Waterproofing of the expansion joint in underground structures

Underground or buried car parks, as well as other structures of this type, are subject to deformations that can occur with fluctuations in the temperature of the outside air, as well as in uneven ground sediments. Deformations are also obtained for seismic and other phenomena. Under the influence of the above factors, there may arise own stresses, which cause the appearance of cracks in the structures. They reduce the bearing capacity and lead to the fact that the layer of waterproofing loses its integrity.

In order to exclude and prevent this phenomenon, in the enclosing and supporting structures of underground structures there must be deformation seams. They reduce bending loads at the points of greatest deformation, in addition, similar phenomena due to the seams are not dangerous.

Solution

Waterproofing of the expansion joint should be carried out after choosing the technology of work. Due to the fact that the loads on such structures are very high, as for transverse and longitudinal directions, the expansion joints in underground structures must differ from those that exist in other parts of the structures. Quite often it is necessary to use an integrated approach that involves several systems, as a result of which the layer of waterproofing shows the qualities of reliability and durability. Today, several methods are known for the construction of such seams, which depend on the width of the seam, deformations and technology of waterproofing structures. Before choosing a solution it is necessary to familiarize yourself with all possible options, considering their disadvantages and advantages.

Use of sealants

Waterproofing of the expansion joint can be carried out with the help of sealants, which are applied after the completion of monolithic works. This option involves filling the seam with a two-component composition that has the qualities of high adhesion to concrete. In the role of a substrate for fixing the sealant layer, a sealant is used, its width should correspond to the size of the seam.

The nodes of the waterproofing of expansion joints can be easily secured by this method, which is the simplest, but has some limitations on the work. They are expressed in a small width of the seam, which does not exceed 30 mm, while its deformability should not be more than 15%. Among other things, the structures constructed in this way should not experience a constant pressure of groundwater.

In order to waterproof such a deformation seam, which will be used under the influence of the groundwater head, in addition to this method, a protective cover-compensator, which is made of 0.5-mm stainless steel sheet, should be used.

Using a flexible membrane

When it is necessary to waterproof the expansion joint, you can increase its width, and then use a flexible membrane. As it may act "Lastina C". Its installation is carried out by the method of fastening with metal clamping bars to the edges of concrete. Preliminarily the surface is treated with a sealant, which has a high adhesivity.

The disadvantage of this method is that it can not be used in structures that are constantly exposed to the pressure of groundwater. If such conditions are met, then in addition to the membrane, you can use a protective casing-compensator, which is made of stainless metal. In the role of the main waterproofing for the two above-mentioned systems, penetrating action materials can be used. They are applied to the surface of concrete and make it waterproof. The lack of such waterproofing is expressed in the fact that in the formation of cracks the structure can lose the integrity of the waterproofing, which causes the penetration of water into the structure.

Application of embedded elements

Waterproofing of the expansion joint can be carried out with the help of embedded elements, which have the form of PVC or rubber profiles. At the same time, a waterproofing key is laid, which is made at the time of the execution of monolithic concrete work. In the course of such manipulations, special inserts must be mounted in the formwork, with the help of them after the pouring of concrete it will be possible to form a deformation seam, concreted with a hydrofoil, it will be inside the ceiling or wall.

Hydropods are made of different materials, for example PVC or rubber. They have different forms and methods of installation in a monolithic construction. When the waterproofing of expansion joints is carried out by this method, it should be taken into account that the indices in the different types of keys in the directions of tension, compression, longitudinal and transverse shear, and water pressure can be different. Everything will depend on the alleged deformation, which will determine the type of key. In addition to waterproofing, special concrete grades are used that have waterproof properties. As an alternative solution, waterproofing can be used, which is based on membranes for underground structures.

Use of the deposited material

Waterproofing of expansion joints from the inside can be carried out with the help of polymeric bituminous material, which is laid according to the method of fusing. Among other things, a sealing harness is used. This system is installed after the completion of monolithic concrete work. A weldable material that does not have a base has a transverse and longitudinal elongation coefficient of 1000%. This indicates that the waterproofing can stretch 10 times.

Due to the fact that the material is supplied in rolls with widths ranging from 330 to 1000 mm, it can be used for any kinds of expansion joints. It can be seams at the joints of vertical and horizontal slabs, in the field of angular expansion joints and seams of complex configuration. The deposited material is installed using a gas burner. When such a waterproofing of expansion joints is used in underground structures, the size change can reach 50 mm without restrictions. If this value is exceeded, then a complex should be used, which involves the use of injection systems.

The use of waterproofing "Neodil"

The device of waterproofing of expansion joints with the help of the Neodil system provides for the fusion of the material onto the lining of the coating. Further, the bundle is sealed and the deposited topcoat is protected. When laying it is necessary to take into account the thermal stability of bitumen, which is 100 ° C. The system comes into operation if the main waterproofing of the seam is damaged.

In the seam of pre-installed pipes under pressure, a special sealant must be applied, which penetrates into the seam cavity and makes it completely hermetic. For the system in the role of the main waterproofing polymer-bitumen membrane "Tegapar 431 TR", which is resistant to aggressive media, is easy to install and has large dimensions.

Features of the use of a waterstarter

Waterproofing of expansion joints in underground structures, the nodes of which can consist of a special key, has the form of a tape installed in the formwork at the stage when the monolith should be poured in pieces. This makes it possible to obtain movable deformation seams. In the hydrostar, there are several special cavities and beads, through which the element is easy to install and guarantees reliability, as well as the plasticity of the joints.

Technology of application of polyurethane sealant

Waterproofing of expansion joints from the inside, as mentioned above, can be carried out with the help of polyurethane sealant. To do this, they should be cleaned from the old waterproofing, dust and detritus of concrete, lay a bundle of foamed polyethylene. It is required to reduce the consumption of sealant. The inner surface is treated with a primer to improve adhesion. Using a spatula or a pistol, the sealant is placed in the cavity of the expansion joint.

Conclusion

In order to ensure that the nodes of the waterproofing of the expansion joints are maximally reliable, when filling them with sealant, the surface must be smoothed with a spatula using soapy water until it is possible to get a smooth base. It is important to remember that the laid tourniquet should be greater than the width of the seam by 10 mm.