended to be reinforced with a self-adhesive serpyanka (mesh). It is easier to use and requires less working time. Plus, you don't have to worry about air bubbles or delamination (which sometimes happens with paper tape).
The disadvantages of this method are (Attention !) lower strength of serpyanka in comparison with paper tape, as well as the need to select a suitable type of putty for application.
When using a serpyanka, it is recommended to first mount it on all joints of the room, firmly pressing the mesh to the previously dust-free surface in order to avoid the formation of wrinkles. Then you need to apply the putty over and into the depth of the mesh with a spatula along the entire length of the mesh, preferably in a thin and even layer
Method of sealing joints using paper tape.
As mentioned earlier, fiberglass mesh works well at the longitudinal joints of gypsum board sheets with a thinned edge. But for the reinforcement of transverse joints, it is not strong enough. Such places require special strength and only paper tape can reduce the risk of cracking here (the main problem of joints). Unlike fiberglass mesh, paper tape forms an extremely strong seam when used with any type of joint filler. However, the procedure for installing paper tape differs from the technology for installing fiberglass mesh and has some subtleties.
Since the paper tape is not self-adhesive, you first need to apply a thin and relatively even layer of putty to the joint for gluing the tape. In this case, you do not need to try to cover all the joints of the room with putty at once, since it can begin to dry out before you reach the last joint with the tape. This, in turn, will lead to an increase in the complexity of the work process and to the formation of air bubbles under the belt. 
It is recommended to finish the joints one by one, especially in the absence of sufficient skills and, accordingly, a low speed of work. Then you need to adjust the tape in the center of the joint and, keeping it taut, slightly press it into the putty, while the ends of the tape should overlap. After that, "stretch" the glued tape with a spatula.
This is usually done from the center of the joint and alternately at both ends. It is important to apply sufficient pressure to properly adhere the tape, but at the same time it should be such that only the excess putty is squeezed out and leave a layer 1.5-2.0 mm thick under the middle of the tape and about 0.8 mm under the edges. There is no need to try to squeeze out as much putty as possible - the tape will have nothing to stick to. After the tape is glued evenly, tightly and without wrinkles, you need to remove the excess putty along the longitudinal edges of the tape with a spatula.
Further work is the same for both options.
And finally, a quote: « Multiple tests for the strength of reinforced joints have shown that joints finished with conventional fiberglass mesh (serpyanka) and conventional joint filler are more prone to cracking than joints finished with paper tape and similar filler. This is because fiberglass mesh (serpyanka) has the ability to stretch under load, even when covered with putty. Overhaul such cracks are difficult. Therefore, it is not recommended to use the normal fiberglass mesh for finishing drywall joints in most cases. "
Paper tape is the most "ancient" and traditional material for reinforcing drywall joints, recommended by gypsum board manufacturers and at the same time the most reliable and still unsurpassed in strength.
The choice of the most reliable reinforcement system is especially relevant for climates with large seasonal fluctuations in temperature and humidity as a preventive measure against cracking.
The process of connecting reinforcement, resulting in continuous reinforcement, is called docking.
V modern construction exists different ways fittings connections:
This method is the most advantageous, respectively, and the most frequently used. If we compare the process of mechanical connection of reinforcement with overlapping reinforcement, then the main advantage here is that there is no significant loss of material. Overlapping docking results in loss a certain amount reinforcement (approximately 27%).
If we compare the mechanical connection of reinforcement with butting by welding, then in this case the speed of work wins, which takes much less time. In addition, welding should only be performed by professional welders in order to avoid low-quality work, which in the future can lead to negative consequences. As a result, if you carry out mechanical docking, you can significantly save on wages for qualified craftsmen.
Even as a result of this method of connection, enough robust construction... It is possible to obtain an equal-strength connection using this method under various weather conditions and at any time of the year.
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Scheme of reinforcement of the foundation with stiffeners: 1 - Mesh of working reinforcement, 2 - Vertical reinforcement.
To mechanically dock fittings, you will need an appropriate tool - a hydraulic press.
Materials required:
The mechanical connection technology is quite simple and consists of the following:
As a result, very little time is required to create a mechanical connection. Instead of couplings, it is allowed to use thick-walled steel pipes or couplings that have a baffle in the center, which greatly simplifies installation.
Strong mechanical joining is possible for reinforcing rods of different diameters. This is done thanks to the presence of replaceable dies in the hydraulic press.
To perform this type of docking, the help of professionals is not needed, almost everyone can cope with the task. But there is one important condition: the work must be performed by two people at once.
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Despite the popularity of mechanical joining, the connection of reinforcement by welding is also no less in demand in construction. There are several methods of arc welding:
To perform this type of work, you will need the following tools:
The main working material is reinforcement.
