Nanotechnology Based Wood Treatments: Weathering performance, reaction to fire and environmental impact
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The selection of appropriate building materials is one factor which determines the sustainability of buildings. Utilization of nanobased treated wooden claddings have been claimed to be efficient towards improving a number of limitations which holds back from using wood as a building material. However, there are also critics related to the potential environmental risks of nanobased treatments (Article I). In this research work, titanium dioxide (TiO2) and clay nanoparticles are incorporated in wood coatings and preservatives to investigate their performance on improving durability and reaction to fire properties of Norway spruce (picea abies). Moreover, the environmental loads or benefits of specimens coated with water based paint modified with TiO2 nanoparticles were investigated with the help of life cycle assessment tools and accelerated ageing test results Weathering of impregnated, coated and untreated specimens was performed in an Atlas solar simulator accelerated ageing test chamber through solar radiation and water spray exposure. The specimens were evaluated by using colour measurements system and Fourier transform infrared (FTIR) analysis. Furthermore, an acceleration factor was calculated in order to estimate the equivalent service life of the wood applied in real climate conditions. This study addresses the use of accelerated climate ageing tests in order to get overview of the performance of nanobased treated wood with respect to weathering (Article IV, Article V, Article VI and Article VII). The effects of increasing the amount of the nanoparticles used in the paint on the weathering properties of the specimens were further analysed (Article VIII). The reaction to fire properties of the specimens were analysed using small scale cone calorimeter tests. The time to ignition, heat release rate, peak and total heat release rate were measured and analysed in the cone calorimeter (Article X). Furthermore, moisture flow management properties of the specimens were assessed (Article II, Article III, Article VI and Article X). Life cycle assessment (LCA) was performed to compare the performance of specimens coated with and without TiO2 nanoparticles containing paints to get an overview of the performance of nanobased treated wooden claddings from a durability and lifecycle point of view (Article IX). The LCA was performed based on environmental product declaration and ecolabel inventory data and maintenance interval determined from accelerated ageing test results. Finally, the overall performance of the treated specimens towards improving the selected wood properties plus their potential environmental impact was summarized using durability, reaction to fire and life cycle analysis test results (Article XI).