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An attempt to evaluate wood resistance against fungal decay in non-sterile conditions by measuring the variation of resistance to bending test
1988 - IRG/WP 2308
The main object of this work was to determine the variation of strength on large test specimens of wood (800 x 45 x 45 mm³) when exposed to accelerated fungal attacks close to natural conditions, out of test vessels. The modulus of elasticity (MOE) and the modulus of rupture (MOR) have been assessed. Thereby, the natural resistance of the wood species to fungal decay, the efficiency of preservative as well as the treatment applied are discussed. The wood tested is a guianese secondary species (Couma guianensis). The fungi tested are two guianese strains of brown and white rot. The exposure time is 12 weeks. No mould contamination has been recorded by use of a selective fungicide. The results obtained show that it is possible to infest in nonsterile conditions large wood specimens. Furthermore, modulus of rupture appears to be the most reliable criterion. The investigation, that requires limited equipment and staff could be performed in any tropical research station as it has been done at CTFT, French Guiana center.
L N Trong

Durability of heat-treated wood
1999 - IRG/WP 99-40145
Heat-treated wood from the French process were laboratory tested against decay using agar block test and a modified soil block test. Water absorption, bending strength, lignin content and acid number were also determined to evaluate the effect of heat treatment. Heat treated samples exhibit a higher lignin content and a lower acid number compared to untreated control indicating the degradation of some hemicellulose and extractives compounds. The significant amount of water absorbed during water soaking or exposure to different relative humidity suggest that the heat treatment help in releasing the stress in wood after the removal of hemicellulose and degradation of lignin rather than the reported significant cross link reaction of organic acid and the benzene ring of lignin. Cubes extracted with water or acetone or chloroform and challenged with pure culture of fungus show an appreciable weight loss which confirm the absence of any extractable compounds toxic to decay fungi during the heat treatment. After 12 weeks exposure for laboratory soil block or 6 to 8 weeks for agar block test, significant weight loss was observed. For soil block test, weight loss of 11% was obtained for heat-treated samples exposed to G. trabeum and 46% for P. placenta. About 56% and 54% weight losses were obtained for southern pine control exposed to G. trabeum and P. placenta, respectively. The weight loss of water and acetone extracted heat-treated sample exposed to P. placenta was 49.7% and 53.9%, respectively. Only about 11% and 14.8% weight loss was obtained for water and acetone samples challenged with G. trabeum. The moisture content of tested sample was about 70 ±10% for the un-heated control and 50 ± 10% for heat-treated samples. This treatment may modified the durability from non resistant to moderate/resistant species depending on fungus species as defined in the ASTM 2017 standard. The data from the bending test indicate that such treatment may create a 10 to 50% reduction in MOR and deflection which will limits the use of such wood for structural purposes.
D P Kamdem, A Pizzi, R Guyonnet, A Jermannaud

Supercritical fluid treatment: Effects on bending strength of white spruce heartwood
1993 - IRG/WP 93-20008
The effects of supercritical carbon dioxide on wood strength were evaluated using white spruce heartwood, a species known to be especially susceptible to collapse during exposure to higher pressures. The effects of pressures of 2000 or 3600 psig and temperatures of 40 or 80°C were evaluated using 30 or 60 minute exposure periods. No significant differences were noted in modulus of rupture or modulus of elasticity between specimens treated with supercritical fluid at selected pressures, temperatures or exposure periods or between treated and untreated control samples. Furthermore, no evidence of crushing or deformation were noted in specimens exposed to higher pressures. These results indicate that exposure to supercritical conditions should not adversely affect material properties of spruce.
S M Smith, J J Morrell, E Sahle-Demessie, K L Levien

Evaluation of bending strength by non-destructive methods of Ezomatzu with white pocket rot
1991 - IRG/WP 2371
The possibility of application of three non-destructive methods was examined for evaluation of bending strength of ezomatsu (Picea jezoensis CARR.) with white pocket rot. As non-destructive methods, the measurements of ultrasonic wave propagation time, impact-induced stress wave propagation time and penetration depth of pin of "PILODYN Wood Tester" were applied to compare with visual evaluation of degree of white pocket rot. The modulus of elasticy in bending, bending strength and stress at proportional limit in bending were decreased according as increase of the degree of white pocket rot evaluated visually, even at "slight and superficial" rot. High correlations were observed between dynamic modulus of elasticity calculated through ultrasonic wave propagation time or stress wave propagation time and modulus of elasticity in bending, and between dynamic modulus of elasticity and bending strength. The penetration depth of pin and modulus of elasticity in bending or bending strength were correlated as well. Based on the results obtained by this experiment, these three non-destructive methods were serviceable to evaluate modulus of elasticity in bending and bending strength of ezomatsu with white pocket rot, same as visual evaluation.
T Tanaka

