S hear performance of timber-GFRP double-lap adhesive joints for civil engineering applications

Adhesive bonding technology make it possible to join different materials and to assemble lightweight joints with high mechanical performance. These advantages over conventional technologies have led to a growing interest in these joints in timber construction. This study reports the results of an experimental campaign on double-lap adhesive joints between timber and GFRP adherends assembled with two different commercial structural epoxy adhesives. The aim of the present study is to evaluate the applicability of the bonding technique in the field of civil engineering and in the manufacture of window frames with adhesive joints (patent application No. 1020000023128, inventor Prof. Munafò). The results obtained after curing under laboratory conditions are compared with those obtained after exposure to high temperatures (40 °C) and relative humidity (100% RH). The results show that the effect of artificial ageing varies depending on the adhesive and generally leads to a reduction in the ultimate strengths and stiffness for both adhesives. The best mechanical performance in terms of ultimate load and stiffness is obtained by the epoxy adhesive EPX1 in each configuration tested, with values for ultimate load and displacements sufficient to ensure the mechanical performance in the range of applications studied. The epoxy adhesive EPX2 showed a significant decay of mechanical performance after artificial ageing and exhibited lower ultimate displacements and loads.