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Moisture distribution in glulam beams with natural cracks observed with CT Scanning before and after rain
2013 - IRG/WP 13-20534
The way cracks in outdoor wooden constructions affect durability is an interesting topic, since a certain amount of cracks can always be found naturally in wood and glued laminated wood. The question in this was, can cracks lead water into the wood and thereby increase the risk for decay and reduce strength and service life. Moisture balance, i.e., water absorption and water distribution were studied in two 2-meter-long glulam beams after exposure to rain. For the experiment, computer tomography and image processing were used. The beams were X-ray scanned on four occasions during one year: August (CT1), September (CT2), June (CT3) and the following August (CT4). One red-painted spruce beam 215 x 315 mm and one oiled pressure-treated pine beam 140 x 315 mm were studied. The study shows that water can enter a crack for many millimeters by capillary forces, but that this does not necessarily occur. How and to what extent water enters into a crack or delamination depends on material, surface treatment, position and size of the crack or delamination and the quantity of rain and wind. The sizes of the cracks depend on the climate, that is, moisture and temperature variation over time. Some of the cracks become invisible during this movement, and the variation can be as much as 2.5 mm over a 36-hour period. Under certain conditions, small cracks disappear as the woods swells.
K Sandberg


Life cycle analysis of utility poles. A Swiss case study
1995 - IRG/WP 95-50040-05
Use of preservative-treated wood products faces increasing public and political pressure because of environmental concerns regarding the chemicals used to protect the wood. However, critics usually focus only on one single aspect of the whole life cycle of treated wood products, disregarding other environmental effects of timber utilization. To evaluate the ecological consequences of wooden utility poles (CCF/CCB impregnated roundwood and glulams) and their alternatives of reinforced concrete and steel, a life cycle assessment was conducted. Based on data from existing Swiss electricity transmission lines, a comprehensive inventory was established of all extractions from, and emissions to the environment caused by each process step. This inventory data was linked to possible environmental impacts using various aggregation methods. An evaluation was made for single poles as well as for whole transmission lines. The results show that impregnated roundwood utility poles in fact have certain environmental benefits when considered over their whole life cycle.
T Künniger, K Richter


Remedial treatments of glulam = diffusion of active ingredients through glue lines from solid wood diffusable preservatives
1996 - IRG/WP 96-30117
Diffusable preservatives are very suitable for use in remedial treatments of laminated beams in which too high moisture content involves the development of wood destroying fungi. The diffusion of active ingredients (boric acid, disodium octoborate, bifluoride) is well observed in solid wood but in a composite wood, the glue lines may appear not only as a barrier for the diffusion but also, may be mechanically affected by the diffused active ingredients. Shear tests were carried out on glulam specimens manufactured with different types of glues: resorcine (RF), ureaformaldehyde (UF), polyurethane (PUR) and polyvinylacetate (PVAc). Diffusion tests were also carried out in accelerated wetted glulam specimens with three diffusable solid preservatives differently exposed in the test samples. Results observed with boron compounds showed that their diffusion does not affect the mechanical resistance of the beams. In another hand, interesting results were obtained concerning the passage of boron and bifluoride through some types of glues. These results will contribute to the optimization of the remedial treatment of glulams.
D Dirol, S Mouras


Glued laminated poles - Progress report after 18 years' testing
1998 - IRG/WP 98-20140
In 1979 a number of glued laminated poles treated with CCA and creosote were placed in a greenhouse at Uppsala, at the Simlångsdalen test field in southern Sweden and under a power line in Vuollerim in northern Sweden in order to study their resistance against biological degradation. The tests have shown that the best performance will be obtained if each laminate is first treated with a water-borne preservative (only CCA was used in this test) and thereafter the laminated pole treated with creosote. Of the 16 creosoted poles in Simlångsdalen and Vuollerim, 13 poles are still free from decay in the sapwood and 3 poles show slight decay. In the heartwood of outer laminates, slight decay was observed in 11 poles.
Ö Bergman, J Jermer


Glue laminated poles - Progress report after 12 years' testing
1992 - IRG/WP 92-3685
In 1979 a number of glued laminated poles treated with CCA and creosote were placed in a greenhouse at Uppsala, at the Simlångsdalen test field in southern Sweden and under a power line just south of the Arctic circle in order to study their resistance against biological degradation. The tests have shown that the comparatively best performance will be obtained if each laminate is first treated with a water-borne preservative (only CCA was used in this test) and thereafter the laminated pole treated with creosote. These poles are after 12 years' exposure in the field still free from decay.
J Jermer, Ö Bergman


