Anchor bolt for concrete: types and methods of fastening

Anchor bolts are crucial building materials because they offer sturdy and reliable connections for a variety of structures. The purpose of these bolts is to secure items to concrete, guaranteeing both security and steadiness. Knowing the different types and techniques of anchor bolt fastening is essential for successful projects, whether you’re building a house, installing heavy machinery, or erecting a sign.

Different applications and load requirements call for different kinds of anchor bolts. The three most popular kinds are epoxy anchors, sleeve anchors, and wedge anchors. Because of their strong holding capacity, wedge anchors are frequently employed in heavy-duty applications. Sleeve anchors are common for medium-duty jobs because they are adaptable and simple to install. Conversely, epoxy anchors offer robust adhesion via adhesive substances, making them perfect for crucial situations requiring the highest level of strength.

Anchor bolt installation requires certain techniques to guarantee optimal performance. Typically, the procedure begins with drilling a hole into the concrete, which is then cleaned to remove any debris. Installing an anchor bolt may require hammering, screwing, or using adhesives to hold it in place, depending on the kind of bolt. The effectiveness of the anchor depends on proper installation, thus it’s critical to utilize the right tools and methods and adhere to manufacturer instructions.

Numerous factors, such as the load requirements, the type of structure to be secured, and the environmental conditions, must be taken into consideration when selecting the appropriate anchor bolt and installation method. You can improve the longevity and safety of your construction projects by making well-informed decisions by being aware of the various kinds of anchor bolts and how to fasten them. Whether you work as a professional builder or are a do-it-yourself enthusiast, knowing these fundamentals will help guarantee that your concrete anchors are durable and secure.

What is an anchor for concrete

The term "anchor" refers to a fastener used to secure relatively heavy objects on concrete, natural stone, and brick constructions. Prior to installing such components, a hole that is the proper size to accept the anchor bolt must be prepared.

These fasteners give the high holding capacity of the fastener inserted in such a hole:

  • Frictional forces are provided by expansion anchors;
  • The adhesive properties of a special composition are provided by chemical elements;
  • Special stop elements interacting with the internal surfaces of the hole are used for cellular concrete and hollow bricks.

The most widely used anchor is a fastening component that is pushed inside the hole to guarantee a very reliable connection.

These bolts can be used to secure the following kinds of objects:

  • Metal profiles;
  • Suspended ceiling structures;
  • Chandeliers and various lamps;
  • Wooden bars, which are used in the installation of ceiling and floor coverings;
  • Stair structures;
  • A variety of products with large mass and dimensions.

There are two main methods for fixing the anchor inside the hole:

  1. By wedging the spacer sleeve inside the hole.
  2. Using a special adhesive composition that binds the surface of the bolt and the inner wall of the hole.

Technical characteristics

The main component of the structure is a stud, and its technical properties and load-bearing capacity are determined by the features of an anchor bolt with a nut. Its lower portion is shaped like a cone, and a nut is screwed onto the threaded portion at the top.

The sleeve, which has longitudinal slots on its side surface that resemble petals, is the second most significant component of the design. When the sleeve is placed on the stud, only the top portion—which houses the product’s nut—remains open.

The anchor bolt with nut works on the following principle:

  • When tightening the nut, which is placed in the hole of the anchor bolt, the stud begins to be drawn into the hole of the sleeve;
  • The conical end of the part unclenches the petals;
  • High reliability of fixing the bolt in a pre-prepared hole is ensured by the expansion sleeve, made by casting and having no welds on the surface that can weaken its design.

Advice: A lock washer needs to be placed on the stud’s thread to stop the nut from going all the way down into the hole.

Every concrete anchor bolt has a designation with its dimensions expressed in millimeters, such as 8 × 10 × 50, where:

  • 8 is the thread size;
  • 10 ​​is the diameter;
  • 50 — product length.

For concrete anchor bolts, specifications have been established regarding their dimensions.

  • The diameters of the flat part of the stud are from 6 mm to 24 mm;
  • Thread diameter, from M5 to M20;
  • Product length, from 18 mm to 400 mm.

Additional technical features of bolts consist of:

  • The force that pulls the anchor out of concrete is from 10.5 kN to 18.3 kN. In this case, the extension of a part of the product may not cause damage to the structure, or completely destroy the connection;
  • Torque – from 10 Nm to 40 Nm;
  • Bending moment – from 5.2 Nm to 25.7 Nm.

Advice: Pay attention to these indicators when choosing an anchor bolt for concrete. The products will be dependable if they do not surpass the aforementioned values.

Non-standard anchors are also acceptable if they are required for the object’s structural integrity. In this instance, specific SNiPs must be followed in the part’s design. Products are covered with zinc to prevent rust and damage.

