Mechanical Properties of Underutilized Hardwood Species and Potential for Use in Fabrication of Cross-Laminated Timber Industrial Mats

This research evaluated the mechanical and physical properties of three underutilized hardwood species according to visual lumber grades. Findings are discussed in relation to the requirements recommended such as density, modulus of rupture (MOR), and modulus of elasticity (MOE) for the manufacture of cross-laminated timber (CLT) industrial mats, which is a potential end use of low-valued hardwood species. Results showed that all species tested had an average MOE greater than that required for CLT lumber. Visual grading was an important component in strength determinations as evidenced by the correlation between MOE and MOR. All grades of red oak (Quercus rubra L.) had higher densities than those of southern yellow pine, which is the traditional wood used in manufacturing CLT industrial mats, with a density of 616 kg/m3 at 12 percent moisture; the average density of the red oak tested was 770 kg/m3 at 13.98 percent moisture. All grades of red oak also had MOE and MOR values that met the requirements for lumber used in the manufacture of CLT industrial mats. For sweetgum (Liquidambar styraciflua L.), all grades met the required values for MOE and MOR, but only Grades 3 and 4 met the required density. All grades of yellow poplar (Liriodendron tulipifera L.) met the required MOE and MOR, but none met the required density.