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In this study, three different shapes and glue coverage rates of joints were evaluated nondestructively using longitudinal and flexural vibration-based methods. Rectangular specimens of 20 × 40 × 360 mm³ (R × T × L) dimensions were prepared from clear eastern beech (Fagus orientalis; Lipsky) wood. Joints were located at the middle of the beams. The selected joint shapes were 45° scarf joint, 30° scarf joint and finger joint with 10 mm length and 3 mm pitch. Longitudinal vibration test proved a better assessment for gluing than flexural efficiency. Some weaker jointed timbers could demonstrate identical Young’s moduli by both longitudinal and flexural vibration-based methods. In the presence of any significant difference between Young’s moduli evaluated by two methods, it was realized that the joints were weak and required to be rejected or assigned to re-manufacturing. The R2 of Timoshenko’s linear model significantly decreased when there was any un-integrity in the joints. This factor was suggested to be used as a potential subsidiary indicator. The vibration-based methods were recommended to be applied for joint assessment of old jointed timbers and for grading newly constructed jointed lumbers.

The composite board industry in Iran is obliged to use residues from forest operation as well as wood industry for competing with paper industry because of shortage of wood. In the present study we investigated the residues from poplar plantation used for particleboard production. Three kinds of wood materials, poplar branches, small diameter poplar wood (3–8 cm) and beech wood, were used in the experiment of particleboard production. The results demonstrated that the characteristic of particleboard made from poplar branches and small diameter wood is comparable to that made from mature beech wood. To avoid too much residual acid in the final board, the properties of boards produced with 1.5% hardener at 175°C press temperature are acceptable, although the properties of particleboard produced with 2% hardener were higher than were higher than that of the board produced with lower hardener (1% or 1.5%).. The MOR, MOE and IB of particleboard made from branches were measured as 14.57, 2015, and 1.32 MPa, respectively, while The MOR, MOE and IB of particleboard produced from small diameter poplar wood were 19.90, 2199, and 1.86 MPa, respectively. The thickness swelling of boards made from branches after 2 and 24 h immersion in water was 20.14% and 31.26%. The utilization of branches and very small diameter wood of poplar is recommended for the survival and developments of particleboard industry in Iran.