Performance of polyurea-coated Douglas-fir timbers exposed in Hilo Hawaii

ABSTRACT

The potential for polyurea coatings to improve wood crossarm performance was assessed on untreated and treated Douglas-fir exposed to termite/fungal attack in Hawaii. Treated materials performed similarly regardless of coating, although coating reduced UV damage. Untreated non-coated timbers were decayed within 2-years of exposure and were unserviceable after 7 years. Upper surfaces of coated, untreated samples experienced pronounced coating loss and contained advanced decay on the undersides of the timbers, but no decay occurred on coated, treated samples. Decay fungi were isolated from treated and non-treated coated arms, but isolation frequency was greater for non-treated materials. Coating thickness declined on both treated and non-treated materials, but the effects were greater on non-treated samples. Termites did not attack treated samples with or without coating, but destroyed untreated, non-coated samples and penetrated the polyurea coating to destroy untreated and borate dipped Douglas-fir. Polyurea coatings provided limited protection for non-treated wood.

KEYWORDS:

• Douglas-fir
• polyurea
• decay
• brown rot
• Antrodia sinuosa
• Formosan termites
• Coptotermes formosanus

ORCID

Jeffrey J. Morrell http://orcid.org/0000-0002-1524-9138

Additional information

Funding

This research was supported through the Oregon State University Utility Pole Research Cooperative, a consortium or electric utilities, chemical companies and wood treaters who collectively support research on improved wood use. The authors appreciate Brooks Manufacturing, Bellingham, WA, USA for providing the samples.