The expansion joint in concrete is a necessary component of this type of construction. They should be done for the reason that when the concrete hardens, and then with a temperature difference and a change in the level of humidity, the concrete slab contracts or expands. If there is no expansion joint, then due to the appearance of internal stresses, various structural deformations and cracks can occur, which reduces strength and durability. Thanks to such solutions, it is possible to evenly distribute the emerging additional loads, preventing deformation processes.
The expansion joint is made when creating buildings of any type, bridges and sidewalks. Over time, it can become clogged with dust or stones, which is why it will not perform the protective functions assigned to it. For this reason, periodic cleaning of the joints should be carried out. It is possible to close expansion joints in concrete using special elastic materials that protect them from contamination, but this will not affect their properties. Before concrete is poured, expansion coefficient calculations are usually made.surface, determine the width and length of the seams, as well as the distance between them.
When cutting the expansion joint, you must be guided by certain recommendations:
- Perform the procedure in a timely manner. From a technological point of view, cutting them into fresh concrete immediately after the surface has been sanded can be called the right solution. If the work is carried out much later, that is, when the material hardens, then cracks may appear along the edges, worsening the spatial characteristics of the material. That is why it is recommended to cut the seams 12 hours after pouring or a day later if the work was carried out at a low temperature.
- The expansion joint in the building must have a design depth that fluctuates between one third and one quarter of the entire thickness of the resulting screed.
- Cutting must be done with the obligatory observance of the interval.
- The cut mesh should not contain internal seams, since cracking occurs first in the internal corners.
- Shrinkage joints should not cross in a T-shape, as such a connection often causes cracks to form across the resulting seam.
- There should not be areas with triangular corners on the mesh, since deformations most often begin at the ends of sharp corners. If it was not possible to avoid a triangular shape, then the figure should be made equilateral.
Expansion jointdesigned to protect walls from cracking during thermal deformations. It can be judged from the following data how large such deformations are: a stone building, which at a temperature level of +20 degrees has a length of 20 meters, at a temperature of -20 degrees becomes 10 millimeters shorter. Perform a seam in the form of a tongue, the depth of which should be approximately 5-10 millimeters.
