The Correct Way to Choose Construction Adhesive

The Correct Way to Choose Construction Adhesive

Silicone structural sealants are increasingly used in construction. Most silicone structural sealants are named according to the application site, and corresponding products should be selected according to the site when used. Structural adhesives are needed for mechanical requirements and bearing force; while sealants are required to play a sealing role, mainly airtight and watertight, and do not need to bear force. In simple terms, structural adhesives bear force, and sealants play a sealing role. Therefore, structural adhesives can replace sealants under certain conditions, but sealants can never replace structural adhesives.

So where should we use sealants?

Structural assembly parts

The sealant used between the curtain wall panel and its supporting structure needs to withstand multiple loads and ensure long-term adhesion. It is not allowed to fall off and must meet the requirements of the national mandatory standard "Silicone Structural Sealant for Buildings" (GB16776). Especially on high-rise and super-high-rise (the term "super-high-rise" is provided by the industry encyclopedia) curtain walls, large-grid glass curtain walls, curtain walls using laminated insulating glass, curtain walls in earthquake-resistant areas of 9 degrees, and even in the combination of these situations, it is more necessary to use high-performance silicone structural sealants. This kind of glue has high tensile strength and elongation at break, and can withstand greater loads with the same bonding width.

Joints of building curtain wall panels

The expansion joints between the panels of the building curtain wall need to be filled with glue, and silicone weather-resistant sealant should be used at this time. It needs to withstand the displacement caused by wind load, dynamic load, and deformation caused by thermal expansion and contraction of the substrate. In the case of tension or compression, the adhesion will not be destroyed, and it also has a good elastic recovery rate. After the displacement of the panel disappears, it can return to its original state. Please refer to the standard "Joint Sealant for Curtain Wall Glass".

Stone panel parts

Special stone silicone sealant must be used for stone panel parts. Because stone itself is a porous material, it is easily contaminated and difficult to remove after contamination. General sealants contain non-reactive low-molecular substances such as plasticizers, which will migrate from the inside of the sealant to the inside of the stone, causing oil stains and dust on the surface of the stone, causing stone pollution. This kind of glue is divided into two categories. One is stone caulking glue, which is used to caulk and seal between stone slabs. The other is dry hanging stone glue, which is used to bond between stone and metal hooks. In the past, rigid epoxy resin stone dry hanging glue was commonly used. When the building vibrates, it also transmits stress to the stone panel, and the stone is easily cracked.

Lighting top position

The displacement of the skylight roof is large and complex due to its own weight load, snow load, wind load, asymmetric load and thermal expansion and contraction of materials. There is not only horizontal displacement but also shear displacement. Especially when using polycarbonate board, its thermal expansion and contraction coefficient is very high, which is six or seven times that of glass. This requires the sealant to have low modulus, high displacement capacity, good material adaptability, and free expansion and contraction. It is best to use 50LM (50 low modulus grade) silicone sealant. Its displacement capacity is plus or minus 50%. The glue used for the skylight roof also requires good transparency and good appearance.

Area between doors and windows

The gap between the aluminum alloy and glass of doors and windows should be filled with sealant that can be cured at room temperature. After complete curing, the glass and aluminum alloy form a whole. In the past, polyacrylate, chloroprene, polyurethane and other materials were used for filling, but they were either easily damaged by external forces or volatilized harmful gases. Silicone sealant does not have such disadvantages and can play a long-term sealing and waterproofing role.