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Silicone transforms global architecture

Article contributed by Dow Corning Corporation, a company specializing in silicon-based technology and innovation, offering more than 7000 products and services.

The Washington Mutual Tower is an example of how the construction industry has been revolutionized by structural silicone glazing which can replace mechanical fasteners as a way to adhere glass to building frames.

As reflections of sun and clouds glide across uninterrupted facades of mirrored glass and metal, building designers take pride in knowing they are designing some of the most functional and innovative buildings that grace city skylines.

In just a generation, the construction industry has been revolutionized by structural silicone glazing, which can replace mechanical fasteners as a way to adhere glass, ceramic, metal, stone and other materials to building frames. “Architectural imaginations soared once the limitations of mechanical fasteners were lifted,” says Ron Fillmore, global industry executive director for Dow Corning’s construction industry. “Today’s buildings are taller, sleeker and more resilient to harsh environments than ever before.”

Exhibiting strength, stability and versatility, the natural chemical properties of silicone sealants enable excellent adhesion and compatibility with multiple substrates, allowing for improved functionality and longevity. Designed to transmit wind-loads from the glass to the building’s framework, silicone glazing systems are able to flex, extend and compress with the daily stress of thermal shear, while maintaining their adhesive strength in the face of earthquakes, hurricane winds, ultraviolet rays, temperature extremes, moisture and acid rain.
Such revolutionary technology began more than 30 years ago as a two-sided glazing system, where vertical joints were glazed with silicone. This advancement served as a springboard for four-sided glazing, and then for the structural glazing of insulating glass panels. “In the early 1960s and 1970s, structural silicone glazing was a new and unproven concept, but the possibilities were tantalizing,” says Fillmore.

Dow Corning engineers evaluated their sealants’ compatibility with all possible substrates, testing for adhesion, movement capability, fatigue and failure. They analyzed joint designs, stresses and environmental variables, and monitored every design and installation detail. “Once the glazing technology proved successful, architects were no longer satisfied with square shapes and two dimensions,” says Fillmore. “They asked for and received the technical support to structurally glaze triangles and other unexpected shapes to create three-dimensional curtainwalls.”

New two-part, fast-cure sealants led to improved quality and performance of curtainwalls, and the use of structural silicone glazing blossomed. Some extreme examples can be found around the world.

In 1985, a 7.1 magnitude earthquake caused billions of dollars of damage to the San Francisco Bay Area. Yet, large lites of glass sealed tightly with silicone remained unscathed at the World Savings Center in Oakland.
Standing tall in the ‘rain shadow’ of the Olympic Mountains, the 55 storey Washington Mutual Tower experiences few dramatic storms. Instead, it is continually shrouded in clouds and coated in drizzle, rarely seeing a sunny day. In nearly 20 years of damp and gloom, punctuated by repeated seismic events, there have been no reported changes in the structural sealants used in the building’s construction.

Natural light streams through the glass panels of the renovated Charlemagne building in Brussels, Belgium. Silicone bonds the structural joints and provides a weather sealant around the panels, maintaining the thermal integrity of the structure.

The third-largest trade fair complex in the world, located in Frankfurt, Germany, covers 476,000 square metres (5,123,621 square feet). For more than 20 years, the building’s structure has remained intact despite extreme variations in temperature, humidity, infrared and ultraviolet radiation.

Home to the Hong Kong Stock Exchange since the 1980s, Exchange Square’s 656 foot towers are among the largest silicone structural projects of its time. The towers are a further testament to silicone’s reliability under extreme weather conditions, holding strong against severe heat, humidity, heavy rains and typhoons. -end-