A Comparative Evaluation of the Behavior of Structural Silicone vs. Acrylic Foam Tape Subjected to High Strain Rates

Since the 1960s, silicone rubber has been used as an adhesive to bond glass/glass and glass/metal constructions for facades; an assembly method known as structural silicone glazing (SSG). More recently, an adhesive acrylic foam tape material has been promoted for the same use. SSG-type glazing systems transfer wind and other applied glazing loads, including those from seismic events, through the adhesive. Seismic events in particular impose loads into glazing systems which far exceed strain rates used in standardized laboratory testing protocols, and the behavior of these two materials under increased strain rates is interesting to consider for adhesively-bonded glazing designs in seismically-active regions. This paper presented data generated using specimens configured for testing in both a shear and a tension mode in which the geometry of the adhesive material in both specimen types was identical with the exception of thickness (the specimens were assembled in the thickness recommended by the product type). The shear specimens were of “lap shear” configuration, whereas the tensile specimens were a “cross tension” design, which mimics actual SSG joints more closely than have previous studies of similar materials. Specimens were tested to destruction at a standardized strain rate (ASTM; 50.8 mm/min (2 in./min)) and at two higher strain rate(s) in the range of those measured during high intensity seismic events with ground-based recording devices: 1100 mm/s (43 in./s) and 5000 mm/s (197 in./s). Comparisons are presented for a one and two-part structural silicone and one acrylic foam tape. Data is presented under freezing, elevated, and ambient temperature conditions.