Fastening products such as concrete anchors can ensure reliable fixation of various objects and structures on concrete surfaces. The problem of attaching various objects to concrete is quite relevant both in the field of capital construction and in the field of repairs carried out by the owners of real estate themselves.
Concrete anchors can provide reliable fastening of any structure
Such difficulties do not arise if the fastener needs to be fixed in a softer material - wood or plastic. If we are talking about concrete, a material characterized by high hardness and, accordingly, fragility, then it is necessary to use special fasteners, which, in particular, include anchor-type bolts.
What is an anchor: general concept
The word “anchor” means a fastener used for fixing various objects on structures made of solid solid materials - concrete, building bricks, natural stone, etc. To install such fasteners, you should prepare a hole with the appropriate dimensions in which the anchor-type bolt will be placed . The high holding capacity of a bolt placed in such a hole can be ensured by:
- friction forces ();
- adhesive abilities of a special composition ();
- a special thrust element interacting with the inner walls of the hole.
The most popular anchor is a fastening element, which, due to the peculiarities of its design, is wedged inside the hole, thereby ensuring high reliability of the connection created. The surface of such bolts, made of carbon steel, is coated with a zinc composition, which eliminates the risk of the occurrence and development of corrosion.
Anchor bolt sizes for concrete
Installation of anchor-type bolts can be carried out in various designs, the manufacturing material of which should differ sufficiently high strength. These include, in particular:
- concrete foundations;
- walls and partitions made of concrete and brick;
- floor slabs, which are usually made of concrete.
Objects and structural elements that are fastened with such bolts are usually:
- rolled metal beams various types;
- elements of suspended ceiling structures;
- lamps and chandeliers;
- wooden beam, used for installation of floor and ceiling coverings;
- elements of staircase structures;
- load-bearing structures with large weight and dimensions.
As mentioned above, fixing an anchor-type bolt inside a pre-prepared hole can be achieved in two main ways:
- by wedging the spacer sleeve inside the hole;
- due to a special adhesive composition that binds the bolt and the inner walls of the hole (chemical anchor).
There are requirements for holes in the fastened part, which should not exceed the values specified in the table. Large gaps can be filled with mortar
Mechanical Anchor Bolts for Concrete
The most common types of anchor bolts include fasteners that operate on a mechanical principle.
Drivers
One such product is a drive-in anchor, which has a thread inside the spacer sleeve. This anchor, designed for concrete and other dense and hard materials, is expanded in the hole using a special device, after which the fastener itself is screwed into it.
Spacers
Expansion anchors for concrete and other building materials are also widespread on the modern market. In the design of such anchor fasteners, which can withstand very significant loads, there is a special wedge, which is responsible for expanding the spacer sleeve. Using such anchors, it is possible to ensure reliable fixation of even heavy objects on a concrete surface - metal gates, large equipment, etc. Meanwhile, it should be borne in mind that the reliability of fastening that such an anchor provides for concrete work largely depends on the strength characteristics of the structure in which it is mounted.
One of the representatives of this family of fasteners is. Bolts of this type are used for installing windows and doors. The spacer sleeve of frame anchors has two wedging zones: at the bolt head and in the body of the load-bearing base.
Double spacer anchors for concrete, as their name suggests, have two spacer sleeves at the same time. Due to this, anchors of this type provide a more reliable grip, which allows them to be used for mounting objects of significant mass.
Wedge
The wedge-type anchor for concrete, mentioned above, can have two design options. In the first case, a hammer and a special punch bit are used to wedge the inner sleeve of such an anchor. After wedging the sleeve, such an additional device is removed from the inside of the anchor and a fastening bolt or pin is screwed into it.
Installation in other types of concrete is somewhat simpler. Their main element is a threaded rod, one end of which is cone-shaped. When tightening the nut, which rests on the surface of the structure in which such a fastener is installed, its conical part expands the spacer sleeve, ensuring its reliable fixation in a pre-prepared hole. In some models of anchor fasteners of this type, there are teeth on the outer surface of the spacer sleeve, which provide better adhesion of this element to the inner walls of the hole.