Relationship between the bending strength and the degree of termite attacks on western hemlock by Coptotermes formosanus Shiraki
1990 - IRG/WP 1434
For the examination of the relationship between the bending strength and the degree of termite attacks, Western Hemlock (Tsuga heterophylla Sarg.) was used. Sixty specimens (4.5 x 4.5 x 82 cm³) were attacked by termites at the culture room of Coptotermes formosanus Shiraki. The termites were introduced on the central parts (10 cm) of specimens. In the case of the 2 points loading, the bending moment is maximum at these parts. According to the results obtained from this experiment, both the modulus of rupture (MOR) and the modulus of elasticity (MOE) were showed significant against the weight loss (WL) of central parts of the specimens. MOR = 713 - 19.9 WL (n=60, r=-0.73**) MOE = 127800 - 1910 WL (n=60, r=-0.58**)
K Suzuki, T Tanaka

Laser incising of spruce lumber for improved preservative penetration
1991 - IRG/WP 3646
Red spruce heartwood specimens were incised using a range of laser beam power levels and pulse durations. The penetration of CCA through these holes into the wood was monitored after pressure treatment. In addition, green and dried spruce samples were incised using two patterns with incision densities of either 16.1 holes/in² or 21.3 holes/in². Following CCA pressure treatment the samples were tested for strength, and the preservative penetration and retention were determined. No strength losses were observed, however a staggered pattern of incision holes appeared to be more desirable from the standpoint of sample failure than the pattern where the incision holes were lined up along the sample face. Preservative penetration for both patterns, in either dried or green samples, was virtually complete as compared to controls where preservative penetration was severely limited.
B Goodell, F A Kamke, Jing Liu

Cantilever bending test of furfurylated poles
2008 - IRG/WP 08-40424
Ten, 8 m long poles of Scots pine (Pinus sylvestris) were treated with furfuryl alcohol to a WPG of approximately 40 %. A bending test was performed according to the principles in the draft European standard for wooden poles, prEN 14229 - Structural timber - Wood Poles for overhead lines. The bending strength and stiffness (MOE) for the poles tested were compared to an earlier study by the Swedish Wood Preservation Committee. In the latter study untreated, CCA-treated, ammoniacal Cu-PCP treated and creosoted poles were tested in bending. These types of poles were considered not to differ in strength and stiffness. The results of the furfurylated poles fit well with the results from the previous study. The bending strength and MOE values obtained are compared to the upper and lower 95-percentile values of the results from the previous study and all poles treated with furfuryl alcohol fit within this interval.Thus, this study indicates that a treatment with furfuryl alcohol does not result in a decrease of strength or stiffness. Further testing with a larger population of poles is necessary in order to get a statistically reliable result. In addition to further demonstration of the durability, the treatment process must be optimised to ensure full sapwood penetration and measures have to be taken to avoid the serious cracking observed in this trial before furfurylation can be considered for treatment of Pinus sylvestris poles.
R Ziethén, J Jermer, A Clang

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

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

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

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

Dimensional stability, biological resistance, and mechanical properties of phenol-resin-treated particleboard
1990 - IRG/WP 3622
Particleboards were treated with a low molecular-weight phenol-formaldehyde (PF) resin and their enhanced properties were evaluated. Besides dipping of particles in aqeous solutions of resin, and spraying of resin solutions before spray of the conventional phenol-formaldehyde resin for adhesive binder, one step treatment by spraying of the mixture of the low molecular-weight resin and the adhesive resin was also employed. After 2-hour boiling, the boards treated at 10% incorporated resin loading (IRL) retained 80% of their strength values in a dry condition. The internal bond strength increased with increasing IRLs, and the boards of 20% IRL showed twice of the value of untreated controls in the same level of board density. Treated particleboards resulted in a more dramatic reduction in the rate of swelling even at low resin loadings. Results obtained from accelerated laboratory tests on biodegradation suggested that incorporated resin-solids worked well to enhance decay and termite resistance of particleboards.
Y Imamura, H Kajita

