Determination of tensile shear strength of lap joints of planed and sanded beech wood

The aim of this research was to evaluate the shear strength of the lap joints of planed and sanded beech wood. A single-component polyurethane adhesive for waterproof joints was used for bonding. The shear strength of the bonded joint was determined according to standard EN 205. It was found that the shear strength of the bonded joint is higher for wood whose surface was lightly sanded with coarse sandpaper. Whilst the average value of the shear strength of planed wood was 13.1 N/mm2, sanded wood achieved more than a 18% higher average shear strength of 15.5 N/mm2. For wood whose surface was sanded before bonding, the experimental measurement also showed a much higher proportion of joint failure in the wood than in the adhesive, as was the case with the planed surface.