Building structural sealant and the performance requirement and application of building sealant

【 Siway sealant 】 sealant application principle and standard of building sealant sealant and structure properties of sealant were discussed, for designers, engineers and the sealant manufacturer.

    A sealant, sealant used in construction seam sealing, construction of all kinds of joints under the influence of factors such as temperature, external force, sealant in seam must bear the change of the joint and the environment (water, light, cold, hot) without being damaged. Sealant priority is elastic, the performance of the sealant quality index is displacement ability. Building sealing schematic standards of the world’s most influential sealant is: ASTMC920 elastic joint sealant specifications and ISO11600, sealant, classification requirements for the design of building structures “. Our country about the sealant standards such as GB/T14683, JC/T881 ISO11600 formulate a JC/T885 main reference. ISO11600 and ASTMC920 have great difference on the products classification. ISO11600 grading ASTMC920 grading the displacement ability) the displacement ability) 25 lm100/5025 hm5020ml. 35.20 HM2512.5 E12.512.5 P7.5 P the author thinks that the classification more scientific, ASTMC920 on sealant from l00/50 to l2.5 level, separate sealant quality grade, and ISO11600 classification from 25 to 7.5, the level is above 25 sealant can’t distinguish, not to high modulus (Ⅲ), low modulus (LM) classification on the design and selection of how to distinguish, and on the difference between levels 20 and 25, material guiding significance to the designers don’t.

    Second, glue line design architect usually use two methods to determine the size of the glue line and select sealant: (1) according to the requirements of beautiful, easy processing, etc of the sealant width, and then calculated glue line variation (temperature, load and other factors), to select suitable sealant. Glue line change 12%, for example, can select level l2.5 sealant, such as glue line change 22%, can select 25 sealant; (2) the selected sealant, sealant displacement capacity to determine the joint width. In the design of our country most of the first kind of way is adopted to define the glue line width. Sometimes encountered in practical engineering glue line size is not reasonable to seal failure situation, reason often is designed according to the first kind of method, but did not check the sealant displacement ability match, or sealant displacement ability can not meet the manufacturers claim.

    Three, the structure of the silicone sealant silicone structural adhesive used for glass curtain wall structure assembly, glass bonding on the main structure, bear the weight of the load of wind load and glass, structural adhesive must have sufficient strength to withstand the load. General architect in the design of curtain wall structure glue line to take 0.14 MPa, structural adhesive for structural adhesive strength is greater than 0.7 YPa and it can achieve the safety factor of five times. Another important performance structural adhesive is modulus of elasticity, designer need to calculate according to the elastic modulus of structural adhesive seam thickness, low modulus sealant is not suitable as a structural adhesive, low modulus rubber under the action of wind load or weight load will produce large displacement, this building is glass curtain wall is not allowed. But the modulus of structural adhesive should not be too high, because of structural adhesive must adapt to glue line deformation caused by temperature. Structural adhesive must have certain elasticity. Standards relating to structural adhesive with: ASTMCl184; GB16776; ETAGO02. Is similar to the three standards, mainly considering structural adhesive under various conditions of strength, cohesiveness, and at the same time pay attention to the modulus of structural adhesive.

    Fourth, the difference of structural adhesive and sealant performance requirements; 1. The strength of the structural adhesive can give greater safety coefficient; 2. Structural adhesive and sealant have essentially different, structural adhesive on the building is to control the glue line change, must have high modulus, and sealant is to adapt to changes in glue line (high displacement ability), cannot use sealant performance indicators (such as the lower modulus, displacement) for structural adhesive; 3. The deflection of structural adhesive capacity (used for calculating structural adhesive seam thickness) and sealant displacement ability () is used to calculate adhesive seam width index are two different concepts, sealant displacement ability refers to the level, sealant to adapt to changes in joint and deflection bear ability refers to the structure of structural adhesive glue by stress strain value of 0.14 YPa. With displacement ability index of the sealant judgment of structural adhesive elastic is wrong. 【 END 】

Post time: Mar-21-2017
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