The influence of different creosote process parameters on penetration, retention and bleeding on glulam
2007 - IRG/WP 07-40368
Different process parameters were used to treat Scots Pine glulam beams with creosote. Parameters like pre-heating, pre-pressure time, pressure and pressure time were changed. Most treatments gave a full or almost full penetration of creosote into the sapwood, but the uptake of creosote in the sapwood varies. All samples, except the one with poor penetration, showed heavily bleeding of creosote for about a year before the creosote hardened. To get a good protection of the glulam without bleeding, it has to be double-treated. The lamellae have to be copper impregnated before gluing and the beam must then be treated with a creosote process as C (short pressure time) in part 1. The inner sapwood that will be untreated with creosote will then be protected by the Cu-preservative.
F G Evans


Glued laminated poles - Progress report after 30 years testing
2010 - IRG/WP 10-20427
In 1979 a number of glued laminated poles treated with CCA and creosote were placed in a greenhouse at Uppsala, at the Simlångsdalen test field in southern Sweden and in a power lane in Vuollerim in northern Sweden in order to study their resistance against biological degradation. The tests have shown that the best performance will be obtained if each lamination is treated with a water-borne preservative (only CCA was used in this test) and thereafter the laminated pole is treated with creosote. After 30 years’ exposure, all the creosoted poles in Simlångsdalen and Vuollerim showed only slight decay (grading 1) in the sapwood on surfaces with gluelines. In the outer laminations the decay grading was 2-3 in the heartwood and 1-2 in the sapwood.
Ö Bergman, J Jermer


Copper nanoparticles in southern pine wood treated with a micronised preservative: Can nanoparticles penetrate the cell walls of tracheids and ray parenchyma?
2010 - IRG/WP 10-30547
This study tests the hypothesis that copper nanoparticles can penetrate the cell walls of southern pine wood treated with a micronised preservative. We examined the nanodistribution of particles in tracheid and ray parenchyma cell walls using state-of-the-art HR (High Resolution)-TEM and HR-STEM (Scanning Transmission Electron Microscope)-EDX. These devices are capable of atomic-scale resolution. FIB (Focused Ion Beam) processing was used to make ultra-thin sections for electron microscopy. Our results show that FIB sectioning in combination with HR-TEM and HR-STEM is a powerful tool for observing the penetration of wood cell walls by nanoparticles or clusters of metal atoms. HR-STEM with a Cs corrector revealed that copper carbonate nanoparticles could not penetrate the cell walls of tracheids. Copper, however, is present in cell walls of tracheids as atoms or ions. In contrast, small copper nanoparticles (2.5 nm in diameter) were able to penetrate ray parenchyma cell walls. These particles were identified as copper carbonate by HR-TEM lattice image analysis. We conclude that the cell walls of unlignified ray parenchyma tissue in southern pine are accessible to copper nanoparticles whereas nanoparticles are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans


LOSP for glulam, when should the treatment be applied?
2011 - IRG/WP 11-30555
Treatment options for outdoor above-ground (H3) exposed glulam of Pinus radiata and P. elliottii were examined. Beams were treated with azole LOSP (containing a zinc tracer) aiming for retentions of 35-40 l/m3 or 70-80 l/m3. Treatment was conducted either before or after gluing. TBTN LOSP and CCA were included as comparative treatments. Test specimens for exposure were cut after treatment, while wafers were also cut for spot testing. Penetration was examined using PAN indicator, with best results for TBTN-treated P. elliottii where image analysis showed 67% mean penetration. The spot test for zinc tracer in the azole-treated glulam was generally ineffective with 15% penetration the highest level detected. Test specimens exposed for two years were given a performance rating from 0 to 8 where 0 is failed and 8 sound. Horizontally exposed untreated test specimens at Innisfail were severely decayed, with the mean rating for P. elliottii 0.4 and for P. radiata 1.4. There was less decay in the accelerated field simulator (AFS). For LOSP azole-treated test specimens at Innisfail, only P. radiata treated before gluing was sound. P. radiata treated after gluing had mean ratings of 7.3 (40 l/m3) and 7.8 (69 l/m3). For P. elliottii, specimens treated to the lower retention (35-40 l/m3) before gluing had a mean rating of 7.9 compared to a mean rating of 7.6 (43 l/m3) when treated after gluing. Going against the trend were the higher retentions in P. elliottii with a mean rating of 6.8 (56 l/m3) when treated before gluing compared to a mean rating of 7.9 (82 l/m3) when treated after gluing, probably reflecting retention level differences. Vertically exposed (like posts) treated test specimens often had more decay. The worst performing vertically exposed glulam was usually treated after gluing. End sealing glulam docked after treatment with CuN or ZnN did not necessarily improve performance. The results to date suggest that treating glulam before gluing will generally give better performance than treatment after gluing.
L J Cookson


