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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2017

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Abstract

Comprehensive approaches to predict performance of wood products are requested by international standards, and the first attempts have been made in the frame of European research projects. However, there is still an imminent need for a methodology to implement the durability and moisture performance of wood in an engineering design method and performance classification system. The aim of this study was therefore to establish an approach to predict service life of wood above ground taking into account the combined effect of wetting ability and durability data. A comprehensive data set was obtained from laboratory durability tests and still ongoing field trials in Norway, Germany and Sweden. In addition, four different wetting ability tests were performed with the same material. Based on a dose– response concept, decay rates for specimens exposed above ground were predicted implementing various indicating factors. A model was developed and optimised taking into account the resistance of wood against soft, white and brown rot as well as relevant types of water uptake and release. Decay rates from above-ground field tests at different test sites in Norway were predicted with the model. In a second step, the model was validated using data from laboratory and field tests performed in Germany and Sweden. The model was found to be fairly reliable, and it has the advantage to get implemented into existing engineering design guidelines. The approach at hand might furthermore be used for implementing wetting ability data into performance classification as requested by European standardisation bodies.

Abstract

Creosote is commonly used as a wood preservative for highway timber bridges in Norway. However, excessive creosote bleeding at various highway timber bridge sites lead to complaints, and a potentially bad reputation for wooden timber bridges. Macro-and microanatomical factors such as the amount of heartwood, annual ring width, annual ring orientation, ray-height and composition and resin canal area were investigated in order to classify seven timber bridges in Norway into bleeding- and non-bleeding bridges. A classification into bleeding and non-bleeding was possible for discriminant categories based on three anatomical factors analysed on wood core samples. The amount of heartwood content dominated the influencing factors, even obscuring the significance of other factors. Classification with a low amount of variables was done preferably on sample level instead of bridge level, due to the restricted number of 17 core samples per bridge.