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Dual Borate and Copper Naphthenate Treatment of Bridge Timbers:- Potential Performance Enhancements and Cost Savings
2017 - IRG/WP 17-40797
Dual treatment technology combining diffusible preservatives with oil borne preservatives, widely used for crossties in the USA, has now also been commercialized with bridge ties/timbers. In order to understand the implications of these changes, the historic service life of creosote treated bridge timbers in northern and southeastern USA were considered as well as field test data for both creosote and copper naphthenate. These were used to estimate potential future service life. Estimates on life expectancy with added borates were also made from published data on performance. Cost benefit analysis based on creosote and copper naphthenate costs as well as assumptions made from field test efficacy data suggest cost savings of up to $20 per timber per year of additional service. Service life extension and the resulting cost savings could be achieved in a number of ways: change preservative from creosote to copper naphthenate; increase active ingredient retention; and/or add dual treatment protection. A preservative change from creosote to copper napthenate would be the simplest and lowest cost way of increasing service life of bridge timbers, with potential savings to both treater and railroad. An increase in copper retention could also give significant life extension, could be carried out at little additional cost and without increasing bleeding. The addition of borate to protect the heartwood also provides significant assumed increase bridge tie life, and can be used with either creosote or copper naphthenate treatments.
J Lloyd, C Brischke, R Bennett, A Taylor

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

Recovery of copper chromium and arsenic from old CCA treated commodities
1998 - IRG/WP 98-50118
Due to the expected increase in spent treated wood over the next several decades, numerous means to reuse and recycle preserved wood have been proposed. Burning this wood for cogeneration or recycling of CCA treated wood into reconstituted composites are possible methods, but they are limited to laboratory scale because of environmental air emission issues and the manufacturing process. In the available literature, laboratory removal of CCA from treated wood has been conducted on 20 mesh size particles or saw dust. This approach requires chipping and grinding of lumber and poles into particles and saw dust. In the current study, about 95 to 100% copper, chromium, and arsenic were removed from 2 by 4's and pole sections without substantial modification of initial sample size. This extraction yield was obtained within 18 hours at temperatures ranging from 80- 100EC using a combination of citric acid and chelating agent at pH 4.
D P Kamdem, Wanli Ma, Jun Zhang, J Zyskowski

The recycling of CCA treated wood
1999 - IRG/WP 99-50140
Efforts to recover CCA from CCA-treated wood have been focused on the extraction of small wood particles. This work describes a method capable of removing CCA from retired CCA treated pine boards without. The percent removal of copper varied from 82% to 94%, 72% to 90% for chromium, and 84% to 98% for arsenic. The mechanical properties of boards after the extraction of CCA was reduced to 30% compared to un-extracted CCA treated boards. The extraction solution containing CCA was concentrated and the chromium 3 oxidized to chromium 6. The resulting CCA solution was used to treat southern pine cubes at a target retention of 6.4 kg/m3. After a laboratory soil block test, the indices of protection of cubes treated with the recovered CCA was comparable to that of cubes treated with fleshly obtained CCA and the weight loss of cubes after the CCA removal was similar to untreated pine sapwood control.
D P Kamdem

Recovery of copper, chromium, and arsenic compounds from the waste preservative-treated wood
1991 - IRG/WP 3651
In Japan, about 40 percents of waste wood is incinerated and the residue is dumped into the landfill site. The waste preservative-treated wood, which is mixed in nontreated wood, is incinerated in the same way, too. However, it will cause the serious problems that the gases contained with high concentration arsenic compounds are discharged from the smokestacks of the incineration facilities and the toxic water with high concentrations of copper, chromium, and arsenic compounds is discharged around landfill sites because the residue contains a lot of these compounds. To solve these problems, it is necessary to develop a method to recover these compounds from the waste preservative-treated wood. In this paper, extraction experiments of copper, chromium, and arsenic compounds from treated wood were carried out and evaluated as a method to recover these compounds. Through the experiments, suitable extractant, its concentration, and extraction conditions such as the temperature, extraction time, and the size of test wood piece were obtained. As the results of these experiments, Cr, Cu, and As compounds in the test wood piece were completely recovered into the extractant under the suitable conditions.
A Honda, Y Kanjo, A Kimoto, K Koshii, S Kashiwazaki

Kiln drying of LSOP treated timber: rate of solvent evaporation, overpaintability and recovery of the solvent
1992 - IRG/WP 92-3711
The rate of solvent evaporation from LOSP treated timber dried in a kiln at 35°C has been investigated. Around 50% solvent removal has been found to be consistent with good overpaintability using a water based acrylic primer. It has been demonstrated that an activated carbon solvent recovery system is capable of removing all the solvent vapour from the outlet of a commercial joinery drying kiIn, that the solvent is subsequently recoverable using steam and that the recovered solvent is suitable for re-use.
P Warburton, L B Sheard