Copper Nanoparticles in Southern Pine Wood Treated with a Micronised Preservative: Nanodistribution of Copper in the Pit Membrane and Border of an Earlywood Bordered Pit
2011 - IRG/WP 11-30566
Copper nanoparticles can penetrate the cell walls of unlignified parenchyma cells in southern pine wood treated with a micronised wood preservative, but they are excluded from lignified tracheid walls. This paper extends these observations to include the cell wall layers of the bordered pit. Focused ion beam and ion milling were used to make an ultra-thin section of the cell wall layers of an earlywood bordered pit excised from southern pine wood that had been treated with a micronised wood preservative. High resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy in combination with energy dispersive analysis of X-rays were used to detect and examine the penetration of the torus and pit border by copper. Copper was more abundant in the torus than in the pit border, but the depth of penetration of copper in both cell wall layers was approximately the same, ~100nm. High resolution transmission electron microscopy was unable to detect crystalline material in either the torus or pit border. Therefore we conclude that copper nanoparticles are unable to penetrate the torus and border of the bordered pit in accord with our previous observation that nanoparticles are excluded from the cell walls of lignified tracheids.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans


Accessibility of Wood Cell Walls to Well-defined Platinum Nanoparticles
2012 - IRG/WP 12-20494
Copper nanoparticles are found in the walls of parenchyma cells in southern pine sapwood treated with a micronised wood preservative, but they are absent from tracheid walls. Hence, we hypothesized that small nanoparticles can penetrate the walls of unlignified parenchyma cells, but are excluded from lignified tracheid walls. This paper tests this hypothesis by treating pine sapwood with an aqueous emulsion of coated, inert, platinum nanoparticles (2-4 nm). A focused ion beam was used to make ultra-thin sections of the cell wall layers of earlywood tracheid and ray parenchyma cells excised from treated southern pine sapwood. High resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy in combination with energy dispersive analysis of x-rays were used to examine the penetration of cell walls by platinum nanoparticles. Platinum nanoparticles were only deposited on the wall adjacent to the cell lumen of tracheids and were not detected in the cell wall. In contrast, platinum nanoparticles penetrated ray parenchyma cell walls. These particles were identified as crystalline (metallic) platinum by lattice image analysis in high resolution transmission electron microscopy. Therefore we conclude that small nanoparticles (2-4 nm) are able to penetrate ray parenchyma cell walls, but are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P D Evans


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


Fire performance of the wood treated with retardant
2012 - IRG/WP 12-40591
To prepare the eco-friendly fire retardant wood, Japanese red pine (Pinus Densiflora), hemlock (Tsuga Heterophylla), and radiate pine (Pinus Radiata) were treated with inorganic chemicals, such as sodium silicate, ammonium phosphate, and ammonium boric acid. Different combination and concentration of those chemicals were injected by pressure treatment methods. The electron-beam treatment was used to increase the chemical penetration into the wood. The fire performance of the fire retardant was investigated. The penetration of chemicals into the wood was enhanced after irradiation of 200 kGy of electron beam. Ignition time of the treated wood was the most effectively retarded by sodium silicate, ammonium phosphate, and ammonium boric acid. The most effective chemical combination was found at 50% sodium silicate and 3% ammonium boric acid; which showed 3-grade flammability defined in the KS F ISO 5660-1 standards.
Jong In Kim, Mi-ran kang, Sang bum Park, Dong won Son


