Your search resulted in 609 documents. Displaying 25 entries per page.
Natural durability of European wood species for exterior use above ground
2003 - IRG/WP 03-10499
The main interest in using more timber for exterior constructions is to protect the environment, where wood is considered an environmentally friendly material. However, chemicals for wood protection are getting more and more restricted, consequently, the focus on the natural durability of wood is increased. Good, well-documented data on the durability of wood species in ground contact exist, which form the basis of the standard EN 350-2:1995. Yet, we have, however, no useful documentation for the natural durability of wood, when used outdoors above ground. The study is large-scale field trials, including more than 30 species, where the objective is to define and document the natural durability of European wood species when used outdoors above ground. The idea of the test set-up is to simulate different application situations of wood to recommend individual wood species for specific purposes – fit to purpose. Two basically different test set-ups are used: 1. Panels in close-to-practice applications: Horizontally oriented with and without covering. Vertically north turning and vertically south turning oriented with and without covering as well as 45 degrees south turning oriented without covering. 2. Lap-joints in standardised field exposures: The set-up is according to the CEN-standard ENV 12037: Wood Preservative – Field Test Method for determining the relative protective effectiveness of a wood preservative exposed out of ground contact – Horizontal lap-joint method. The paper presents the results of the appearance, the moisture fluctuation, mould growth and wood decay after 3 years field trial.
B Lindegaard, N Morsing
Durability of exterior natural wood finishes in Brazil
1985 - IRG/WP 3343
Wood finishes systems were evaluated in natural weathering conditions during 5 (five) years, over "Parana-pine" (Araucaria angustifolia). Test samples results show that: - Semitransparent wood preservative stains, based on polimerized linseed oil, provided very good protection to the wood, compared with the one based on alkyd varnish; - Solid color wood preservative stains provided good durability. However, film degrading process was identical to the one of conventional finishes; - Conventional paint and varnish showed decomposition caused by cracking, checking and flaking (scaling).
D R Macedo
How to Increase the Lifespan of Exterior Wood Coatings
2015 - IRG/WP 15-40700
In addition to aesthetic appeal, coatings are designed to protect the wood from weathering degradation in outdoor conditions. This paper gives an overview of the effects of main components of coating, coating properties, and wood treatments on coating performance. Understanding how different type of resins (alkyd, acrylic or polyurethane), amount of pigments, type of solvents (organic or water), and major additives will affect coating performance on wood, helps coating formulators to develop more durable coatings. It is beneficial for both wood scientists and coating chemists to learn which properties of coating has the highest impact on predicting its service life when exposed to weathering. For instance, measuring glass transition temperature (Tg) will define the degree of flexibility of a coating. Since wood swells and shrinks due to moisture uptake and subsequent drying; therefore, flexibility of a coating plays a critical role in defining its durability on wood in exterior conditions. Or learning how a new preservative formulation or a new modification technique changes the surface properties of wood will help coating formulators to develop more suitable coatings for that specific modified wood. An example will be given on why coatings that were formulated for chromated copper arsenate treated wood were not as effective when applied on Cu-based or heat-treated wood. Also, how these factors can help to increase the service life of exterior wood coatings will be further discussed.
