Your search resulted in 163 documents. Displaying 25 entries per page.
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
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
Accelerated laboratory soil contact decay test using soil amended with composted wood
2004 - IRG/WP 04-20284
The effect of amending soil with wood compost on the decay rate of wood wafers in contact with the unsterile soil, as measured by radial compression strength loss, was explored. It was found that the addition of composted wood to the soil significantly increased the wood decay rate. The reason for this acceleration in wood decay is not entirely clear, but appears to be at least partially associated with the fungal inoculum provided by the wood compost. These results indicate that this method may be useful in the development of accelerated soil contact decay tests.
D D Nicholas, H Borazjani, T Schultz
Strength properties of preservative treated pine and spruce wood after super-heated steaming
1984 - IRG/WP 3313
Possible changes of strength properties of CCF pressure impregnated pine and spruce with subsequent steaming at 110°C respective 120°C for 30 min were examined. For spruce analysis of variance indicated that none of the processes had a significant effect on bending strength, compression strength and the corresponding modulus of elasticity as well as on impact bending strength and shear strength radial resp. tangential to the grain. For pine no changes in the bending strength and the compression strength could be detected. The impact bending strength of unsteamed or steamed impregnated samples decreased with 12% compared to non-treated controls due to the brittleness of the salt-impregnated timber. It could be proved that neither steam treatment of 110°C nor of 120°C for 30 min. alone causes a significant change of strength properties of pine and spruce. Arising variations can be explained from anatomical wood properties as well as salt deposits in the samples as a consequence to impregnation.
Use of compression strength loss for measuring decay in the soil block test
1996 - IRG/WP 96-20083
The possibility of using radial direction compression strength of wood, rather than mass loss, was evaluated for both a brown-rot fungus (Gloeophyllum trabeum) and white-rot fungus (Trametes versicolor). With untreated pine wafers (5 x 19 x 19 mm³ - l x r x t) exposed to Gloeophyllum trabeum in a soil block test for five days, the compression strength loss was nearly 50% compared to a 5% mass loss. For Trametes versicolor the compression strength loss after 14 days was 25% compared to 0% mass loss. Both CCA and didecyldimethylammonium chloride treated wafers were evaluated against these fungi in the soil block test using both four and six weeks exposure periods. It was found that the toxic threshold values were approximately the same when determined by both compression strength loss and weight loss. However, more definitive toxic threshold values were obtained with compression strength loss. In comparing data from the four and six week exposure times for Gloeophyllum trabeum, it was found that lower toxic threshold values were consistently obtained for the former, regardless of whether compression strength loss or mass loss data was used. Based on the results of this study it appears that compression strength is a much better method for evaluating decay in the soil block test.
D D Nicholas, Zhongwei Jin
Nondestructive assessment of biodegradation in southern pine sapwood exposed to attack by natural populations of decay fungi and subterranean termites
1994 - IRG/WP 94-20042
Field methods for evaluating decay resistance of experimentally treated materials lack a means for quantitative measurement of residual strength. Quantitative relationships between speed of impact-induced waves travelling parallel to the grain and residual compressive strength have been demonstrated in softwood attacked by brown rot-decay fungi, but the effects of termites have not been documented. We tested southern pine sapwood stakes that were vertically inserted for one-half their length in soil in a southern pine forest in southern Mississippi. The results showed that measurement of both speed and attenuation of a reciprocating impact-induced wave will yield quantitative information on extent of total biodegradation in southern pine sapwood, independent of organism causing the damage.
