Anchor is a fastener that combines the design features of a bolt and a dowel. It is used for fixing into stone, brick, concrete and other hard and porous materials. The use of anchors makes it possible to achieve high fastening strength, which significantly exceeds the capabilities of a dowel or screw.
Classification of anchors by size
Anchor name with German language translates as "anchor". Indeed, this fastener provides a secure fixation. It is used when you need to fix the horizontal bar or other sports equipment on the wall. It is used in the installation of air conditioners, for fixing balcony elements to the facade, for fixing plumbing, etc. Anchor bolts withstand a large dynamic load, vibration and other mechanical stress.
These fasteners are divided into groups according to size:
- Small - diameter up to 8 mm, and length up to 55 mm.
- Medium - diameter up to 12 mm with a length of up to 120 mm.
- Large - reach a thickness of 24 mm and a length of up to 220 mm.
In construction, the choice of anchors depends on the requirements of GOST. For certain purposes, clear parameters of the fasteners to be used are established.
Classic anchor designs
The design of the anchor bolt may differ in the method of installation, as well as connection various elements to them. The most popular varieties of this fastener are the following designs:
- Spacers.
- Drop-in.
- Wedge.
Spacers
Expansion anchors are the most common design. It is a bolt or stud, the nose of which is made in the form of a cone. A sleeve with a longitudinal section is put on this rod. Since its inner diameter is smaller than the cone on the nose, it cannot come off the hairpin. A special nut on the top of the anchor protruding from the wall, when screwed, drags a stud onto itself, which cannot pass through the sleeve and unclenches it. As a result, the latter is deformed, adhering tightly to the walls of the hole and holding the entire anchor fastener as a whole.
Spacer fasteners provide effective fixation only in those materials that have a dense internal structure. It is primarily concrete. If such anchors are mounted in hollow materials, then special strength cannot be achieved.
The expansion anchor comes with:
- Gadget.
- Crochet.
- Ring.
- Double spacer.
- Hex head.
Nut Anchors They are a stud that is pressed with a regular nut. It uses a long sleeve, which provides a large contact area inside the hole. The peculiarity of using such an anchor lies not only in the fact that a certain structure can be pressed against the wall with a nut, but also makes it possible to screw another nut onto its stud. It can be an eye nut or a special welded tip of any shape.
Anchors with ring or hook are almost identical in design as with the nut. They use a stud, at the end of which a mounting ring or hook is provided. The deformation sleeve itself has a dense top with a knurled thread. When the pin is unscrewed, the sleeve expands, because it has longitudinal through slots that make the central part more plastic. This fastener is used in cases where it is necessary to hook a cord, cable or rope. It can also be used to connect the chain to the wall. In everyday life, they are usually used to securely hang a chandelier from the ceiling. Also, children's swings in apartments are attached to them.
Double-spaced anchors have a special design. The main difference between this fastener is that when unscrewing the stud, one spacer sleeve enters the second. The expansion is carried out close to the end of the anchor, which is especially important if it is necessary to fix it in a porous material. Due to the fact that the fasteners are fixed in the depth of the wall, the maximum possible fixation is ensured.
Anchor with hexagon head represents almost the same design as with the nut. The only difference is that instead of a stud and nut, it uses a regular bolt. When twisting, the cone at the end begins to drag the sleeve to the bolt head, simultaneously crushing its walls. As a result, it tightly compresses the sleeve and deforms it until the hole dimensions are completely filled. This design can be calculated under wrench, as well as additionally for a screwdriver. Such anchors are rarely made large, and usually their diameter does not exceed 12 mm.
Wedge
Wedge anchors are a long metal stud, at the end of which there is a deformation sleeve. When screwing the pin, the small petals expand. This happens in the depth of the wall far from the front part, therefore cracking of the material is excluded.
driven
A driven anchor bolt is fundamentally different from other designs. To ensure its disclosure, it is necessary to first plant the sleeve itself, and only then screw in the pin. In order to use such fasteners, it is necessary to prepare a hole, and then put the anchor sleeve into it. After that, a pin is applied to the installed sleeve, which must be hit with a hammer. This allows you to deform the sleeve and press it tightly against the walls of the hole. Next, the pin is removed and the bolt is screwed, to which the fixation is carried out.
