Your search resulted in 162 documents. Displaying 25 entries per page.
Mechanical resistance of Pinus radiata CCA treated and face jointed with PVA adhesive
1999 - IRG/WP 99-40140
Due to the increased use of Pinus radiata timber composites (laminated structural members, panels, etc), its low natural durability and the toxicity of phenol-formaldehyde type adhesives, a PVA (polyvinyl acetate) adhesive was evaluated in machined and rough CCA treated and untreated face joint samples under DIN 68602 (EN 204-205) standard for groups of requirement 3 and 4. The results showed that the adhesive resisted the face joint in machined samples without CCA treatment. Rough wood samples did not meet the standard. The effect of the CCA treatment up to 4 kg oxide/m3 prior to the bonding produced a decrease in the mechanical strength of the joint in both types of roughness. Treated and machined samples had similar behaviour as rough untreated samples. The selected adhesive is not good in applications on weather exposed service of composites, since in group 3 requirement all samples failed the bending test at the adhesive joint and not at the clean wood portion.
M C Rose, L Reyes, P León
Relationship between bond strength and surface characteristics of CCA-treated Douglas-fir
1993 - IRG/WP 93-30008
Chromated-copper-arsenate (CCA) treated Douglas-fir was laminated using a commercial phenol-resorcinol resin. CCA treatment enhanced the water repelleney of wood espeeially in the presence of extractives. However, the shear strength of CCA treated wood was 12% lower in dry condition and 38% lower in wet condition after six cycles of vacuum-pressure test than that of untreated wood. Slight removal of treated wood surface by planer or sander contributed for better adhesion, although it was not enough. The characteristics of treated wood surface was analyzed by X-ray photoelectron spectroscopy (XPS). CCA treatment increased C1 (C-H) and decreased C2 (C-OH), indicating migrated exctractives have enhanced the water repelleney of treated surface. The removal of hydrophobic surface of CCA-treated wood decreased C1 component of C1s spectra on the new surface.
K Yamamoto, J N R Ruddick
Biological durabilityof cement-bonded particleboard
1997 - IRG/WP 97-20115
Cement-bonded particleboard (CBP) is a panel product manufactured from a combination of wood particle and cement with various ratio. The wood particle is used as reinforced material and the cement as an inorganic binder. Because of its many excellent properties, such as high weathering resistance, sound attenuation, and good acceptance for a range of surface treatments, CBP is widely used as a facade material in Japan. The present study is carried out to investigate the biological durability of CBP. The tested material was a standard commercial CBP product and obtained directly from one Japanese producing company. Two experiments were conducted. One was decay test by applying an Japanese standard method. The other one studied the effect of fungal attack on the internal bonding strength (IB) of the material. Two other commercial structural wood-based composites, i.e. Oriented Strand Board (OSB) and Medium Density Fiberboard (MDF), were also included in the study with the purpose of comparison.
Qiao Wang, M Takahashi
Wettability and bonding strength of wood thermally-treated with different combinations of soy oil and chemical additives
2009 - IRG/WP 09-40454
Thermal treatment is a method which has gained wider acceptability as an alternative to the chemical treatment in wood preservation. In order to maximize the benefits of this technique several options have been adopted including the use of soy oil in transferring the heat to the wood. Available information on thermal treatment in general and the oil method in particular show that there are still need for further investigations on the possibilities of improving the available options in order to evolve new techniques. Thermal treatment of three wood species of commercial importance in Canada and North America in general was carried out at in different combinations of soy oil, slack wax and cobalt stain medium. The effect of chemical additives in soy oil during thermal treatment depends on both wood species and the type of additives. The slack wax generally has higher impacts than the cobalt stain and black spruce (Picea mariana) shows more consistent response to the effects of the chemical additives.