R C De Groot, R J Ross, W Nelson
Determination of toxicity data for preservatives against Basidiomycetes by measuring the reduction in compression strength of wood
1988 - IRG/WP 2297
Blocks of Pinus radiata D. Don were treated to 12 retention levels with CCA and NaPCP. These were exposed for 12 weeks in agar jars to the dry rot (brown rot) Serpula lacrymans (Schum. ex Fr.) S.F. Gray. After mass loss determination, the same blocks were tested for reduction in compression strength parallel to the grain. Using both these parameters, together with interpolated 6 week strength loss data, toxic values (in accordance with the Polish standard procedure) and toxic limits (in accordance with the British standard) were calculated. The differences between efficaceous and non-efficaceous retentions of the two preservatives was greater for strength reduction data than for mass loss data. Reconsideration of the use of compression strength, as an alternative to mass loss measurements, is recommended
J Wazny, J D Thornton
Decay rates and strength and stiffness loss in foundation beams
1992 - IRG/WP 92-1563
The TNO Centre for Timber Research has executed an extensive research programme into the rate of decay in foundation beams, as a result of lowering of ground water tables. The aim of the research was to develop a method, predicting the decrease in strength and stiffness in beams, due to wood decay during drytime of foundation beams. With the calculated extremes in decay, the damage caused by local settlements of the foundation can be estimated. Though this research deals with untreated timber only, the results yield information which may be used for methods of testing treated timber in ground contact. From 1987 to 1989 literature studies and field inspections have been evaluated, and the most important influencing factors were described. In the following laboratory research the aim was, to quantify the influence of these factors (wood species, dimensions, age, soil wetness, temperature, fluctuation of water) on the decay rate. The rate of decay was measured by mass loss after one year of exposure in a wet but aerated soil, using pine and spruce in different dimensions. For part of the specimens, decrease in strength properties was also measured. Results indicate, that for timber with high moisture contents (over 80%), the decay type is dominated by softrot (95%) and is mainly determined by the surface/volume ratio. The relation between mass loss and loss of strength and stiffness was determined. These results will be used for calculating the deformation of foundation.
P Esser, H S Buitenkamp
A comparison analysis of eight strains of Serpula lacrymans (Schum. ex Fr.) S.F. Gray
1991 - IRG/WP 2362
Investigations were previously carried out to compare eight strains of Serpula lacrymans (Schum. ex Fr.) S.F. Gray (some used in various countries as standard test strains): FPRL 12C (England), FPRL 12E (Germany), Warsaw III (Poland), HFP 7802 (Japan), DFP 16508, 16509, 16521 and 16522 (Australia). Studies included growth rate and dry mass of mycelium, decay capacity, reduction of compression strength, toxic values of CCA and NaPCP tested with agar-plate method (ED50, ED100, LD100) and a modified agar-block method using mass-loss and reduction of compression strength criteria. All of the data obtained are presented here together for the first time, in both table and graphic formats. Further comparison between these results will be presented later (in the final part of the series in 'Holzforschung').
J Wazny, J D Thornton
Effects of sodium hypochlorite on compression strength and copper retention of spruce wood treated with copper azole and alkaline copper quat
2007 - IRG/WP 07-40362
This work investigates the effects of sodium hypochlorite on compression strength values and copper retention ratios of refractory spruce wood (Picea oriental L.) treated with the waterborne preservative Copper Azole, (CBA-A, Tanalith-E 3492) and alkaline copper quat (ACQ-2200). Before the copper azole and alkaline copper quat treatment, the samples were immersed in 500 ml of sodium hypochlorite solution for three different durations (2, 4, and 6 hours). A 2 % active ingredient solutions of CBA-A and ACQ were applied for use in vacuum treatment of the sapwood samples. Average copper contents of the specimens were higher than that of the control groups except of the 6-hours sodium hypochlorite treatment in ACQ impregnation. The highest copper value was seen in the variation the 6-hours sodium hypochlorite treatment in the CBA-A impregnation. Compression strength values generally slightly reduced compared to the control groups especially in ACQ impregnation.
S Yildiz, E Dizman, A Temiz, Ü C Yildiz
Effects of Murgul Copper Process flue gases (SO2) on compression strength parallel to the grain of Beech (Fagus orientalis Lipsky.) wood
2008 - IRG/WP 08-40404
In this study was investigated the effect on the compression strength parallel to the grain as mechanical properties of Fagus orientalis Lipsky. wood exposed to SO2 gas and non-exposed. In the experiments the two of four (total) were obtained from Artvin-Ortaköy region and the other two from Artvin-Murgul region. The compression strength parallel to the grain was calculated at the compare of trees are taken from two distinct region. The obtained data of SO2 exposed specimens were compared with non-exposed ones. According to the obtained data of this study suggestions were given. At the end of study no effect of SO2 gas has been determined on the compression strength parallel to the grain of Fagus orientalis Lipsky. wood.
