Analysis of the problem of waterproof sealing of MS glue building

1. It is not recommended that silicone sealants be used for
sealing seals on building facades
Silicone building sealants (commonly known as silicone sealants) are a widely used material in silicone polymeric materials that can be cured into elastic rubber at room temperature without heating, lighting or other auxiliary conditions, and are very convenient to use, except with general organic Silicone materials resistant to high and low temperature, climate aging, high electrical insulation and other excellent characteristics, but also has a variety of substrate bonding good, strong resistance to change and so on, developed countries in Europe and the United States in the 1960s developed silicone sealant products for the construction industry, because of its aluminum alloy and glass has excellent bonding, mainly used in glass curtain walls, doors and windows and other industries. Since the 1990s, China's silicone sealant industry with the rise of the construction industry and rapid development, in the competition with polysulfur, polyurethane glue, acrylic gum, etc., with its excellent comprehensive performance and cost-effective, access to the majority of the market share.
With the rise of assembly buildings in China, traditional building sealant enterprises are also actively promoting products, but for silicone glue in assembly building applications, especially the assembly of external wall panels fill seal, there are

.
in the choice of building sealants, in neighbouring Japan, which has a longer history of assembly construction, there is a "fit for play" theory, that is, according to the characteristics of different materials to choose the most suitable application site. For the sealant of the assembled exterior wall plate, it is recommended to use "silane modified sealant".
MS sealant, is the silane functional group modified to a specific polymer end, cured body structure remains unchanged, still retains the original structure of excellent performance, but the way of curing crosslinking has changed. The curing cross-line thermodyscope of MS sealants is similar to silicone sealants: the silicone group at the end of the polymer reacts cross-linkedly under the action of moisture, but the difference is that the curing of MS sealants does not require a catalyst, and the silicone hydroxyl and alkyl produced by alkyl hydrolyzing react to shrink, removing low-molecular alcohols, and finally forming an interoperability network structure of Si-O-Si crosslinking as the reaction continues. In the whole curing process of MS sealant, only small molecules of alcohol are released, which will not cause harm to human body and belong to the environmentally friendly curing system.
since its successful development in the 1980s, MS sealant products have been used successfully in Japan for more than 30 years, especially in the filling seals of assembled buildings. At the same time, because in the case of dry hanging stone curtain wall often occur due to plasticizer infiltration and adsorption of dust caused by the pollution phenomenon, so that silicone sealant in the same porous type of concrete prefabriated exterior wall plate application has been questioned, coupled with the low surface energy characteristics of silicone sealant, the coating can not be spread on its surface, (shear strength is small) so not recommended for use in the assembly wall board.
2. Two-component and single-component silane modified sealants, which
is more suitable for sealing the exterior wall panels of
buildings?
two-component silane modified sealant, is a need to 4.4kg A component master agent and 400g B component curing agent, in the construction site using a special small mixing equipment mixed evenly, with a special glue gun pumping and then extruding glue construction modified sealant. According to the usual domestic adhesive habits, in the convenience of use slightly less than conventional single-component sealants, but in Japan for many years of assembly-type construction practice, applied to prefabribriated exterior wall panels more than 90% of the silane modified sealants are two-component products. Domestic such as Vanke and other assembly construction industry pioneers, has been in its assembly projects using two-component modified sealant products. Why is that?
, if the two-part product can master the operation of the key, the actual efficiency is very high and can avoid waste. Such as Japan's professional glue workers after many years of practice and experience, the construction of two-group products has a set of standard operating methods, high quality, fast speed. On the other hand, the hot-pressure cold pull test in Japan's JISA 5758-2004 Building Sealing Materials standard simulates the actual use of assembly building sealants, i.e. compression of 30% at 90 degrees C and stretching 30% at temperatures of -10 degrees C, and experiencing 2000 cycles can still guarantee non-destruction and maintain elastic resilience. "9030" standard is an important basis for determining excellent assembly building sealants, usually two-component silane modified sealants on this standard pass rate is much higher than single components. Moreover, the two-component adhesive can be quickly cured to avoid the single-component colloid due to maintenance and curing period seam repeated displacement changes, resulting in internal defects of the colloid, thereby reducing the risk of colloidal cracking or de-sticking, which is also one of the outstanding advantages of the two-component silane modified sealant.
3. The problem of coating cracking at the seam site
Professional industrial production has controlled the dimensional accuracy of the assembly exterior wall plate in the "mm" level, but under the influence of various comprehensive factors, the overall accuracy of the lifting wall plate seams still belongs to the "cm" level, the upper and lower floors of the outer wall seam spacing 1 to 3 cm phenomenon is very common, if the outer wall plate sealing glue to form the facade line, it is inevitable that the upper and lower adjacent plates do not affect the beauty. Therefore, in order to ensure that the entire facade glue lines from top to bottom straight effect, generally will use the first hit the outer wall sealant, after painting the outer wall paint, with the way of coating cover to form a straight separation line, which inevitably appears the paint cover on the sealant situation.
and the usual exterior coating, due to its own lack of elasticity, in the face of sealant telescopic changes, can not keep pace with the sealant, it is easy to crack the skin. Here, we recommend the use of silicone elastic exterior coating, which is a silicone material as a film material, prepared by a special process of excellent anti-aging performance of the coating, especially with the outer wall plate sealant the same displacement capacity, elasticity is very good, can fundamentally solve the construction of the exterior wall, especially the assembly building of the plastic seam position of the paint cracking problem.
4. There are many factors that affect the effectiveness of the waterproof seal
the outer wall and need to be considered comprehensively.
the processing and construction accuracy of prefabribribribried wall panels, sometimes directly affect the effect of waterproof sealing of external walls. For example, the outer wall plate manufacturing has leakage, lack of slurry, or site installation accuracy deviation, the need for late slit or repair processing, may lead to the same gap in different positions wide and narrow, to fill the foam rod process brings great difficulties, some parts can not be clamped and other issues, which easily lead to the construction of the outer wall plate sealant and seams on both sides of the insufficient degree of solidity or collage thickness, and other problems, thus burying the sealing glue leakage. For example, in the inside of the wall plate using pre-embedded rubber water bar in the concrete, by pressing up and down to play a second layer of waterproofing, but the actual application of the effect is not ideal, because this way requires the outer wall plate installation accuracy is very high, a slight misal position can not press the rubber strip, lose the role of waterproof seal.
5. The combination of water blocking and hydrophobic is the best
waterproofing measures.
the "blocking water" scheme used in waterproofing traditional buildings is not suitable in assembled buildings with a large number of stitches. Simply hope to rely on the external wall plate sealant is safe to block the rain outside, unrealistic, or even if realized, the cost is very high, will cause unnecessary waste. And the concept of "hydrophobic", refers to the design to take into account that there will be a part of the water through various ways to enter, through a reasonable design, this part of the breakthrough into the water smoothly guide into the drainage structure, it will be discharged outside, to avoid further penetration into the room. Only the combination of blocking and dredging is the best waterproofing method for assembly buildings.
a comprehensive point of view, in the current domestic construction enterprises outside the wall board sealant understanding is not comprehensive enough, by the construction sealant enterprise is responsible for the assembly of the building exterior wall board adhesive construction (package material) is a very good way. As the saying goes, "three-point materials, seven-point construction", professional materials by the professional team to do, can put an end to many problems. For the owner, it is also possible to avoid problems with the material side and the construction side push each other.