Classification of Tropical Pinus spp. Wood Based on Growth Rings

Abstract

The Brazilian Standard (NBR) for Timber Structures Design must consider, for mechanical grading and structural design, the relationship between the physical–mechanical properties and the growth ring characteristics of Pinus spp. Growth ring characteristics are essential variables for estimating the physical–mechanical properties of wood. Therefore, this study aimed to assess the relationship between growth rings and the physical–mechanical properties of defect-free Pinus spp. timber. Non-destructive tests were performed, including longitudinal and transverse vibration, stress wave, and static bending tests, as well as the determination of basic and apparent densities, followed by a destructive rupture test. In addition, latewood width, latewood proportion, and the number of growth rings were measured. Pearson’s correlation matrix was used to analyze the association between physical–mechanical properties and growth ring characteristics. All Pearson correlation coefficients (r) were significant (p < 0.05). The results showed that latewood width explained 62% of basic density and 60% of apparent density, but only 18% of static elasticity. Consequently, the combined assessment of growth ring characteristics and physical–mechanical properties enabled the mechanical characterization of Pinus spp. based on growth rings.