Mill variation in bending strength and stiffness of in-grade southern pine No. 2 2 × 4 lumber |
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| Authors: | Joseph Dahlen P David Jones R Daniel Seale Rubin Shmulsky |
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| Institution: | 1. Warnell School of Forestry and Natural Resources, University of Georgia, 180 E Green Street, Athens, GA, 30602-2152, USA
2. Department of Forest Products, Mississippi State University, Mail Stop 9820, Mississippi State, MS, 39759, USA
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| Abstract: | Visually graded southern pine (SP) has wide variability within grade. For 2 × 4 lumber, this variability has increased because it is harvested from both natural forests and plantation forests where trees contain high percentages of juvenile wood. To investigate resource variability, six kiln-dried No. 2 2 × 4 SP packages were acquired from six mills. From each package, 124 samples were destructively tested in bending. Mean modulus of elasticity (MOE15) ranged from 9.2 to 13.1 GPa, and three mills did not meet the design values (11.0 GPa). Bending strength (F b) ranged from 7.6 to 11.9 MPa, and four mills did not meet the design values (10.3 MPa). Analysis of variance of MOE15 and F b showed significant differences between mills. MOE15 explained from 33 to 51 % of the variability in F b. These data suggest that variation between mills is high and destructive testing is critical for more accurate characterization of lumber properties. |
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