There is limited and controversial experience within industry and academia related to the decay of wood plastic composite (WPC) materials subject to laboratory testing and exterior exposure. There is also a lack of data comparing laboratory test results with the field performance for these composites. The objective of this work was to generate data to address this niche. Experimental WPCs were made for testing in such a way that they matched the manufacturing process, dimensions, and water absorption of selected commercial decking boards. Samples made were divided into two identical groups of materials. The first group was exposed in exterior conditions in Vancouver, BC and Hilo, Hawaii at sun and shadow sites. Water absorption and biological activity were monitored by field inspection, density change measurement and optical and scanning electron microscopy. The second group of samples were used for soil block culture testing performed according to ASTM D1413 (or AWPA E10). Specimens of different sizes were conditioned by exposure to cold or warm water as well as a high humidity environment at elevated temperature. Results of decay fungi activity were reported as specimens weight loss or corresponding density decrease. The observed density changes during field exposure and soil block culture testing were compared. It was found that experimental WPC exposed to aggressive exterior conditions underwent decay, which was detected by microscopic inspection of boards cross-section and calculated density decrease. However, no characteristic decay fungi fruiting bodies were found on sample surfaces during field inspections. The decay process of tested materials in the field seems to require an initiation period dependent on exposure site. The shortest initiation time and the most aggressive environment for decay WPC were found at the sunny site in Hilo. Laboratory soil block culture testing showed weight loss and density decrease of experimental WPC dependent on conditioning. To match the density decrease in field exposure with that observed in laboratory testing, conditioning of samples was required.
展开▼