L Awoyemi, P A Cooper, T Ung
Influence addition of boron compounds to adhesives on the bonding quality and fungicidal properties of glued wood
2010 - IRG/WP 10-40497
Wood is one of the most important construction materials. However, users of wood face two issues: limited dimensions and insufficient durability. These issues have been overcome with the development of bonding and wood preservation. The preservation of glued wood is elucidated in this paper. Through the addition of boric acid to adhesives, we tried to improve the fungicidal properties of glued wood. The results of mechanical testing (shear strength and delamination) showed that the addition of boric acid to glue did not have a negative impact on the performance of the glued wood. On the contrary, some properties were even improved. Unfortunately, the addition of boric acid to impregnated wood does not improve the resistance of the glued wood to brown rot fungi.
M Humar, B Lesar, A Ugovsek, M Kariz, P Kralj, M Šernek
Microbiological degradation of wooden piles in building foundations
1988 - IRG/WP 1370
White rot, soft rot and bacterial attack have been detected in softwood piles under buildings. In some cases bacteria were found to be the main degradation organisms in the studied piles. The water content of degraded piles was very high. The compression strength was quite low also in the piles deteriorated by bacteria. The density of wood was very variable, and the degree of degradation could not be evaluated according to density analyses.
L Paajanen, H Viitanen
Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi
Improvements of monitoring the effects of soil organisms on wood in fungal cellar tests
1996 - IRG/WP 96-20093
Accelerated testing the durability of preservative treated timber in a so called "fungal cellar" or "soil-bed" to evaluate its performance in ground contact is widespread practice. In order to obtain a more accurate and reproducible estimate of preservative performance, several institutes, among them the BAM in Berlin, have routinely carried out static bending tests in addition to visual examination. These tests were usually performed with a defined maximum load or deflection path regardless of the remaining degree of elasticity of the test specimens. Recent studies at the BAM revealed that by modifying the method, i.e. by restricting the applied load to the non-destructive interval for each individual test specimen, the calculated modulus of elasticity (MOE) reflect the changing strength properties caused by biological deterioration and allow within a relatively short time valuable predictions on the service life of the treated timber in soil contact.
I Stephan, S Göller, D Rudolph
Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden
E.R.C. Pole Tester
1982 - IRG/WP 2190
Operating instructions for the ECRC pole-strength tester 120kNm 'PEST'.
The utilisation and preservation of Eucalyptus globulus agricultural stakes from Portugal
1989 - IRG/WP 3520
This paper reviews the development and utilisation of Tanalith C treated Eucalyptus globulus stakes: particular reference is made to their use in vineyards. The treatment characteristics of commercially available stakes will be described and penetration patterns evaluated.
A Milne e Carmo, D A Lewis, A Lyman
Quantitative assessment of the condition of field specimens
1981 - IRG/WP 2154
Suggestions for a discussion on the desirability of an extension to the existing procedure of assessment of the condition of field specimens by adding more objective, reproducible methods in order to obtain earlier and more specific information than at present on the effect of biological attack on strength and other properties of the specimens as well as the time aspect.
Dimensional stabilization of wood with dimethylol compounds
1987 - IRG/WP 3412
This study showed that a substantial degree of dimensional stability can be imparted to wood by crosslinking with low concentrations of dimethyloldihydroxyethyleneurea. It was demonstrated that by selecting the right catalyst system the cure temperature can be reduced to the point that strength loss of the treated wood is minimized.
D D Nicholas, A D Williams
Performance results of wood treated with CCA-PEG
1986 - IRG/WP 3363
The addition of polyethylene glycol (PEG) to the CCA system has been shown to reduce the surface hardness of poles and ease spur penetration during climbing. This paper addresses the results of tests dealing with preservative retention and penetration, permanence of CCA and PEG, strength, drying rate, and checking characteristics.
W P Trumble, E E Messina
Effects of various preservative treatments on the mechanical and physical properties of plywood
1993 - IRG/WP 93-40007
The technical properties of plywood are related to both the intrinsic characteristics of its composing wood species and the quality and performance of the glue bond which acts as an interface between veneer sheets. Consequently mechanical and physical testing and glue bond strength analysis offer an appropriate means for studying the effect of preservative treatments on the overall quality of plywood. A range of boards was treated with waterborne and oilborne preservatives. Changes in modulus of elasticity, modulus of rupture and tensile strength were noted as well as variations in physical properties. Analysis of the glue bond strength was done by shear strength testing and determination of the amount of wood failure after different ageing procedures.
