Physical and Mechanical Properties of Loblolly and Slash Pine Wood from Uruguayan Plantations

Abstract

The available wood supply in Uruguay comprises trees that grow so fast in intensively managed plantations that they reach saw timber size in 25 years or fewer. Trees harvested at this age contain high proportions of juvenile wood that may lead to lumber low in stiffness and strength. A project was conducted to characterize fast-growing wood, determine engineering properties, and assign visual structural grades of lumber. The present study evaluated properties of 15-and 25-year-old loblolly (Pinus taeda L.) and slash (Pinus elliottii Eng.) pine to better understand the current available locally produced wood material. A total of 175 stump bolts from trees from two commercial plantations provided inner and outer small clear specimens for property evaluation. Specific gravity, bending, compression parallel to grain and perpendicular to grain, and shear tests were conducted. Most properties significantly increased radially away from the pith. The outer wood appears to be denser, stiffer, and stronger than the inner wood in both plantations. Wood from 15-year-old San Jose ´trees showed significantly lower properties than 25-year-old Paysandu ´trees, and had considerably inferior properties compared with values listed in the Wood Handbook (US Department of Agriculture 1999). Our results on 25-year-old Paysandu ´small clear specimens showed properties similar to those of previous studies on small clear and structural size pieces. Therefore, it can be expected that lumber from 25-year-old Paysandu ´trees will eventually comply with required properties for structural use. A second on-going phase of this study addressing structural size specimens will help to establish more definite conclusions.

Elastic Behavior of Fast-Growth Uruguayan Pine Determined from Compression and Bending Tests

“…As a result, elastic behavior was guaranteed for loads lower than 0.4-times the maximum load required in EN 408 (2011). The mean values of 27 and 26 N/mm 2 for the compression strength parallel to the grain agreed with previous results for the same species (Moya et al 2013).…”

“…The material for this study was obtained from pieces of pine lumber (Pinus elliottii and P. taeda) from a more general research study (Moya et al 2009). Ten boards (150 x 60 x 3300 mm) with the physical and elastic axes of symmetry matching in the L, R, and T directions were carefully selected.…”

“…Table 1 shows the elastic constants for mature loblolly and slash pine wood. In Uruguay, most information about the elastic properties of pine species is limited to the longitudinal modulus of elasticity obtained from static bending tests (O'Neill et al 2002(O'Neill et al , 2003Moya et al 2013). Due to its easy implementation, bending…”

Caracterización estructural de madera aserrada de pinos cultivados en Uruguay

“…Estudios previos (Moya et al 2013) realizados sobre cuerpos de prueba de pequeñas dimensiones y libre de defectos mostraron diferencias significativas entre la madera de los muestreos M1 y M2. Esta observación fue verificada en el presente estudio para piezas de tamaño estructural mediante análisis de varianza (ANOVA).…”

An Acoustics Operations Study for Loblolly Pine (Pinus taeda) Standing Saw Timber with Different Thinning History

“…The rotation age needed to meet design values can also vary by up to ± 10 years, depending on various genetic and environmental factors (Biblis et al 1993(Biblis et al , 1995. Finally, unless grown outside the U.S. (Moya et al 2013), any genetic gains will take approximately 25 years to be realized in the field from seedling to sawtimber harvest. As such, being able to quantify and inventory the potential stiffness of a southern pine stand through some rapid techniques would perhaps be more efficient and allow for stands to be harvested at the right stiffness, as opposed to some specified age.…”