Epoxy-based adhesives are currently adopted for repair works on site, as they are suitable for jobs where the use of pressure is not possible and clean regular gluing edges are difficult to get. However, some factors have limited a wider use of structural adhesives, namely in historical timber structures. One reason is that a long service life has not yet been fully proven for synthetic adhesives since the natural ageing of actual glued joints is no older than sixty years and standard accelerated ageing tests are not yet available. Several research projects have been recently set aiming to gather a wider and systematic knowledge on the long-term performance of epoxy adhesives as well as the bonding durability under high service temperature or humidity, and the influence of variables like pre-ageing, moisture content or hardwood species. The present paper discusses a number of test methods that have been proposed to evaluate the performance of epoxy bonds, outlining the corresponding difficulties, application and significance.
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