How does the test methodology influence the outcome of durability testing of thermally modified wood

IRG/WP 15-40699

A Gellerich, S Bollmus, H Militz

Thermally modified wood is commercially available on the European market since many years. Today, many production units with various production capacities and different modification processes exist. Industrial scale wood heat treatment processes, under the trade name of ThermoWood were developed in Finland. ThermoWood has two standard treatment classes with different target properties, namely Thermo-S (stability) and Thermo-D (durability). The objective of this study was the investigation of the durability of ThermoWood against wood destroying fungi in laboratory tests. Thereby two key issues were in the focus, the comparison of two European laboratory test standards, namely CEN/TS 15083-1 and EN 113 and a comparison of ThermoWood of different suppliers. Therefore commercially treated wood (Spruce and Scots pine) was used from 5 different producers of the ITWA. Sapwood as well as heartwood was tested. The durability classes were calculated depending on test setup, treatment class and wooden part. The results have shown that the quality of thermally modified wood delivered by five different suppliers of the material was very homogeneous, although the wood material was produced in different commercial facilities with different raw material. The durability classification showed similar results for both calculations which are based on the CEN/TS 15083-1 and EN 113/EN 350-1. As it was expected, Thermo-S modified wood was less durable than Thermo-D modified wood, because of the different target properties of the treatment classes. Furthermore the results displayed no clearly differences between wood species and sap- and heartwood parts regarding the durability classification within the same treatment class.


Keywords: thermally modified wood, durability test, durability classification

Conference: 15-05-10/14 Vina del Mar, Chile


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