Long seam welding of reinforcement is used to connect horizontal and vertical rods. This type of joining is possible with overlaps or overlapping. An overlapping connection is made with long seams, but an option with the use of arc points is also possible. It is also possible to connect reinforcing bars with short and long overlap or double-sided and one-sided seam.
The welded joints of the reinforcing bar plates are short or long. In this case, it is allowed to move the pads along the length. Welding of reinforcement is carried out with various flank seams.
In the process of welding with double-sided seams, hot longitudinal cracks sometimes occur during the application of the second joint on the other side. To prevent their appearance, it is necessary to carefully select the type of electrodes and strictly adhere to the technological mode of welding.
Broken-through welded seams can be multi-pass or single-pass, it depends on the diameter of the joined rods. The current for arc welding is selected depending on the type of electrodes. It is important to take into account one condition: in the process of welding valves located in a vertical position, the current is required 10-20% less than for rods in a horizontal position.
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In the presence of highly qualified welders or with small amounts of work, multilayer welding without the use of forming elements is often used for joining reinforcement bars. This method is most suitable for connecting vertical fittings. The angles of bevels, their direction, bluntness and dimensions, groove shapes, and gaps between the rods are standard.
Welding of reinforcement with multilayer seams is performed using a single electrode. The weld seam is first applied on one side of the groove, and then over the entire width on the other. During the welding of the groove, it is necessary to periodically clean the weld metal from the slag.
The mode for this type of welding is set to the one indicated in the passport data of the electrodes. In this case, they are usually applied with a calcium fluoride coating.
Application of drywall as finishing material for walls allows you to achieve flat surface... Moreover, in some cases, there is no need to align the wall itself. A smooth wall cannot be made only with drywall; auxiliary materials must also be used. One of them is drywall reinforcement tape. It helps to create inconspicuous joints between sheets, as well as strong and even corners. We will talk about it further.
Reinforced drywall tape is an ideal material for reinforcing and sealing joints and corners. The purpose of its use, as a rule, is to prevent the appearance of cracks in the putty between hl. When choosing quality material and correct installation good results can be achieved. This material is versatile, as it is widely used.
There are several types:
It is possible to achieve a flat surface and perfect joints regardless of the type of reinforcing tape.
Any of them are intended for these purposes.
Related article: DIY chair: tools and materials
Before applying the reinforcing layer to the joint, it must be prepared. The fact is that drywall can be straight and rounded. If the edges are rounded, then preliminary work is not necessary. In this case, the putty perfectly closes the gap. And in the case of even corners, they need to be finalized. To do this, you need to cut them off with a clerical knife at an angle of 45 degrees so that an angle of 90 degrees is formed between the sheets.
Next, you need to prepare the putty or use the finished one. It fills the joint between the sheets and a few centimeters of the edge of the sheet. The putty should be applied slightly wider than the reinforcing tape. To do the job well, you need to have necessary tool- spatulas (one narrow and two wide, one of them should be wider than 300 millimeters).
So, the application process begins with the fact that the joints need to be filled with putty. To do this, take a narrow spatula and apply the mixture inside. We rub all excess on the adjacent surface of the sheets. A reinforcing tape is applied to this layer, its width should cover the surface near the seam by at least one hundred millimeters. Next, the tape should be well pressed into the not yet solidified layer of putty, only we leave the joint as it is. It is necessary to try to prevent the appearance of waves, but to make sure that the film adheres tightly to the wall in all places. After all the requirements are met, it is necessary to allow the joint to dry. You will have to wait about twenty hours, or better a day.
The presence of a reinforcing film at the joint is noticeable. To get rid of the protrusion and make the joint flush with the rest of the surface, you need to take a wide spatula and clean the surface from excess putty (bumps, drips, etc.). The second stage of leveling is applying a fresh coat. To do this, you need to use the trowel even wider than the first time to cover more of the surface. This layer should be very thin. At this stage, you need to try to make the bump invisible. If necessary, you can use a spatula even wider, and putties one more layer. You just need to understand that the thinner it is, the smoother the surface will be. After that, the layer should dry out. If it doesn't work the first time, you need to repeat this action several times until the surface meets the desired requirements.
| Type of seams | Description |
| 1. Shrinkage. | These are, in fact, temporary lines that are arranged in cast-in-place concrete buildings directly during the process of pouring the mixture. The fact is that when concrete dries, it tends to shrink, and because of this, cracks may appear. And so it turns out that the mixture is compressed, all the pressure goes to the void line, which expands under such "pressure". After the entire mass has solidified, the shrinkage notch is closed. |
| 2. Sedimentary and temperature lines. | Everything is clear from the name. Such incisions protect the building from deformation during shrinkage and from temperature fluctuations. Settlement lines are located on all building elements and in the foundation as well. Temperature ones are made everywhere except for the foundation. |
| 3. Anti-seismic. | These lines seem to divide the building into separate sections, blocks. At the same time, double walls or racks are made at the place of passage of such seams, which significantly increases the level of stability of the entire structure as a whole. |
Such is the classification.
