Adhesive Joints in Glass and Solar Engineering

The architecture of the past 100 years is characterized by a desire for ever greater transparency. Inevitably, that goes hand in hand with a constantly growing proportion of glass in the building envelope. But owing to the brittle nature of glass, there are only limited options for transferring tried-and-tested methods of jointing—derived from structural steelwork and other engineering disciplines—to this material. However, adhesive joints are much more suited to creating a material bond between glass components. Structural adhesive joints for load bearing glass components have been the subject of research and development work all over Europe in recent years. This article looks at some of that work. The research has led to the development of practical adhesive joints for glass-glass and glass-metal connections. The work includes the study of surface pretreatments and aging scenarios so that types of application for the tensile and shear loads encountered in practice can be specified. Material specimens tested at various load application rates and temperatures enable the material parameters to be determined. A torsion specimen with a glued butt joint is being used to improve the in situ testing of glass-metal connections. There are plenty of potential applications for adhesive joints in structural glazing and solar technology, including the following: Point adhesive joints for overhead glazing and for oversize photovoltaic modules subjected to high environmental loads, linear adhesive joints for hybrid steel-glass composite beams with good ductility and for glass fins with a reduced cross-section in minimized steel-and-glass facades, or full-bond adhesive joints for photovoltaic facades suspended in front of a ventilation cavity and for fully transparent load bearing adhesive joints to an all-glass pavilion (first approved application in Germany).