Wood plastic composites (WPC) are a new group of materials, which are mainly used outside close to ground or in ground contact. Many WPC-Products contain between 70% and 75% wood. From experience it is very well known that WPC is not fully resistant against biological attack, but the mode of action and the importance of the attack for the product stability are different from solid wood. Hence the new standard for deckings made from WPC (prEN 15534-4) includes an obligatory durability testing against basidiomycetes, if the product is used under use class 3 conditions. Compared to untreated solid wood WPC exhibits a much slower and lower water uptake. This property helps to prevent biological colonization in an early stage, although it does not serve as complete protection mechanism. Concerning durability testing, it is difficult to reach sufficient moisture content in the time frame of testing. Furthermore the interpretation of test results is difficult, since the mass loss to strength relation is unknown. Additionally moisture uptake causes an irreversible strength loss of WPC. In order to overcome the mentioned problems a new testing method is described in prEN 15534-1. In this paper several test methods for WPC were carried out and evaluated regarding their suitability for durability testing of WPC against basidiomycetes under laboratory conditions. The tests included various pre-wetting methods. Materials with various compositions and sample sizes were compared. After durability testing the mass loss and changes in strength and stiffness of the samples were evaluated. The results of different test methods have shown that the new standard prEN 15534-1 provides an efficient test design, which allows the measurement and evaluation of the durability of WPC under laboratory conditions.
Keywords: wood plastic composites, basidiomycetes, biological durability, laboratory testing, EN 15534
Authors
Krause A.
Department of Wood Science, University of Hamburg, Hamburg
Department of Wood Biology and Wood Products, University of Göttingen, Göttingen
Gellerich A.
Department of Wood Biology and Wood Products, University of Göttingen, Göttingen
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