Although concrete is a widely used and versatile material in construction, it is not without its peculiarities. Controlling how concrete expands and contracts in response to temperature changes is one of the main challenges with the material. If you don’t take proper care of it, this can cause cracks and other problems that could weaken the durability and aesthetic appeal of your concrete surfaces. Expansion joints are useful in this situation.
In order to let concrete move naturally without breaking, expansion joints are essential. They help to preserve the structural integrity of your project by establishing a buffer zone where the concrete can freely expand and contract. The longevity of concrete surfaces is greatly increased by the strategic placement of these joints during the building process.
This article will explain expansion joints, explain why they are needed, and show you how to install them. Understanding the function of expansion joints can help you make sure that your concrete holds up over time, whether you’re working on a new construction project or maintaining an existing structure.
| What are expansion joints? | Expansion joints are gaps placed at intervals in concrete to allow for the natural expansion and contraction of the material. |
| Why are they important? | They prevent cracks and other damage by giving the concrete space to expand and contract with temperature changes. |
| How are they installed? | Expansion joints are usually installed by placing flexible material like rubber or foam within the gap during the pouring of the concrete. |
| Where are they used? | Expansion joints are commonly used in large concrete structures like sidewalks, driveways, and buildings. |
| Maintenance tips | Keep expansion joints clean and free of debris to ensure they function properly. Replace any damaged joint material as needed. |
- What is an expansion joint?
- Necessity of the device
- What are expansion joints??
- How they are performed?
- Expansion joint in the screed
- Video on the topic
- How to seal expansion joints in the blind area? | postroy-sam.com
- Expansion joint on the blind area
- Sealing the reduction of volume and deformation of concrete floor joints
- How to make a temperature joint of a blind area
- HOW to properly SEAL expansion joints in a blind area so that they do not tear in the winter.A HOUSE for the price of a ONE-ROOM APARTMENT
What is an expansion joint?
This deliberate breaking apart of a concrete base (floor, wall, roof, etc.) lessens the impact of both internal and external forces (stresses), which causes the concrete monolith to disintegrate and deform uncontrollably throughout its depth. Building performance indicators may decline as a result of these deformations. The compensation section, which is made up of multiple separate pieces, responds to and attenuates variations in the geometry of the concrete slab. These joints play a significant role in guaranteeing the dependability and longevity of constructions.
Necessity of the device
In the context of buildings changing their geometric dimensions due to operating temperature and humidity variations, shrinkage of the frame, and settling of concrete monoliths that are hardening, the structural elements of buildings are interconnected and constantly interact with one another. All of this results in stresses in the nodes of a single structural element, though these changes in element geometry are frequently undetectable to the naked eye. By correcting for variations in the geometric dimensions (expansion, compression, twisting, shearing, bending, etc.) of the material resulting from factors acting on concrete (or in concrete), the creation of cuts encourages the uniform distribution of additional loads (forces, stresses).
Structures are always impacted by loads, but in the absence of expansion joints, these effects include deterioration of the foundation’s properties, the formation of cracks, indications of structural deformation, an increase in internal stresses, a reduction in service life, etc. For instance, the slight dimensional changes caused by heating and cooling of walls result in stresses within the material. The stresses increase with the walls’ larger dimensions.
They are transmitted through a rigidly connected frame to ceilings, beams, stairs, foundations, etc. and cause cracking (in concrete screeds, interior decoration). The integrity of the building’s rigid structure will be immediately threatened by even a slight shift in the wall’s position at the source of stress. Even the frame of the building may be destroyed depending on how long and how strong the impacts are. If temperature cuts are not made in them, movements and seasonal heaving of the soils also show up as a factor in the destruction of blind areas.
What are expansion joints??
The primary characteristic of their classification is the type of loads that the cuts have to offset. They are separated into sedimentary, insulating, and temperature deformation, as well as stationary (conditionally) technological and shrinkage. When a cushion of material that was cast earlier adjoins the edge of a new section of the monolith, technological gaps are created along with disruptions in the concrete working process.
By breaking up the slab, shrinkage cuts lessen the tensile stresses in the hardening material. This makes it easier for cracks to propagate beneath the cut without reaching its surface or for a fracture to occur along the seam. They make up for shrinkage and deformation brought on by uneven moisture loss in the screed’s various sections. Buildings are separated into sections by exterior temperature cuts, which guard against deformations brought on by variations in the temperature of the concrete.
They are frequently used in conjunction with joints, which serve to offset vertical shifts in individual structural components brought on by uneven soil settlement beneath the building. Expansion joints mitigate torsional deformations, transverse and longitudinal stresses on structural elements at the assembly joints. These are created where the floor meets columns, flights of stairs, ramps, curbstones, breaks in the material’s planes, places where screed heights are stepped, etc.
At the intersection of the floor with walls, stairs, columns, etc., insulation joints must be formed. Their job is to stop deformations (such as shrinkage, temperature, etc.) from the structure frame from transferring to the floor screed. This kind of separation stops shock waves from traveling through the screed and back into the premises. To account for the movement of soils and structures in relation to the blind area, expansion joints are created. Load damping is provided by its fragmentation and elastic attachment to the foundation.
