Mechanical characterization of visually classified, small-diameter laricio pine round timber

This work reports the mechanical characterization of small-diameter logs (diameter < 23 cm) of laricio pine (Pinus nigra subsp. Saltzmannii) from the forests of Cuenca, Spain. Some 445 machine-rounded small logs with final diameters of 8, 10, 12 and 14 cm were examined in accordance with the standard EN 14251, and the conclusion reached that ungraded material can be assigned a strength class of C14 (according to EN 338), while graded material can be assigned to different combinations of strength classes (C18/C14 or C20/C16) depending on the visual grading standard used. Grading yields were examined using three different standards, DIN 4074, VPS-SRT-2 and prEN 14544, and the results obtained with each compared to those provided by the optimal ranking methodology set out in standard EN 14081-2. VPS-SRT-2 appeared to be the most suitable visual grading standard. There is a need to design mixed grading methods based on the use of non-destructive tests and the visual evaluation of specific wood features.