This study aims to evaluate the structural behaviour of dowel laminated timber (DLT) made of fast-growing pine and eucalyptus lamellae and different dowel diameters. Shear tests on dowelled connections and four-point bending tests on structural size panels were performed, and the slip modulus and bending properties, respectively, were obtained. The bending stiffness and strength of pine panels fastened with guatambú (5.05 and 20.05 kN/mm²) or eucalyptus dowels (5.29 and 17.13 kN/mm²), suggesting that dowel species had no influence on the panel’s bending properties. The analysis of the bending stiffness and strength of eucalyptus panels fastened with 18 mm (11.04 and 44.29 kN/mm²) or with 15 mm dowel diameter (11.06 and 51.50 kN/mm²) indicated that dowel diameter had no substantial influence on the bending properties. Furthermore, the stiffness values of the panels were similar to those of their constitutive individual lamellas, which, in turn, did not comply with the structural requirements of the Uruguayan Standard. Additional analytical results of the effective stiffness using the slip modulus were close to those found in the experimental bending tests. The results from this study are useful in understanding the mechanical behaviour of DLT panels and provide the basis for the improvement of Uruguayan mass timber products.

This study presents the experimental results of adhesive and metal-free laminated timber products made of Uruguayan pine. Dowel laminated timber (DLT) and wooden nail laminated timber (WNLT) were prepared using C22 pine lamellas and joined by wooden dowels or nails with diameters of 20 mm and 5.3 mm, respectively. For comparison, laminated timber products joined with 3.2 mm steel nails (NLT) were manufactured. Two nailing patterns, straight horizontal and zigzag, and three spacing between fasteners, 300, 250 and 150 mm were analysed. Shear tests on timber connections and four-point bending tests on structural size panels were performed, and the slip modulus and bending properties, respectively, were obtained. DLT connections showed significantly higher slip modulus values compared to WNLT and NLT connections. The bending stiffness (9.7 - 11.5 kN/mm2) and strength (35.4 – 57.4 N/mm2) of the DLT, WNLT and NLT panels did not show significant differences, suggesting that the connector material (wood or steel) and the diameter did not influence the load-carrying capacity of the panel. In general, the failure mode in the panels was in tension, probably attributed to pronounced fibre deviations and the presence of knots near the load application area. These findings suggest that adhesive and metal-free laminated timber products made of Uruguayan pine have structural properties that allow their use in residential floors, advancing towards more sustainable construction systems.