Recycling and disposal of timber treated with waterborne copper based preservatives
1993 - IRG/WP 93-50008
Recycling and disposal technologies are briefly reviewed. Details are given of chemical extraction techniques suitable for recovery of copper from timber treated with a new copper based preservative, and traditional chromium based products. Details of thermal decomposition tests according to the DIN 53436 protocol under flaming and non-flaming conditions are given. The decomposition products were analysed for C0, CO2,O2, NOx and arsine. Preservative treated timber showed higher mass loss than untreated timber at 400°C indicating that oxidation was promoted by the presence of preservative at this temperature. At 800°C, 99% mass loss occurred in all cases. Gas analysis showed little difference in combustion products and oxygen uptake between treatments at both temperatures. No arsine gas was detected in the decomposition products of CCA treated timber. A further series of burning tests was carried out to determine the fate of the heavy metals in treated timber samples during thermal decomposition, and to determine suitable extraction techniques to recover the metal for recycling from the residual ash. Using a new copper based preservative the residual copper in the ash had very low water solubility, whereas quantitative extraction could be obtained using acidic extraction techniques. Findings regarding arsenic recovery from CCA treated timber were comparable with those reported by other workers.
J A Cornfield, S Vollam, P Fardell

Application of paint primers after light organic solvent preservative treatment
1986 - IRG/WP 3381
The application of three alternative paint primers is investigated, including a slow-drying oil-based primer, a fast-drying oil-based primer, and a fast-drying water-based primer. The treatment schedules employed, in particular the evacuation period after treatment, have a marked effect on subsequent paintability. Priming can potentially be carried out immediately after treatment with approved Timber Preservation Authority schedules, providing that (1) a fast-drying primer is employed (either water-based or oil-based), (2) solvent recovery by evacuation is continued for an extended period (45 min, c. -85 kPa) immediately after treatment, and (3) either the Lowry or the Bethell process is employed.
P Vinden

Development of a novel treatment process and its applications
1998 - IRG/WP 98-40111
An efficient treatment process called "Isostatic Compression Recovery (ICR) Process" for impregnating liquids into wood has been developed. The process comprises steps of isostatic compression of wood in the liquid at temperatures above its softening temperature and subsequent recovery of its original volume under liquid pressure. A large amount of surrounding liquid is absorbed into the wood in the process of volume relaxation through end surfaces. The process is suitable to uniformly impregnate wood with chemicals which are either liquid or form solutions stable at the treatment temperature. As an example of application of the ICR process, impregnation of Japanese cedar (Cryptomeria japonica) and Radiata pine (Pinus radiata) lumber with borates at high retention is demonstrated , where as much as 60% w/w of borate is impregnated in Japanese cedar lumber in a single treatment.
T Arakawa, M Funato, A Hoshino, T Muraki

Thermal decomposition behavior of CCA-treated wood for safe disposal and the safe recovery of heavy metals through pyrolysis
2006 - IRG/WP 06-50238
If we could estimate the chemical changes in heavy metals by temperature in chromated copper arsenate (CCA)-treated wood during pyrolysis, it is expected that we could solve the environmental problems of heavy metals, which may occur during pyrolysis, and therefore, the thermal decomposition behavior of effective elements of CCA-treated wood was examined to find a safe disposal method. First, CCA-treated wood was combusted at a temperature that prevents volatilization of arsenic compounds, and the arsenic compounds were extracted from carbonized wood. Then, it was considered how to recover heavy metals from chromium compounds and copper compounds. The Thermo Gravimetric Analysis (TGA) result of CCA-treated wood showed that arsenic (III) oxide was volatilized into the atmosphere at 300? and arsenic (V) oxide was volatilized at 800?. When heavy metals were recovered from the carbonized-treated wood after thermal decomposition of CCA-treated wood at 300?, which could suppress the volatilization of arsenic compounds, it was relatively easy to recover copper and arsenic while it was difficult to recover chromium from the carbonized-treated wood.
Dong Won Son, Dong-heub Lee, Sun-hae Cheon, Myung Jae Lee