The rod anchor, which is also a wedge type, differs from the usual one in its increased dimensions (bolt length). Using this anchor, multilayer systems with significant thickness are installed.
The choice of the type of anchor is made based not only on its dimensions, which are specified by GOST, but also on the type of fastening that must be performed with its help. It is also important to calculate the load that will fall on the concrete anchor. When performing this calculation, it should be borne in mind that the load on the fastening element should not exceed 25% of that indicated by GOST.
Chemical Anchor Bolts for Concrete
A fastener of this type is a concrete anchor screw, the fixation of which in the hole is ensured by a special adhesive composition. The adhesive composition with which chemical anchors are fixed is poured into a pre-made and thoroughly cleaned hole to two-thirds of its length. An anchor bolt of the appropriate size is installed in the hole with glue. After the adhesive composition has completely hardened, the required item is attached.
It often happens that we need to fix different numbers of parts, bolts or structures on the wall. This is why a lot of different fastening options have been created. For example, for wood, as a rule, self-tapping screws are used, and for concrete, cement or brick, you need to use a special device called an anchor bolt.
The use of such fasteners makes it possible to fix quite heavy things on walls and ceilings. As an example, you can name a water heater, a sports wall, or a satellite TV dish on the roof or wall of a house. In itself, such a mount consists of an internal bolt, a nut at the end and a housing. The bolt also has a plastic gasket that prevents water from penetrating inside and damaging the bolt.
The main types of such bolts
The first, most popular of which is to install an anchor bolt with a nut. Such a bolt consists of a stud and a nut with a body, which is equipped with a washer; after securing such an anchor, the stud will protrude somewhat beyond the edges of the bolt, which allows you to increase its length. This type of fastening is intended for use in cement, concrete and partitions made from it, solid brick or stone. It is better not to use such fasteners in all other materials.
The second type is an anchor bolt with a hook. Such fastening will be needed for hanging removable items or structures that have a large weight, as well as temporary fastening of chains, cables and ropes to brick, concrete or other surfaces. Such a bolt consists of a collet and a pin, in one part and in the other, which is also placed in a sleeve. This type of fastening is perfect for concrete surfaces, natural stone and solid brick. All other materials that have a lower density will not be suitable. The last, most common type of fastening is the anchor bolt with a ring. It is used to suspend permanent heavy structures, such as gates, or to secure cables, chains and ropes on brick, concrete or natural stone surfaces. This anchor is made like a hairpin with a ring that is not welded at the end. At the other end there is a collet with an outer shell and a thread. The anchor is made of galvanized steel and is suitable for installation in natural stone, concrete or solid brick.
To use various wood compounds in the field of construction, you cannot do without just tools, but also without the appropriate experience. That is why inexperienced craftsmen do not always make such connections accurately. One of best options— professionals use various types of fasteners for the array, which are made of metal.
Many surviving architectural monuments made of wood were built without nails, using only an ax. This fact causes true pleasure to this day. However, centuries later, the fasteners made of metal, used to build solid wood buildings, have changed radically, and it is for this reason that today it makes no sense to repeat the experience of our ancestors.
It is preferable to build quickly and without difficulties. Let's talk in more detail about the fasteners offered by manufacturers, taking as an example details that make it possible to simplify as much as possible the connection of beams with floor joists or solid wall surfaces.
Perforated fasteners
When beams, as well as floor surface logs, are hidden in the interior space, they can be connected using beam shoes. This fastener for wood structures is suitable for fastening solid wood not just to wood, but also to concrete and brickwork. It is created from durable steel.
Manufacturers advise fastening such fasteners to the parts being connected with special screws, and in case of excessive load, or fixing to a stone material, use the holes for the necessary bolts. In addition to anchor shoes, today you can purchase special clamps and much more.
Tenon and groove
This galvanized wood fastener consists of a tongue and groove section that fit together to provide better transfer of horizontal as well as vertical forces.
The connection can be visible or hidden; for these purposes, the steel parts are recessed into special grooves in advance.
Three-dimensional slats
The modern Italian company produces fastening elements that are placed perpendicularly and vertically at an angle, using T-type slats created by extrusion from a high-strength steel alloy. They are produced in several modifications designed for different levels of loads.