Chemical anchors
Chemical, or adhesive, anchors are very reliable fasteners that provide a strong hold. This fastener is a set of ordinary studs and glue. To use such fasteners, a hole is drilled, which is cleaned of dust and subsequently filled with adhesive. After that, a hairpin is inserted into it and left to solidify. The disadvantage of such fasteners is that it takes a long time to gain maximum strength. In the case of conventional anchors, fasteners can be used immediately.
Chemical fasteners are used in cases where you need to fix in a soft or porous material that cannot withstand a large load. In order to achieve the highest possible holding force for the stud, it is necessary to properly prepare the hole. First, the drill deepens to the required distance, after which a cone-shaped void is sampled in a circular motion. It is necessary to make sure that the bottom of the hole is much wider than its neck. This will allow more glue to be poured in. After hardening, it will not only hold the stud by sticking to the walls, but it will also physically not be able to break out of the hole, due to the narrow exit.
How to use a regular anchor correctly
In order for the anchor to work to its fullest, it is necessary to conduct it correct installation. First of all, you need to choose the one that will correspond to the diameter of the anchor. It is not necessary that it be a fraction of a millimeter thicker, since when drilling , or , the resulting hole will always be slightly larger, due to the rattling of the tool in the hands. It is worth controlling the depth so as not to overdo it, as this will reduce the performance of the fastener. Next, be sure to blow the hole to remove crumbs and dust from it. This can be done with a cylinder of compressed air, or in extreme cases with a syringe. Only then can the anchor be inserted and tightened.
Some builders, to increase the reliability of fasteners when working with porous materials, prefer additional use adhesive compounds. In particular, liquid nails are used. A small amount of mass is squeezed into the hole, after which an anchor bolt is driven into it. In fact, after tightening the spacer, a rigid fixation is provided not only with ribs, but also with glue.
Usually, when installing the anchor, it is quite difficult to drive it into the prepared hole. If there are no problems with this, then the hole turned out to be excessively thick and you cannot count on a reliable connection. If this happens, then you will have to choose a thicker anchor.
In order to drive the fastener into the prepared hole, it can be hammered using. In this case, you need to use a soft lining. If fasteners with a hook or ring at the end are fixed, then you can beat directly. In the case when the top of the anchor is a threaded connection, then impacts can damage it. It is necessary to combine the tip of the stud and the side of the nut at the same level. After that, apply wooden block and strikes with a hammer. As soon as the fastener comes to the end, you can tighten it with.
How to pull out an anchor bolt
The connection received by the anchor is very reliable, but there are times when the need for it ends. In this case, it is necessary to remove the fastener from the wall. This is quite difficult, but quite doable. To work, you need a wrench, as well as a hammer and. First you need to unscrew the pin so that it no longer bursts the sleeve. This procedure differs depending on the anchor design. In some cases, you can simply tighten the bolt, while in others, loosen the nut and use a hammer to drive the stud deep into the hole.
After the sleeve is released, it can be pulled out. In most cases, pliers will not be able to catch on it, so you will need to destroy a little wall around the hole in which the anchor is planted. To do this, a chisel is substituted near the anchor sleeve, and a groove is made about 1 cm deep. After that, it will be possible to catch on the sleeve with pliers and pull it out.
Anchor bolt is a popular fastener, with the help of which they solve the problem of fixing and fixing heavy metal or other structures in the wall. These include prefabricated consoles, hinged products, various partitions, etc. The technology for using such bolts is simple, they differ in GOST standards, shape, type of fastening of the nut, as well as in the content of chemicals and materials in the composition.
Technical classification of anchor bolts
The production and manufacture of all anchors in our market is regulated in accordance with the GOST-24379 standards of 2012. They are made from high-alloy and durable types of industrial steel. This part is a metal rod of various diameters and lengths, the end of which is threaded and has a special fastening in the form of a conical nut.
The basic principle of the anchor bolt is based on it. When the rod enters concrete or other material, the fastener coupling is deformed, resulting in a powerful and durable connection. After screwing in, such fasteners can only be pulled out with part of the base and with the help of special equipment.
In addition to the types and sizes of anchors, it is customary to divide them according to the method of their fastening. The latter is determined on the basis of specific features and necessary character loads. Thus, all anchor bolts are distinguished by:
- Option to enter the main material. The most common are screw, drilling, driving, etc.).
- The method of sealing in the immediate place of fixing (expansion, expansion, tubular, etc.).
- Structural features and form. There are cylindrical, conical, solid or prefabricated, rod.