Bifenthrin recovery from glue-line-treated plywood
2007 - IRG/WP 07-20355
Plywood and laminated veneer lumber (LVL) can be protected from termite damage by addition of bifenthrin to the adhesive used in product manufacture. However, conditions associated with this manufacturing process may lead to deterioration or immobilisation of the active ingredient. In order to determine compliance with treatment specifications, it is important that the concentration of a preservative in the manufactured product can be accurately determined. Plywood test panels were prepared from hoop pine (Araucaria cunninghamii) veneers, using four types of adhesive; isocyanate, high alkali phenol formaldehyde (PF), low alkali PF and urea formaldehyde (UF). Bifenthrin was added to each adhesive mix to achieve three concentrations of the active ingredient in the final product. After manufacture, the concentrations of bifenthrin were determined using two sampling techniques. The concentration of bifenthrin recovered from the treated product varied with the type of adhesive used. The implications for compliance monitoring are discussed.
J Norton, L Stephens

Primary Study on Compressed Preservative-treated Wood (CPW) for Outdoor Applications
2008 - IRG/WP 08-40412
In this study, the compressed wood samples pre-treated with hot water bath or water spraying were immersed in the ammoniacal copper quat –type D (ACQ-D) preservative solution to get compressed preservative-treated wood (CPW). The liquid absorption and the recovery rate of compression deformation of the compressed wood was determined, as well as the surface hardness, the distribution of density and CuO retention in the thickness direction of CPW. The results showed that: (1) the recovery rate and liquid absorption were closely related with each other. Generally a higher recovery rate of compressed deformation corresponded to a higher liquid absorption; (2) the liquid absorption of compressed wood with pre-treatments was about 1.5 times of the untreated control samples, and the surface hardness of the CWP prepared with this method was 3~4 times of that of the untreated control samples; while the corresponding values of those without pre-treatments were more than 2.0 times and about 1.6 times, respectively; (3) the density distribution of the CWP with pre-treatments were much more uniform in the thickness direction, additionally the retention of CuO appeared to be much higher and had a clear trend of higher retention on surfaces and lower inside compared with that of the CWP without pre-treatments. In conclusion, the CPW prepared in this study can achieve both surface densification and preservation, which are suitable for outdoor applications.
Jinzhen Cao, Jia Mao

Rapid Microwave-Assisted Acid Extraction of Metals from Chromated Copper Arsenate (CCA)-Treated Southern Pine Wood
2009 - IRG/WP 09-50262
The effects of acid concentration, reaction time, and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with three different acids (i.e., acetic acid, oxalic acid, and phosphoric acid) was investigated using in microwave reactor. Oxalic acid was effective in removing 100% of the chromium and arsenic at 160°C and 30 min., and acetic acid could remove 98% of the copper and arsenic at the same conditions. Oxalic acid greatly improved the extraction efficiency of arsenic and chromium when time was prolonged from 10 min. to 30 min. Acetic acid also showed improved ability to remove arsenic and copper when the reaction temperature was increased from 90°C to 160°C.
Bin Yu, Chung Y Hse, T F Shupe

Hydrofluoroalkanes as carrier solvents for timber preservation
2009 - IRG/WP 09-40463
Hydrofluoroalkanes are a specific category of hydrofluorocarbon (HFC) commonly used in refrigeration applications. Some HFCs hold potential for use as carrier fluids for preservatives used to protect timber above ground. They do not share the most significant disadvantages of currently used carriers for these applications. At ‘conventional’ operating pressures, they are capable of rapid, full penetration of some timbers generally considered refractory, such as spruce and the heartwood of radiata pine. But they are comparatively expensive and, while they are not detrimental to the ozone layer, they would contribute significantly to the greenhouse effect if released. Impregnation process conditions can be optimised to maximise biocide solubility and impregnation speed and depth.
M J Kennedy, B Walker, C Erskine

Effect of Nano-Silver Treatment on Densified Wood Properties. Part One: Swelling, Recovery Set, Bending Strength
2010 - IRG/WP 10-40533
In this research the effect of Nano-Silver treatment on compressed wood properties, was studied. Wood specimens were cut from Popolus alba (poplar) and impregnated with Nano-Silver and water. Then the saturated samples were compressed through radial direction in a hot press under pressure of 6 MPa, for 1 and 4 hours. The temperatures of press were 150°C and 175°C. Swelling (24h), recovery set and bending strength of compressed samples were tested according to ASTM D-1324 and all data were analyzed statistically. The results showed that the least amounts of swelling after 24 hours soaking in water were seen in specimens which were impregnated with Nano-silver and compressed in 150°C for 1 hour. Also, the least amounts of recovery set were seen in impregnated specimens with Nano-Silver and compressed in temperature of 150°C for 4 hours. The best bending strengths belonged to the dry (non-treated) specimens which compressed in 175°C for 4 hours.
G Rassam, H Reza Taghiyari, B Jamnani, M Ali Khaje