The fastening system must be selected according to the size range of sections of the combined beams and the dynamic as well as static loads acting on them.
During the installation process, the slatted base is attached to the beam using self-tapping screws. Then a groove of the same size as the slatted shelf is created on the end part, attached to the base of the joist beam. If there is no perforation, the shelf is equipped with a log and the connection is secured using self-tapping screws.
Hidden details Hedgehog
These connectors are steel washers, the base of which is equipped with holes drilled under the slope. These holes are for self-tapping screws. In the center of the washer there is a threaded hole into which a pin is inserted. Its free end is threaded into a special hole and secured on the back side of the beam with a piece with an enclosed washer.
The created connection functions perfectly not only in pull-out, but also in shear. If there is excessive load in the area of the end part of the joist, it is possible to install several elements at the same time.
Fasteners with complex threads
Unusual self-tapping screws that make it possible to save time, cash, since this option does not require metal parts. Self-tapping screws are equipped with threads, which help create a high degree of resistance when pulled out, and are also tightly screwed into an array, which completely changes their traditional functioning.
In this case, the work of the screws occurs exclusively by pulling out, which gives them the opportunity to absorb most of the forces that fall on the connection. So, you can fasten elements at an angle, combine parts, minimizing their deflection, as in the photo of wood fasteners below.
Special purpose self-tapping screws
Using similar elements, fairly massive wooden products are attached. The cap has milled ribs and is easily recessed into the product, while the tip is created like a drill. In the middle of the screw, the cutter makes a larger hole, helping to tighten the element as tightly as possible.
An adjustable self-tapping screw will be useful for fastening door frames, window openings, and solid wood sheathing to wood and metal. The self-tapping screw is screwed directly into the box, as well as the wall surface located behind it, or the power part.
The self-tapping screw acts as a weather vane for high-quality fastening of solid wood cladding to a base made of steel. It has a tip in the form of a drill and wings placed above it to expand the hole in the tree.
When drilling metal products, the wings break. As a result, having made a thread in a metal part, the self-tapping screw fits tightly to it, while the solid element is attracted by its head to the metal.
Photos of wooden fasteners
In order to ensure high reliability of the connection using an anchor bolt, it is important not only to select it correctly in size and type of structure, but also to know how to properly fasten such a product.
There is a wide variety of anchor bolts, differing in their design and principle of operation, so it is important to know how to attach a particular type of anchor
The classic design anchor bolt provides reliable connection not only due to the frictional forces of its outer surface with the walls of the mounting hole, but also due to the fact that its spacer sleeve increases in diameter when a threaded element is screwed into it. The reliability of installation of such a fastening element is also influenced by the strength characteristics of the building structure material, which should also be taken into account.
For all fasteners in question, the drill to perform mounting hole is selected according to the diameter of the anchor, with the exception of impact-type anchor bolts.
With nut
The structural elements of this type of anchor bolt are:
- a threaded rod, one end of which is made in the shape of a cone, and a nut is screwed onto the other;
- a spacer screwed onto a stud (its lower end has longitudinal slots on the side surface, which form peculiar petals).
Reliable fixation of such a fastening element is ensured due to the fact that the petals of the spacer sleeve are unclenched, which occurs when they are exposed to the conical end of the pin. In order for the tapered end of such a bolt to begin to enter the bushing and open its petals, a nut is used.
Fasten an anchor bolt with a nut in the foundation or any other building structure made of concrete, performing the following steps:
- drill a hole, the diameter of which must correspond to the cross-sectional size of the spacer sleeve;
- thoroughly clean the mounting hole;
- carefully hammer in with a hammer;
- By tightening the nut, you achieve reliable fastening of the anchor.
After the installation of the anchor bolt is completed, you can unscrew the nut from the top of the stud and begin installing the required item.
When choosing products of this type, you should keep in mind that they demonstrate their effectiveness only if they are mounted in durable and solid materials (concrete, brick, natural stone, etc.). Manufacturers, in order to ensure high reliability and corrosion resistance of such products, make them from high-quality steel with a zinc coating.