Depending on the last item in the list, anchors are classified into temporary and permanent according to the nature of their action. Reliable fastening and connection of the anchor with one or another material occurs due to friction and stop. Chemical types, which contain special fast-curing resins in the capsule, are held inside with a powerful adhesive base.
The main technical characteristic of any anchor is its tensile strength. This is a value that is easily calculated by the formula and measured in kN (kilonewtons).
The GOST regulation allows the use of various bolts for fastenings, the "explosive index" of which is more than 10.5 kN.
When calculating the anchors required in terms of shape and degree of action, criteria such as torque and bending moment must also be taken into account. Under the terms of the same GOST, the maximum allowable value is 25 Nm (Newton meters), and the minimum threshold is 5.2 Nm.
Thus, the higher the bending force of the bolt, the stronger its connection to the base. If the construction object goes beyond the established standards, there is an additional classification of anchors, the characteristics of which vary depending on specific indicators according to SNIP 2. 09. 03.
Types of anchor bolts and an overview of their areas of application
Anchors of various shapes and properties are mainly used where there is a need to strengthen structures with a large weight and elements that can move under a certain influence. Such bolts are also successfully used for the foundation, they are used to fasten products with high performance and tensile strength.
Most often, this fastener is used in such cases:
- for strengthening fences, railings, heavy stairs, balconies, building consoles, etc.;
- for attachment to natural stone, concrete or brick wall of various designs;
- with improved fasteners for suspension systems and mechanisms (construction beams, splits, etc.).
Depending on the specific application and shape, all anchor bolts are divided into 2 main types - mechanical and chemical. Both options have their pros and cons, they are used both in a complex and separately from each other.
Mechanical type fasteners - features of popular options
The most versatile and popular type of anchor is a bolt with a hook or a metal ring at the end of the thread. It is used mainly for suspended equipment and materials that are removed from the wall during their operation for repair or replacement (air conditioners, antennas, suspension panels, etc.).
GOST regulates maximum length such a bolt, which should not exceed 60 mm. The minimum diameter is 6 mm. A feature of the use of such fasteners is the presence of a nut or a hook at the end of the rod, due to which there is a reliable fixation and clamping inside the base.
Impact anchor (bolt with spacer or foundation and mountain). Another common fastener, which completely lacks a nut and a threaded head. The peculiarity of the bolt is that with dense hammer blows, the stem and tube are wedged, and this leads to a reliable connection. Impact anchors are used primarily for adhesion to concrete base, if necessary, hang on it and attach various heavy materials, since the design allows you to use this fastener for any massive objects, including a foundation pit.
"Hidden anchor" with a head. The parameters of its operation are based on the principle of friction force between the base and the conical sleeve, bushing or spring ring. The bolt can also be double-spaced (two heads, bushings or rings), therefore it is able to withstand heavy loads. Most often used for fastening complex and heavy structures to the base of the foundation or walls.
Hexagonal anchor bolt. A feature of the fastener is the head on the rod, which is made in the form of a hexagon. A powerful grip with one or another material occurs due to the friction of the nut, which is located at the bottom. This variety also includes anchors with a "cross-shaped" head. One piece is quite capable of withstanding medium loads, for example, the installation of an antenna.
Frame anchor fastener. The "lightest" version of the bolt, which is used mainly for fastening simple wooden and plastic elements. The custom-shaped head self-levels on the surface, which provides a reliable and durable grip.
Stud for connection with concrete. Anchoring with a bolt of this type occurs due to the presence of two fastening tips. It is screwed in with a conventional nut and is used for hanging heavy structures in the form of canopies, load-bearing consoles, balconies, etc.
Chemical anchors - a powerful alternative for construction
Unlike standard mechanical anchors, in chemical bolts, in addition to the metal base, which creates thrust and friction, there is also an additional substance. With its help, instant bonding occurs inside the base, which leads to a more reliable fixation.
The main advantages of using chemical anchor bolts in construction are:
- versatility. Such a screw is used for both external and internal work;
- resistance to vibration and fluctuations. This indicator allows you to use them for any designs;
- effective application for walls and bases made of thin or "loose" materials. Chemical anchoring is carried out on any surface, including today's popular aerated concrete.
In addition to chemical and standard mechanical options, there are more "highly specialized": mountain, floor, ceiling, facade, spring or ground anchors. They are used much less often for specific actions on construction site, and their production is less efficient.
