Epoxies are increasingly used in construction for structural applications and properties such as creep are very important. For this reason, the thermo-viscoelastic properties and creep response of two commercial, ambient cure structural epoxy adhesives were analyzed and compared. The adhesives were formulated by the same manufacturer and were chemically similar, but one system contained accelerators to shorten its cure time. Dynamic mechanical tests were performed on the two systems, and time-temperature superposition was applied to obtain master curves. The method of Ninomiya and Ferry was then used to estimate the long term tensile creep compliance of the two systems. Differences were observed in the dynamic mechanical properties of the two adhesive systems as well as in their estimated creep compliance behavior, which were attributed to differences in the curing agent(s) and accelerator(s) used in the adhesive systems. To determine how well these curves could predict trends in behavior for real world applications, full-scale creep testing was conducted on anchor bolts bonded with the epoxy systems and subjected to large sustained loads. Full-scale creep testing results also revealed significant differences in the behavior of the two epoxies, and these differences were in excellent agreement with the predictions from the laboratory experiments. This suggests that dynamic mechanical testing may have potential to identify possible creep problems in such materials.
Citation: Journal of Materials in Civil Engineering
Pub Type: Journals
epoxy, dynamic mechanical thermal analysis, time-temperature superposition, creep compliance, anchor bolts