Per Jostein Hovde

Coated wooden claddings and the influence of nanoparticles on the weathering performance

Accelerated climate aging experiments and cup measurements have been performed to investigate the effect of adding TiO2 nanoparticles and nanoclay to acrylic stain coatings against the influence of weathering. The coated specimens resistance toward solar radiation and water spray was evaluated by the discoloration rate from visual assessment and color analysis and by the chemical changes observed by Fourier transform infrared spectroscopy. Furthermore water vapor resistance was examined by the cup measurements. The nanomaterial containing coatings provided in general better protection against the artificial aging than the unmodified coating, showing the nanomaterials may have a natural place in coatings for protection of wood.

Accelerated climate aging of building materials and their characterization by Fourier transform infrared radiation analysis

Building materials and their durability and aging are essential to the performance of buildings and their building physical aspects over time. Accelerated climate aging investigations are carried out in order to study the durability of various building materials in a substantial shorter time span than natural weather aging would have allowed. Climate parameters such as temperature that includes freezing/thawing cycles, relative air humidity, water spray amount, solar and/or ultraviolet (UV) radiation and exposure duration are controlled in different climate aging apparatuses. Various aging processes in building materials, aging both by natural and accelerated climate exposure, may be studied in an attenuated total reflectance (ATR) Fourier transform infrared (FTIR) radiation analysis following the decomposition and/or formation of chemical bonds in these building materials and products. ATR-FTIR analysis of different building material samples exhibit various levels of experimental difficulties. In this investigation we have studied the FTIR spectra of climate-weathered wood, wood rot, mold fungus on wood, mold fungus on plasterboard, and plastic degradation by UV radiation. Both qualitative and quantitative results may be obtained by an ATR-FTIR analysis. In order to determine the aging progress and assess the effective lifetime of materials, components, or products, FTIR spectra should be recorded before, during, and after the climate aging. Hence, FTIR may be developed as an important tool to track the condition of various materials, components, and products during the lifetime of a building, and thereby applied as a tool for condition assessment, selection of maintenance intervals, and service life prediction of buildings.

Impregnated wooden claddings and the influence of nanoparticles on the weathering performance

Abstract This work was an investigation of the effect of nanoparticles on the durability of wood specimens exposed to artificial weathering. TiO2 and clay nanoparticles were mixed with preservative (Wolmanit CX-8) for improving the durability of Norway spruce (Picea abies). Impregnated and untreated specimens were subjected to Atlas Solar Simulator accelerated ageing test chamber for solar radiation and water spray exposure. The effectiveness of the treatment against colour and chemical changes was investigated using CIEL*a*b* colour measurements system and Fourier transform infrared analysis. The present study showed that the wood specimens that had been treated with preservatives containing nanoparticles were slightly more stable against artificial ageing than both untreated specimens and specimens treated with preservative alone.

Empirical prediction of smoke production in the ISO Room Corner Fire Test by use of ISO Cone Calorimeter Fire Test data

The combustion conditions in the ISO Room Corner Fire Test make it possible to predict full scale smoke production by use of prediction models and bench scale fire test data procured by the ISO Cone Calorimeter Fire Test. The full scale smoke production is governed by the type of material burning only if the rate of heat release is less than 400–600 kW. For higher rates of heat release, the smoke production is more governed by the combustion conditions. The influence of the combustion conditions on the full scale smoke production reduces the possibilities of smoke prediction to materials causing flashover within 10 min in the ISO Room Corner Fire Test. The smoke to heat ratio SQ (m2MJ) was used to compare smoke production between the scales. In general, the comparison revealed that the smoke yield was significantly less in full scale than in bench scale, especially for the plastics. Plastics do yield more smoke than wood based materials in both scales, but the differences in full scale are not as extreme as indicated by the bench scale smoke data. No simple correlations between the scales seem to exist. Multiple regression studies on empirical smoke prediction models show that bench scale fire parameters can be used to predict full scale fire performance. A quite accurate empirical smoke prediction model is presented for the group of materials which caused flashover within 10 min. The model predicts the full scale rate of smoke production at a rate of heat release of 400 kW. The presented results might be used to assess the fire safety hazard of visible smoke, but benchmarks of smoke hazard do not seem to exist. Thus further studies and agreement on safety levels and principles are needed for general visibility analysis concerning fire safety engineering purposes. Copyright

