SSG in Korea

The history of the structural silicone glazing system in Korea had its beginnings in the mid-1980s. The first two-sided structural silicone project (a glass light or panel mechanically attached to the glazing system on two of its four sides and structurally glazed on the other two) was introduced in Korea in 1986. The pro­ject name was City-Bank Korea and the glazing system utilized a one-part sili­cone structural sealant that was imported from the United States. Korea’s first four-sided structural silicone glazing (glazing system utilizing silicone adhesive on all four sides of a panel without any mechanical capturing) was completed in 1992, also utilizing one-part silicone from the US. In the mid-1990s the first unitized glazing system was introduced in Korea using two-part factory in­stalled, fast curing structural silicone sealant.

Although structural silicone glazing has been utilized for approximately 30 years in Korea, the understanding of its technology was low and limited. Consequently, Korean projects experienced many quality issues during assem­bly and construction, even in very recently finished buildings. Adhesion loss and water infiltration occurred on more than one project, and the time and cost to repair these issues were substantial. More importantly, assessing responsibility for such failures by each participant in the construction process is highly ardu­ous. The causes of such failures are difficult to pinpoint, but one of the culprits would be the lack of availability of an “industry guide" for structural silicone sealant and its application. Knowing the troubles and hurdles associated with SSG, the Cooperative Organization for Standard Development (COSD) and some industry players have been working toward developing a national guide for structural glazing and sealant.

Both ASTM C1401 [1] and ASTM C1369 [2] point out that structural glazing is a high-performance application and not all silicone sealants are suitable for a structural glazing application. They support this further by suggesting that only silicone structural sealants which have been developed and tested specifically for structural glazing applications should be used. The authors of this paper would like to better inform the domestic market about the actual performances of SSG products locally available based on the evaluation following the interna­tional industry standard ISO/FDIS 28278-1 [3].

Perhaps as many as 10 super-tall buildings (over 300 m tall) will be erected in Korea in the near future, some of them are already planned and/or under

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construction. The erection of such momentous projects locally is a critical point of national pride and prosperity for a country proud to show its growth since the Korean War. Despite the earnest ambition of Korean culture and its work­ers, there are many aspects regarding the use of SSG that must be reviewed and corrected for construction practices of glazing at the job site and selection of proper building material. Since SSG is one of the chief factors with respect to the performance of a curtain wall system, it is critical that it is selected and in­stalled properly in accordance with industry standards. Currently, the only guideline to classify the kinds of sealant for weather sealant and structural sili­cone sealant is KS F 4910 [4] which is similar to ISO 11600 [5]. Korean national standards for structural sealant and structural glazing guidelines will be ready soon based on ISO/FDIS 28278-1 and 2 [1,6]. The authors of this paper have contributed to the objective of an adoption of an international standard for SSG in Korea by evaluating locally available structural silicone sealants.

In order to achieve a successful facade system installation there are many factors to be reviewed and confirmed before commencing with the assembly. These factors also affect the total life cycle of the building. If there are any kinds of unexpected water or air leaks occurring in the facade system, the cost of heat­ing and cooling for the building will be increased. As such, the authors would like to share some technical guidance for choosing the proper silicone material by providing the actual evaluation following internationally relevant industry standards. To our knowledge, this is the first publication focused on the evalua­tion of structural sealants available in Korea.

In this study, 14 different structural silicone products from Korea have been evaluated by ISO/FDIS 28278-1. The Annex B of this standard requires that every structural silicone sealant should have minimum values for tensile strength at rupture for the proposed test conditions. The values are also utilized for calculating the required silicone structural sealant bite for each structural glazing purpose using a certain safety factor during the process. The standard also describes that there should not be much of a tensile property drop after weathering because weathering data can reflect long term safety performance issues of curtain wall glazing throughout the life cycle of the building.