Your search resulted in 154 documents. Displaying 25 entries per page.
Wood protection by nano silver against white rot
2011 - IRG/WP 11-30554
This research was done with the aim of investigation on the natural durability of poplar (populous deltoides) in natural situation and treated with nano silver against the white rot. Testing samples was treated with the method of modified soaking and nano silver in 3 treating level of 0,200 and 400ppm. In this study effect of coriolus versicolor fungus (identificated as white rot) on populous deltoides in natural and treated situation was analyzed. In conducting mentioned evaluation, kolleschal method according to DIN 52176 and B.S. 838:1961 was used in completely randomized block design. Specimens were contaminated with cultured fungus for 14 weeks(22ºc,%75relative humidity).after this period weight reduction, compressive strength(parallel to grain), impact strength were measured. Results have shown that the effect of treated nano silver on durability of populous deltoides was positive and the average of weight reduction of control sample and 200ppm was measured more than 400ppm,so that according to Findlay 1967 classify this type was promoted from completely non durability to Slightly durability. Comparisons of averages have shown that the effect of treated nano silver on compressive strength (parallel to grain), in both moods after and before effect of fungus was positive and leads to its increase. Comparison of average results in impact strength test shown that there was no significant difference in non contaminated samples and at the treating level of 0 (control),200ppm and 400ppm at the level of 5%,but there was significant difference between contaminated samples and at the treating level of 400ppm had more average strength in comparison to200ppm and control.
V Tazakor Rezai, A Usefi, M Soltani
Study on the Effect of Combined Nanosilver-Hygrothermal Treatment on Wood Properties
2012 - IRG/WP 12-40581
In this study, the impregnation process with nanosilver solution, before hygrothermal treatment was carried out to investigate its effect on some physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky) and Russian imported spruce (Picea abies). Wood specimens were impregnated with nanosilver solution (400ppm) in an impregnation tank under pressure of 0.25 Mpa, for 20 minutes. Hygrothermal treatment was carried out at the temperatures of 120, 150 and 180ºC for 1, 3 and hours. One group of specimens was only hygrothermally treated and considered as controls. Values of volumetric swelling after 24 hours soaking in water, bending strength, impact load resistance and compressive strength parallel to the grain were measured. The results showed that by increasing the temperature of hygrothermal treatment volumetric swelling and mechanical properties of specimens were decreased. The duration of treatment has no significant effects on mechanical properties. Also, in wood specimens which were impregnated with nanosilver solution and treated at 180ºC, volumetric swelling were lower than controls, without any significant decrease in mechanical properties. On the whole, it could be said that with nano silver impregnation of wood, hygrothermal treatment can be carried out at higher temperature (180ºC) to achieve better dimensional stability with no more decrease in mechanical properties.
G Rassam, H Reza Taghiyari, A Karimi, B Jamnani, M Ebrahimi
Study on the Effect of Combined Nanosilver-Hygrothermal Treatment on Wood Properties
2012 - IRG/WP 12-40581
In this study, the impregnation process with nanosilver solution, before hygrothermal treatment was carried out to investigate its effect on some physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky) and imported Russian spruce (Picea abies). Wood specimens were impregnated with nanosilver solution (400ppm) in an impregnation tank under pressure of 0.25 Mpa, for 20 minutes. Hygrothermal treatment was carried out at the temperatures of 120, 150 and 180ºC for 1, 3 and 5 hours. One group of specimens was only hygrothermally treated and considered as controls. Values of volumetric swelling after 24 hours soaking in water, bending strength, impact load resistance and compressive strength parallel to the grain were measured. The results showed that by increasing of the hygrothermal treatment temperature, volumetric swelling and mechanical properties of specimens were decreased. The duration of treatment had no significant effect on mechanical properties. Also, in wood specimens which were impregnated with nanosilver solution and treated at 180ºC, volumetric swelling were lower than controls, without any significant decrease in mechanical properties. On the whole, it could be said with nano silver impregnation of wood, hygrothermal treatment can be carried out at higher temperature (180ºC) to achieve better dimensional stability with no more decrease in mechanical properties.