Water absorption and desorption of non treated, pressure impregnated, and pine oil treated glulam made of small diameter Scots pine and Norway spruce
2012 - IRG/WP 12-40616
A growing proportion of harvested timber originates from the first or second commercial thinning stands in Finland, which means smaller average log volumes in comparison to final felling stands. Smaller log volume means challenging wood properties such as higher proportion of juvenile wood and sapwood. Due to these facts, products made of small diameter logs are prone to twist and check, and have reduced durability against weather. The objective of the study was to define the water absorption and desorption velocity of non treated, pressure impregnated and pine oil treated glulam. The 6 inner lamellae of the glulam beams originated from small-sized logs, whereas the surface lamellae were made of larger logs. Beams with 44 x 200 mm cross cut dimensions were glued using MUF resin and divided into three treatment groups. Treatment 1 was not impregnated, treatment 2 was impregnated into AB class with copper-based preservative in commercial pressure process, and treatment 3 was impregnated with pine oil using the process of Ekopine Ltd. After the treatments, 20 pieces of 200 mm-long specimens were sawn from each treatment group. The cross cut surfaces of the specimens were sealed using waterproof varnish to ensure that the water movement took place via the side surfaces of the specimens. The air-dry specimens (MC 7.7–12.6%) were immersed into water for 6 weeks. After that, they were brought to a standard climate (65% RH, 20 C temperature). Again, their mass was recorded until it did not change anymore. Pine oil impregnated glulam resisted the water absorption more than non treated and pressure impregnated glulam. Due to the low initial MC after the absorption period, pine oil impregnated glulam dried rapidly below 20% MC, while the drying of non treated and pressure impregnated glulam to the same level took 3-4 weeks. In conclusion, pine oil impregnation of timber from small-sized logs can be considered an effective and ecological preservation method for timber used in outdoor constructions. For load carrying structures, pine oil impregnation appears to be an efficient way to maintain the MC of wood below the level that enables mould growth.
H Heräjärvi, V Möttönen, R Stöd


Effect of electron beam irradiation on the fire retardant penetration into wood
2013 - IRG/WP 13-40642
Electron beam processing which can fast and easy change the nature of the material has received considerable attention recently. Studies using electron beam has been conducted in various fields and it has been applied in many industrial sectors. Electron beam has higher energy than other electromagnetic waves. It has excellent object permeability. It affects degradation of intermolecular cross-linking between molecules or atoms bond formation, polymerization. High permeability of the electron beam has applied to improve penetration of fire retardant into wood. Changes in the characteristics of the wood, retention of the retardant on different electron beam dose, leaching resistance of treated wood were examined. Scanning electron microscopy EDS analysis has been conducted to investigate the chemical elements and to calculate the distribution of each component.
Dong won Son, Jong Sin Lee, Mee Ran Kang, Sang Bum Park


Borate Redistribution in Glulam in an Above Ground Field Test
2014 - IRG/WP 14-30652
Researchers have refocused on the use of boratesin the wood protection industry in the last two decades due to their broad spectrum effectiveness against fungi and insects, and favourable environmental characteristics. This study was designed to determine borate distribution in a limited number of samples from a large field test of composites protected by a combination of coating and borate treatment by two processes.The intended application of these products was exterior components of buildings with considerable protection by design, but the test method was designed to be a much more severe exposure. A variety of structural composites had been machined into ɣ-joint test samples, then borate-treated by two methods: a surface-applied penetrating process, and a dip treatment with borate/glycol plus insertion of copper/borate rods.After application of the coating the test samples had been installed in a long-term above-ground outdoor weathering trial at FPInnovations’ Maple Ridge, British Columbia test site. After seven years of exposure, selected glulam beams of black spruce, white spruce, and Douglas-fir samples were destructively sampled and analyzed for borate retention and penetration, with results compared to unexposed material.Results showed that borateshad migrated from the surface of exposed samples to inside the wood, as deep as 50 mm, and in many samples were present in concentrations that would be sufficient to prevent fungal decay.
P I Morris, A Temiz, J Ingram


Solid Timber Bridges – Latest Developments
2017 - IRG/WP 17-40788
The technology of gluing in wood construction has evolved considerably in recent years. This has been shown especially in timber bridges that Glulam is now the main building material. A further development is the so-called block gluing, which provides a good basis for supporting structures. Numerous bridges, especially in central Europe, appeal by unique design and monolithic and solid construction. These structures base on two main developments: block lamination of glulam and the composite of timber and concrete to one structural system.
F Miebach