An improved model of this type of anchor bolt is a double-expansion anchor, which, due to its design features, can be successfully fastened not only in durable concrete, but also in hollow and porous materials. Such a bolt has two bushings at once, which expand during the process of tightening the threaded element, creating more reliable fastening in a wall or foundation.
Wedge
An anchor of this type, the spacer or wedge sleeve of which has a shortened length, is also a modification of a fastener with a nut. The wedge element that expands such a bushing is the reverse end of the threaded part of the bolt, which has a conical shape.
The big advantage of using them is that for their reliable fastening there is no need to maintain the exact diameter of the mounting hole; moreover, it does not need to be cleaned of construction dust. Such a bolt is secured in the mounting hole, and its spacer element is expanded by tightening the nut.
Hex head
The threaded part of such a fastener is a classic bolt, the reverse end of which also has a conical shape. Screwing into the spacer sleeve, such a bolt opens it with its conical shank, ensuring reliable fastening of the product to the wall or foundation.
Such an anchor should be secured by inserting and carefully hammering it into a previously prepared and cleaned hole. Then you need to securely fasten the bolt by tightening its hex head.
Bolts of this type, which may have a hook or ring instead of a hex head, are used to perform installation work for concrete, stone and others building materials with a dense internal structure.
Drums
Anchor bolts of this type consist of:
- a hollow metal rod, on the upper part of which there is a thread for a fastening nut, and the lower part is a spacer coupling with longitudinal slots on the side surface;
- a striking element (nail), which, when driven into a hollow rod, precisely ensures the expansion of its lower part;
- nuts and washers, which are needed only to secure the required object with such a bolt.
Thus, in order to correctly and reliably fasten such a bolt in a wall or other building structure, it is necessary not only to insert it into the mounting hole, but also to drive an impact element into it, which will open the petals of the spacer coupling.
Taking into account the fact that when installing such a bolt, significant shock loads arise, it is not recommended to fasten it in porous and fragile materials.
Four-segment
The design of such an anchor bolt does not include a wedge part, and the expansion of the spacer sleeve, divided into four segments by longitudinal slots, occurs when the bolt is screwed in, which moves the tetrahedral element in its internal cavity. The four lobes, which are formed by slots on the side surface of the spacer, are initially compressed and form the conical tip of such a bolt. When a bolt is screwed in, which moves a threaded tetrahedral element inside the spacer sleeve, the segments expand, which allows the anchor to be securely fastened in the mounting hole.
The petals of such a product open quite wide and this happens very carefully. That is why it can be mounted in porous and even hollow materials. The threaded element, which is usually not supplied with such an anchor product, can be a bolt with a regular hex head or a bolt whose upper part is crowned with a ring or hook.
Drivers
A drive-in anchor is the simplest anchor-type fastener, the design of which consists of a spacer sleeve with a conical-shaped internal hole. To install this at the required point of the building structure, it must be hammered into the mounting hole, and then a threaded element must be screwed into it, which will ensure the expansion of the bushing petals.
The material for the manufacture of such fasteners, the process correct installation which can be seen in the video, can be galvanized steel or brass.
Are anchors suitable for wood? How to securely attach a chandelier, hanging bed or other massive thing to a wooden beam with them? What other means can be used when merging wood structures? Let's find out!
Types of anchors
The word “anchor” is of Germanic origin, its main meaning is “anchor”. Anchor fasteners are used when installing various products on a base made of wood or concrete.
There are several types of “anchors”:
- spacer;
- persistent;
- adhesive;
- Bolt Molly.
The expansion anchor is held in the workpiece by frictional force. To maximize it, the rod installed in the hole is expanded with a plastic dowel or wedge stop with a thread inside.
The fixation of the thrust bolt is ensured by the ribbed or expanding part of it embedded in the base. This is exactly how the fastenings used when installing heavy production plants on a concrete foundation are designed.
Adhesive “anchors,” as the name implies, adhere to the surface due to the sticky composition entering the void between the walls of the hole and the ribbed rod. Most often, the role of an adhesive mixture is performed by a polymer resin with a hardener.
