Tensile shear strength and microscopic characterization of structural polyurethane adhesive modified with basalt fibers

This research work analyzed the shear strength of a bonded joint and the effect of basalt fibers added to a one- component polyurethane adhesive for load-bearing purposes. The shear strength was ascertained according to standard EN 302-1, and it was found that the addition of basalt fibers to the adhesive resulted in an increase in the shear strength of the bonded joint. The increase in strength was particularly evident when cold water was applied to the bonded joint, with the mean shear strength of the basalt fiber modified adhesive being 2.6 N/mm² higher than the unmodified adhesive. However, in a standard climate without water exposure, the difference between the modified and unmodified adhesive was minimal. It was also confirmed that surface modification of basalt fibers by silanization resulted in very good adhesion of the polyurethane to the basalt fibers.