Structural Sealant is a versatile adhesive used in the assembly and installation of structural glazing. It has high strength and flexibility.
Current durability assessment methods schedule separate test programmes for climatic and mechanical loads. This study presents a new durability test that simultaneously exposes system specimens to weathering and mechanical loading simulating 50 years of service.
Structural Sealant is a high strength, high durability building sealant suitable for structural bonding and sealing. It is able to withstand large loads and resist degradation factors that affect other building sealants and cause them to fail, contributing to significant maintenance costs.
Several durability tests are available for testing the performance of construction sealants, most of which combine simultaneous exposure to cyclic movement and artificial weathering. However, these tests do not adequately test the key mechanical properties of a sealant joint. Their evaluation relies mainly on visual examination of changes in the cohesion and adhesion of the tested system.
A new method of evaluating the performance of a sealant during natural aging uses an instrument to record the elastic moduli of the system under stress. This data is then used to compare the dynamic response of different sealants. This approach enables the comparison of results for a given test method between two or more different specimens, regardless of the experimental conditions under which the specimens are subjected to stress.
The results of this study showed that a 1st generation 2-part structural silicone that underwent 23+2 years of natural aging and cyclic movement cycles passed the ETAG002-1 critical performance criteria for initial mechanical strength and residual strength with flying colors. The 2nd generation, on the other hand, was able to pass these requirements only with marginal loss of adhesive strength at the corners of the test specimens.
Structural Sealant is very effective in protecting construction projects against the harsh elements of nature. It is resistant to the damaging effects of wind, sun and rain. In addition, it has excellent structural bonding strength. It can also be used in the bonding of weight structures. It has a high tear resistance, elongation at Structural Sealant break and tensile strength. It can also resist ultraviolet light and acid rain. Structural silicone sealants are also suitable for use in areas where a lot of movement takes place.
Current durability assessment methods schedule separate test programmes for climatic and mechanical load exposure. The mechanical response of the test specimens to cyclic weathering and mechanical loading is assessed from the visual examination of changes in cohesion, adhesion and appearance.
Dynamic mechanical parameters, such as moduli and dissipated energy, provide additional information about the behaviour of the test specimens during cyclic exposure. The tensile and shear strengths and moduli of sections cut from system specimens exposed to combined loading show a significant decrease compared to those of the reference and non-exposed specimens. The course of the dissipated energies shows that series A specimens with a stiffer sealant have a greater damping capacity than those of series B during combined exposure. This is a result of the difference in elasticity between shear and tensile elastic materials.
The structural sealant must be able to accommodate movement of the joints, as well as vibration and other environmental stresses. This is a very important feature. The sealant must be able to deform under stress, but when the stress is removed, it should return to its original shape without failure. This is called plasticity.
It is also very important that the sealant be able to take a constant load for an extended period of time. It is really helpful if the manufacturer has data on how much dead load the sealant can hold for a specified time and that it will not experience adhesive or cohesive (creep rupture) failure.
The aging of the sealant should not be detrimental to its performance over its expected life. This is especially important if the structural sealant will be exposed to outdoor weathering. A long-term weathering test is recommended, as well as a controlled, temperature dependent dynamic loading test.
Another important feature of a structural sealant is its compatibility with other materials. This is a very important feature, as sealants are often placed in contact with or near other construction materials. The sealant must be able to work with other construction materials, such as aluminum, wood and concrete, without compromising its cure profile or performance. The manufacturer should be able to provide information about the sealant’s compatibility with other construction materials.
When working with adhesives and sealants, there are certain safety concerns that must be addressed. Many of these concerns involve the airborne particles, decomposition products and uncured components that are present during the application process. Additionally, the equipment Structural Sealant and accessories used in the processing, mixing, compounding, curing and sealing of adhesives and sealants can also be hazardous if not properly handled. All workers working with these chemicals should receive appropriate training and use proper safety procedures.
After 23 years of exposure in the natural aging environment, test specimens dismantled from the hybrid SSG structure at IFT Rosenheim were subjected to destructive tensile tests and the key ETAG002-1 performance indicators – Initial Mechanical Strength and Residual Strength. The study, conducted by B.Sc. students, demonstrated that the structural silicone sealant had remained at its original strength and met all requirements set forth in ETAG002-1 after both natural and accelerated aging.
The results of this study are reassuring and may give conservative building code authorities the confidence they need to approve four-sided structural glazing without the addition of supplementary safety retainers. However, the final decision will ultimately be up to the local building codes officials. However, this research can help them make an informed decision based on the results of the test specimens from the IFT Rosenheim facade. Moreover, the results of this study are also in line with previous studies of structural silicone sealants that have been subjected to similar natural aging tests.