Instructions for installing fasteners with your own hands
Technology of fastening and installation of anchors standard view uncomplicated. The first step is to drill a hole in the wall with a drill or puncher. The hole should match as closely as possible with the diameter of the bolt used, so the drill or drill is selected based on these data.
All well-known manufacturers of this fastener produce their products in accordance with accepted standards, why choose necessary element for proper drilling is not difficult. Be sure to calculate the specified length of the product, since it is very difficult to pull out both the mechanical and chemical anchors with incomplete tightening, and it will leave only with part of the finish and the wall.
After drilling, the resulting hole is purged from the collected dust and dirt. It is most convenient to do this with the help of a professional construction vacuum cleaner. The anchor should not go in easily, it is best to drive it in with tight blows of a hammer or sledgehammer for a more reliable and high-quality fastening.
The nut is tightened to the stop, which allows the tapered rod to wedged out correctly inside the concrete or other stone base. Then unscrew the pebbles, install on the rod necessary material and screw it back as tightly as possible with a wrench or ratchet.
This instruction is also relevant for chemical anchors, but they are usually wider due to the presence of a special filler inside the glass (solid), which should also be taken into account during installation. Be careful with this type of anchor, when it falls, it breaks, releasing toxic substances that should not get on the skin, clothing, etc.
In a variety of construction works, it is necessary to constantly fasten any structures and materials to load-bearing surfaces - the ceiling, walls, facade and even the ground. But if you can use an ordinary nail for mounting on plywood or a clay brick wall, then when working with concrete or silicate brick you will need a more powerful fastener - an anchor, about the methods and places of fastening of which we will talk today.
The actual fastening of something to something is provided mainly by friction forces. The hardware is immersed in the base material and upon contact with it, the same friction arises that holds both the fastener itself and the attached element. Obviously, the friction force is determined by the characteristics of the material.
On the other hand, a pull-out load acts on the fastener, as well as a bending load, torsion, and so on, and if the friction force is less than the pull-out load, the fastener will be destroyed, which is usually observed when mounting heavy objects and structures. Anchor is a device that allows you to significantly increase the friction force, as well as create additional factors to hold.
This video will tell you about the principle of operation of the anchor:
Product concept
How does this happen? If we compare ordinary and threaded, it turns out that the second hardware provides where best mount by increasing the working surface. Anker is the next step in this direction.
Any of its design implies the presence of an element that is wedged in the body of the material. That is, when immersed in the surface material, the anchor does not differ in function from a nail, but as soon as any load is applied to it - shock, pull-out, bending, twisting, the working part of the anchor already in the material is wedged and creates additional emphasis. Such a connection is so strong that fasteners are used in the installation of the heaviest structures - from massive household appliances to industrial chimneys and building frames.
However, this is not the only feature of the anchor. The heavy attached structure creates a large load. In the normal case, this force acts on the fastener, which leads to pulling out. The anchor, due to its structure, transfers most of the load to the base material, thereby significantly increasing the strength and reliability of fastening.
There is also a limitation here: a large load can only be transferred to a durable, and, most importantly, dense material. Therefore, anchors are used when working with concrete, and are not used when attaching to, or. It is worth noting that special and quite effective anchors are also produced for such materials, since the issue of fastening, nevertheless, remains open.
Advantages and disadvantages
Anchor - specialized fasteners. Of course, you can fix the lamp in wooden wall and with his help. But economically it will be unprofitable, since the cost of products is very noticeable, so the use of fasteners is advisable only in their area. The product is fully consistent with its purpose.
The advantages of fasteners are undeniable:
- very high bearing capacity, noticeably higher than that of other types of hardware;
- a variety of designs and sizes - you can choose the best option for fastening any material or design;
- fasteners are made of the most durable steels, resistant to any type of corrosion, so it is not only reliable, but also durable hardware. According to its characteristics, it is designed for the same service life as bearing surfaces or structures;
- installation, although it has its own characteristics, is quite simple and ensures the minimum time for repair or construction;
- anchors can always be used to reinforce an existing structure, and the latter does not need to be dismantled for this;
- most anchors are resistant not only to static, but also to dynamic loads, especially vibration ones.
The disadvantages are related to the design features:
- in most cases, anchors are expensive;
- most models require a large depth and large hole diameter;
- fasteners are not universal. An anchor is used for fastening to dense concrete and solid brick, brick wall. There are special models for porous concrete.