Exterior birch plywood: potentiality of the thermo-hydro treatment
2016 - IRG/WP 16-40743
It has been found in the present study that, in laboratory fungi tests after leaching with water (EN 84), exterior birch (Betula spp.) plywood, as birch solid wood, is subjected to degradation by rot fungi. This limits the use of such plywood outdoors or in building structures in high humidity conditions. The possibility to improve the birch plywood fungal resistance was investigated in two ways: 1) thermo-hydro treatment (THT) of birch veneers, followed by its gluing with adhesive (experimental plywood), 2) THT of the industrial plywood (reference plywood). Taking into account the sensitivity of birch solid wood against the thermal treatment in water vapour medium at elevated pressure established in the previous tests, and the small thickness of veneers, four mild modification regimes were chosen (°C /min): 150/10, 150/50, 160/10, 160/50. For THT veneers, improvement of the physical properties (equilibrium moisture content, capillary water absorption, antiswelling efficiency) was achieved, but the samples’ fungal resistance conformed only to the durability class 3 according to EN 350-1. The plywood glued from THT veneers with a phenol-formaldehyde (PF) film did not demonstrate essentially better durability. The industrial untreated plywood in the test according to EN 12083 showed the durability class 1 according to EN 350-1, but after leaching, mass loss was similar to the control birch wood indices. Better durability was achieved, thermally modifying the industrial plywood in the regime 160/50 (class 3, moderately durable). The chemical changes of veneers (wood components, methoxyl groups) as a result of the THT action were analysed by chemical analysis and instrumental methods (elemental composition, Py-GC/MS analysis). To understand the effect of water leaching on the plywood fungal resistance, water leachates of veneers, plywood and the polymerised adhesive were analysed. It has been suggested that the durability of untreated plywood is influenced by the water soluble phenolic and/or furan type compounds, but the effect of fungi on THT birch veneers can be influenced by the low-molecular carbohydrate and lignin degradation products, formed in the thermal treatment.
B Andersons, I Andersone, A Meija-Feldmane, I Irbe, A Janberga, J Grinins
Performance of wood exterior structures above ground in Spain. Performance and durability of a shelter of spruce in a shopping centre after 20 years
2022 - IRG/WP 22-20680
Across Europe is very common to find wood exterior structures mainly build in sawn and glue-laminated wood. Most of these exterior wood structures use softwood wood species such as: fir, spruce, pine or douglas. In Spain exterior wood structures, became more and more popular since nineties, when sawn and glue-laminated wood were utilized for building exterior wood structures in overall Spain. In most cases, damages due to early decays appear before ten years of service life and the magnitude and extent of the damages can be important and in some wood exterior structures, the magnitude and extent of the damage due to early decay is such that it has reduced the cross section and strength of wood components, affecting the safety of these structures. The aim of this study is to understand the key factors in the performance and durability of wood exterior structures in Spain affecting by early decays, showing the case study of an wood exterior structure located in the city of Ponferrada in the Northwest of Spain, analyzing the influence of the diversity wood species, preservative treatments and protection by design (detail designs); combined with the variability of environmental conditions (different climatic zones and exposure to weathering), use classes and position and thickness of wood elements and the influence in the emergence of early pathological processes associated primarily with fungal decay (wood destroying fungi) and wood destroying insects in lesser extent.
D Lorenzo, A Lozano, M Alonso, J Fernández-Golfín, M Touza, J Benito
Finishes for outdoor timbers
1975 - IRG/WP 378
Proposed method for out-of-ground contact trials of exterior joinery protection systems
1981 - IRG/WP 2157
Methods for testing the efficacy of preservative treatments for exterior joinery are described using the format of a European Standard. Commercially used treatments applied to jointed test units (L-joints) which are then protected by conventional finishes are exposed to normal outdoor hazards out of ground contact. Assessment is made a) by determining eventual failure through decay and b) by destructive examination of replicate treated and untreated units, after increasing time intervals, rating comparative performance in terms of wood permeability increase and the progress of microbial colonisation.
J K Carey, D F Purslow, J G Savory
Effects of acetylation on the dimensional stability and decay resistance of kenaf (Hibiscus cannabinus L.) fiberboard
1996 - IRG/WP 96-40059
The objective of this study was to investigate the influence of the acetylation treated kenaf fiber, Phenol formaldehyde resin content level, and three fungi species on the dimensional stability and decay resistance of high density non wood composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness, length changes, and decay resistance of the high density kenaf fiberboards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Rowell
Wood preservation in Lithuania
2004 - IRG/WP 04-30363
This article is intended to give basic information on wood preservation activities in Lithuania and the main actors in wood preservations practice and research. Currently the main actors in practical Lithuanian wood preservation activity are enterprises of wood preservation industry united by the Lithuanian Wood Preservation Association. The most intensive activity in wood preservation practice and research started after 2001. The only active institution in wood preservation research currently is Lithuanian Forest Research Institute with 2 running projects. Lithuanian University of Agriculture and Kaunas University of Technology are active in standardization and have potential to start research. Main obstacles for future development of wood preservation research are: insufficient interest of industry in research and lack of skilled scientists.
Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 3: Full penetration of the refractory sapwood of white cypress
2000 - IRG/WP 00-40167
The heartwood of white cypress, Callitris glaucophylla, is renowned for its termite resistance and durability against decay. The sapwood, which can represent up to 30% of log volume, is non-durable and refractory to conventional preservative treatment. Previous work ascribes the lack of permeability to oily deposits within tracheids and ray cells. Environmental scanning electron microscopy was used to investigate ultrastructural aspects of sapwood permeability. Several pre-treatment processes to improve permeability were tested with limited success. Solvent drying allowed preservative penetration but damaged the structure of the timber. Neither, long term water soaking nor an oscillating pressure/vacuum cycle had any effect on porosity to water-borne treatments. Through extensive modifications to a standard VPI process we can now repeatedly achieve full penetration with organic solvent-based wood preservative solutions into white cypress sapwood. Effects of this process on the strength of the timber are being evaluated. Work is continuing as to the most effective and efficient treatment schedule and the latest results will be presented at IRG 31.
M J Kennedy, L M Stephens, M A Powell
European standardization for wood preservation
1988 - IRG/WP 2321
European standardization for wood preservation
1989 - IRG/WP 2335
The susceptibility of 35 Amazon wood species to Cryptotermes brevis (Walker)
1982 - IRG/WP 1160
Laboratory tests were carried to evaluate the susceptibility of 35 Amazon hardwoods to Cryptotermes brevis (Walker). The results were analysed statistically and showed that five wood species were non resistant, nine were resistant and the other twenty-one in between those classes of resistance.
M D Canedo
Possibility of use of wood species per class of biological risks. Attempt to determine criteria based on Pr EN 350-1/2/3
1992 - IRG/WP 92-2409
Development of marine borers research in Sao Paulo State, Brazil
1985 - IRG/WP 4117
This paper describes some field tests which have been carried on marine sites in Sao Paulo State mainly to investigate the natural resistance of Brazilian woods and the occurrence of marine borers. Some laboratory breeding tests which are being developed are also describe
G A C Lopez
Interspecific variability of European oak durability against white rot fungi (Coriolus versicolor): Comparison between sessile oak and peduncle oak (Quercus petraea and Quercus robur)
2001 - IRG/WP 01-10393
The knowledge of wood natural durability against biologic predators enable its external use. The resistance of European oak wood was reported like durable according to the EN 350-2. However, some individuals may contain high durable wood. Our research was focused to understand this variability in oak population that represent the first french species (4.1 millions of ha). Natural durability of European oak heartwood (Quercus petraea and Quercus robur) against white rot fungi (Coriolus versicolor) was tested according to european standard EN 113. The experimental material consists in 23 oaks robur and 26 petraea oaks sampled from 9 French regions. For each tree, 3 twin samples were taken off from heartwood situated at 1.30 m from the bottom of the tree. Different effects were tested by hierarchic variance analysis: "species", "forest within species" and "tree within forest". The tree effect is very significant for biologic natural resistance. Variability between species was also demonstrated. Although the species effect is significant, it's relatively weak compared with tree differences (it was declared significant 5%). Durability classification was determined according European standard EN 350-1. 69.2% of petraea oak trees are classified as high durable, 19.2% durable, 7.7% moderately durable and 3.8% slightly durable. In the case of robur oak 91.3% of trees are classified as high durable and 8.7% durable.
