Temperature changes, humidity, the climate as a whole, seismic and dynamic loads are factors that often lead to structural deformation. So that changes in the volume of building materials (expansion or contraction due to temperature differences) or subsidence of elements (due to errors in the calculation of the foundation or insufficient reliability of the soil) do not entail the destruction of the entire structure, it is advisable to use a deformation seam.
Types of expansion jointsDepending on what type of deformation is necessary to prevent, the seams distinguish between temperature, shrink, anti-seismic and sedimentary.
A temperature expansion joint is used to prevent horizontal changes. When calculating an industrial building with a frame structure, the seams are placed at least every 60 m for unheated buildings and 40 m for unheated buildings. As a rule, expansion joints affect only above-ground structures, while the foundation is less affected by temperature differences.
A sedimentary expansion joint is necessary in order to prevent the appearance of cracks in structural elements as a result of the fact that the load is distributed unevenly or the soils are weak and some elements sag. In contrast to the temperature joint, sedimentary divides the foundation as well.
Antiseismic expansion joints in buildings located in an area with increased seismic activity are practically necessary. At their expense, the building is divided into blocks, essentially independent of each other, and therefore in the event of an earthquake, the destruction or deformation of one block will not affect the others.
If your structure consists of monolithic reinforced concrete walls, a shrinkable expansion joint is necessary. The fact is that concrete has the property of shrinking and decreasing in size - that is, a wall poured directly at the construction site, and not assembled from reinforced concrete panels, will certainly decrease in volume, forming a gap. For the convenience of further work, a shrink joint is made before filling the next wall, and after the concrete dries, the joints and gaps are closed.
Sealing and insulating joints
It is very important to pay particular attention to this aspect: the seams must be well protected from external factors. For this, various types of insulation and aggregate are used. Polyurethane or epoxy sealants are a good option: they have high hardness and are not very elastic; another variant -
the use of a polyethylene foam cord followed by sealing with a sealant. Another option is to fill the expansion joint with
mineral wool. And the expansion joint in the wall, filled with mineral wool, must be repaired with an elastic mass that is weather resistant and protects the aggregate from moisture and moisture. In addition to the fillers, the seam can be protected with a profile or strap of suitable size.
Suture Dimensions
The width of expansion joints varies from 0.3 cm to 100, depending on the type of joint, as well as the operating conditions of the building. Temperature joints reach 4 cm (narrow), and shrink joints are medium (4-10 cm) and wide (10-100 cm).