G Rassam, H Reza Taghiyari, A Karimi, B Jamnani, M Ebrahimi
Investigation of Nanocopper-Hygrothermally Treated Wood Properties
2013 - IRG/WP 13-40644
Nanometals with high thermal conductivity can be considered as modifiers, especially in thermal modification of wood. This study was aimed to investigate some physical and mechanical properties of nanocopper impregnated Iranian beach (Fagus orientalis Lipsky), which was hygrothermally treated. For this purpose, nanocopper solution (400 ppm) was used for impregnation process. Hygrothermal treatment was carried out at temperatures of 120, 150 and 180ºC for 1, 3 and 5 hours. Volumetric swelling after 24 hours soaking in water (Vol. S24h), moduli of rupture and elasticity (MOR and MOE), compressive strength parallel to the grain (Cs║) and hardness values (H) of specimens were determined. The minimum volumetric swelling of specimens was obtained in nanocopper impregnated specimens at the treatment temperature of 180ºC and duration of 5 hours. MOR, MOE and hardness values were decreased with more increase in temperature. The best values for these properties were obtained in nanocopper impregnated specimens, which were hygrothermally treated at temperature of 120ᵒC for 1 hour. Compressive strength values were decreased by increasing of temperature and duration of hygrothermal treatment and the maximum values of this property were seen in non-impregnated specimens, which were treated at the temperature of 120ᵒC for 1 hour. It was revealed that at temperature of 180ᵒC and duration of 5 hours, there were no significant differences in mechanical properties of nanocopper impregnated and non-impregnated specimens. These results showed that by nanocopper impregnation of wood, hygrothermal treatment could be carried out at higher temperature and longer duration to obtain a wood product with appropriate properties.
G Rassam, B Jamnani, A Faraji Heris
Changes in mechanical and chemical properties of wood exposed outdoors
2014 - IRG/WP 14-20550
The aim of this study was to investigate differences in certain mechanical and chemical properties of three different wood species (common beach (Fagus sylvatica), Norway spruce (Picea abies), and copper-ethanolamine (CuE) impregnated Norway spruce (Picea abies)) that were exposed in use class 3 (CEN, 2006) for periods between 4 and 30 months. The results show, that changes in the investigated mechanical and chemical properties coincide, with first signs of fungal degradation after 12 to 18 months of outdoor exposure.
N Thaler, C Brischke, D Žlindra, V Vek, M Humar
Impact of heat treatment on physico-mechanical properties of torrefied Antholceistha djalonensis wood
2017 - IRG/WP 17-40811
Thermal modification at relatively high temperatures is an effective method to improve the dimensional stability and mechanical properties of wood. This study was carried out to investigate the impact of heat treatment on the physic-mechanical properties of torrefied Anthocleistha djalonensis wood. Thirty nine defect-free specimens of dimensions 20 mm × 20 mm × 60 were prepared for the determination of dimensional stability and compression test. For the evaluation of static bending strength tests, thirty nine specimens of dimensions 20 mm × 20 mm x 300 mm were prepared. The specimens (at constant m.c. of 12%) were thermally treated at temperatures of 120, 140, 160 and 180oC for 60, 90 and 120 minutes duration. The wood samples were introduced into the furnace and ramped to the temperature at which the actual heat treatment occurred. Density, Moisture content, Weight Loss, Void Volume, Water absorption, Volume swelling, Modulus of Elasticity (MOE), Modulus of Rupture (MOR), Maximum Compression Strength and Hardness of the torrefied and untreated samples were investigated. Heat treatment revealed a clear effect on the physical and mechanical properties of hardwood species. The mean values of the density showed a significant reduction as a function of treatment condition. An increase of the modulus of elasticity during the bending test has been noticed after heat treatment. The minimum MOE value of samples was 3266 N/mm2at 120 °C for 1h while the maximum MOE of samples was 3908 N/mm2 at 160 °C for 2h , whereas the compressive strength parallel to the fibre increased after heat treatment. it can be concluded that thermal modification improves dimensional stability and mechanical properties of wood samples. Technological properties generally decreased with increasing heat-treatment intensity. The modulus of Elasticity of the wood were greatly influenced and enhanced by temperature.