The main difference between the anchor and other types of hardware is its high bearing capacity. According to the principle of operation - retention due to friction forces and additional volume, it is similar to a dowel. But the latter is designed for medium loads, is usually made of plastic and, in fact, is not an independent fastener, but acts only as a spacer.
About whether an anchor is produced for fastening door frame, brackets, braces, timber, floor slabs, aerated concrete, toilet bowl or bathtub to the wall, fastening the log to concrete floor, as well as other applications of anchors.
Types of such hardware
Specificity various materials products also require special fasteners, so there are a lot of varieties of products. They differ markedly in design, scope, and cost.
All anchors are divided into mechanical and chemical:
- mechanical- fastening is implemented due to friction forces and the shape of the thrust;
- - the adhesive force is at work here. This group is much smaller because chemical method takes more time and depends on the temperature: adhesive or cement mortar have to grab. In addition, installation with their help is not so convenient.
About installation different types anchors will tell this video:
By design features
The most informative classification is the division according to design features.
- - Anchor-bolt or anchor-stud. This is a metal rod, one end of which is made in the form of a cone. A spacer sleeve is placed on the cone. On the other side there is a thread. As a rule, the anchor is supplied with a washer and nut, although there is an exception: the ceiling wedge anchor has only a locking head. Fasteners are placed in a pre-drilled hole and tightened with a wrench. In this case, the bushing is pushed onto the cone and wedged, increasing in volume. The wedge anchor withstands the heaviest loads, but also creates a high stress in the material in the contact zone. It cannot be used in loose porous concrete. Reduces the load on a model with two spacer sleeves.
- Sleeve– The spacer sleeve has the same length as the metal rod. The latter has a wedge-shaped head. When tightening, the nut moves along the rod and expands the sleeve. Such fasteners create less stress in the material, therefore it can be used both on more and in solid clay bricks. Installation requirements are low, through-mounting is possible. However, the bearing capacity of fasteners is lower than that of wedge fasteners, so they are less common.
- expanding- an improved version of the sleeve, more complex structure. A 3-4 petal sleeve is bursting with a special spring and expanding nut. The fastening is thus formed both by friction and by shape. The fixture has the same bearing capacity, as wedge anchor, but does not create tension in the zone of contact with the material. It is used during installation both on dense and light, and on cellular concrete and hollow brick. An expanding anchor is an expensive product, therefore it is used mainly by professionals.
- – the inner surface of the threaded sleeve has a conical shape and cuts. Inside finds a wedge. When struck with a hammer, the wedge moves inside the sleeve and bursts it. The drop-in anchor is designed to work with concrete and solid brick. Its installation is very simple and takes a minimum of time, however, it also makes the load on the material even greater than the wedge one.
The exception is special fasteners, such as "Cycon". Here, when the anchor is driven in, the sleeve moves onto the wedge and wedged. The hole itself must be of a special shape - with an expansion in the depth of the material, which is possible only when using a special drill.
- Special- this category includes atypical products with a narrow specialization, for example: self-tightening, frame anchors with a nylon sleeve, fasteners for geogrids, special fasteners for hollow structures, and so on.
Fastening a pipe with an anchor (photo)
By area of application
Another classification is related to the scope of the product. Anchors, as is clear from their design, are not universal.
- To work on concrete walls - almost all types of anchors are designed for installation in dense heavy material. The exception is harder to find.
- Special fasteners for porous materials- for example, the same "Cycon" or expanding anchor.
- - a special design used when necessary to fix the frame or walls to the foundation. Fasteners are massive and difficult to install.
- – Option for remote mounting. In this way it is possible to fasten with anchors in durable materials through a layer of fragile thermal insulation material or decorative material.
- - the anchor is designed for fixing suspended structures, ceiling systems, equipment and lighting fixtures to the ceiling.
- – modification to anchor the structure or structure to the ground. Can replace the foundation.
- frame– closest to the dowels, have a plastic spacer sleeve.
Fastener Specifications
Compare anchors with each other different structure- a thankless job. Depending on the device and material, the indicators will be completely different. But since high strength and load-bearing capacity are associated with greater cost, there is a certain combination of price and product features. And this allows you to choose the best fasteners not only in terms of technical parameters, but also in terms of cost.
The size range of products depends on the purpose. Of course, the ceiling model will always have a more modest size and a smaller range of them compared to the foundation bolts. But in general, a relatively large length is common design feature- otherwise it is difficult to form a reliable mount.