Microwave-Assisted Organic Acids Extraction of Chromate Copper Arsenate (CCA)-Treated Southern Pine
2010 - IRG/WP 10-50267
The extraction effects of acid concentration, reaction time and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with two different organic acids (i.e., acetic acid and oxalic acid) was investigated using a microwave reactor. Oxalic acid was effective in removing 100% of the chromium and arsenic at 160ºC and 30 min. reaction time. Acetic acid could remove 98% of the copper and arsenic at the same condition. Oxalic acid significantly improved the extraction efficiency of arsenic and chromium when time was prolonged from 10min. to 30min. The HSAB (Pearson acid base concept) concept was applied to explain why oxalic acid removed more chromium and less copper compared with acetic acid. Acetic acid also showed an improved ability to remove arsenic and copper when the reaction temperature was increased from 90ºC to 160ºC.
Bin Yu, Chung Y Hse, T F Shupe

A Green and Novel Technology for Recovering Copper and Wood from Treated Wood Waste – Part II: Optimization, copper metal recovery, and process design
2017 - IRG/WP 17-50326
The US consumes 70 million pounds of copper and produces 580 million cubic feet treated wood annually. The EPA disallows burning and reusing treated wood waste due to health/environmental concerns. Vast quantities of copper and wood are landfilled. Two safe and low cost extraction systems, citric acid and ammonium citrate, were identified in Part I of this study. In Part II of the study, effects of extraction conditions such as time, temperature, and equilibrium copper concentration were determined. More than 95% of copper was removed either at ambient temperature for 8 hours or at 40oC for 4 hours. The resulting solution was used in consecutive extractions with new batches of wood until copper reached its rate limiting concentration. The study demonstrated that copper in the extraction solutions could be electroplated onto various metal surfaces, thus efficiently recovered. This process regenerated aqueous solutions to be reused for future extraction. A chemical/engineering process was developed with this study for extracting copper from treated wood wastes, recovering copper from extraction solutions by electroplating, and cyclic use of regenerated aqueous solution. This green and novel technology can keep copper and wood from the landfill and bring tremendous environmental, economic, and social benefits.
S Chen, R Patel

Response of Terminalia mantaly H. Perrier wood to beetles tunneling in Southern Nigeria
2018 - IRG/WP 18-10918
Terminalia mantaly (TM), is extremely susceptible to beetles attack, as evidenced by the many scars and/or tunnels on nearly all the trees in the Southern Nigeria. However, information on the responses of wood to insects tunnelling is poorly known for tropical species. To examine the response of TM stem wood to beetles tunnelling in the University of Port Harcourt, we scheduled field observational visitations and measurements daily once. The tunnelling beetles were identified as Apate terebrans. All the trees responded to tunnelling through sequential exudations of resin and gum for mean duration of 47.25±8.25 and 27.42±4.83 days, respectively. Resin significantly contained higher concentrations of compound phenol ˃ tannin ˃ terpenoids ˃ alkaloids ˃ saponin than gum while gum significantly contained elevated contents of element chloride ˃ calcium ˃ Iron ˃ lead ˃ zinc compared to resin, indicating their specificity roles in the healing scenario of TM wood to A. terebrans tunnelling. Healing period was largely positively correlated with tunnel depth (r = 0.990, p<0.000), reflecting the opportunity for greater biochemical responses during the healing process. The results suggest that the resilience of TM against insects attack is highly possible, but the possibility for further degradations by secondary agents is high.
G A Adedeji, U Zakka, A A Aiyeloja, A I Ochuba

Adhesion durability of the thinnest CLT in Japan treated by solvent recovery system
2019 - IRG/WP 19-40882
The purpose of this study is to clarify the adhesion durability of the thinnest CLT (36 mm thickness) in Japan impregnated with preservatives (azole neonicotinoid compounds (AZN)) under solvent recovery system so called “dry pressure process” for long-term durability. The adhesion durability tests were conducted in accordance with the Japanese Agricultural Standard (JAS) of Cross-Laminated-Timber (2013), and the peeling tests and the block shear tests were performed. As a result, the AZN treated CLT retained sufficient adhesion durability.
K Kawakami, W Ohmura

Alternative products enhancing dimensional stability comparing to conventional treated products in Japan
2019 - IRG/WP 19-40885
The Act on the Promotion of the Utilization of Wood in Public Buildings (2010) in Japan has made a new stream of the utilization field of timber from housing constructions to larger scale non-housing constructions. After the act, the performance of dimensional stability in preservative treated products becomes more important factor than before. Therefore, various technologies have been developed, and the trend of wood protection market shifts from conventional products treated with water-born preservatives to new ones such as a solvent recovery process known as the Dry-Process, deeper penetration treatment by low-pressure spray, and combination of active ingredients and anti-shrinkage reagents.
K Yamamoto, D Tezuka, Y Sugai, S Maeda, I Momohara