How to make expansion joints in concrete floors (structures): device, filling

An essential component of concrete structures and floors are expansion joints. They prolong the life of your concrete work by reducing cracks and mitigating the stress caused by shifting temperatures, movement, and settling. Without them, the expansion and contraction of concrete could result in unsightly or harmful cracks.

We’ll look at how to make and fill expansion joints in concrete floors in this article. We’ll go over how to set up these joints, what kind of materials to fill them with, and the best ways to make sure they function properly. A more stable and long-lasting concrete surface can be achieved by comprehending expansion joints, whether you’re working on a new project or maintaining an existing one.

Main features and need for use

Numerous factors can cause cracks in concrete floors to propagate, which compromises the strength of the building as a whole as well as the coating’s quality and longevity. Shrinkage expansions and the stress they cause can be totally eliminated or at least lessened with the timely and appropriate placement of expansion joints.

Concrete deformation is primarily caused by creep of the material, chemical reactions within the material, shrinkage processes of the floor and building, earthquakes, temperature changes, and variations in air humidity.

• The total area of ​​the screed is more than 40 square meters
• The floor is made of a complex configuration
• Any side of the room in length exceeds 8 meters
• During operation, elevated temperatures and high humidity are observed
• According to SNiP, joints are made: at the joints of the floor, near doorways along the entire perimeter of the walls

1. During concreting – after pouring and grinding, a strip treated with an anti-adhesive composition is mounted in the intended place of the joint, which is then removed after the monolith hardens, the grooves are sealed with a sealant.
2. On a hardened base – the seams are sawed on the hardened floor with special tools, a grinder with diamond discs. Usually, seams are made two to three days after finishing the concrete. When cutting seams, it is important to maintain a constant depth (it should be equal to 30% of the thickness of the screed) and evenness and integrity of the edges.

• Marking the floor surface.
• Checking and setting up equipment.
• Trial seam cutting with quality check.
• Cutting grooves on the remaining area with formation in the same direction in which the filling was performed.
• Sealing seams with sealant.

Types of commonly used seams

Concrete floors, reinforced concrete, and concrete structures all have seams. A variety of seam configurations are used for specific functions and to mitigate certain adverse impacts on the concrete monolith.

Seam spacing

The purpose of expansion joints is to limit and minimize different kinds of stresses in concrete floors. It’s crucial to determine the distance and pattern accurately when executing them. According to the standards, there should be no more than 150 meters—or 90 meters—between the seams in heated prefabricated buildings and monolithic structures. The distance is 20% shorter in the absence of heating.

If not, the lengths are chosen based on the floor’s dimensions, form, and other characteristics. It is advisable to cut them into squares. Typically, they are made in several-meter-squares and are drawn around columns and other structural elements to prevent T-shaped seams and sharp corners. There will be fewer cracks the smaller the seam map.

Independent device of a waterproof expansion joint with a metal profile

A unique metal profile can be used to install expansion joints in concrete floors, which is useful for industrial settings.

• A long plastering rule or cord is used to mark the line for cutting grooves 20-30 cm wide and up to 4 cm deep (corresponds to the height of the metal profile).
• Cutting the seam with a chaser (several at once, followed by cutting out the concrete with a hammer drill, cleaning with a circular grinding machine).

• Carrying out level control using a laser level.
• Filling the bottom of the seam with a layer of hardened polymer concrete, finishing the surface.
• Inserting special bolts into the profiles, installing them in the correct position, connecting two profiles into a single structure with fixation with nuts and connecting elements. The distance between the profiles can be different, it is indicated in the project taking into account the type of expansion joint. Make sure that the lower plane of the profiles lies without distortions in any direction. The profile fits into place without effort. A guide rod and a hole are located at the joints of the profiles, which guarantee the strength of the connection of several elements into one structure. Before joining, the elements can be smeared with high-quality metal glue.

• Fastening the profile with dowels, drilling holes of the required diameter on wide horizontal planes according to the size of the plastic elements of the dowels. The approximate depth of the hole that is drilled should be 2-3 centimeters greater than the length of the dowel, then it will be easier to drive it in.
• Screwing the metal elements of the dowels all the way with an electric drill, checking the quality of fixation. Dowels are attached in increments of 40-50 centimeters.
• Dismantling the installation kit – removing the nuts and metal tie, which is secured with bushings with internal threads. After unscrewing, the bolts do not need to be cut off, since they are located below the upper plane of the profiles and in the future a decorative insert will be attached to them. On the profiles you also need to unscrew the nuts temporarily fixing the bolts.
• Laying an elastic replaceable insert: a roll is rolled out along the profile (starting from the end), pressed into the landing protrusions carefully and until it stops. The insert should lie flat, without gaps or distortions, the remaining piece is cut off with a mounting knife.
• Installation of decorative overlays made of stainless alloy steel (most often used for loaded floors) or aluminum. The ends of the mounting bolts enter the surface of the overlays. Everything is fixed with nuts, the position is adjusted, excluding gaps between adjacent elements. Next, you need to remove the protective film.
• Installation of the protective casing on the profile (it is removed after the coating has hardened).
• Pouring the floor with concrete.

It is essential to properly create expansion joints in concrete structures and floors in order to preserve their integrity over time. You can effectively control the natural expansion and contraction of concrete by carefully planning and installing these joints, averting unsightly cracks and possible damage.

Selecting the appropriate materials and joint placement and filling techniques is part of the process. Every stage, from choosing joint fillers to making sure joints are properly spaced, affects how long-lasting and effective your concrete surface will be overall.

You can increase the lifespan of your concrete structures and make sure they continue to be both aesthetically pleasing and functional by adhering to the installation and maintenance guidelines. You should invest in the long-term health of your concrete structures and floors by having expansion joints installed correctly.

For concrete floors and structures to handle stress and avoid cracking from movement and temperature changes, expansion joints are essential. To guarantee that your concrete surfaces stay strong and intact, this article will walk you through the process of creating these joints, including how to fill and install them correctly. We’ll go over the necessary equipment and methods for a flawless installation, ensuring that your concrete work endures over time.

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