N Ay, E Topaloglu, A Uncu
Measurement of wood decay by dynamic MOE in an accelerated soil contact test
2008 - IRG/WP 08-20390
Current laboratory and field testing of preservatives involves various techniques to determine the extent of fungal attack, including visual inspection, mass loss, and static bending and compression strength measurements. The objective of this study was to compare decay measurement by conventional compression strength versus dynamic MOE, employing small wood stakes in an accelerated laboratory soil-contact wood decay test. The maximum decay was generally observed close to the center of the stake. An average correlation of 0.884 was observed between the average compression and dynamic MOE strength losses.
Gan Li, D D Nicholas, T P Schultz
Evaluation of ACQ-D treated Chinese fir and Mongolian Scots pine with different post-treatments after 20 months of exposure
2010 - IRG/WP 10-30530
The performance of alkaline copper quat-type D (ACQ-D) treated Chinese fir (Cunninghamia lanceolata Hook.) and Mongolian Scots pine (Pinus sylvestris Linn. var. mongolica Litv.) stakes after 20 months exposure in Chengdu and Guangzhou of southern China were evaluated according to AWPA standard E07-07. The ACQ-D treatments used two concentration levels (0.5 and 1.0%) and four different post-treatments (air drying for 1 month, conditioning at 70°C, 80% R.H. for 24h, oven drying at 110°C for 24h, boiling in water for 15h), respectively. The field test results showed that the natural durability of Chinese fir is a little better than Mongolian Scots pine but the untreated sapwood stakes of both wood species were mostly destroyed after 20 months exposure. After ACQ-D treatment, the sapwood of both wood species showed much better biological performance. Among the four post-treatments, the oven drying method (OD) rated the worst by showing slight reduction in biological performance and the most obvious reduction in compression strength after exposure, while the other three post-treatments performed similarly. It suggested that both post-treatments of HC (conditioning in humidity chamber) and HW (hot water bath) could be good selections for accelerating copper fixation in ACQ-D treated wood. And also, Chinese fir from plantation forests could be a potential wood species for preservation.
Lili Yu, Jinzhen Cao, Wei Gao, Haitao Su
The assessment of biological and mechanical properties of wood treated with ionic liquids – N,N-dimethylamine and 1-decylimidazole derivatives
2012 - IRG/WP 12-40582
This paper presents the results of tests of the effectiveness of action of new imidazolium and bis-ammonium ionic liquids against Basidiomycotina and Ascomycotina wood-destroying fungi. All the investigated ionic liquids showed high fungicidal action against Coniophora puteana. In order to characterize the influence of ionic liquids on mechanical wood properties, the compression strength along the grain was investigated. The obtained results showed that impregnation of Scots pine sapwood with ionic liquid: [1,9-(2,8 dioxanenano]bis(dimethyloctylammonium nitrate) had no negative effect on the compression strength parallel to grain. The investigated compounds characterised by thermal stability, may be applied as biologically active components of wood impregnates in combination with other biocides.
Combined effects of thermal modification and ACQ-D impregnation on properties of southern yellow pine wood
2013 - IRG/WP 13-40637
In this study, samples of southern yellow pine sapwood were first thermally modified and then treated by the alkaline copper quat-type D (ACQ-D) wood preservative. Two heating temperature (180℃ and 220℃) and two concentrations of ACQ-D solution (0.9% and 1.35%) were used in the experiments. The combined effects of thermal modification and ACQ-D on leaching performance, mechanical properties and mold resistance of the treated wood were then investigated. The results of the experiments indicated that thermal modification increased the percentage of copper leaching and decreased the MOR and MOE of wood, and also it affected the compression strength parallel to grain. After the ACQ-D impregnation, the bending properties of thermally modified wood got lowered to some extent. The anti-mold experiment indicated that the ACQ-D impregnation could improve the mold resistance of thermally modified wood.
Wang Wang, Yuan Zhu, Jinzhen Cao
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
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