In the world of modern architecture, underlying factors like new technologies, material upgrades, environmental requirements, and aesthetic complexity pave the way for limitless innovations. One example is glass, a building construction material that has been dramatically refined through time and has undergone a series of breakthroughs. It came from being a more decorative material to being an integral structural component. Glass has shifted from its artisanal roots toward the world of mass production .
Glass has been utilized in construction for a long time now – from the London Crystal Palace, a building that dates back to 1851 and constitutes 300,000 glass sheets, to the new Hayden Planetarium in New York. The planetarium was completed in 2000 at the American Museum of Natural History in Manhattan, with a massive 87-foot-diameter sphere that seemingly floats in the center of a breathtaking glass cube. These are only two of many architectural projects in the world that display the astounding possibilities of utilizing glass .
Apart from its elegant aesthetic features, the versatility of glass as a construction material is more so fascinating. Its different properties, types, and applications made glass a global industry in the 21st century. With its wide array of functionality, glass is becoming more and more loved by architects globally.
Properties of glass
Glass possesses the following properties which make it an advantageous choice of material in the construction industry:
1. Transparency and Translucency
Transparency provides a point of connection with the outside world, as generally observed in the façade of buildings. The transparency of the glass is caused by its non-crystalline nature and the peculiarity of the bonds within the glass itself. Also, with the advent of technology, the glass may be made more opaque to exhibit translucency. Such properties allow the glass to manipulate light for certain purposes .
Glass has a good insulating response against visible light transmission, heat, electricity, and electromagnetic radiation. It resists well against sound transmission, as well, provided that there is an appropriate thickness used. For example, the only effective way to increase acoustic insulation of a single glass pane is through increasing its thickness, as its damping and stiffness cannot be changed. Thicker glass tends to provide more significant sound reduction .
In general, regular glass has low impact resistance, cracking or shattering easily under impact. Still, certain types of glass, such as tempered glass or heat-strengthened glass exhibit high impact resistance values. Glass strengthening techniques such as etching, thermal strengthening, ion exchange strengthening, vitreous enameling, chemical strengthening, and fibre reinforcement allow glasses to have an increased deformation resistance under load .
4. Chemical Resistance and Fire Resistance
Glass is highly resistant to chemical reactions driven by different environmental or acidic conditions. It can withstand the effects of most chemicals, such as ammonia and sulfuric acid. In the case of fire, heat-treated glasses are capable of stopping the propagation of flames into adjoining spaces, significantly blocking smoke and toxic gases that emanate from burning furniture and materials. It can create additional thermal insulation or reduced passage of thermal radiation .
Glass as a material is 100% recyclable. It can be recycled without compromising quality or purity. Recycled glass helps conserve energy by reducing emissions and consumption of raw materials .
Types of glass used in the construction industry
The architectural glass comes in different strength categories, namely: annealed glass, fully tempered glass, and heat-tempered glass. On the other hand, there are specialized glass types made with different qualities to enhance performance, namely: laminated glass, insulating glass, coated glass, tinted glass, and wire glass.
1. Float (Annealed) Glass
Float glass, also called annealed glass, is the most common among types of architectural glass. It is made from raw materials such as silica, carbonate, sulfate, and limestone. Float glass has outstanding surface quality as it does not undergo heat treatment and therefore is not subject to distortion usually produced from glass tempering. It is often used in residential structures. However, in the case of breakage, annealed glass dangerously breaks into sharp shards [8,9].
2. Fully Tempered (Toughened) Glass
Fully tempered glass is subject to heat-toughening, i.e. heating to a specific temperature of about 650 °C followed by rapid cooling under a sharp airflow. This results in enhanced strength, ductility, and mechanical resistance. Upon cooling, the inside structure of the tempered glass undergoes tensile stress, while the outside surface experiences compression stress, resulting in increased tensile bending strength and impact resistance higher than those of float glass.
Fully tempered glass possesses the strength of more than four times that of annealed glass, giving high resistance against breakage, and thus minimizing risks of personal injury and property damage. Toughened glass is usually used in escalator side panels, windshields of sports cars, glass floors, and curtain walls of high rise buildings, among others [8,9].
3. Heat-Strengthened Glass
Heat-strengthened glass is a semi-hardened, partially toughened glass that is strong and resistant to breakage from heat stresses or wind loads. Its strength and breakage resistance are at least two times those of annealed glass. The heat treatment results in some levels of distortion and instances of breakage would produce large shards [8,9].
4. Laminated Glass
Laminated glass is made of two or more panes of heat-strengthened or tempered glass with an intermediate foil (e.g., ethylene vinyl acetate or polyvinyl butyral). It is a type of safety glass that prevents the fallout of dangerous glass shards when shattered. Its plastic interlayer also provides protection from ultraviolet rays and good acoustical characteristics.
5. Insulating Glass
Insulating glass is composed of two or more panes of glass, separated by a spacer material and sealed hermetically. They are commonly used for condensation control and thermal insulation. The insulating airspace can be filled during the production process with either dry air or low-conductivity gas such as argon or sulfur hexafluoride. Insulating glass is made to significantly prevent heat transfer to and out of the building, reducing heat gain and loss to give a superior thermal performance.
6. Coated Glass
Coated glass is glass covered with metallic compounds such as iron oxides and tin compounds that not only provide aesthetic appeal but also regulate its heat performance by reflecting visible light and infrared radiation. For example, thin and durable films of metal or metal oxides can be placed on the surface of clear or tinted glass sheets in order to manufacture reflective coated glass. Coated glass reduces visual glare and unwanted sunlight from entering a building .
7. Wire Glass
Wire glass features a steel wire mesh embedded in the plate glass, which helps it hold together in case of cracking. It is also used as a fire retardant . However, the wire mesh generates weak points throughout the glass structure, weakening its strength and impact resistance.
Glass in modern architecture
Constant innovations and technological advancements continue to increase the possibilities for the use of glass in the world of architecture and engineering. With its aesthetic appeal, versatility, and capability to harness natural light better than any other material, glass elevates itself as an indispensable component in modern age building .
Numerous spectacular buildings are a testament to its superb value. The Szezecin’s Philharmonic Hall in Poland features ribbed glass peaking to its pitched roof. The Gores Group Headquarters in Beverly Hills display glass panes forming an array of circles and diamonds. The Christ Cathedral in California’s Garden Grove reflects the beauty of its surroundings through its mirrored glass panels. These wonders of architecture are all made possible with the miracle of glass .
In response to the immense value of glass nowadays, glass manufacturing companies ceaselessly collaborate with architects and designers alike to stretch the opportunities in utilizing glass in architecture. For instance, SCHOTT, a manufacturer of architectural glass with more than 130 years of experience, specializes in areas of glass materials, formulations, and advanced technologies that strive to carry out such endeavours. The glass producer has also offered services in the preservation and protection of sensitive cultural objects and historical façades with its anti-reflective protective glasses .
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