Concrete dowels are widely used as a mounting base for the use of screws and anchors. Such elements are classified into types according to the strength of concrete, since the reliability of fastening depends on their quality. The concrete base can be heavy and light (porous), while the latter is characterized by low resistance to compression, and heavy - on the contrary, for this reason it can be under pressure for a long time.
Specifications
The principle of operation of the dowel is similar to a wedge. On the case there are antennae located opposite the reverse stroke, due to this it can not be pulled out after installation in the wall. Final and complete fastening occurs after a screw is inserted into it. Due to wedging, the mount is held securely in the wall for many years.
The material used to make the dowel is dependent on the mass of the object that needs fixing. Plastic concrete dowels are suitable for small structures, for example, furniture. Steel options are used for more impressive objects, their principle of operation is similar to a plastic element.
Area of use
The purpose is to fasten plumbing fixtures, pipelines, electrical equipment. It is necessary to pre-drill a hole of a suitable size, which is noted in the instructions for use, clean from fine dust, only after that the dowel and anchor are inserted.
If necessary, suspend a heavy load on a concrete base using the maximum screw diameter. It is important to observe the ratio of the length of the dowel for a certain operational load and the correct selection of the fasteners themselves, since they must be somewhat longer.
Yesterday and today
Before the invention of such devices, a “cork” of wood was used. It was inserted into a dry hole, either coated with glue, cement mortar or alabaster. This design did not differ in durability and reliability, due to shrinkage of the mortar and drying of the tree.
Currently, high-quality plastic (for example, polyethylene) or steel in combination with load-bearing parts (self-tapping screws, nails and their variations) with a resistant coating that prevents the occurrence of corrosion, or made of stainless steel, is used for the manufacture of a dowel for concrete.
A nail dowel is the easiest option. Unlike standard nails, the screwing method is used to install it.
Classification
According to the method of use, all elements are divided into two groups. Standard dowels are inserted into the drilled (drilled) holes in the base without fixed structures.
Due to the fact that such a technique is used only in two places of installation, due to the mismatch between the holes of the part and the array, frame dowels are produced , suggesting simultaneous development of the base and structure. This eliminates the possibility of mismatch.
Such options have found their application in a wide range of works, but the greatest efficiency is noted in the installation of door and window frames in hollow and solid bodies. Also, due to their use, it is possible to quickly dismantle while maintaining the same appearance of the box.
Conventionally, the building dowel is divided into two groups for use:
- with the anchoring principle of fasteners for multi-hollow and laminated wall structures;
- expandable options for massive walls.
Universal mount
Intends a new system for use in industry and everyday life. It has gained wide distribution due to the distinctive technical properties, high technology and ease of use.
The Hilti Chemical Anchor is used for rod bearing parts for various purposes. Composite material made from synthetic strong resins provides sufficient strength. Among the distinctive characteristics, it is worth noting a significant increase in the level of quality of elements in tension and kink. Chemical properties increase the installation quality of steel products and exceed standard options. These results can be achieved by excellent adhesion of the core and base, with the hardened composition of the synthetic resin.
The Hilti chemical two-element anchor allows fastening of elements with high weight on any concrete and stone planes. A high level of sealing is an added benefit. This plays a special role when operating in high humidity conditions. Some types of bases do not allow the formation of high-quality fastening of metal products using steel or plastic dowels. This applies to loose building materials, among which is natural stone, hollow brick and aerated concrete.
Dowels designed for heavy loads are made of metal alloys and equipped with threaded elements (bolts and studs). They are suitable for installing hoisting hoists, gates for garages, as well as sun awnings. In accordance with safety precautions, metal options must be used to fix the suspended ceiling, since in case of fire the plastic can melt and there is a risk of the ceiling falling.
Elements for porous material can be mounted without drilling holes. The dowel for concrete and brick easily enters the wall with a standard screwdriver due to the large thread on the outside and the tip, which resembles a feather drill.
Butterfly
A characteristic feature is the design. It is a non-abutment element having longitudinal protrusions. The latter are necessary to prevent cranking. There is also a retaining board and folding fixing ribs. The ribs expand the plane of contact with the support, and the side does not fall into the existing hole. This option has become widespread in fixing skirting boards, shelves and lighting elements. The standard sizes of dowels of this type are 14x35 and 5x25 mm.
The expansion bolt shield for foam and aerated concrete
It has high ribs, significantly increasing the area of the connection between the hole and the element. In this case, preliminary manufacturing of holes is required.
Classic nylon dowels for concrete, the price of which starts from 200 rubles per 100 pieces, which are most widely used, allow you to get rid of the main part of the installation difficulties. They are suitable for any wall construction and are used with screws up to 15 mm in size.
The dowel is held in the hole of the corresponding diameter with the help of the antennae facing back, after wedging firmly held by the existing large teeth.
Also, the traditional elements are dowels used for aerated concrete. Holes are drilled for them according to their core diameter. The fasteners are hammered into the hole with a hammer, the base is held by wedging with a screw and the presence of ribs in the form of a spiral.
A distinctive feature of universal dowels is that when fixed to a hollow base, they “calculate” the hollow space. An anchor dowel for concrete expands in the cavity and is fixed in it. When used in a concrete or brick base, after expansion it tightly contacts the walls of the drilled hole.
Features
The proper use of a dowel for concrete requires the selection of suitable drilling, installation equipment. During work, it is important to track the perpendicular direction of the drill to the material, while it is forbidden to use a worn drill or not suitable for a particular base.
The cut hole must be thoroughly cleaned of dust and residual materials. The matching of depth and diameter is important. Drills manufactured to produce solid building materials should not be used on boards and sheets. Work with aerated concrete is characterized by drilling smaller holes, compared with the dowel itself.