When choosing products, the consumer is most interested in the maximum and working load. The latter is 25–30% of the maximum. It should be noted that the bearing capacity is also affected by the base material. The figures are usually given for compressed concrete with a density of less than 1800 kg / m3.
wedge
Wedge anchor - basic design, galvanized steel:
- sizes vary from 6 * 40 to 12 * 120 mm, however, from different manufacturers size range may not match;
- the maximum thickness of the attached material ranges from 5 to 20 mm;
- the minimum thickness of the bearing surface should be from 53 to 120 mm;
- and, finally, the main parameter, the minimum pull-out force - from 1.4 to 6 kN.
Its special version - the ceiling wedge anchor, is not much inferior to the main models: the maximum thickness of the material is 5-8 mm, the pull-out force is from 3.6 to 5 kN at maximum size products 6*60 mm.
Sleeve
Sleeve anchor:
- sizes range from 8/15*65 mm to 12/50*115 mm;
- maximum thickness of fastened elements - from 15 to 50 mm;
- ultimate bending moment - from 5.2 to 25 Nm;
- pull-out load - from 10.5 to 18.3 kN.
Spacer
Expansion anchor - data of one of the modifications are given:
- dimensions - the total length of the product varies from 98 to 235 mm;
- the thickness of the attached elements ranges from 20 to 60 mm;
- the minimum thickness of the base material is from 120 to 300 mm;
- pull-out load in the compressed zone of concrete - from 11.2 to 44.1 kN;
- pull-out load in the tensile zone of concrete (lightweight materials) - from 4.8 to 31.5 kN.
Zabivnoy
Drive-in anchor - characteristics are given for one of the models. Production material - galvanized steel:
- dimensions - length varies from 25 to 50 mm;
- the thickness of the attached part is not standardized, since it does not depend on the anchor part;
- minimum base thickness - from 100 to 130 mm;
- pull-out load in the compressed zone - from 3.9 to 12.6 kN. The minimum load in the compressed zone of concrete is the same.
And now we will find out what set of materials is needed for the manufacture of the anchor fastening, and what is the composition of the metal elements.
Product materials
Anchors designed to hold heavy materials and structures, and therefore are made mostly of durable steel grades. However, there are exceptions.
- Steel - more precisely, high-quality structural steel, low-carbon, alloyed, cold-worked. This material is the most durable and reliable. Also used is carbon steel for cold heading, structural free-cutting steel. The choice of strength class is determined by the purpose of fasteners: the higher the expected loads, the higher the strength class.
- Stainless steel - or corrosion resistant. The alloy not only has the highest strength characteristics, but is also not subject to corrosion. Such fasteners are used in the most critical areas.
- Non-ferrous metals - the best known are brass and zinc-aluminum alloys. The material is rarely used, mainly for domestic work.
- - special types of products may include plastic - polyamide, sleeve and steel rod. Another option is fiberglass, which is not much inferior in strength to metals.
Since the anchors are designed for a long service life, their corrosion resistance should be discussed separately. Stainless steel does not rust. Other types of alloys are protected by a coating.
- Galvanic galvanizing - by electrolysis;
- Chromating - zinc plating followed by treatment with a solution of chromic acid in order to obtain a film of zinc chromates;
- Hot dip galvanizing - immersion of the product in molten zinc.
Complex fasteners from several parts can be made from different materials. Steel for different parts is selected based on the expected load. For example, Fisher's compound wedge anchor is designed as follows: the sleeve and body are made of free cutting steel, and the bolt is made of alloyed grade 10.9.
Anchoring is the most durable and reliable fastening, as it provides retention due to at least 2 factors - friction forces and shape. Anchors are indispensable in all cases where installation is required from really heavy equipment and structures to household appliances.
This video contains useful tips for installing anchors:
Anchor bolts- if we consider the principle of operation of the two main types of fasteners - the anchor and the dowel, then the anchor has a significant advantage. The metal anchor, in addition to the friction force, is held at the base with the help of a “stop” in the form of a kind of anchor, obtained due to the expansion part of the shank. To friction is added the force of resistance to the destruction of the base material.
There is also chemical anchors, they use quick-hardening adhesives instead of a metal sleeve, which are injected into the hole before installing the anchor bolt. The result is a monolithic connection with the base.
There is a large range of anchors on the market, but they can all be divided into several classes.