E A Iyiola, B Olufemi, J A Fuwape, J M Owoyemi
Experimental study on compressive strength performance of cross laminated timber with biodeterioration damage
2019 - IRG/WP 19-40883
The mass timber construction has attracted attention around the world. The reasons are due to the environmental impacts and the potential of the strength performance and quantity of the wood. Nowadays, CLT is one of the most important materials for the timber constructions. If we use CLT as a building material, we should consider the biodegradation risk for long time use. From an estimation of future performance and aging degradation viewpoint, it is important to know the relationship between the residual strength and the degree of biodeterioration in CLT. In this study, we prepared the CLT damaged by brown rot fungi and termites, and conducted the compression test with them. As a result, a positive correlation was suggested between the residual stress and mass loss ratio in the decay specimens, although, there was a low correlation between them in the case of termite damage specimens. It is difficult to estimate the residual strength from the mass loss because of the wide range strength at the same mass loss. In addition, the edge gluing had no influence on the compressive strength. The estimation of the residual strength from mass loss was found to be difficult. However, it was found that the rate of damage to the parallel layer may be affecting the strength, because the CLT’s strong and weak directions indicate almost same degree of correlations between stress and mass loss ratio.
T Mori, Y Otsubo, R Inoue, M Ikeda, K Kambara, W Ohmura
Estimation of residual compressive strength on cross laminated timber with biodeterioration damage
2021 - IRG/WP 21-40918
CLT is susceptible to biodeterioration such as fungal decay and termite attack during long-term use for buildings. It is necessary to know the residual strength performance of biodegraded CLT for estimating future performance and aging of CLT. In this study, compression tests of CLT damaged by brown rot fungi and termites were conducted to clarify the relationship between residual strength and mass loss rate. The relationship between strength and defect rate of effective area (parallel layer’s area) calculated from CT scan data was also investigated. As a result, it was found that there is a negative correlation between the defect rate of the effective area and the strength, regardless of whether the deterioration factor is decay or termites, and this relationship may be used to estimate the residual strength. In the case of termite-damaged specimens, a low correlation was found between residual stress and mass loss rate, suggesting that it is difficult to estimate residual strength from the mass loss.
R Inoue, T Mori, K Kambara, W Ohmura
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
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'.
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
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
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
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
Improvement of liquid penetration of wood by precompression under appropriate conditions and recovery process
1993 - IRG/WP 93-40014
A new system for enhancing the penetration of liquid into wood using a precompression treatment was designed, and the effects of compressive deformation and recovery on liquid uptake were evaluated. Precompression of up to 60% under appropriate moisture and heat conditions effectively increased the penetration of liquid into refractory wood samples of practical sizes without producing any strength reduction. Water-saturated wood was compressed perpendicularly to the grain at temperature of 30 to 80°C, and two types of pretreated wood were prepared; i.e., set-recovered wood in which loading was released immediately after precompression, and preset-fixed wood which was dried under the influence of a decompressive force. The amount of liquid taken up by set-recovered wood was 2-3 times that taken up by untreated wood. When preset-fixed wood was dipped in liquid and the deforming force was released, liquid penetration was more than 25 times that seen in untreated softwood heartwood. Liquid effectively penetrated even long samples when pressure impregnation was applied to precompressed and preset-fixed wood. No significant reduction of strength was observed for treated wood except for that which had been precompressed up to 60%. Fracture of pit membranes during compression with little damage to unpitted cell-walls and an elastic recovery process were believed to improve liquid penetration with negligible compression defects.
I Iida, Y Imamura
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