Strain joint: prevent distortion of the structure
Temperature changes, humidity, climate in general,seismic and dynamic loads are factors that often lead to deformation of the structure. In order to change the volume of building materials (expansion or contraction due to temperature difference) or subsidence of elements (due to errors in calculating the foundation or insufficient reliability of soils) did not entail the destruction of the entire structure, it is desirable to apply a deformation seam.
Types of expansion joints
Depending on the prevention of what type of deformation is necessary, the seams distinguish between temperature, shrinkage, antiseismic and sedimentary.
The temperature strain joint is used forIn order to prevent horizontal changes. When calculating an industrial building with a framework structure, the seams are placed at least every 60 m for heated and 40 m for unheated buildings. As a rule, temperature seams affect only above-ground structures, while the foundation is less exposed to temperature differences.
Sedimentary strain joint is necessary in order,to prevent the appearance of cracks in the structural elements due to the fact that the load is distributed unevenly or the soils are weak and some elements sag. In contrast to the temperature seam, the sedimentary separates the foundation.
Anti-seismic expansion joints in buildings,located in a zone with increased seismic activity, are practically necessary. At their expense, the building is divided into blocks that are essentially independent of each other, and therefore, in the event of an earthquake, the destruction or deformation of one block will not affect others.
If your construction consists of monolithicreinforced concrete walls, shrinkage joint is necessary. The fact is that concrete has the property of shrinking and shrinking in size - that is, a wall that is flooded directly on the site of construction, and not assembled from reinforced concrete panels, will certainly decrease in volume, forming a gap. For convenience of the further works the shrinkage seam is done before filling of the next wall, and after concrete will dry up, seams and backlashes close up.
Sealing and seam insulation
This aspect is very important to pay special attention toattention: seams should be well protected from external factors. For this, different types of insulation and aggregate are used. Polyurethane or epoxy sealants - a good option: they have high hardness and are not very elastic; another variant -use of polyethylene foam cord withsubsequent sealing with a sealant. Another option is the filling of the expansion joint with mineral wool. A deformation joint in the wall, filled with mineral wool, must be sealed with an elastic mass, resistant to weather conditions and protecting the aggregate from moisture and damp. In addition to aggregates, the seam can be protected with a profile or a bar of suitable size.
The width of the expansion joints varies from 0.3 cmup to 100, depending on the type of joint, as well as the operating conditions of the building. Temperature joints reach 4 cm (narrow), and shrinkage is medium (4-10 cm) and wide (10-100 cm).