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.
2019
Sammendrag
No abstract has been registered
Sammendrag
Carbon footprint over the life cycle is one of the most common environmental performance indicators. In recent years, several wood material producers have published environmental product declarations (EPDs) according to the EN 15804, which makes it possible to compare the carbon footprint of product alternatives. The objective of this study was to investigate the effect of service life aspects by comparing the carbon footprint of treated wood decking products with similar performance expectations. The results showed that the modified wood products had substantially larger carbon footprints during manufacturing than preservative-treated decking materials. Replacement of modified wood during service life creates a huge impact on life cycle carbon footprint, while maintenance with oil provided a large contribution for preservative-treated decking. Hence, service life and maintenance intervals are crucial for the performance ranking between products. The methodological issues to be aware of are: how the functional unit specifies the key performance requirements for the installed product, and whether full replacement is the best modeling option in cases where the decking installation is close to the end of the required service life.
Sammendrag
In built environments the combustibility of wood is a great concern, which limits the use of wood as a building material due to legislation. The reaction-to-fire properties of wood can be altered with the use of fire-retardant chemicals, and most of the commonly used fire retardants already have a long history of use. However, only limited information is available on the impact of different fire retardants on the adhesion properties of wood. Additionally, comparative studies between chemicals from different groups of fire retardants is scarce. The objective of this study was to investigate and compare the effects of two commonly used fire retardants, sodium silicate (SS) and diammonium phosphate (DAP), on veneer properties, the focus being especially on thermal behavior and adhesion. Thermal properties and combustibility were studied using thermogravimetric analysis (TGA), flame test and calorimetry. Glue bond strength was analyzed with an automated bonding evaluation system (ABES) and the leaching of chemicals was determined according to EN84. Additionally, the surface characteristics of modified veneers were imaged with scanning electron microscopy (SEM). Results revealed notable differences in the thermal properties of SS and DAP, with DAP having better fire-retardant performance in all thermal testing. SS also affected thermal properties and combustibility of modified veneers, but the effect was only moderate compared to DAP. Neither SS or DAP had any significant resistance against leaching but ABES testing showed a notable increase in the glue bond strength of DAP modified veneers.
Sammendrag
Acetylated wood is a durable and dimensionally stable product with many potential applications in exterior timber structures. Research has shown that acetylated wood can be effectively bonded by various adhesive types. However, one of the most commonly used adhesives for timber constructions, melamine urea formaldehyde (MUF), shows poor performance in combination with acetylated wood in delamination tests based on cyclic wetting and drying. The hydrophobic acetylated wood surface leads to reduced adhesion due to poorer adhesive wetting and fewer chemical bonds between the resin and the wood polymers. The use of a resorcinol-formaldehyde (RF)-based primer on the acetylated wood surface prior to the application of MUF leads to positive gluing results with both acetylated radiata pine and beech, providing significantly improved resistance to delamination. Radial penetration of the primer and MUF in acetylated wood shows higher penetration compared with untreated wood. In addition, a phenol resorcinol-formaldehyde adhesive system showed high resistance against delamination and can be used for gluing of acetylated wood.
Forfattere
Charlotte Grosse Warren J. Grigsby Marion Noël Andreas Treu Marie-France Thévenon Philippe GérardinSammendrag
When exposed to moisture, wood undergoes swelling and is susceptible to fungal degradation. Chemical modification via oligomeric lactic acid (OLA) treatment has been found to be a promising environmentally friendly solution to this disadvantage. In this study, wood was impregnated with OLA and then variously heat treated to polymerize the OLA in situ. The effect of curing temperature and time on OLA polymerization has been determined chemically. Dimensional stability was examined by water immersion and hygroscopicity measurements and biological decay resistance also evaluated. OLA impregnation followed by heat treatment enhanced wood properties. OLA cure at 160 °C for 48 h resulted in treated wood with greater dimensional stability and biological resistance.
Sammendrag
Surface mould growth contributes to the colour changes of outdoor exposed wood over time. Modelling mould growth can thus help visualize wooden facades’ colour development, which can improve facade design and service life. However, existing wood mould models do not consider transient wetting effects that occur outdoors due to precipitation and condensation. To address this, four mould models were evaluated using laboratory experimental data that included exposure to transient wetting. First, the models (the original and the updated VTT model, the biohygrothermal model and the mould resistance design (MRD) model) were evaluated for Scots pine sapwood. For this evaluation, the transient wetting effect was implemented in the models by using hourly wood surface relative humidity (RH), calculated from electrical resistance measurements, as input. This showed that the original and the updated VTT model gave best fit to the experimental data. However, further evaluation of these two models for more wood materials showed that the updated VTT model was sensitive to the choice of material parameters. Large discrepancies occurred when varying the material parameters in the updated VTT model. Finally, different estimates of RH were tested in the original VTT model. Using wood surface RH as input gave best fit to the experimental data, and ambient air RH gave poorest fit. Overall, the results indicate that the original VTT model is fairly reliable and can be used to predict mould growth on wooden claddings exposed to transient wetting as long as the wood surface climate is used as climatic input data.
Foredrag – My experience with COST networks – cooperation, scientific boost and friendship
Lone Ross
Forfattere
Lone RossSammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
Laboratory screening tests are commonly used to indicate wood materials’ resistance or susceptibility to surface mould growth, but the results can deviate from what happens during outdoor exposure. In this study, the aim was to investigate how well agar plate screening tests and water uptake tests can predict mould growth on exterior wooden claddings. The tested wood materials included Norway spruce heartwood (Picea abies), sapwood and heartwood of Scots pine (Pinus sylvestris), aspen (Populus tremula), acetylated Radiata pine (Pinus radiata) and DMDHEU-modifed Scots pine sapwood. The agar plate test included four inoculation methods (two monoculture spore suspensions of Aureobasidium species, one mixed-culture spore suspension, and inoculation from outdoor air) and three incubation temperatures (5, 16 and 27 °C). Inoculation method and incubation temperature had signifcant efects on the mould rating in the agar plate screening test, but none of the agar plate test combinations gave good indications of outdoor performance. Results from the agar plate test gave signifcantly negative correlations or no signifcant correlation with results from the outdoor test. However, the water uptake test gave signifcantly positive correlations with outdoor mould rating, and could be a useful indicator of susceptibility of uncoated wooden claddings to surface mould growth.
Sammendrag
This study addresses changes in visual appearance of unpainted wood materials exposed outdoors. Specimens of aspen (Populus tremula), Norway spruce (Picea abies), untreated Scots pine (Pinus sylvestris), DMDHEU-modified Scots pine and acetylated Radiata pine (Pinus radiata) were exposed facing south in Ås, Norway for 62 weeks. During this period, mould growth coverage, lightness (L*) and the uniformity of the weather grey colour were assessed. Mould growth coverage was evaluated visually using a rating system. L* and the uniformity were evaluated using image analysis. The increase in mould rating of the wood materials developed in varying speed, but all specimens had reached the maximum rating after 42 weeks. Until then, the changes in L* correlated significantly with the mould rating. However, the specimens continued to darken after they had reached maximum mould rating. DMDHEU was the only material that obtained a more uniform colour as a consequence of the weathering.