Klasyfikacja jakościowo-wytrzymałościowa drewna sosny zwyczajnej z Polski zachodniej w wybranych badaniach nieniszczących

The results of the conducted research and analysis concerning quality of Scots pine (Pinus sylvestris L.) wood for the selected region of Western Poland, in the case of a fresh mixed forest habitat and mature wood stands, confirmed the dependence of the heartwood zone on the function of pine wood diameter tested. Despite the relatively large variation in the width of annual growth in tested pine wood, it may be classified as close-grained wood with an average share of late wood at 36%. Measurement of strength parameters showed results confirming technical maturity of Scots pine wood. Testing of the longitudinal elasticity modulus in bending indicated that the lowest values of the tested parameter were obtained for radial elements, particu-larly pith elements. Comparable trends were demonstrated in all surveyed forest habitats. Examination of elements obtained from central wood confirmed the highest strength values in the group of tangential samples. High modulus values were also recorded for side wood. By averaging the values of the modulus obtained from log centre a signifi-cant dispersion of values was observed. On the basis of the tested elastic properties of pine wood originating from designated areas in Poland, it can be stated that wood of the side zone is characterized by lower or comparable qualitative variability in relation to the examined central wood. The tests assessed characteristics of the longitudinal elasticity module in relation to wood density. In the analyzed cases positive correlations of the tested parameters were confirmed. On the basis of strength classification of structural timber mechanical properties of Polish pine wood from selected natural and forestry areas facilitated its classification into strength classes. Testing results for elastic proper-ties of the experimental material indicate high variability in timber quality. The general verification of the presented results confirms lower strength properties (elastic modulus) for the material from the log centre. At the same time, the technical advantages of side timber have been demonstrated. When comparing the results obtained in two methodi-cally separate tests of the elastic modulus in large dimensional solid elements, one can notice an overestimation of the "sonic" value of the modulus in relation to the modulus of elasticity obtained in the static test. The results indicate very good strength properties of Scots pine wood from the Polish raw material base. Glued elements obtained from side timber are characterized by comparable properties to the solid wood elements of the central zone.