Establishing Design Values and Durability Assessment of Western Juniper

Western juniper is a conifer that is native to Oregon, California, Washington, Nevada, and Idaho. Juniper is known to have highly decay resistant heartwood and is a popular choice for finished furniture. With recent forest management practices over the past 100 years have resulted in an immense population increase in western juniper stands, transforming the grasslands/sagebrush into juniper forests. Landowners have been encouraged to cutback western juniper to restore grassland habitat, but there is no major market associated with juniper. This study assessed the strength and durability properties of western juniper in order to develop design values in collaboration with the West Coast Lumber Inspection Bureau. Samples were harvested from three locations in eastern Oregon, one location in northeast California, and one location in southwest Idaho. Tests were performed according to procedures described in ASTM Standard D143 small-clear specimens for compression, bending, and shear. Average strength values were calculated and compared to similar wood species. Most properties were similar to those of other species, but modulus of elasticity was significantly lower. The differences between species might be attributed to cell wall structure and distribution of lignin in the cells. Design values for western juniper were calculated using the strength values following the ASTM Standard D245 procedure for establishing structural grades and related allowable properties for visually graded lumber. Durability of western juniper was assessed using laboratory decay tests, marine tests, and ground contact exposure. The long term marine durability and ground contact tests are still on going. The laboratory decay test indicated that western juniper heartwood was highly resistant to attack by brown and white rot fungi.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Research Project Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 49p

Subject/Index Terms

Filing Info

  • Accession Number: 01670912
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-OR-RD-18-15, OSU WSE TR17-3, Project 304-721
  • Files: TRIS, ATRI, USDOT, STATEDOT
  • Created Date: May 16 2018 12:23PM