How to fix anchor bolts

Anchor bolts are one of the main fasteners, without which it is difficult to imagine the process of construction and repair. Without these irreplaceable helpers, it is not possible to erect almost all structures, at the base of which lies concrete or brickwork. From German, the word "anchor" is translated as "anchor", and it is not in vain. The very principle of the work of anchor bolts is built on the fact that, thanks to its design, it seems to keep the hinged structure in the concrete.

Anchor bolts. Fields of application

The history of the anchor bolt has started quite recently. Earlier, wooden cork was used as this fastener. From a piece of wood cut a cork with a large diameter, rather than the dimensions of the screw. Then, in the concrete, a hole was drilled, with a slightly smaller diameter, and a plug was slammed into it, into which, in turn, a screw was screwed. Under its action, the plug expanded and did not drop out of the hole, holding the entire structure.

True, this "anchor" had a lot of flaws. First, wood has not very suitable characteristics for this purpose. Such corks were very often destroyed by moisture in the concrete. In addition, they could not be used for mounting such heavy structures as a suspended ceiling. Secondly, these plugs needed to be made manually, which took a lot of time. Imagine figuring out more than a hundred pieces of such fasteners to make repairs in one room.

To solve these problems, engineers have developed plastic anchors. They were able to remove some of the complexities that the builders had faced before. Such elements have become more accurate in size, easier to assemble, and less susceptible to the harmful effects of the external environment. However, they did not become a panacea. The fact is that plastic can not withstand heavy loads, under which it is usually deformed, which leads to the destruction of the structure.

Almost all problems were solved using metal anchor bolts. Thanks to them it became possible to install on the walls quite heavy structures, such as brackets for air conditioners, satellite dishes, to fasten massive metal doors, cable garters, for which an anchor bolt with a hook is used. For the same purpose, an anchor bolt with a ring can perfectly fit. Due to different configurations of metal anchors, they are multifunctional and suitable for various tasks.

In industry, anchor bolts have been used for a long time. If you look at the power line, you can see that its supports are on a concrete foundation, bolted exactly by these bots. They are exposed according to drawing data and poured with concrete. Then the metal structure is fastened to the anchors. Almost all heavy equipment at large industrial facilities is installed on anchors. Calculation of anchor bolts for such structures is one of the important tasks at the design stage of the facility.

Classification of metal anchors

Speaking of the classification of these fasteners, several categories can be distinguished.

Anchor bolts are distinguished in the way of action into two groups:

1. Chemical anchors. The method of action of this type of fastener is based on the substance, which is encapsulated inside the dowel. When the worker installs the anchor and starts to twist it, the capsule with the adhesive substance breaks and fills the entire hole. Such anchors are indispensable when in the walls or in the slabs on which they are installed there are voids. However, these fasteners have their drawbacks. When installing them, you need to wait a little while before fixing the structure to them.
2. Mechanical anchors. They are more common and popular than chemical ones. The principle of operation of such an anchor is based on the wedging of the metal sleeve, due to the spacer, which moves along the inner surface of the sleeve by threading the stud or bolt.

Depending on the design of the anchor bolts, they are divided into several main groups, distinguished by the principle of action.

1. Wedge. This type of anchor works thanks to a wedge at the end of its sleeve. When it is slammed into the hole, the wedge moves along the inner surface of the sleeve and thereby opens it, so that the anchor bolt is fixed in the hole. In some models of fasteners, the wedge is wedged by inserting a special rod inside, which is then removed and a special pin is placed in its place.
2. Hammered. The fastening of such anchors is due to the specially produced edges of the sleeve. These parts of the fasteners are usually made of soft metal and when the anchor is clogged, they simply wedge, fixing it in the hole. Such a simple construction of the anchor requires a clear compliance with the dimensions of the hole both in length and in diameter. Use this type of fasteners mainly in monolith-concrete or stone. Expanded anchor or butterfly. Such fasteners are used mainly in thin-walled materials. This is an end-to-end anchor with a special sleeve design that has slits in the middle. When the screw of the anchor is twisted, its rear moves along the thread, thereby deforming the sleeve. It opens, forming so-called petals, which press the anchor to the inner surface of the plate. These fasteners are used to fasten structures to plasterboard, plastic or fiberboard. A small weight of anchor bolts of this type, perfectly suited for solving very complex tasks.
3. Spacer anchor. This type of fasteners is the most popular and popular. Such popularity is based on the fact that they do not require the exact depth of the hole to be set. The principle of its work lies in the collet method of expanding the sleeve by moving a cone-shaped bushing over it. Such anchors are used in full brick or concrete.

The material for the production of anchor bolts is high-alloy stainless steels, which are additionally coated with an anti-corrosion coating. An internal bolt or stud is made with a metric thread with a diameter of 6 mm to 30 mm. Qualitative indicators for anchors are the standard for tearing force and cut.

How to install an anchor bolt

This operation does not require special knowledge or skills, and everyone can install such fasteners correctly. On the Internet, it is possible to find a lot of videos on how to fix an anchor bolt. The algorithm for installing an anchor bolt with a nut is as follows:

1. Estimate the condition of the wall. Quite often in houses of old construction, a layer of plaster was applied to the walls, which can not hold the anchor. Therefore, the estimated length of the fastening element must be increased by the thickness of the plaster. That is, if an anchor length of 50 mm is required to mount the bracket and the plaster layer is 20 mm, then the minimum length of the anchor bolts should be 70 mm.
2. We select a drill with a diameter of 0.5 mm less than or equal to the size of the anchor bolt. It is not recommended to drill too large a hole. The fastening sleeve must go into the drilled hole with a little effort.
3. Apply the marking to the surface. Do this as necessary as possible, otherwise after fixing the anchor, it will be impossible to pull it out.
4. Drilling of holes in concrete is performed by a drill or impact drill with a drill with a special carbide tip. Brick better to drill without impact, so as not to damage its structure.
5. The drilled hole must be cleaned of dust with a brush, a vacuum cleaner or a can of compressed air.
6. Next, with light hammer blows, install the anchor sleeve. If this does not work out, do not hit it hard with a hammer, you can spoil everything. Walk one more time with a drill, gently rocking the drill to unfold the hole.
7. Then screw the anchor bolt into the sleeve, then screw the nut onto it. When the nut reaches the sleeve, clamp it with a key.

Fastening with anchor bolts "butterflies" cornices to a false ceiling

If you have a suspended ceiling in your house, then mount the cornice better on a special anchor, the so-called "butterfly".To do this, take the cornice and drill in it holes, diameter equal to the dimensions of the screw dowel. Then on the drilled holes we make marks on the surface of the ceiling. After that, in the ceiling we drill holes, with a diameter equal to the dimensions of the sleeve.

Install the sleeve in the hole and fix it. One of the structural features of such anchors are hooks at the end of the sleeve, thanks to which it clings to the surface and does not scroll. Then take the cornice and fix it to the screws. When the screws are scrolled, the sleeve is deformed and opens, holding the cornice.

Installation of anchor bolts on the foundation

If you need to install metal structures on a concrete foundation, after the base has solidified, drill a hole with a diameter slightly larger than the dimensions of the bolt. Then fill the hole with a special solution and lower the bolt there. After the solution has dried, we set up the metal structure.