Anchor bolt with nut: how to fix
In fact, this is a stud with a nut and washer, which is screwed into a coupling (threaded sleeve). Therefore, it may be called an anchor bolt with a nut or a stud anchor. How to fix anchor bolts with a nut, we study in detail on our own and use it.
Anchor bolt (foundation bolt) with nut
On the one hand, a nut with a washer is screwed onto the stud, on the other, a “wedge” in the form of a cone is located. In the wide part, the wedge corresponds to the diameter of the coupling, in the narrow part - to the stud. The coupling from the side of the wedge has a notch and longitudinal slots.
Installation is quite simple, how to fix anchor bolts with a nut - even a beginner will understand.
Anchor bolt: fastening scheme
A hole is drilled in the base for the coupling, cleaned of dust. A part is hung on the anchor, inserted into the hole and hammered with gentle blows of the hammer until it stops. Then tighten the nut a few turns.
Screwing on the stud, the nut "unscrews" it from the coupling, as a result, the wedge bursts the coupling along the entire length with slots.
Anchor bolts are made of galvanized steel. Used for concrete, stone, solid brick.
There is an "improved version" of such an anchor - a two-spacer one.
Double-spaced anchor bolt
It has two movable sleeves with slots, one of which fits into the other with a cone. When screwing the nut, the shank pushes one sleeve over the other. The first one bursts with the cone of the wedge and itself bursts the middle sleeve, forming two fastening belts.
Wedge anchor - how to fix
This type can be considered as a modification of the previous one. The coupling is made in the form of a movable short sleeve-ring at the end of the stud from the side of the shank (wedge).
The principle of operation is similar, there is a slight difference - it does not require precise drilling to the depth of the hole and its cleaning from dust. The hole is drilled with a margin, the anchor is inserted to the desired depth and the nut is screwed, bursting the sleeve with the shank.
Hex Stud Anchor
This is a classic bolt with a washer that is screwed into a sleeve with longitudinal slots at the end. The tail conical nut serves as a spacer.
Installation is standard - a hole is drilled, cleaned, an anchor is inserted with a hinged part and slightly knocked out. It remains to tighten the anchor bolts a few turns - the nut enters the coupling with a cone and bursts it.
Anchor stud - installation diagram
The scope of application is the same as that of the previous types - fastening heavy structures to a base made of concrete, stone and solid brick.
This type of bolt may end in a ring or a hook. They allow you to simply hang structures after mounting the anchor, otherwise there are no differences.
Impact Anchor Bolts - how to fix anchor bolt.
This model combines the functions anchor and nail.
Impact Stud Anchor
It consists of a hollow metal rod, one end of which is made in the form of a stud threaded for a nut and washer, the other is a sleeve with a four-blade spacer.
Installation, how to fix an anchor bolt - an anchor bolt must be hammered into the base hole, into which a nail is driven in turn. The petals of the sleeve diverge. The nut serves only to fix the attached part.
Expanding anchor four-segment
According to the principle of operation, this type is closer to an anchor with a nut or a hex head. Although it does not have a wedge or cone-shaped nut on the shank of the stud or bolt, and the expansion occurs due to the bolt itself being screwed into the hollow sleeve, which moves the internal tetrahedral element.
Anchor bolt four-segment
The anchor consists of a cylinder with four slots that end in a narrow ring. The slats are held by a flat spring, after which the slots are wedge-shaped. Moving, the tetrahedral threaded element bursts these wedges.
Anchor stud installation diagram
The bolt is not included in the kit, but is selected depending on the size of the suspended structure.
In addition to the bolt, a bolt with a hook or ring can be screwed into the expansion anchor. These modifications are supplied with them in the kit.
Due to the wide opening of the lamella-wedges, expandable anchors can also be mounted in weak bases - hollow (slotted) bricks, gas or foam concrete blocks.
Drive-in anchor - how to fix anchor bolt.
One of the easiest anchor types to install.
The device is a threaded sleeve having a slot from the driven end, a conical internal shape and a wedge.
Installation - a driven anchor is inserted into the prepared hole and, using a special impact nozzle, the cut part is burst with a wedge. When the anchor bolts are screwed in, the petals diverge even wider, increasing grip.
Made from galvanized steel or brass.
screw anchor
Has a special design. The slots in the sleeve are not completely cut and end with a ring with a nut. Closer to the head and in the middle of the sleeve, the lamellas are weakened. By tightening the screw, the nut is displaced and bursts the lamellas in the middle.