Please note that the device of expansion joints in concrete implies their mandatory processing - these are not voids. As a rule, such cuts are sealed with either sealants or special profiles or elastic inserts. If this is not done, then the visual appearance deteriorates significantly and, of course, the thermal insulation qualities of the structure are lost.
Filling the deformation line with a special profile
Now you can move on to how exactly such a temperature protection is done.
Installation of expansion joints
As already mentioned, we will get acquainted with the technology using the example of the device of concrete floors and blind areas around the perimeter of the building. Why exactly these constructions? Because in most cases they are made with their own hands and with typical mistakes (see also the article "Mesh for concrete - types and applications").
And the mistakes are precisely 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 with such technology.
Please note that the installation of expansion joints in concrete is also performed in the walls. Moreover, even if they are not made of a monolith, but also of ordinary bricks or blocks.
Now you can start directly to work. Brief instructions for pouring the floor and blind area, in which the main focus will be on the arrangement of the seams.
So, let's begin.
Blind area protection
Filling the blind area
This element of the house is done something like this:
Tip: the reinforcement rods must be inserted into the walls of the house. For this, work is performed such as diamond drilling of holes in concrete, into which the ends of the reinforcement are inserted.
The expansion joint is made just before the concrete is poured. It is done along the line connecting the walls and the blind area. In order to organize such seams, you just need to insert not very thick boards between the plane of the walls and the blind area.
In addition, seams are made across the blind area - in the same way (with the help of boards placed on the edge). In this case, the distance between expansion joints in reinforced concrete of this type should be approximately 1.5 - 2 meters.
Formwork for the blind area, taking into account temperature protection
It turns out that the mixture will fill the entire space, except for those lines where the boards are installed. After the concrete has hardened, the boards are removed and the gaps are filled with either sealant or polyethylene foam tape.
The main thing here is to make sure that the connection between the house and the blind area does not turn out to be empty - otherwise water will penetrate into it and, accordingly, there will be no sense from this structure.
We now turn to the construction of floors with seams.
Seams in concrete floors
We will not consider the procedure for pouring a concrete floor, since expansion joints on such a plane can be arranged after the initial solidification of the mixture.
Of course, it is better to do this before pouring, so that cracks do not appear on the surface when the concrete dries, but, in principle, this is not necessary if you make protective lines before the concrete is 100% frozen. As a rule, complete solidification occurs in a few weeks - during this time you can have time to make seams, you must agree.
Protective incision in concrete
So, how are the seams in the screed made.
What we got in the end is that now, in the case of expansion of the concrete mass, deformation will occur at the edges of the screed, along the lines where the seams pass. In these places, the extreme lines of concrete will crack a little at the most, but the main finish floor covering will remain completely intact and unharmed.
Close up seams
Which, of course, will save you money, since you will not need to spend money on maintenance.
Actually, this is where our review of this technology is over, and now we can summarize.
It turns out that arranging expansion joints in the concrete structure outdoors and indoors is a very desirable measure, as a result of which the overall service life of the entire structure as a whole is significantly extended.
It turns out that having invested once in the device of such expansion joints in concrete, you also save on minor maintenance.
We figured out what kind of protective expansion joints are and how the protection against the effects of different temperatures is arranged. We hope that the instructions will be useful to you in practice. Well, if you want to know even more information on this topic, then we advise you to watch the additional video in this article.
The expansion joint is an integral part and the most important measure in the construction of concrete floors.
There are three main types of expansion joints:
Insulation seams are arranged along walls, around columns and around foundations for equipment in order to exclude the transfer of deformations from building structures to the floor screed.
The insulating joint is made by laying the insulating material along the building structures immediately before pouring the concrete mixture.
Shrinkage seams are necessary in order to prevent chaotic cracking of the screed during the hardening process. They allow you to create straight planes of slack in concrete. As a result, the screed cracks in a given direction.
Shrinkage seams should be cut along the column axes, and butted with the corners of the seams along the perimeter of the columns.
Floor maps formed by contraction joints should be as square as possible. Elongated or L-shaped cards should be avoided. The length of the card must not exceed 1.5 times its width. Shrinkage joints should be straight and, if possible, free from branches.
