Silicone spandrel glass coatings: Mitigating glass breakage risk from thermal and other stresses

Chris Fronsoe, Timothy Krytenberg, Kris Vockler, John Swanson, Lawrence Carbary, Chris Barry, Stephane Hoffman, George Torok, Scott Norville, Samir Blanchet

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Curtain wall design commonly uses insulating glass units for vision and spandrel glazing to provide better visual harmonization of building façade glass. Risks with this design approach include higher thermal stresses, especially when low-emissivity coatings are used on insulating glass units in spandrel areas. Ceramic enamel frit – commonly used to opacify spandrel glass – is known to induce a bending strength reduction of up to 50%. The ability of ceramic enamel frit coated glass to resist thermal stress is similarly reduced. Multiple incidences of thermal stress related fracture have occurred with heat-strengthened, ceramic enamel frit opacified spandrel glass. An increased chance of spontaneous breakage, by nickel sulfide inclusions, may occur if ceramic enamel frit opacified spandrel glass is fully-tempered to withstand the thermal stresses that it is exposed to. Silicone spandrel glass coatings have been examined as a solution to prevent the strength reduction in heat-treated glass when ceramic enamel frit is applied as an opacifier. Four-point bending tests were used to investigate the flexural strength of coated heat-strengthened and fully-tempered glass. Ball drop testing was used to investigate the impact resistance of coated fully-tempered glass. Test data shows silicone coatings have no adverse effect on the flexural strength or impact resistance of the substrate and, in some instances, improve it. Therefore, silicone opacifiers do not reduce the resistance to thermal stress of heat-treated glass. These coatings also provide fallout protection in accordance with ASTM C1048 (ASTM, 2012). This suggests using a silicone opacifier on heat-treated spandrel glass could greatly reduce the risk of fracture resulting from thermally induced tensile stress, flexural stress, and impact related glass breakage in addition to reducing risk of injury from fallout if breakage occurs.

Original languageEnglish
Title of host publicationChallenging Glass 6
Subtitle of host publicationConference on Architectural and Structural Applications of Glass, CGC 2018 - Proceedings
EditorsChristian Louter, Freek Bos, Jan Belis, Fred Veer, Rob Nijsse
PublisherTU Delft Open
Pages185-194
Number of pages10
ISBN (Electronic)9789463660440
DOIs
StatePublished - Jan 1 2018
Event6th Challenging Glass Conference on Architectural and Structural Applications of Glass, CGC 2018 - Delft, Netherlands
Duration: May 17 2018May 18 2018

Publication series

NameChallenging Glass 6: Conference on Architectural and Structural Applications of Glass, CGC 2018 - Proceedings

Conference

Conference6th Challenging Glass Conference on Architectural and Structural Applications of Glass, CGC 2018
CountryNetherlands
CityDelft
Period05/17/1805/18/18

Keywords

  • Architectural glass
  • Ball drop
  • Ceramic enamel frit
  • Four-point bending
  • Glass strength
  • Glass weakness
  • Insulating glass units
  • Silicone coatings
  • Uniform lateral load

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  • Cite this

    Fronsoe, C., Krytenberg, T., Vockler, K., Swanson, J., Carbary, L., Barry, C., Hoffman, S., Torok, G., Norville, S., & Blanchet, S. (2018). Silicone spandrel glass coatings: Mitigating glass breakage risk from thermal and other stresses. In C. Louter, F. Bos, J. Belis, F. Veer, & R. Nijsse (Eds.), Challenging Glass 6: Conference on Architectural and Structural Applications of Glass, CGC 2018 - Proceedings (pp. 185-194). (Challenging Glass 6: Conference on Architectural and Structural Applications of Glass, CGC 2018 - Proceedings). TU Delft Open. https://doi.org/10.7480/cgc.6.2132