Cheng Piao

The termiticidal properties of superhydrophobic wood surfaces treated with ZnO nanorods

ZnO is a cost-effective and more environmentally friendly wood preservative than other metallic-based formulations. ZnO-stearate treatment imparts superhydrophobicity to wood surfaces, thereby providing triple protection to wood products, i.e., superhydrophobicity, inhibition to insects and microorganisms, and UV radiation protection. The objective of this study was to evaluate ZnO-stearate hydrophobic treatments of southern pine sapwood for resistance to Formosan subterranean termites. The data indicated that ZnO-stearate superhydrophobic treatment of southern pine wood samples received excellent mean visual ratings and mean weight loss values. The mean termite mortality was moderate. Unidentified fibril-like substances were found on the wood surfaces that were damaged by the termites.ZusammenfassungZnO ist ein kostengünstiges und umweltfreundlicheres Holzschutzmittel als viele andere Rezepturen auf Metallbasis. Eine Imprägnierung mit ZnO-Stearat verleiht der Holzoberfläche Superhydrophobizität mit Dreifachschutz, d.h. Superhydrophobizität, Wirkung gegen Insekten und Mikroorganismen sowie Schutz vor UV-Strahlung. Ziel dieser Studie war es, die Resistenz von mit ZnO-Stearat behandeltem Southern Pine Splintholz gegen die Formosan Bodentermiten zu untersuchen. Die Ergebnisse zeigten, dass der mittlere visuell festgestellte Zerstörungsgrad und der mittlere Masseverlust der mit ZnO-Stearat superhydrophobisch behandelten Southern Pine Splintholzproben sehr gering waren. Die mittlere Termitensterblichkeitsrate war mäßig. Auf den durch Termiten befallenen Holzoberflächen wurden unbekannte fibrillenartige Substanzen gefunden.

Laminated crossarms made from decommissioned chromated copper arsenate-treated utility pole wood. Part I: Mechanical and acoustic properties.

In recent years, rising concern over the disposal of preservative treated wood has generated interest in the reuse and recycling of this biomass resource. The primary objective of this study was to evaluate the bending strength and stiffness of laminated crossarms consisting entirely of virgin wood, entirely of decommissioned chromated copper arsenate (CCA)–treated utility pole wood, or a mixture of virgin wood and decommissioned CCA-treated utility pole wood after treatment with pentachlorophenol (penta). The secondary objective was to correlate acoustic properties of the laminated crossarms with their mechanical properties. Solid sawn virgin wood crossarms, solid sawn crossarms cut from decommissioned CCA-treated utility pole wood, and the laminated crossarms were evaluated for strength, stiffness, strain, and acoustic properties. The solid sawn virgin wood crossarms and all compositions of laminated crossarms met the American National Standards Institute minimum strength requirement. Only the solid saw...

Glue-line bonding performance of decommissioned CCA-treated wood. Part II: Retreated with CCA.

Disposal of decommissioned chromated copper arsenate (CCA-treated wood as landfill has become an important environmental concern. Reusing and recycling decommissioned treated wood seems to be the most practical environmental solution to the problem. In a previous report, 6-ply laminated beams made from decommissioned CCA-treated southern pine (Pinus spp.) wood utility poles and 6-ply laminated beams made from untreated virgin wood were studied to evaluate the effects of surface preparation method and cross-sectional region (high or low CCA retention) on bonding shear strength, wood failure, and delamination. In this study, 6-ply laminated beams having the same composition as those of the previous study were made and then pressure-treated (i.e., retreated) with CCA prior to being evaluated in the same manner as in the previous study. This study revealed that gains in CCA retention (as a result of retreatment with CCA) for beams made from decommissioned utility pole wood were similar to the gains for beams made from untreated virgin wood. CCA retreatment had little overall effect on either glue-line shear strength or wood failure of beams made from decommissioned wood utility poles, but overall substantially increased shear strength and wood failure of beams made from virgin wood. CCA retreatment also reduced the delamination of both beams made from decommissioned utility pole wood and beams made from virgin wood. Additional testing is warranted to further investigate the bonding performance of decommissioned CCA-treated transmission utility pole wood.

Recycling of Pentachlorophenol-Treated Southern Pine Utility Poles. Part I: Preservative Retention and Mechanical Properties

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. M...

Residual strength and stiffness of lumber from decommissioned chromated copper arsenate-treated southern pine utility poles

The reusability of decommissioned treated wood is primarily dependent on the residual strength of the wood after service. Determining the residual strength can provide useful information for structural design and reuse of the decommissioned treated wood. This study evaluated the residual strength of decommissioned chromated copper arsenate–treated utility pole wood. Eleven decommissioned southern pine (Pinus spp.) distribution poles and pole sections were evaluated, using small clear samples, for bending strength and stiffness across and along each pole. Results showed that the strength of the decommissioned treated wood varied across and along each pole and among the poles. Average modulus of rupture (MOR) was 80.9 percent of the typical MOR of longleaf pine (Pinus palustris) virgin wood, and average modulus of elasticity (MOE) was 83.9 percent of the typical MOE. Average MOR of the samples in the outer surface (first test zone) was 7.5 percent lower than the average MOR of the adjacent samples toward th...

Recycling of Pentachlorophenol-Treated Southern Pine Utility Poles. Part II: Mechanical and Delamination Properties of Laminated Beams

Reusing decommissioned utility poles and other preservative-treated wood reduces the total amount of preservatives in the environment and the need to fall the trees in the forest, offering economic and ecological advantages. In a previous study, the pentachlorophenol (penta) retention and mechanical properties of decommissioned penta-treated southern pine utility poles and pole sections were investigated. The current study evaluated the mechanical and delamination properties of laminated beams made of penta-treated utility pole wood. A total of 45 laminated beams and 15 solid-sawn beams were fabricated from decommissioned penta-treated utility pole wood and untreated southern pine virgin wood. Three composition schemes and two surface preparation methods were investigated for their effects on penta retention, bending, glue-line shear, and delamination properties of the laminated beams. Penta-treated utility pole wood absorbed more penta than virgin wood during retreatment. The bending strength of the lami...

Laminated crossarms made from decommissioned chromated copper arsenate-treated utility pole wood. Part II: Preservative retention, glue-line shear, and delamination.

Laminated utility pole crossarms constitute one of the potential industrial products that can be produced from decommissioned wood utility poles. A previous report evaluated the mechanical properties of laminated utility pole crossarms made from decommissioned chromated copper arsenate (CCA)―treated southern pine (Pinus spp.) utility pole wood, untreated virgin wood, and a mixture of virgin wood and decommissioned utility pole wood. In particular, the bending strength, stiffness, and acoustic properties were assessed after pentachlorophenol (penta) retreatment. This study evaluated CCA and penta retention, glue-line shear, and glue-line delamination of the laminated crossarms. The results of this study show that, after penta retreatment, penta retention increased in correlation to the presence of increasing numbers of treated wood plies in the beams. All the laminated crossarms met the minimum shear strength requirement of 8.60 MPa, which is specified in American Society for Testing and Materials (ASTM) Standard D2559. Most of the laminated crossarms (22 of 24) showed a delamination average of less than 5 percent. However, none of the beams met the individual glue-line delamination requirement (1%) of ASTM Standard D2559. More glue-line delamination was found between two utility pole wood plies and between a utility pole wood ply and a virgin wood ply than between two virgin wood plies. Delamination could be a concern for utility pole wood laminated crossarms to be used in an adverse environment. A better gluing system is needed to improve the delamination performance of utility pole wood laminated beams for exterior applications.