In November 2020, the Brazilian Association of Technical Standards (ABNT) published the ABNT NBR 16918 standard, which establishes the general requirements related to heat-strengthened glass. This type of glass, widely used in the North American and European market, has not yet found relevant space in the Brazilian market.
In this short article, we will address the possible benefits of using heat-strengthened glass for a glass/ Saflex® PVB interlayer/glass laminate configuration, especially its post-breakage behavior.
Heat-strengthened glass has intermediate characteristics compared to annealed glass and fully tempered glass. For example, the thermal stress resistance of heat-strengthened glass resists to about 70°C, while annealed glass resists to about 40°C and fully tempered glass resists up to about 200°C. The mechanical properties of heat-strengthened glass also fall between annealed and fully-tempered glass.
In addition to its thermal and mechanical properties, its breaking pattern also falls in the intermediate range. When annealed glass breaks, large and dangerous fragments form that may be capable of causing serious injuries. Fully tempered glass (processed according to ABNT NBR 14698), however, tends to fragment into small pieces with a maximum size of 100 mm, which can drastically reduce the potential for serious cuts and piercing injuries. Heat-strengthened glass produces fragments of intermediate size, typically between the sizes seen in annealed glass and fully tempered glass.
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