J Van Acker, M Stevens
Research on the effects of wood preservatives on the physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky)
1985 - IRG/WP 3351
This research work was conducted with the aim of using preservatives such as Basilit and Wolman Salts with Iranian beech and to study any physical and mechanical changes these might have on the beech species of Iran. Samples were divided into three groups; one group were used as untreated controls, the second group was treated with Basilit and the third group was treated with Wolmanit. Results obtained according to the AFNOR French system of standards were: (1) After 140 days the moisture content of each group had reached 7.3%. (2) Samples with Wolmanit absorbed twice as much as those with Basilit and the two groups has some differences in specific gravity. (3) The volumetric shrinkage of wood preserved with Wolmanit was one fifth of that treated with Basilit. (4) In bending tests the samples treated with Wolmanit had more strength up to point of rupture than those preserved with Basilit. (5) The modulus of elasticity was more in samples preserved with Basilit than in those preserved with Wolmanit. (6) In compression parallel to the grain the samples impregnated with Basilit had more resistance than in those impregnated with Wolmanit. (7) In tension tests, the samples preserved with Basilit were stronger than those treated with Wolmanit. (8) In impact bending tests, the Basilit samples were stronger than the the Wolmanit ones. (9) In hardness tests, the resistance to indentation was less with the samples treated with Basilit than with those treated with Wolmanit; the Basilit seems to make the wood softer and from this result this type of treated wood could be recommended for use by carpenters and in woodworking shops.
The performance of wood preservatives in soil-bed soft rot tests
1993 - IRG/WP 93-20007
Testing the efficacy of wood preservatives in soil is recognised as a fundamental part of the assessment of long-term wood protection in ground contact. Laboratory based tests can provide a hazardous environment in which a preservative can be challenged by a range of micro-organisms. This paper presents the results of tests carried out to investigate the performance of wood preservatives in a wet soil environment using both strength loss and weight loss as the main criteria for performance assessment.
G R Williams, S Caswell
Studies on the preservation of structrual plywood - Part 1: Decay resistance of structural plywood
1974 - IRG/WP 238
The weight loss and the decreases in the compression strength and in the modulus of elasticity were measured to determine the decay resistance of structural plywood (lauan). Test pieces (50x25xA mm³) were exposed to the wood destroying fungi (Coriolus versicolor and Coriolellus palustris) for 2-3 or 2-4 months. After exposure, the measurement of the compression strength was carried out on the pieces of different thickness (A = 6,12 and 18 mm) and different fibre direction of the face veneer (0°, 45° and 90° to the long side of the test piece). The results obtained were as follows: 1.: The weight loss was small. The greatest weight loss was 9.4% on decaying by Coriolellus palustris for 4 months. 2.: The decreases in the compression strength and in the modulus of elasticity were greater than the weight loss. On decaying by Coriolellus palustris for 4 months, the ratio of decrease of the compression strength was 75% (6 mm - 0°). 3.: For differences of the thickness and of the fibre direction, the weight loss and the decreases the modulus of elasticity in the compression strength and in the modulus of elasticity showed tendencies in order 0° > 45° > 90° and 6 > 12 > 18 mm. 4.: According to the experiment, the face veneer is liable to be easily attacked by the wood destroying fungi, but the decrease in the compression strength was great. So, the face veneer and the cross section should be protected with preservatives for structural use.
K Minami, Y Kenjo, S Sugiyama
Airborne algae as a wood degradation factor
1992 - IRG/WP 92-1549
The occurrence of airborne (aerophytic) algae on wood is a very frequent phenomenon. However, there is currently a lack of information concerning their effect on the wood tissue. Some important genus of algae infesting wood under natural conditions are listed, as well as the results of experimental studies in the "in vitro" culture concerning the effect of two selected algal species on some physico-mechanical properties and on the structure of beech and Scots pine woods.
