Wood-plastic composites (WPCs) have become an integral part of the residential deck market in North America - their market share has more than doubled in the last 5 years and some estimates suggest they will surpass 30 percent of the market before the end of the decade. Initially, these materials were assumed to be inherently resistant to fungi and insects and were touted by the manufacturers as being a 'maintenance free' product. It was thought that the thermoplastic resin would completely envelop the wood particle, thereby protecting it against wood-destroying organisms. The issue of WPC durability continues to receive considerable attention and is the focus of dedicated sessions at international conferences such as this one. To date, standards and test methods that are utilized as part of the product development cycle have continued to focus on testing 'virgin', unweathered material and have, for the most part, overlooked the importance of rigorous, long-term field testing. By comparison, the development of wood preservatives to treat solid lumber for the residential deck market involves extensive field testing as a necessary component in the standards approval process. This paper looks at the issue of field testing as related to WPCs and highlights how such tests can yield a dramatically different perception of durability as compared to standard industry tests on unweathered material. These results from the field show that WPCs can achieve the necessary moisture content capable of initiating and supporting fungal decay.
展开▼
