For reinforced concrete structures to remain structurally sound and long-lasting, expansion joints are essential. Without them, structures such as buildings and other constructions may be vulnerable to environmental factors like temperature changes and cracking.
Expansion joints provide controlled movement in both monolithic and prefabricated structures, lowering the possibility of structural issues. Precise planning and installation are necessary for this process to guarantee durability and efficacy.
This article will guide you through the steps of creating expansion joints in reinforced concrete, whether you are working on a large-scale project or a smaller construction task. Understanding these techniques will help you maintain the strength and safety of your structures.
For reinforced concrete monolithic and prefabricated structures, the creation of an efficient expansion joint is essential to avoiding damage and cracks brought on by temperature fluctuations and structural movement. To accommodate the concrete’s natural expansion and contraction, joints must be thoughtfully planned and placed at key points. Your concrete structures will last longer and be more durable if you know how to make these joints and what materials work best for them.
- What is an expansion joint
- The largest distances between expansion joints in reinforced concrete structures
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What is an expansion joint
Expansion joints are designed by the project to split the building structure into pieces in the horizontal (vertical) plane, allowing for the redistributing of stress in specific areas of the supporting frame. The geometric dimensions, position, and properties of reinforced concrete may alter significantly if this stress is not removed.
The buildings can be given the design value of elastic mobility because of the seams. Depending on the kind of stress they are intended to offset, expansion joints can be classified as seismic, sedimentary, structural, shrinkage joints, or temperature joints.
The structure is split into independent blocks when an expansion joint is created, giving the monolith flexibility and the capacity to support heavy loads without deforming. A unique insulating material that is flexible and resistant to different impacts is used to seal the joints.
When it comes to monolithic reinforced concrete, an expansion joint is essentially a surface cut that separates the structure into blocks of a specific size. Every joint is intended to carry out a specific function. In reinforced concrete screeds, a shrinkage joint is incorporated to stop surface cracks from developing as the concrete gradually hardens and gains strength.
In this instance, there is no room for even slight rounding or turning—the seams are made straight. The depth, screed width, and site type (closed/open) all directly affect how far apart they are from one another.
Buildings can use combinations of various types of joints because of their unique location and structural characteristics, which can protect against multiple potential causes of deformation at the same time. This method is particularly useful when building tall, multistory structures with a lot of distinct components and structures.
– most frequently utilized in structures with varying floor counts (one wing of a building having two floors, the other having three, etc.). It turns out that the ground is unevenly compressed by the building’s various parts, which presses against the walls and foundation and results in cracks. A sedimentary expansion joint fortifies the framework and guards against deterioration. Vertically, from the base to the roof, it is executed. fixes various building components. A sealant needs to be applied to the joints.
- Placing parts of the structure on soil with different properties
- When making extensions to an existing building
- If individual parts of the structure have a height difference of more than 10 meters
- All cases in which uneven foundation subsidence can be expected
The largest distances between expansion joints in reinforced concrete structures
For standard-type structures with crack resistance of the third category with stressed/non-stressed products, shrinkage and temperature indicators are not calculated as long as the joint spacing is less than the permitted limits. Both vertical and horizontal expansion joints are possible.
- For frame structures made of wood and metal – 40 meters for external buildings, 60 meters for heated
- Prefabricated solid structures – 30 meters for unheated buildings and 50 meters for heated ones
- Monolithic frame structures made of heavy grades of concrete – 30 and 50 meters, respectively
- Monolithic frame structures made of lightweight concrete – 25 and 40 meters, respectively
- Monolithic buildings made of solid compositions – 25 meters for unheated premises and 40 for heated ones
- Cellular concrete – 20 and 30 meters, respectively
The distance between joints in a one-story reinforced frame building can be increased by 20% on average in comparison to the values listed in the table. When constructing vertical connections in the middle of a divided block in frame buildings, the tabular data can be utilized. These connections are positioned along the block’s edges and, when subjected to deformations, bring the frame’s operation more in line with a comparable solid structure.
- They are performed in all buildings with crack resistance of the first and second categories.
- They run along the entire height of the building, due to which deformation in individual areas of the structure occurs freely. The seams can run from the top of the foundation to the beginning of the roof, dividing the walls and all the floors.
- The width of a standard seam is 2-3 centimeters, the seam is filled with tow soaked in roofing felt or resin, several layers of roofing felt, sealant.
- Installation of paired beams on 2 columns guarantees the correct expansion joint in prefabricated and monolithic structures. In frame buildings, it is comfortable when serious and dynamic loads appear on the floors.
- A settlement seam is needed when the building is at different heights or ground.
- A temperature-shrinkage seam is needed when connecting a new extension to an old structure.
- Expanding pairs of columns with support on individual foundations, as well as installing counter beam consoles make it possible to make a high-quality expansion joint. Also, often between the individual parts of the building, the deposit is made from the slabs and beams.
- In monolithic buildings, the shrinkage joint is formed as follows: from one part of the structure, the end of the beam rests freely on the console; it is a continuation of the crossbar of another part of the structure. Elements that touch are connected carefully to avoid friction that destroys the consoles.
Expansion Joint Type | Description |
Monolithic Structures | Create joints during concrete pouring by inserting joint strips or foam, allowing for movement and preventing cracks. |
Prefabricated Structures | Install joints between prefabricated elements, using sealants or rubber strips to absorb movement and ensure flexibility. |
When it comes to preserving the longevity and structural integrity of reinforced concrete structures, expansion joints are essential. They aid in preventing cracks and structural damage by permitting movement brought on by variations in temperature, shrinkage, and other circumstances.
Careful planning and execution are necessary to create effective expansion joints in both monolithic and prefabricated structures. This entails picking the appropriate materials, figuring out the ideal joint spacing, and making sure the right installation methods are used.
To make sure expansion joints keep working as intended, regular upkeep and inspection are necessary. Promptly addressing any issues can help prevent more serious issues later on, maintaining the longevity and safety of the structure.
Builders can improve the resilience and performance of reinforced concrete structures and make sure they endure over time by comprehending and applying the principles of expansion joint construction.