Specially designed for weak and hollow substrates. It can be produced not only with a screw, but also with studs, hooks, rings.
In order to properly install anchor bolts, it is necessary to take into account the type and strength of the base, choose the optimal type of anchor for a particular part and determine its load capacity.
And although some types do not require high accuracy in drilling a hole (for example, expandable), the more accurate it is, the more reliable the adhesion of the anchor to the base.
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Recently, to fix any elements into the wall, special wooden plugs were used - dowels that were driven into previously drilled channels to ensure that the fasteners were held in a solid base.
However, such dowels were characterized by many disadvantages, including shrinkage or swelling. All this led to violations of the direct function. The next "evolutionary" stage was plastic dowels, which are compact, cheap and have a good fixing property.
But they also have disadvantages - delayed deformation with a significant weakening of the expansion restraint. This was especially evident in monolithic concrete structures, when the plastic burst and the dowels freely exited the channel.
Given the above shortcomings, an anchor was invented - the most reliable way commits for today. It clings to solid material like an anchor, preventing various factors from breaking the fastening.
Let's take a closer look at this latest development in the field of fasteners.
Commonly used types of anchors
Products are divided according to the type of application into:
- synthetic (chemical)- has a capsule with glue in the design, which collapses when the bolt is screwed in. The glue flows out and fastens the walls of the channel with the bolt after the composition dries. The disadvantage is the need to wait for the glue to dry, after which it is only possible to “load” the product. The advantages are undeniable - strong fixation and reliable retention in both monolithic and lightweight wall bases;
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- metal- simpler in structure, consists of a metal sleeve and a screwed bolt. An anchor is inserted into the drilled channel in a untwisted form, and when the bolt is screwed onto the thread, the sleeve expands (expands) with its walls firmly pressed into the channel surface. The main advantages are fastening strength, the ability to create shallow fasteners and the feasibility of reuse. The disadvantage is the high cost.
In addition, there is a classification by functional type:
- clamping- acts on the principle of opening the fastening petals and the middle deformation of the sleeve when the bolt is tightened. In addition to the main application (thick walls) it is used for thin structures, for example, from drywall;
- snipe- the design provides for an end screw (or wedge) that pushes the walls of the sleeve apart when the core is screwed in. There is a modification with a grooved rod that wedging the sleeve. Then it is removed from the threaded passage, and a core bolt is screwed in its place. This version of the anchor requires an exact match of the dimensional parameters of the holes and fasteners;
- spacer (crushed)- the most common variation. When twisting the cone-like sleeve, the rear sleeve part expands. The element does not need strict observance of the dimensions of the channel and sleeve. Used for fixing to concrete and brick walls;
- driven in- the simplest option, used without additional difficulties. The sleeve is soft and when the core bolt is tightened, it begins to deform with a tight stop against the channel walls, which creates a strong fixation. The anchor is used for natural stone and monolithic walls.
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Anchor screwing technique
To perform high-quality anchoring, it is necessary to use metal (steel) elements with an anti-corrosion protective coating, for example, M-30.
In addition, you need to be aware that all connections are characterized by certain hole parameters and the norms of the applied force for twisting.
They depend on the properties of the wall or covering. So, for durable concrete, the minimum insertion depth is 8.0 cm with a load of less than 7.1 kN, and for thin material, these values are half as much.
Let's analyze step by step the right technology fixing spacer (crushed) anchor fasteners in a concrete wall.
Stage 1. Calculation of the required bolt length
Very often, walls have a layer of finishing material, such as plaster. For sound fixing, it is necessary to place the bolt into the base to a depth of more than 5.0 cm. Therefore, the length of the anchor sleeve should have a length of 5 + the thickness of the plaster.
Stage 2. Determining the desired diameter (diameter) of the hole and the depth of the channel
It is necessary to carefully control the diameter of the channel for the anchor bolt, since the parameter of the applied force for twisting depends on this value. The sleeve must fit snugly and absolutely perpendicularly into the channel. Depth drilled hole must exceed the length of the anchor by 2.2–3.8 mm.
Stage 3. Marking and drilling a hole
The creation of the hole for the anchor must be optimally accurate, since the bolt cannot be moved after installation. Marking must be done very carefully. Then, a hole is made with the necessary drill and the channel is cleaned from fragments and dust particles.