A shear test for structural adhesives used in the consolidation of old timber

A test method was developed specifically for structural adhesives used in thick joints. It is based on compressive shear loading of glued joints (GJ)and solid wood (SW) specimens, before and after a suitable accelerated ageing cycle. The evaluation of results is based on the ratios of wet strength and on the comparison of GJ specimens to SW specimens which are prepared from the same batch of wood, in order to minimise the influence of the variability in wood characteristics. On a group of 10 epoxy-based adhesives, specifically marketed for the consolidation of old timber structures, the method has proved to be effective to differentiate the performances of each product.