In order to secure structures to concrete and ensure stability and safety, anchor bolts are necessary. Different applications and load requirements call for different kinds of anchor bolts, such as epoxy anchors, sleeve anchors, and expansion bolts. These bolts can be secured using a variety of techniques, including adhesive compounds and drilling and inserting. The integrity of any concrete-based construction depends on knowing the proper kind of anchor bolt and fastening technique, which offers dependable and durable support for structures, equipment, and other installations.

Types of fasteners

Concrete anchor bolts come in a variety of forms, and each has a distinct function.

The following table displays fastener features and photos:

A hole is drilled for its installation prior to its installation. The primary distinction with the screw is that it can be fastened without a jacket. A tiny wedge that expands when screwed in is located in the center of the sleeve.

Apart from the types mentioned above, there are products like:

Selection of an anchor

These bolts are widely used because they come in a variety of types that vary in size and ability to withstand loads in addition to type. A table showing how the anchor diameter depends on the load applied to it is shown below.

In actuality, anchors are typically chosen based on higher maximum allowable load indicators than those found in official regulatory documentation.

Since January 1982, this kind of fastener has been produced in accordance with the state standard GOST 24379.1-80. The document lays out the fundamental specifications for the materials that are used to make each part, as well as any allowed deviations from the standard for the primary dimensions.

The weight of the structure it is attached to should be your primary consideration when selecting a concrete bolt size; the higher this indicator, the longer and larger the diameter of the anchor should be. The thickness of the surface that the anchor will be installed into must also be considered. Otherwise, if the length is selected poorly, it may pierce the floors or walls completely.

You must choose the diameter of the pre-drilled hole for the anchor precisely in order to install it. You can choose the hole’s diameter for the fastener installation from the table:

Advice: Don’t go over the holes that are required when fastening parts according to the table. If not, substantial spaces will need to be filled with mortar, which could weaken the bond.

Rules for installing an anchor with a nut

If errors were committed during installation, then even the most carefully chosen anchor bolt and nut will not guarantee dependable fastening of an object. Anchor bolt fastening in concrete is guaranteed to be dependable and long-lasting when a few basic guidelines are followed.

The following steps are recommended by the instructions to install an anchor with a nut:

  • Drill the required hole on the surface for fastening the object. The diameter of the hole for the expansion sleeve should be such that the sleeve enters it with a slight tension. This is done with a hammer drill and a drill of the appropriate size;
  • The hole is thoroughly cleaned of construction dust, crumbling material. If the hole is small, this can be done with a regular medical bulb and a brush of the required diameter. In the case of a long and large diameter drilled hole, high-quality cleaning is obtained using a vacuum cleaner;
  • After preparing the hole, insert the anchor bolt;
  • Tighten the nut until the expansion sleeve securely fixes the fastener;
  • After securely fixing the anchor in the hole, the nut can be unscrewed, leaving the threaded end free to install the fixed object;
  • Put on the washer and screw on the nut.
Type of Anchor Bolt Methods of Fastening
Expansion Bolts Inserted into a drilled hole, then expanded by tightening the bolt.
Wedge Anchors Placed into a pre-drilled hole, wedge is pulled up by tightening to secure the bolt.
Sleeve Anchors Inserted into a hole, sleeve expands as the bolt is tightened, securing it in place.
Drop-In Anchors Placed in a drilled hole, internal plug is driven down to expand the anchor.
Concrete Screws Screwed directly into a pre-drilled hole in the concrete.

In order to fasten machinery and structures to concrete surfaces, anchor bolts are necessary. They are available in a variety of varieties, each appropriate for a particular application and load level. The most popular kinds are chemical, mechanical expansion, and cast-in-place anchors; each has special benefits and installation techniques.

Strong, long-lasting support is provided by cast-in-place anchors, which are inserted into concrete prior to it hardening. Mechanical expansion anchors, like sleeve and wedge anchors, expand inside the concrete hole they drill and provide strong holding power that can be used in a variety of situations. Chemical anchors, particularly in critical structural applications, offer flexibility and a high load-bearing capacity by using adhesives to bond the bolt to the concrete.

For stability and safety, selecting the appropriate anchor bolt and installation technique is essential. It is necessary to take into account variables including load requirements, environmental factors, and application-specific requirements. The maximum performance and durability of the anchoring system are ensured by using proper installation techniques, which include accurate drilling, hole cleaning, and adhering to the manufacturer’s instructions.

Making informed decisions for building and renovation projects is facilitated by having a thorough understanding of the types and techniques of anchor bolt fastening to concrete. Making the right choice when choosing an anchor bolt guarantees a dependable and durable attachment to concrete surfaces, whether it is used to fasten large machinery, structural components, or other fixtures.

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Anna Vasilieva

Journalist with a technical education, specializing in construction topics. I can explain complex technical topics in simple and accessible language.

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