In this thesis, we evaluated the relative properties of glued laminated timber after three years of exposure in the test field of the Department of Wood Science and Technology at University of Ljubljana. For comparison, we used data obtained from a one year of exposure and reference samples without exposure, which were obtained by Jure Jelšnik in his thesis.We tested spruce, beech and larch specimens as well as solid spruce. PVAc, MUF and PUR adhesives were used for gluing, and some samples were surface treated with a thick coating of Silvanolin or Silvacera. We were interested in the change in mechanical and visual properties after three years of exposure. Decomposition was evaluated according to the SIST EN 252 standard. Mechanical properties were determined with a Zwick Roell Z100 universal testing machine. We carried out a test of compressive and shear strength, delamination of adhesive joints and bending of the adhesive. After three years of exposure, we observed decreases in all values in all tests compared to previous years. The thermally modified beech cracked and fell apart. The shear strength of the glues that were glued with PVAc adhesives deteriorated, and in some cases the glue even completely loosened. Specimens with surface treatment had better properties than specimens without surface treatment.
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