In aisles and driveways, shrinkage joints should be spaced at a distance equal to the width of the screed. Tracks wider than 300-360cm should have a longitudinal seam in the center. When concreting in open areas, the distance between the joints should not exceed 3m in all directions. As a general rule, the smaller the card, the less chance of chaotic cracking.
Shrinkage joints are cut after finishing the concrete surface.
Usually, the seams are cut with 6x6 m cards in the same sequence in which the concrete was laid. The seams should be cut to a depth of 1/3 of the screed thickness. This creates a zone of weakness in the screed, and concrete, when shrinking, gives a crack in this particular zone, i.e. cracks directionally, not chaotically. In this case, the edges of the formed crack have a certain roughness, which excludes their vertical displacement until the crack becomes too wide.
Structural seams are set up where the day's work on placing the concrete has been completed.
The shape of the screed edge for a structural seam is usually made according to the principle of a thorn in a groove; you can use sleepers (slats) laid across the seam. The slats should be installed in the middle of the screed depth at correct angles to the seam. One end of the rail must be oiled with bitumen to move freely in the screed.
Structural joints work like shrinkage joints - they allow small horizontal movements, but not vertical ones. It is desirable that the structural joint coincides with the shrinkage joint.
The device of the expansion joint should be carried out in strict accordance with the developed project. If any changes occur (for example, weld size or material change), the design of the expansion joint must be agreed with the representatives of the design organization.
In the presence of wet processes in the room, the tightness of the seams is of particular importance, since the lack of tightness leads to peeling of organic coatings from the floor slab. This process is especially active with an increased background of indoor temperatures.
During the production of work, the number and location of the seams are established based not only on the coefficient of thermal expansion of materials, but also taking into account the shrinkage of concrete and possible deformations that most often occur at the areas where the floor joins the foundations for equipment, walls and columns.
Sealing seams allows you to protect the seam from the penetration of water and aggressive media, as well as from clogging.
The type of sealant depends on the loads and operating conditions. For example, in many industrial and food applications, floors must be easy to clean and withstand high traffic loads.
Sealants for these floors must be firm enough to support the edges of the joint and prevent chipping, and flexible enough to withstand easy opening and closing of the joint.
Cracking in concrete can be reduced by reducing the amount of water used for mixing. But concrete, even with a low water content, shrinks, and besides, concrete made with some fillers can shrink more than concrete with other fillers.
Since it is impossible to eliminate the shrinkage of concrete made from traditional cements, the best solution is to give the crack an opportunity to appear in the place where its appearance is desirable and, moreover, in the form of a straight line. This is the expansion joint.
Seams can be made in fresh concrete with a special cutter. In dry concrete, the seams are sawn through. But even in screeds with cut or sawn expansion joints, cracks sometimes appear in other places. The likelihood of such cracks can be reduced by doing the following:
Cut the seams on time
By calling or writing to us, you can always get free samples of materials for trial application and advice from our specialists.
If the joints are cut in fresh concrete, time is of no importance. But if they are cut later, then random cracks are likely to appear. The cutting of seams in freshly poured concrete is done immediately after the surface has been sanded. On dry concrete, the seams should be cut as quickly as possible so that the edges of the seams do not begin to crumble. It is usually recommended to do this after 12 hours at normal temperature, at low temperature - 24 hours after placing the concrete.
Cut the seams to the required depth
Seams cut with conventional seam cutters should be between 1/4 and 1/3 of the thickness of the screed. Seams made with special cutters on fresh concrete may be shallower.
Cut seams at required intervals
Typically, the interval for cutting seams is selected in the range (24-36) x (screed thickness). On a 10cm screed, the seams are cut at a distance of 240cm to 360cm from each other. For concrete with higher taper slump and shrinkage, it is preferable to have a cutting interval closer to 240cm.
Exclude interior corners
Cracks are more likely to appear at inner corners. The mesh of seams should be such as to exclude the formation of internal corners.
Eliminate T-shaped intersection of seams
T-shaped intersection of the seams results in a crack through the intersected seam. T-intersections should be avoided when planning the mesh.
Areas bounded by seams should have a shape close to a square
If the length of the section is 1.5 times the width, then a crack is likely to appear in the middle of the long side. The seam pattern should be such as to exclude the formation of long and narrow sections.
Avoid the formation of triangular areas with sharp corners
Plots triangular with sharp corners usually crack at the end of a sharp corner. In general, triangles should be avoided, however, if this is to be done, the seams should form an equilateral triangle.
Sometimes cracks form in concrete that has not gained strength. These shrinkage cracks usually occur in dry, hot and windy conditions. If during the placement of concrete exactly such weather, then concrete with synthetic fibers should be used, and in the process of laying and grouting concrete, wet its surface with water.
