Technical feasibility of flakeboard production from recycled CCA-treated wood

Abstract

Chromated copper arsenate (CCA) treated wood is an economical, durable and aesthetically pleasing residential material used for many exterior application such as decks, fences, playground equipment, utility poles, and others. It has been most widely used in North America since the 1970’s. A large volume of CCA-treated wood is currently coming out of service. Traditional landfilling or incineration is environmentally unacceptable. Recycling CCA-treated wood into composite products is one alternative to ease the disposal problem. It also has the potential to relieve harvesting pressure from the nation's forestlands. After recycling, the remaining CCA content in the wood can still have preserving capability against decay. In this study, the effects of different ratios of recycled CCA-treated wood and untreated virgin wood on flakeboard properties were compared. The mechanical, physical, decay resistance, elemental concentrations, and leaching characteristics of flakeboards manufactured from five different ratios of recycled CCA-treated wood and untreated virgin southern pine wood were investigated. The ratios were 100:0, 75:25, 50:50, 25:75, and 0:100. The CCA retention levels of out-of-service CCA-treated posts (experimental raw material) as well as the flakeboard fabricated from the different ratios of recycled CCA-treated wood and untreated virgin wood were also tested. The median ratio with 50% of CCA-treated wood and un-treated wood was found to be the optimum combination. In this case, residual CCA level was sufficient enough to prevent substantial weight losses for the decay tests but low enough so that panel mechanical and physical properties were not substantially adversely affected.