Fourier Transform Infrared Radiation Spectroscopy Applied for Wood Rot Decay and Mould Fungi Growth Detection

Material characterization may be carried out by the attenuated total reflectance (ATR) Fourier transform infrared (FTIR) radiation spectroscopical technique, which represents a powerful experimental tool. The ATR technique may be applied on both solid state materials, liquids, and gases with none or only minor sample preparations, also including materials which are nontransparent to IR radiation. This facilitation is made possible by pressing the sample directly onto various crystals, for example, diamond, with high refractive indices, in a special reflectance setup. Thus ATR saves time and enables the study of materials in a pristine condition, that is, the comprehensive sample preparation by pressing thin KBr pellets in traditional FTIR transmittance spectroscopy is hence avoided. Materials and their ageing processes, both ageing by natural and accelerated climate exposure, decomposition and formation of chemical bonds and products, may be studied in an ATR-FTIR analysis. In this work, the ATR-FTIR technique is utilized to detect wood rot decay and mould fungi growth on various building material substrates. An experimental challenge and aim is to be able to detect the wood rot decay and mould fungi growth at early stages when it is barely visible to the naked eye. Another goal is to be able to distinguish between various species of fungi and wood rot.

Durability, reaction to fire properties, and environmental impact of treated and untreated wooden claddings

Abstract This work summarizes the output of durability, reaction to fire properties, and environmental impact of wooden claddings subjected to treatments modified with TiO2 and clay nanoparticles. The objective was to investigate the effects of 1 wt% of TiO2 and clay nanoparticles in existing water-based and stain coatings and preservatives regarding the properties mentioned above. Water vapor resistance properties were used to assess the moisture transfer properties of the specimens by using the cup test. The reactions to fire properties of the specimens were analyzed using small-scale cone calorimeter test. Accelerated aging was used to study the weathering properties of specimens, where the performance of the specimens with aging was characterized using Fourier transform infrared (FTIR) analysis. The effect of increasing the percentage of nanoparticles from 1 wt% to 3 wt% on the weathering properties of the specimens was further analyzed. Moreover, comparison between the overall environmental impact between unmodified water-based paint and water-based paint modified with 1 wt% of TiO2 nanoparticles was performed using available environmental data and weathering test results as analyzed by FTIR.

Investigations of Accelerated Climate Aged Wood Substrates by Fourier Transform Infrared Material Characterization

Fourier transform infrared (FTIR) material characterization by applying the attenuated total reflectance (ATR) experimental technique represents a powerful measurement tool. The ATR technique may be applied on both solid state materials, liquids and gases with none or only minor sample preparations, also including materials which are nontransparent to infrared radiation. This facilitation is made possible by pressing the sample directly onto various crystals, for example, diamond, with high refractive indices, in a special reflectance setup. Materials undergoing ageing processes by natural and accelerated climate exposure, decomposition and formation of chemical bonds and products, may be studied in an ATR-FTIR analysis. In this work, the ATR-FTIR technique is utilized to detect changes in selected wood building material substrates subjected to accelerated climate exposure conditions. Changes in specific FTIR absorbance peaks are designated to different wood deterioration processes. One aim is by ATR-FTIR analysis to be able to quantitatively determine the length of the wood ageing time before priming/treatment. Climate parameters like temperature (including freezing/thawing), relative air humidity, wind driven rain amount, solar and/or ultraviolet radiation, and exposure duration may be controlled in different climate ageing apparatuses. Both impregnated and raw wood samples have been employed in the experimental investigations.

Effect of internal hydrophobation, silica fume and w/c on compressive strength of hardened cement pastes

Internal hydrophobation by adding hydrophobic agents during the mixing process is a method for reducing water permeability of cement based materials. It can be used as an alternative to other methods such as reducing water cement ratio (w/c) or using silica fume (SF). However, it may affect other properties of cement based materials such as compressive strength. In this paper the results of an experimental study on compressive strength of different hcps with main variables w/c, SF and hydrophobic agents are presented. Rapeseed oil and alkyl alkoxysilane were selected as hydrophobic agents. Although, a low dosage of hydrophobic agents can be more effective than lowering w/c or adding SF in reducing water permeability, an obvious reduction was observed in compressive strength by this way of internal hydrophobation compared to the other above mentioned methods. Different reasons such as lower hydration degree, chemical reactions of hydrophobic agents and non-uniform distribution of hydrophobic materials in t...