N Ayadi, B Charrier, M Irmouli, J P Charpentier, C J Allemand, F Feuillat, R Keller
Durability of larch (Larix spp.) wood against brown-rot fungi
1997 - IRG/WP 97-10228
Durability of the heartwood of Larix decidua, L. sibirica, L. gmelinii, L. gmelinii var japonica, L. gmelinii var olgensis and L. sibirica x decidua against brown rot fungi Coniophora puteana, Poria placenta and Gloeophyllum trabeum was tested according to EN 113 test method. Parallel samples were used to study the amount and composition of wood extractives. The sample trees originated from the research forest of Punkaharju Research Station. The average age of the trees was 60 years. In addition, from L. sibirica also trees at 25 and 102 years were used. Results show that the durability of larch is depending on species, age of the tree, the wood part (inner or outer heartwood) and fungus. The average durability of larch heartwood was equal to class 3 or 4 (moderately or slightly durable, according to the standard EN350:2) and comparable with the durability of pine heartwood (Pinus sylvestris L). However, the durability of L. gmelinii var olgensis and L. sibirica (102 years old) was on the higher level than that of the other studied species but the durability varied even within the same board. Also the durability of wood from L. sibirica grown in the Russian side (Siberia) was studied. It was equal to that of the trees grown in Finland. The average amount of resin acids of larch heartwood was only about 0.1% (dry weight). In contrast, the heartwood of scots pine may contain up to 4.0% of resin acids. Resin acids are found to inhibit the linear growth of certain fungi. Interestingly, the largest amounts of resin acids (0.3%) were found in the heartwood of L. gmelinii which also showed high durability. The concentration of water soluble extracts (mainly arabinogalactan) of larch heartwood was quite large, varying between 3.2 - 20.5%. The concentration of water soluble extracts in the heartwood increased along the age of the trees. Lowest level of extractives were found in Larix decidua which was also the least decay resistant species. The durability of wood in different targets and the role of different chemical compounds of larch heartwood on decay resistance needs to be clarified.
H Viitanen, L Paajanen, P Saranpää, P Viitaniemi
Inspection results of preservative treated stakes, maximum 33 years in field
1992 - IRG/WP 92-3690
Since in 1958, we have undertaken field experiments in Japan. For these field experiments, we used sapwoods of Japanese cedar called Sugi (Cryptomeria japonica) because of majority of plantation forest soft wood species in Japan. For some preservatives, we added sapwood of Japanese beech called Buna (Fagus crenata), a main Japanese hard wood species. Dimensions of these specimens were 30 x 30 x 600 mm³ (T x R x L). About 30 preservatives mainly water born but 20% of oil born preservatives included, were examined for this test. We checked the damage rating every year by the observation. The service life of the preservative treated stakes were estimated at the period when the average damage rating of stakes were reached beyond 2.5 . Creosote oil, creosote oil mixed heavy oil (75:25 and 50:50) and creosote oil mixed coal tar (75:25 and 50:50) are still sound conditions for 33 years. CCA (JIS K 1554 Type 1) 2% and Tancas C 2% are still sound conditions for 28 years. Because of soft rot, the treated Buna specimens were shorten as ones of treated Sugi.
K Suzuki, K Yamamoto, M Inoue, S Matsuoka
Natural Resistance of timbers to marine borer attack. COIPM/IRG CO-OPERATION. Final report concerning panels exposed in the sea at Sekondi, Ghana
1979 - IRG/WP 449
The test was carried out according to Document COIPM/72.044, Revised procedure for the testing of naturally durable timbers against marine borers. The panels of the three species remaining in the test at the end of 1978 were removed and assessed visually. An average rating was given to the panels of each species.
F F K Ampong
The effect of sapwood on the rate of deterioration of fence posts
1986 - IRG/WP 1277
In order to evaluate the effect of the presence of sapwood on the rate of deterioration of fence posts, 30 specimens with and without sapwood of Eucalyptus citriodora, Eucalyptus paniculata, Eucalyptus saligna and Eucalyptus tereticornis were exposed in three test sites in the State of São Paulo, Brazil. The results of the inspection carried out in 1985, after 5 years of exposure, are reported in the present paper.