Acetylation of lignocellulosic materials
1989 - IRG/WP 3516
A simplified procedure for the acetylation of lignocellulosic materials has been developed. The acetylation is done with a limited amount of liquid acetic anhydride without the addition of a catalyst or an organic co-solvent. Dimensional stability and biological resistance are both much improved by the acetylation. Equilibrium moisture content in acetylated material is considerably lower than in unmodified material. No reduction of bending strength was found for acetylated solid wood samples. The process can be employed for both fibers, wood particles and solid wood. The process is applicable to hardwoods and softwoods, including solid spruce wood, and to non-wood fibers such as jute.
P Larsson, A-M Tillman

Properties of plywood and Oriented Strand Board manufactured with an organic insecticide incorporated in the adhesive formulation
2000 - IRG/WP 00-40174
The efficacy of Fipronil as an insecticide has been established by laboratory and field experiments and commercial use against a broad range of insect pests for various crops. It can be used by either foliar or soil application. Development is underway for the non-agricultural uses of fipronil. Research is ongoing for the control of ants, cockroaches, fleas, ticks, houseflies, mosquitoes, termites and other pests. Several countries in the world have experienced extensive termites damage. The protection of structural and non-structural cellulosic products against termites may be required in the near future. With the increase uses of wood composites in wide ranging applications, protection against termites will represent one of the criteria of material selection. Fipronil was added in the formulation of adhesive during the laboratory manufacture of plywood and oriented strand board. The average MOE and MOR from of plywood was about 1.1 to 1.2 million psi and 8000 to 9100 psi, respectively. Shear strength and wood failure varies from 191.6 to 239.9 psi and 73% to 92%, respectively. Analyses of variance showed that statistically there were no significant different of all properties tested between fipronil concentration (0 - 375 ppm) at 5% level. This study indicates that fipronil has no affect on MOE and MOR under bending regime, and on the shear strength and the wood failure. After 18 months above and ground contact exposure in Gainesville, Florida, a level of 150 to 200 ppm successfully control the termite attack.
D P Kamdem, J H Hope, A Jermannaud

Paper for discussion - Incising of spruce to improve preservative penetration
1973 - IRG/WP 318
Large quantities of whitewood or Norway spruce (Picea abies) are regularly imported into the United Kingdom from continental Europe. In addition, increasing amounts of Sitka spruce (Picea sitchensis) are likely to become available over the next decade from the Forestry Commission. In many ways spruce is a good structural timber, eg it is relatively cheap and easily available, it has adequate strength properties and is easily worked. However, as a long life structural material it suffers the disadvantage of low resistance to fungal and insect attack of both its sapwood and heartwood. In addition, the material is resistant to impregnation with preservative fluid using normal pressure methods. If preservative penetration were improved, the species could be utilised in several building and fencing situations from which it is at present excluded because of its susceptibility to rapid biodegrade. Considerable effort has been spent in trying to improve the preservative impregnation of spruce wood and some degree of success has been achieved in the treatment of round timbers. Here the problem is to improve treatability of the sapwood band so that this is fully penetrated, providing a protective sleeve around untreated heartwood. Successful treatments of this type may be attained by water storage on 'ponding' prior to seasoning followed by pressure impregnation or by sap displacement treatment of freshly-felled logs (eg the Boucherie process). In 'square' sawn timber however, exposed surfaces contain a significant proportion of heartwood, which does not respond to either of the processes mentioned above. Penetration and absorption of impermeable species can be improved by incising. Generally, however, in the United Kingdom, incising has been employed only on large section engineering timbers (eg railway sleepers and marine piling) using a tooth size which damages the timber surface to an unacceptable extent see BS 913:1954 and 4072:1966) for application to the smaller section sizes encountered in building or light fencing material. The present work is concerned with the development of a level of incision sufficient to allow protection against biodegrade, without weakening the timber or damaging its surface to an unacceptable extent. The purpose of this account is to show the degree of improvement in penetration and absorption brought about by such incisions.
W B Banks

Biological and physical properties of phenolic-resin treated wood before and after natural weathering
1999 - IRG/WP 99-40132
Biological and physical properties of phenolic resin-treated particleboards, which were made from fast growing tress and agrowaste as raw materials, were evaluated before and after natural weathering in tropical climate. The particles were sprayed with a mixture of a low molecular weight phenol-formaldehyde resin (5.0, 7.5 and 10% loading) and the adhesive phenol resin (8% loading). Results with laboratory biological tests revealed that low-molecular weight resin solids worked well to enhance the decay and termite resistance of particleboards in proportional to the resin loading. The physical properties such as IB strength, MOR and MOE also increased with the resin loading. After exposure to natural weathering, these properties decreased gradually due to the effect of sunshine or rain-water, but the treated particleboards with 7.5% and 10% resin loadings still maintained the higher levels of these properties.
S Yusuf, Y Sudiyani, H Kajita, Y Imamura, M Takahashi

