Why the curtain wall "permeate pollution"! Sealant must be selected right!

In this issue, we will discuss the pollution problem of curtain wall. We may see the situation as shown in the figure below on some building curtain walls: some "marks" and "flow marks" appear on both sides of the sealant, and some areas are very large. What are the causes of these pollution? Is it because of improper selection of sealant? How to solve and prevent?

The curtain wall, as the outer protection structure of the building, not only has the functions of sound insulation, heat insulation and rainproof, but also has good decorative properties, so that the whole building can achieve beautiful appearance. With the development of curtain wall materials, architects can achieve the architectural decoration effect that is difficult to achieve before through the design of building curtain wall. However, if the curtain wall has serious pollution, it not only fails to achieve the expected aesthetic effect, but also may seriously affect the overall aesthetic appearance of the building.

In actual engineering cases, no matter it is stone curtain wall, aluminum plate curtain wall, aluminum plastic plate curtain wall or even glass curtain wall, curtain wall pollution is likely to appear. The forms of curtain wall pollution can be divided into the following two categories: permeation pollution and vertical flow pollution. These two forms of pollution have similar places, but the causes and solutions are not the same, this issue Baiyun online to introduce the relevant content of infiltration pollution.

1, the performance of infiltration pollution

Permeable contamination is similar to the surface discoloration of the panel material caused by the infiltration of oily substances into the panel material in contact with the glue joint. This phenomenon generally occurs in the adjacent glue joint of the panel material, more commonly seen in the stone curtain wall. In addition, porous curtain wall materials such as ceramic board and fiber cement board also have the phenomenon of seepage pollution. The case is the completion of the project soon, it was found that there is infiltration pollution, through close observation, we can see that the panel material in contact with the glue joint due to the infiltration of oil and appear obvious discoloration.

An international convention and exhibition center is located on the seashore. The design party integrates the Marine design elements, and the whole building presents the shape of "white shell". In order to achieve the design effect, the panel material is white GRC plate, and the joint seal is made of a brand of sealant. When completed, it was very beautiful, but the good times did not last long. Because there was no anti-pollution sealant, a few months later, there was obvious infiltration pollution.

In addition, some curtain wall projects use the surface coated aluminum plate, aluminum plastic plate and other decorative materials, also have penetration pollution, individual oil in the surface of the panel material coating penetration spread, pollution area is large, pollution phenomenon is very obvious, serious impact on the appearance of curtain wall.

2. Cause analysis, prevention and solution of seepage pollution

1) for stone, ceramic plate and other porous panel material seepage pollution, mainly because the panel material and joint sealant contact, the plasticizer and other small molecules in the sealant will infiltrate into the interior of the porous material, resulting in the discoloration of the panel around the glue seam, the formation of seepage pollution.

Once the seepage pollution of stone, ceramic plate and other porous panel materials can not be eliminated, in order to control the further spread of pollution, the usual method is to get rid of the pollution source as soon as possible -- the joint sealant that causes pollution is cut off as soon as possible, and the special stone sealant that is free of pollution is used for re-injection construction.

For this kind of problem, we once again remind users: stone curtain wall and other porous plate joint sealant must use special stone sealant, and the product should meet the national standard GB/T 23261 "stone building sealant". Sealant products of some manufacturers on the market claim to be stone sealant, but actually do not meet the national standard GB/T 23261 "stone building sealant". At present, there is still a considerable part of the sealant filled with mineral oil on the market. Due to the chemical composition difference between mineral oil and silicone polymer, the sealant may migrate out of the colloid within a short time after use, and penetrate into the interior of porous materials, forming infiltration pollution. This kind of sealant products can not be used for stone and other porous plate joint sealing.

2) for the surface coated aluminum plate, aluminum plastic plate and other decorative materials penetration pollution, mainly because of the poor aging resistance of the surface coating, coating aging after loose, powder, the plasticizer in the sealant penetrated into the aging coating, the formation of penetration and diffusion on the surface of the coating. This infiltration pollution on light-colored aluminum panels, aluminum plastic panels or other light-colored decorative materials will be more obvious than the corresponding dark materials, so more attention should be paid when using them.

Sealant plasticizer diffusion to powder coating pollution is difficult to clean. In view of this kind of infiltration pollution, the general treatment method is to repaint and renovate the face plate.

For this kind of problem, we suggest that the user: when choosing the curtain wall panel material, the panel material with good aging resistance should be selected; For the panel material with surface coating, the surface coating should also have good aging resistance. Especially for light-colored aluminum plate, aluminum-plastic plate or other light-colored decorative materials, the durability of surface coating and the anti-pollution of sealant should be put forward higher requirements. Before use, the customer shall confirm the durability of the panel material and surface coating with the material supplier, and send the material to the sealant manufacturer or the relevant third party to test the compatibility and contamination of the sealant with the material.

If the aluminum plate coating may become loose and powdered after aging, it is recommended to choose anti-pollution silicone weathering sealant.

Curtain wall infiltration pollution is caused by the performance of sealant, the material of the panel or the performance of the surface coating. Next time, we will continue to introduce another form of curtain wall pollution -- the expression of vertical flow pollution, cause analysis and corresponding prevention and solution, please pay attention!