M S Cavalcante, G A C Lopez, E S F Mucci, R G Montagna
Wood furfurylation process and properties of furfurylated wood
2004 - IRG/WP 04-40289
The first processes for “furfurylation” of wood (wood modification with furfuryl alcohol) were developed several decades ago. Furfuryl alcohol is a renewable chemical since it is derived from furfural, which is produced from hydrolysed biomass waste. Over the last decade modernised processes for furfurylation of wood have been developed. These new processes are based on new catalytic systems and process additives. Two main processes for production of furfurylated wood have been developed for WPT (Wood Polymer Technology ASA) by the authors – Kebony 100 for high modification levels of hardwoods and VisorWood for lower modification levels of pine. Commercial production according to the Kebony process has been running since August 2000, mainly for flooring. A small Kebony production plant is now in operation in Lithuania. A larger Kebony/VisorWood production plant started up in September 2003 in Porsgrunn, Norway. Several new plants operating according to the VisorWood process, each with an annual capacity of 10 000 m³ or more, are under construction. The properties of furfurylated wood depend on the retention of grafted/polymerised furfuryl alcohol (PFA) in the wood. At high modification levels (high retention of PFA) the enhancement of a wide variety of properties are achieved: an exceptional hardness increase, exceptional resistance to microbial decay and insect attack, high resistance to chemical degradation, increase in MOR & MOE, and high dimensional stability. At lower modification levels many property enhancements also occur, however to slightly lower extent. Notable are resistance to microbial decay and insect attack, increase in MOR & MOE, and relatively high dimensional stability.
M Westin, S Lande, M Schneider
Durability of pine modified by 9 different methods
2004 - IRG/WP 04-40288
The decay resistance was studied for pine modified by nine methods of wood modification: 1) Acetylation, 2) Treatment with methylated melamine resin (MMF), 3) Acetylation followed by post-treatment with MMF-resin, 4) Thermal modification, 5) Furfurylation, 6) Maleoylation (using water solution of MG or ethanol solution of maleic anhydride), 7) Succinylation, 8) NMA-modification and 9) modification with reactive linseed oil derivative (UZA), Wood blocks of Scots pine (Pinus sylvestris L.) sapwood were modified in pilot plants. Methods 1-5 were performed by the authors at Chalmers University of Technology or at BFH in Hamburg. Methods 5-9 were part of a European research project (the Chemowood project, FAIR-CT97-3187) and therefore each of these modifications was performed by the project participant responsible for the method. For laboratory testing in TMCs (modified European standard ENV 807) and pure basidiomycete culture bioassays, smaller test specimens were cut from the modified wood blocks. Most of the modification methods were applied on test specimens for marine field testing (EN 275) and some methods to produce mini-stakes for field tests in five Swedish fields. Some modification methods result in modified wood with poor durability, whereas other methods (acetylation, furfurylation and MMF-treatment) seem to provide excellent resistance to microbial decay.
M Westin, A O Rapp, T Nilsson
Chemical compounds from Eperua falcata and Eperua grandiflora heartwood and their biological activities against wood destroying fungus (Coriolus versicolor)
2005 - IRG/WP 05-30373
The chemistry analysis of the compounds present in dichloromethane and ethanolic fraction as well as bioassays enables to understand the durability differences of Eperua falcata and Eperua grandiflora. The principal distinction between these two species is the acidic subfraction of diterpenoic extract, which is antifungic in Eperua falcata when tested in in-vitro conditions. This study also enables to show that ethanolic fraction plays an important role in the mechanism of natural durability. It also reports the first isolation of cativic acid in Eperua falcata wood.
N Amusant, C Moretti, B Richard, E Prost, J M Nuzillard, M-F Thévenon
Wood in concrete. Summary of discussion at IRG 14, Surfers Paradise, Australia
1984 - IRG/WP 3264
The performance of untreated and preservative treated wood when placed in direct contact with concrete was considered in a discussion session at IRG 14. While published reports in this area are scarce, research is in progress internationally and a variety of practices are currently available to minimize any additional hazard posed by contact with concrete. This report summarizes the points raised at the IRG discussion.
R J Murphy
Report of the meetings of the Refractory Timbers Sub-group, Rotorua, New Zealand, 15 & 17 May 1990
1990 - IRG/WP 3637
R J Murphy