Evaluation of chemical densification of three hardwood species through in-situ electron beam polymerization
2020 - IRG/WP 20-40893
Hardwoods are the most suitable species for wood flooring for their appearance as well as their hardness. Yet, improving hardness can provide substantial benefit for the wood flooring market. Chemical densification of wood and in-situ polymerization through electron beam technology was chosen to increase hardness of three hardwoods (Yellow birch (YB) (Betula alleghaniensis Britt.), Sugar maple (SM) (Acer saccharum Marshall) and Red Oak (RO) (Quercus rubra L.)). Monomer formulations were chosen for their viscosity. Impregnation was carried out through a simple vacuum process and was followed by 100 kGy electron beam irradiation to allow in-situ polymerization. Successful polymerization was proved by infrared spectroscopy and thermogravimetric analysis. Chemical retention and hardness of densified and reference samples were measured. Chemical retention (CR) varied between the three species being the lowest for porous red oak and the highest for diffuse porous yellow birch. CR also decreased with increasing viscosity of the impregnant for SM and YB. However, viscosity did not affect chemical retention of RO samples. Hardness of wood increased substantially for all treatments and all species and was comparable to that of Jatoba. Densified YB samples showed greater improvement of hardness compared to RO and SM due to higher chemical retention. Results also showed that with low chemical retention, hardness was improved but densified wood hardness is mostly influenced by wood properties. While the three species showed significant hardness improvement, yellow birch seems more suitable for densification.
J Triquet, P Blanchet, V Landry


Fungal colonisations in and on industrially manufactured acetylated glulam in UC 3
2020 - IRG/WP 20-40900
This poster paper describes one of the first cases where industrially acetylated glulam was colonized by wood-destroying fungi after less than 10 years of exposure in use class 3.2. Remarkable is that fruiting bodies of white as well as brown rot fungi were found on one and the same bench element. The first visible wood destroying fungi was the white rot fungus Schizophyllum commune followed by the brown rot fungi Gloeophyllum trabeum or Dacrymyces sp. Besides this, ascomycetes were found inside and algae on the surface of the modified glulam. It might be that this diversity of organisms enhanced the early attack. Even if the source of infection and its extent could not be sufficiently clarified, it can be assumed that the moisture and spore entry occurred mainly via the open adhesive joints or longitudinal cracks.
J Müller, E Melcher, T Potsch


Aiming for eco-friendly log production and wooden construction!
2021 - IRG/WP 21-50365
In order to reduce greenhouse gas (GHG) emissions to zero by 2050 in the fields of forest and forest products, it is necessary to promote appropriate management and renewal of planted forests, and development of wooden building materials and the wooden construction of mid-to-high-rise buildings with lower GHG emissions. Unless we also try to reduce the environmental loads other than GHG for such development, we cannot simply replace it with other materials and construction methods. Therefore, we assessed GHG emissions up to the production of domestic logs which are the raw materials for all wood-based materials. The environmental loads of an office building made of the fireproof glulam impregnated with fire-retardant and an apartment using gypsum board-covered CLT were also assessed with those of steel-framed and reinforced concrete buildings. As a result, in log production, it is necessary to reforest after clear-cutting, and in order to give mid-to-high-rise wooden buildings the fire resistance required in Japan, gypsum board should not be used or alternatives with low environmental impact should be used.
N Hattori


Surface chemical wood densification through in situ electron beam polymerization: description and dose study
2022 - IRG/WP 22-40933
Traditional wood chemical densification processes can be used to improve wood mechanical properties by increasing density of the material throughout its thickness. While mechanical surface densification has heavily been investigated, surface treatments involving impregnation of monomers remain unexplored. This study describes a new material, surface densified through lateral impregnation of acrylate monomers and their in-situ polymerization using high-energy electron beams. Yellow birch (Betula alleghaniensis, Britt.) was surface densified and its morphology was studied using X-Ray density profiles and microtomography. Brinell hardness of densified samples increased while irradiated controls showed lower hardness compared to untreated controls. Effect of electron beam dose was studied at 25, 50 and 100 kGy. Using acetone extraction and GC-MS, residual monomers were found at low dose while degradation of wood was observed ah higher dose using FT-IR. This study demonstrates how carefully choosing the electron beam dose impacts the material in different ways.
J Triquet, P Blanchet, V Landry