Biodetioration and strength reductions in preservative treated aspen waferboard
1983 - IRG/WP 2195
Experimental aspen waferboards, bonded with liquid or powdered phenol formaldehyde resins and treated by various methods with a wide selection of preservatives, were tested for fungal resistance in accelerated laboratory trials. Mold growth on the surface as well as weight and strength losses due to the actions of decay fungi were determined. Testing of board strength after decay in high and moderate-hazard exposure conditions required modification of decay tests used for solid wood. A range of protection was noted with no preservative system exceeding the efficacy of the inorganic salt formulations. Averaged over all treatments, strength loss and weight loss are well correlated. Field exposures of effective treatments are underway.
E L Schmidt, H J Hall, R O Gertjejansen, R C De Groot

Changes in some important mechanical and physical properties of untreated and treated mining timber after exposure to the conditions of a colliery
1996 - IRG/WP 96-20082
Each of salt treated and untreated mining timber (wedge) pairs with 5x15 cm² cross-section and 155 cm length prepared from Scots pine, Bornmüller's fir and oriental beech was cut in the small standard test specimens to determine changes in some important mechanical and physical properties, 13 month after exposure to the conditions of Kozlu Hard Coal Mines in the depth of 52 m. Thus, the method for determining the effects of decay on structural timber in service were described. Losses in impact bending, static bending and modulus of elasticity, and specific gravity were calculated as a percentage of the values for controls. Furthermore, relations between residual strength values and losses in specific gravity were statistically evaluated. Decreases in impact bending strength of all controls were ranged from 70% to 88%, in static bending strength from 71% to 73%, in modulus of elasticity from 50% to 56% while losses in specific gravity were ranged from 9% to 11%. The strength losses of wedge blocks treated with CCB salts were found between 3% and 6%, and changes in specific gravity were lower than 1%. Brown and white rot decay were determined on softwood and hardwood samples respectively.
A Bobat

Supply of wooden transmission and telephone poles in Tanzania: Problems and possible solutions
1987 - IRG/WP 3424
The eucalypts which have been used widely for utility poles for more than 30 years have dwindled remarkably from traditional supply areas. Consequently, pole-using authorities are considering importing poles from abroad. This alternative is considered unrealistic and costly. The aims of this paper are: - to dispel fears of pole scarcity and to show that an abundant resource of a variety of tree species, consisting of both hardwoods and softwoods, considered suitable for poles, is available; - to point out obstacles that hinder the full utilization of this natural and renewable wealth; - and to suggest workable solutions to the pole supply problems.
K K Murira, S A Diwani

Material properties of acetylated beech plywood
2008 - IRG/WP 08-40425
The effect of acetylation process on dimensional stability and mechanical properties of plywood made by Oriental beech layers (Fagus orientalis Lipsky) were studied. The layers cut into sizes of 200×200×2 mm and acetylated in 120°C for 30 and 60 min. Thickness swelling (TS%), water absorption (WA%) and anti-swelling¬ efficiency (ASE%) of specimens were measured. Mechanical properties (MOE, MOR and impact resistance) were also tested. Results indicated that dimensional stability of acetylated plywood was significantly higher than untreated samples. MOE and MOR in severe acetylated specimens were lower than untreated, but no significant difference observed between values of impact resistance between untreated and acetylated plywoods.
A Talaei

Effects of concentration and temperature of CCA and CCB on wood strength of Turkish fir (Abies bornmulleriana Mattf.)
2009 - IRG/WP 09-40450
The purpose of this study was to present evidence for the effects of concentration and temperature of solutions of water-borne preservatives (chromated copper arsenate, CCA and chromated copper boron, CCB) on the static bending properties (modulus of elasticity, MOE and modulus of rupture, MOR) of Turkish fir (Abies bornmulleriana Mattf.). Wood samples were mechanically tested after a mild full cell preservative treatment with 2.5 and 3.0% CCA and CCB solutions heated to 30 and 40 °C.Untreated controls were included for comparison.The experimental data indicated that heating the solutions of both CCA and CCB caused a greater shift in the fluid uptake, i.e. it increased with temperature up to 30 ºC, but at 40 ºC it was lower than that of unheated controls. In absolute terms, the fluid uptake of either preservative solutions was higher particularly in lower concentrations. CCB treatment had a greater fluid uptake for all cases. Results also showed that the effects of increasing concentration and temperature of both water-borne preservatives on MOE and MOR were very highly significant, while these strength properties were a significantly lower after the wood treatment with concentration of 3.0 % and heated at 40 ºC. Both MOE and MOR decreased even more by the treatment of CCB. It was therefore concluded that the strength properties of Turkish fir based on MOE and MOR were affected to a small extent by the full-cell vacuum/pressure wood treatment by using CCA and CCB with the concentrations of 2.5 and 3.0 % heated at 30 and 40 ºC. The worst case was 3.0% CCB treatment at 40 °C which resulted in a 5.0% reduction in MOE and a 5.2% reduction in MOR.
I Usta, M Hale