How they are performed?
With diamond or abrasive wheels, seams can be formed in two ways:
- installation – when at the pouring stage, the concrete is divided into fragments using damping materials laid throughout the entire depth of the slab (glass, timber, polymer tapes, plastic lining, etc.), which may be removed from the seam or remain in it;
- cutting – when the hardening concrete slab is cut to a fixed depth, and the formed seams are sealed with polymer sealants, mastics, covered with special structures or left unfilled. The pitch (strip width) of cutting is determined as follows: the height of the screed (in cm) is multiplied by the factor “24”. The result is the step of arranging the seams (in cm).
They can only intersect at right angles because they are made to be perfectly straight. In addition, the joints of the cuts shouldn’t in plan form a "T." The figure is made equilateral when the intersection of seams in the shape of a triangle cannot be excluded from the plan. The height of the artificial stone layer determines the minimum joint width, which is 0.6 cm. Cutting wet concrete can be done 12 to 72 hours after laying (depending on the air temperature), but the situation should be disregarded if the concrete has dried completely and the material crumbles at the cut edge.
The sections’ depths range from 1/4 to 1/2 the slab’s height. When the aspect ratio of a given "rectangle" is less than 1:1.5, the indoor floor area—up to 30 m2—is deemed indivisible. Shrinkage joints split large areas into smaller or similar areas. A monolith must have seams crossing it when it is 25 meters or longer in length. Longitudinal seams are created if the hardening material’s paths are three meters or wider.
Slabs exposed to precipitation are cut at intervals of three meters, with a single piece’s maximum area not to exceed nine meters squared. Transverse seams split monoliths of paths (corridors) at up to 6 m intervals (typically twice the width of the material being laid), breaking up L-shaped turns into rectangles (squares). Additionally, slots are used to divide floor coverings of various materials, bases near doorways in rooms, and locations where the screed height varies.
These seams, which include those beneath the parquet flooring, are sealed in the open rather than filled. The floor slabs that encircle the columns must be cut in a square pattern, with the corners situated across from the columns’ flat faces (the square created by the seams is rotated 45 degrees with respect to the columns’ faces). Specialized systems inserted into or applied to the cut bases guarantee their structural integrity. These are seals and profiles made of metal.
Bitumen, sealing compound, or roofing felt are used to fill the wall joints in the blind area. Throughout the full depth of the concrete pour, seams that are perpendicular to the wall cross sections of the blind area that range in length from two to 2.5 meters. A board (perpendicular formwork) is used to create this kind of divider. It is laid on edge with its upper edge aligned with the formwork’s surface. Septic tanks and hot bitumen are used to treat boards with a maximum thickness of 3 cm. Additionally, unique vinyl tapes up to 15 mm thick are utilized. The formwork is then concreted.
For concrete structures to remain durable and intact, expansion joints are essential. They prevent damage or cracks by allowing concrete to expand and contract in response to temperature changes. Extension joints contribute to the prevention of structural problems and the extension of the life of concrete surfaces by mitigating the stresses brought on by temperature variations and ground movement. Anyone working on concrete construction or maintenance projects needs to understand these joints and install them correctly.
Expansion joint in the screed
The area and layout of the room determine the pattern of cuts that separate the screed. The depth of the wall joints is equal to the screed’s total height. They are packed with silicone elastic gaskets that are up to 10 mm thick. Furthermore, the filler slabs are not cut to the full height of the material; rather, they are cut at the level of doorways and corridors. In the same way, it needs to be kept apart from the staircase.
The room is divided into rectangular (square) components with a side no longer than 6 meters if its area exceeds 30 m2 or if it has L-shaped sections. The room’s installed columns are additionally divided by square-shaped incisions made at the base of each column. The cut is made along the edges of the reinforcement frame’s sheets if the screed has reinforcement.
The cuts in the middle of the monolith are typically connected, for instance, to the size of the floor tiles (the seam should go between them). The screed is cut in heated floors at the margins of the heat-generating element fields. The height of the cut dictates its depth, which is further influenced by the existence of floor-mounted heating pipes. In these circumstances, 1/3 to 1/2 of the thickness of the concrete mass is removed.
To sum up, expansion joints are necessary to control the natural expansion and contraction of concrete. By allowing the concrete to settle and shift without putting stress on the surrounding material, they help prevent unsightly cracks and possible structural damage. Including these joints in your design is essential for long-lasting durability, regardless of whether you’re working on a large industrial floor, a sidewalk, or a driveway.
Your concrete project’s longevity and performance can be greatly impacted by selecting the appropriate expansion joint type and installing it correctly. Understanding the unique requirements of your project will help you make the best decision, from flexible materials that absorb movement to more rigid options that offer high strength.
All things considered, taking the time and making the effort to install expansion joints correctly is a small step that will pay off greatly down the road. It enhances the overall safety and structural integrity of your concrete surfaces in addition to helping to preserve their aesthetic appeal. These considerations will guarantee that your concrete projects continue to be both aesthetically pleasing and functional for many years to come.