The Molly bolt is used when hanging products on low-strength partitions made of gypsum fiber board, chipboard, gypsum plasterboard and hollow brick. In the process of tightening, Molly pushes the outer shell apart. As a result, a stop appears that is in extensive contact with the base.
Note: craftsmen often call adhesive anchors “chemical”.
Now let's figure out what type of anchor bolts are suitable for in various ways fastening to wooden structures:
- The Molly Bolt can only be used on surfaces that have large voids inside. That is, this method is only suitable for hanging relatively light objects on partitions made of boards, chipboard and lining;
- thrust anchors are used only in the process of creating a massive foundation. In the case of wood, this is the growth stage of the tree trunk, so such fastenings will not suit us;
- glue “anchors” can be used when working with wood, but this is not always advisable due to the high price of this product.
Important: large changes in humidity can lead to loss of adhesion between the body of the chemical anchor made of hardened resin and the walls of the hole, which will cause the fastening to become unusable.
Based on the above facts, we can conclude that the anchor fasteners for wood must be spacer. However, another important factor should be taken into account here: depending on where the force is directed, the strength of the wood may vary:
- If the force vector runs parallel to the fibers, the material is more tensile;
- If the force vector is perpendicular to the fibers, the destructive force will be several times less.
In simple terms, wood is more likely to split if you wedge it between the grain. At the same time, typical expansion fasteners produce a radial expansion force, which can pose a danger to the wooden base.
To reduce the pushing force, craftsmen resort to a simple maneuver:
- The wood itself is used as a dowel (propping element);
- The hole for the rod is made only slightly smaller than the diameter of the ridges of its thread.
The design that matches this description is probably familiar to you - it’s... an ordinary screw!
Wood fasteners
Fasteners suitable for connecting wooden structures have several features:
Manufacturing options
The most common types of wood anchors are:
- hex head bolt. It is used for attaching various brackets, plates and other flat and large structures with lugs to wooden bases;
- a stud with a nut, which is screwed in with a wrench (open-end or adjustable);
- a hook that acts as a strong suspension and is suitable for mounting chandeliers, hanging shelves, lanterns, and so on;
- the ring performs the same functions as the hook. Its main distinctive feature is that the ring prevents the suspended product from jumping off it when moving in space (for example, the ring can be used to create a children's swing). To attach a suspended structure to it, threaded or spring carabiners are used.
Installation
How to screw a wood anchor with your own hands so that the fastening is as reliable as possible and the base does not split?
The procedure in this case is not at all different from the technique of screwing in a large diameter screw:
- drill a hole at the mounting point. Its diameter must correspond to the diameter of the fastener along the thread recesses. So, a channel for a 10 mm rod must be made with an 8 mm drill;
- apply a certain amount of liquid or solid soap to the threads for lubrication;
- screw the rod in to its full depth.
Important! The depth of the hole should correspond to the length of the rod. If the depth is less, then the bursting force on the wood will increase sharply, which can lead to the appearance of cracks (if not immediately, then as the structure is used).
Other types of fasteners
In addition to “anchors”, wooden structures can be connected using ordinary bolts, studs, perforated plates and corners.
Bolts
With their help, you can fasten two or more overlapping parts (however, the joined products must be quite thin). This method of fastening is convenient to use when building rafters: two boards are laid overlapping by three of their widths and, through pre-drilled holes, are tightened with two or three fasteners with nuts and wide washers.
Hairpins
The stud is similar, but has the advantage of having nuts on both sides. This fastener design allows you to tighten the fastener without turning the rod. This is convenient if the pin is jammed by the connected parts. In addition, if the rod is long, the force required to rotate it can be very large.
Corners and overlays
Perforated steel plates and angles should not be considered as competitors to anchors.
These types of fasteners complement each other:
using corners, you can join the floor joist boards with beams or crowns without cutting (butt-joint);
plates allow you to connect boards in a similar way when splicing rafters or joists.
Important! To make such a connection reliable, choose a plate with a length of at least five times the width of the board. In addition, to fasten boards with overlays, you should use not “anchors” or self-tapping screws, but bolts with wide washers.
Conclusion
Understanding how to interact with wood different kinds anchors will help you choose the optimal solution to your tasks.
Video: how to install anchors