K J Krajewski, J Wazny
The performance of softwood species used as poles in Queensland
1985 - IRG/WP 1253
In Queensland, the conifer Pinus elliottii could provide material suitable for use as poles. Full size pole material has been readily treated with CCA with no significant loss in strength. Seasoning of logs prior to treatment requires particular attention in the wet tropical and sub-tropical regions of Queensland. Experimental and in service field tests have indicated excellent performance of CCA treated Pinus elliottii.
L E Leightley
The Pilodyn instrument as a non-destructive tester of the shock resistance of wood
1978 - IRG/WP 2107
A new non-destructive shock resistance tester, the PILODYN, has been developed. The instrument measures the fracture surface area created by a constant amount of energy. It operates by shooting a blunt pin into wood by an exact amount of energy. The penetration depth is read on a scale. A wide field of application is open to a non-destructive shock resistance tester such as: 1) assessment of the residual strength of poles decaying from the outside; 2) laboratory evaluation of biodeteriorated wood; 3) the state of wood foundations and woody pilework; 4) degree of chemical decomposition of wood; 5) degree of thermal decomposition of wood; 6) measurement of the density (strength) of standing trees; 7) measurement of the density (strength) of sawn timber; 8) production control of wood based panel boards. A review of existing test results as well as new results are presented containing items 1, 6 and 7. An evaluation of the potential of the PILODYN is attempted.
Heat treated timber in Finland
2000 - IRG/WP 00-40158
Heat treatment permanently changes the physical and chemical properties of wood by means of high temperatures (150 - 240°C). Heat treatment darkens the colour of the wood. Heat treatment improves the equilibrium moisture content of the wood and the shrinkage and swelling of the wood is reduced. Very high temperatures improve the resistance to rot and also reduce the susceptibility to fungal decay. At the same time the strength properties of the timber are reduced: the bending strength can fall by 30%, depending on the treatment conditions and the cleavage strength (tensile strength perpendicular to fibres) may be reduced to a half, which makes heat treated timber split easily. The improved characteristics of heat treated timber offer the timber product industry many potential and attractive new opportunities. Also wood species having no commercial value as such can be heat treated and in this way new uses can be found for these species.
T Syrjänen, E Kangas
An experimental method to simulate incipient decay of wood by basidiomycete fungi
2000 - IRG/WP 00-20200
At very early stages of decay of wood by basidiomycete fungi, strength loss can be measured from wood before any measurable weight loss. Therefore, strength loss is a more efficient measure of incipient decay than weight loss. However, common standard decay tests (e.g. EN 113 or ASTM D2017) use weight loss as the measure of decay. A method was developed that allowed progressive removal of samples so that all stages of colonisation and decay could be monitored by strength testing, weight loss determination and chemical analysis. Our results indicated that substantial and rapid decay (90% strength loss and 40% weight loss after 12 weeks) of southern pine by brown rot fungi was possible using the method. Our results also demonstrate a direct relationship between strength loss and weight loss and suggest a quantitative relationship between strength loss and chemical composition (hemicellulose sugars) during incipient decay of southern pine by basidiomycete fungi.
S F Curling, J E Winandy, C A Clausen
Ancillary properties of vapor boron-treated composites
2001 - IRG/WP 01-40210
This paper discusses the water absorption, thickness swelling, and internal bond strength of North American composites treated using a vapor boron treatment process. For oriented strandboard, high boron loadings led to lower internal bond strength and lower thickness swelling. Water absorption results were variable but no deleterious effect of treatment was noted. For medium density fiberboard, the highest loadings led to reduced internal bond strength. Thickness swelling decreased with increasing boron level, but not significantly. As with OSB, water absorption results varied.
W A Jones, H M Barnes, R J Murphy
Bibliography: Interactions of wood preservatives with wood, metals, glues, paints and concretes
1983 - IRG/WP 3271