Since December, there have been some temperature drops around the world:
Nordic region: Nordic region ushered in severe cold and blizzards in the first week of 2024, with extreme low temperatures of -43.6℃ and -42.5℃ in Sweden and Finland respectively. Subsequently, the impact of the big temperature drop further spread to Western Europe and Central Europe, and the United Kingdom and Germany issued yellow weather alerts for freezing.
Central and Southern Europe: The temperature in central and southern Europe and other places dropped by 10 to 15℃, and the temperature in high-altitude mountainous areas dropped by 15 to 20℃. The temperature in some areas of northern Germany, southern Poland, eastern Czech Republic, northern Slovakia, and central Romania dropped significantly.
Parts of China: The temperature in most parts of Northeast China, southeastern East China, central and southern South China, and southeastern Southwest China is lower than the same period of previous years.
North America: The temperature in northeastern United States and central and northern Canada dropped by 4 to 8℃, and exceeded 12℃ in some places.
Other parts of Asia: The temperature in central Russia dropped by 6 to 10℃, and exceeded 12℃ in some places.
The sudden drop in temperature and the howling cold wind come together. As an important auxiliary material widely used in bonding and sealing in the fields of building curtain walls, doors and windows, interior decoration, etc., sealants work diligently in every detail. Even in winter, they never stop working diligently to isolate the cold outside the "barrier".
The ambient temperature in winter is very low, and the following problems may occur:
(1) Under low temperature and low humidity conditions, the curing speed and bonding speed of silicone structural sealants are slower than normal, which will cause the maintenance time to be longer and affect the construction.
(2) When the temperature is too low, the wettability of silicone structural sealants and the substrate surface is reduced, and there may be imperceptible fog or frost on the substrate surface, which affects the adhesion of silicone structural sealants to the substrate.
Winter construction countermeasures
So what should we pay attention to in order to avoid the above problems?
At present, there are two types of building silicone structural sealants used in curtain wall construction: one is a single-component silicone structural sealant, and the other is a two-component silicone structural sealant. The curing mechanism and factors affecting the curing of these two types of silicone structural sealants are shown in the table below.
| One component |
Two component |
| It reacts with water in the air and solidifies gradually from the surface to the inside. (The deeper the glue seam, the longer it takes to fully cure) | Cured by the reaction of component A (containing a small amount of water), component B and moisture in the air, the surface and the inside are cured at the same time, the surface curing speed is faster than the internal curing speed, affected by the size of the glue seam and the sealing situation) |
| The curing speed is slower than that of two-component, the speed cannot be adjusted, and it is easily affected by the ambient temperature and humidity. Generally speaking, the lower the temperature, the slower the reaction speed; the lower the humidity, the slower the reaction speed. | The curing speed is fast, and the speed can be adjusted by the amount of component B. It is less affected by the ambient humidity and more affected by the temperature. Generally speaking, the lower the temperature, the slower the curing. |
According to Section 9.1 of JGJ 102-2013 "Technical Specifications for Glass Curtain Wall Engineering", the injection of silicone structural sealant should be carried out under ambient temperature and humidity conditions that meet the product specifications. For example, the environmental requirements for the use of siway silicone structural sealant products are: a clean environment with a temperature of 10℃ to 40℃ and a relative humidity of 40% to 80%, and avoid construction in rainy and snowy weather.
In winter construction, to ensure that the construction temperature is not lower than 10℃, appropriate heating measures should be taken. If the user needs to construct in an environment slightly lower than 10℃ due to special circumstances, it is recommended to first conduct a small-scale glue test and peeling adhesion test to confirm that the curing and bonding effects of the silicone sealant are good, and appropriately extend the maintenance time according to the situation. If necessary, consider using xylene to clean and apply primer to promote bonding speed and reduce the risk of poor bonding due to low temperature.
Countermeasures for slow curing
① Take appropriate heating measures;
② Two-component sealant should first be tested for breaking to determine the appropriate mixing ratio;
③ Single-component sealant needs to be tested for surface drying time to determine whether it can be cured in this environment;
④ It is recommended to extend the curing period after gluing to ensure that the sealant has sufficient curing and curing time.
Countermeasures for bonding failure
① Adhesion test should be carried out in advance before construction, and construction should be carried out strictly in accordance with the method recommended by the adhesion test.
② If necessary, consider using xylene for cleaning and applying primer to promote bonding speed and reduce the risk of poor bonding caused by low temperature.
③ After the silicone structural sealant is injected, the curing process should be carried out in a clean and ventilated environment. When the temperature and humidity of the curing environment are low, the curing time needs to be appropriately extended. Among them, the curing condition of the single-component structural sealant has a significant relationship with the curing time. Under the same environment, the longer the curing time, the higher the degree of curing.
If necessary, measures can be taken to increase the ambient temperature and humidity. The final rubber tapping test should be used as the basis to fully determine the maintenance time of the finished unit. Only after the finished rubber tapping test is qualified (see the figure below) can it be installed and transported.
As one of the building materials, sealant plays a vital role and directly affects the function, service life and value of the building, so the construction process must be strictly regulated when using glue. When constructing in winter and low temperature conditions, the actual bonding of the sealant must be verified in accordance with relevant standards to ensure that the sealant can effectively guarantee the sealing effect of the building. Founded in 1984, Shanghai siway, adhering to the heart of craftsmanship, is committed to providing sealing system glue solutions for global building curtain walls, hollow glass, door and window systems, civil glue, prefabricated buildings and industrial fields such as energy, transportation, lighting, electrical appliances, 5G communications and consumer electronics, smart homes, power supplies, etc., leading the industry's safe, healthy, green and sustainable development, and making your perfect choice from the subtle details.
In this cold season, let us care for every detail with a warm heart to ensure the construction quality and effect of silicone structural sealants.
Contact Us
Shanghai Siway Curtain Material Co.Ltd
No.1 Puhui Road ,Songjiang Dist,Shanghai,CHINA Tel: +86 21 37682288
Fax:+86 21 37682288
Post time: Dec-19-2024