The Glue Application Process for Glass Curtain Walls

1. Material selection: compatibility and durability are the basis

Glass curtain wall glue application needs to select special sealants according to design requirements, such as silicone structural sealants (load bearing) and silicone weathering sealants (anti-environmental erosion). Structural glue must pass compatibility tests to ensure that the bonding strength with glass, aluminum frames and other substrates meets the standards, and must be used within the shelf life to avoid bonding failure due to expiration. Weathering glue must have UV resistance, high and low temperature resistance and waterproof properties. For example, a project used inferior weathering glue and leakage occurred three years later, and the maintenance cost increased by 40%.

2. Cleaning of substrate: the key step to determine the success of bonding

Before construction, acetone, isopropyl alcohol and other solvents should be used to thoroughly remove oil, dust and water stains on the surface of the substrate. The cleaning range should be greater than 2 times the width of the glue joint, and secondary pollution should be avoided. For example, a project in Nanchang had glue joints fall off due to incomplete cleaning, and it took 15 days to rework. After cleaning, the glue injection must be completed within 60 minutes, otherwise it needs to be reprocessed.

3. Glue joint design: scientific calculation to ensure structural stability

The width of the glue joint must be determined by mechanical calculation, with a minimum width of 6mm, a normal width of 8mm, and a width of 10-12mm in high wind pressure or earthquake areas. The thickness should be greater than 3.5mm, and the thickness of the weather-resistant glue should be 30-40mm. Too thin is easy to crack, and too thick is unevenly cured. Due to insufficient glue joint design, a super high-rise building encountered local water seepage after a typhoon, which confirmed the importance of standard design.

4. Environmental control: strict restrictions on temperature, humidity and weather

The construction environment temperature should be controlled at 5-40℃, and the humidity should be less than 80%. Rainy days, low temperatures or high temperatures will delay curing or cause bubbles. For example, a project in Shenzhen was forced to be constructed during the rainy season, resulting in 30% failure of the glue joints. It is recommended to choose cloudy or evening hours to avoid direct sunlight causing colloid foaming.

5. Professional construction: standardized operation and teamwork

The injection of glue must be operated by certified professionals, and the two-person synchronous hitting technology is used to ensure that the glue joints are filled densely. The angle of the glue gun is maintained at 45°, and the glue gun is squeezed at a uniform speed to avoid glue breakage or bubbles. When scraping the glue, a special tool is used to form a slightly concave surface to improve drainage performance. Due to insufficient teamwork, the flatness deviation of the glue joint of a certain international exhibition center project exceeded 20%, and it was forced to rework.

6. Curing and maintenance: dual control of time and conditions

It takes 7-14 days for the structural glue to cure, and external impact or water stains should be avoided during this period. Weathering glue takes about 2 hours to dry on the surface, and 24-72 hours to fully cure. A landmark building in Shanghai removed the protective layer before the maintenance period was over, resulting in glue surface pollution and affecting the appearance.

7. Quality inspection: Multi-dimensional acceptance to eliminate hidden dangers

During acceptance, the continuity, density and surface flatness of the glue joints must be tested, and an ultrasonic detector must be used to check for hollows or bubbles. Record the batch number, construction time and environmental parameters of the glue, and archive them for at least 10 years for traceability. A case showed that a project in Hangzhou missed a 2mm glue joint gap during acceptance, which caused a curtain wall glass fall-off accident three years later.

8. Post-maintenance: regular inspection and repair strategy

At least one comprehensive inspection should be carried out every year, focusing on checking for aging, cracking or leakage of glue joints. Local defects can be repaired using the “wet sealing” technology, that is, removing the old glue and re-injecting the glue. A building in the United States has extended the life of the curtain wall from 20 years to 35 years through regular maintenance. It is recommended to use drones with infrared thermal imaging technology to efficiently locate potential danger areas.

Summary

Glass curtain wall glue application technology is the core guarantee of building safety and beauty, and it must run through the entire cycle of design, construction, acceptance and maintenance. Through scientific material selection, standardized operation and dynamic monitoring, the performance of the curtain wall can be significantly improved and the operation and maintenance costs can be reduced. With the application of new materials (such as polysilsesquioxane coating) and intelligent detection technology, the glue application process will move towards higher precision and durability in the future.

Authoritative reference:

• Construction Specifications for Curtain Wall Gluing (JGJ 102-2003)
• American Curtain Wall Association Sealant Repair Guide
• Nanchang Curtain Wall Project Case Analysis