Effects Of Wood Preservative On Mechanical Properties Of Glulam Manufactured From Lower Density Malaysian Tropical Timber
2012 - IRG/WP 12-40590
This study is to investigate the effect of wood preservative on the mechanical properties of glulam timbers made from low density Malaysian hardwood timbers. Utilization of lower density Malaysian tropical timber for structural applications have not exploited extensively due to their inferior strength. By converting into treated glued laminated (glulam) timbers it could offer the possibility of this timber as competitive structural materials. Nevertheless, wood preservative has been known to interfere with mechanical properties and strength performance of wood. Therefore, to achieve the objective of the study 5-ply of glulam beams with 100mm(w)x 150mm(t) x3000(l)mm dimension were manufactured using sawn timber treated with wood preservative copper chrome arsenate (CCA)(Tanalith). Timber species from low density timber with strength Group (SG) 5, Bintangor (Calophyllum spp) and SG 7, Sesendok (Endospremum spp) were selected for this study. All glulam beams were fabricated in accordance with MS 758:2001. 3-point bending test was conducted based on ASTM D198-84 (ASTM 1987a) to determine the modulus of elasticity (MOE) and modulus of rupture (MOR) of treated glulam timbers. Shear test was also been conducted in order to understand the effect of adhesive bonds and performance on CCA (Tanalith) treated glulam timber. The experimental work also included untreated timber of the same species used as control. Results showed that treated glulam for both of Sesendok samples had the highest MOE and MOR values of 66106N/mm2 and 123N/mm2 respectively. Correspondingly, for untreated control samples were indicated lowest MOE and MOR values of 51036N/mm2 and 112.28N/mm2. Bintangor had indicated the highest MOE and MOR values of 53546N/mm2 and 119.66N/mm2. Overall properties of treated samples tested in work resulted in higher values compared to untreated samples. No significant different for MOE values for both treated Bintangor glulam and Sesendok glulam. All specimens were reached 100% wood failures with more than 10N/mm2 of shear strength. From the results of this study, it can be concluded that by preservative treatment it could upgrade the performance of low density timbers as structural materials.
L Francis, Z Ahmad

Resistance of WPC against wood destroying fungi
2013 - IRG/WP 13-40627
The investigation of biological durability is a fundamental topic to assess the performance of Wood Plastic Composites (WPC) particularly for outdoor applications. In the last years, different test setups based on existing standards on the field of wood as well as the field of plastics were used for WPC. But the test methodologies give different information about the durability of the tested material. The objective of this study was to investigate the resistance of WPC against wood destroying basidiomycetes adapted to prEN 15534-1 (2012) which was adjusted to test WPC. Additionally to the mass loss, MOE and MOR of the tested material before and after water storage as well as after fungal test were evaluated. The tested material showed very low mass losses and no significantly decrease in MOR and MOE caused by fungal decay. Rather the MOE and MOR are strongly decreased caused by water uptake. The mechanical evaluation after water storage and decay testing may provide additional important information, which might strongly affect the long-term behavior and durability of the material in outside application.
A Gellerich, S Bollmus, A Krause

Interaction of Boultonizing and through-boring of Douglas fir sapwood
2018 - IRG/WP 18-40833
The interaction of combining through-boring and Boultonizing treatment effects on strength properties was investigated. Small, clear Douglas fir beams were through-bored and/or Boultonized in full factorial design and evaluated for toughness, MOE and MOR. The simulated through-boring treatment lowered the mechanical properties but the Boultonizing process did not. There was also no evidence for a negative synergistic interaction of the through-boring and Boultonizing treatments. These data suggest that there is no need for concern about combining through-boring and Boultonizing treatments for Douglas fir utility poles, and actually may help industry further as the results also suggest that commonly applied mechanical property reductions for Boultonizing treatments may not be necessary.
F Gasteiger, J Lloyd, A Taylor

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