Recycling of pentachlorophenol-treated southern pine utility poles. Part I: Preservative retention and mechanical properties.

摘要

Reusing decommissioned wood utility poles will extend the service life of the treated wood and offer economic and ecological advantages. The aim of this study was to evaluate pentachlorophenol (penta) retention and distribution, together with physical and mechanical properties of penta-treated southern pine (Pinus spp.) utility poles for reuse and recycling. Fifteen penta-treated decommissioned southern pine utility poles and pole sections were collected and studied. As expected, residual penta retention decreased from outside to the pith and from the top to the bottom of the poles. Of the 15 poles tested, penta retention averages at the two outer test zones varied from 3.9 to 5.6 kg/m3, while the overall penta retention averages of these poles varied from 3.2 to 5.4 kg/m3. The modulus of rupture (MOR) and modulus of elasticity (MOE) averages of the 15 poles and pole sections were 33.7 and 68.1 percent lower, respectively, than the published MOR and MOE values of virgin loblolly pine (Pinus taeda) wood. MOR and MOE varied in an M shape across the diameters of the poles due to surface aging. The shallow, aged surface layers, particularly of older poles, had low strength and relatively high penta retention, suggesting that surface layers should be removed from the recycled poles. However, most of the remaining pole portions had medium to high strength and were therefore reusable for other products.