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 sawn decommissioned CCA-treated utility pole crossarms failed to meet the minimum strength requirement. Both crossarm composition and surface preparation had no significant effect on the strength of laminated crossarms. Maximum strain decreased with an increase in the number of utility pole wood plies in the laminated crossarms. Cubic relationships were found between stress wave acoustic velocity and the number of utility pole plies contained in the laminated crossarms. Both before and after penta treatment, a linear relationship was found between bending modulus of elasticity and stress wave acoustic velocity of the laminated crossarms. Penta treatment significantly reduced stress wave acoustic velocity for all categories of crossarms, both laminated and solid sawn.