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A new model for wetting and drying of wood end-grain – with implications for durability and service-life
2011 - IRG/WP 11-20477
New experimental data for wetting and drying of wood end-grain, Sandberg (2009), imply that traditional models for moisture transport are not at all applicable. A new model is developed to consider the phenomenological behaviour of water transport in and out of end-grain, using the pore water pressure and sorption scanning properties. Modelling results are compared to experimental results and the consequences for durability are discussed.
L-O Nilsson, K Sandberg


Butt-end incising to improve penetration and retention of creosote in Eucalyptus saligna power transmission poles in Kenya. Preliminary results
2002 - IRG/WP 02-40249
Incising as a possible technique to improve penetration and retention of creosote in the butt end of Eucalyptus saligna power transmission poles in Kenya was investigated. Debarked, butt-end samples from whole poles were seasoned (15% MC), incised using four patterns of incisions, sealed at the top or small diameter end, and pressure treated with a mixture of creosote-furnace oil (60/40 mix) at a commercial plant using a full cell process. They were then conditioned in the open for 3 months to allow evaporation, migration, and bleeding. The samples were subsequently leached in running tap water for 21 days, air-dried for 8 weeks under cover and retentions calculated on a weight-gain basis and compared. Discs were removed from the middle (450mm) of the samples, and radial penetration assessed visually and measured. Compared to un-incised samples, both penetration and retention were substantially improved in samples with closer incisions of 20 mm x 20 mm, by 58.6% or 89.8 mm and 87.0% or 146.4 Kg/m3 respectively. Wider incisions 0f 40 mm x 40 mm achieved lower improvements, 17.3% or 66.4 mm for penetration and 19.8% or 93.8 Kg/M3 for retention. The 4 incising patterns achieved consistently higher penetration and retention of creosote compared to un-incised control samples, which achieved lower average penetrations (56.6mm) and retentions (78.3Kg/M3). Butt-end, or incising the ground-contact sections of transmission poles may be a feasible technique for improving both penetration and retention in the more vulnerable portions of poles, and thus substantially increase service lives of eucalyptus poles in the country. Further investigations are necessary to establish patterns of incision and appropriate treatment schedules.
R Venkatasamy


Butt-end incising to improve penetration and retention of CCA in Eucalyptus saligna telegraph poles in Kenya: Preliminary results
2002 - IRG/WP 02-40243
Incising to improve penetration and retention of Copper Chrome Arsenate (CCA) in the butt end of Eucalyptus saligna telegraph poles was investigated. Debarked, seasoned (15% MC) butt-end samples from full size telegraph poles were incised using four patterns of incisions, sealed at the top or small diameter end, and pressure treated, together with un-incised samples, with CCA-C (3.0% oxide type) at a commercial pole treatment plant, using a full cell process. After conditioning under cover for 6 weeks to allow fixation and air-drying to 15% MC, samples were leached in running tap water for 12 days, re-dried to 15% MC, retentions calculated on a weight gain basis and compared. Discs were removed from the middle 50mm sections of samples, sprayed with Chrome-azurol S, and average radial penetration computed. In comparison to un-incised samples, both penetration and retention were substantially improved in samples with closer incisions of 20 mm x 20 mm, by 59.9 %, or 79.3 mm and 59.0%, or 28.3 Kg/m3 respectively. For the wider incisions of 40 mm x 40 mm, improvements were lower, 13.1%, or 56.1 mm for penetration and 19.7%, or 21.3 Kg/m3 for retention. Un-incised samples achieved consistently lower average penetrations of 49.6 mm and retentions of 17.8 Kg/M3. Butt-end incising maybe a feasible technique for improving the otherwise unacceptable short service lives of eucalyptus telegraph poles in the country. Intensity, depth, and method of incising, together with appropriate treatment schedules, need to be investigated further.
R Venkatasamy


Life cycle assessment of creosote treated wood and tall oil treated wood with focus on end-of-life
2016 - IRG/WP 16-50320
The use of creosote for protecting wood products in heavy-duty application outdoors has been common for many years, but stricter regulations have limited creosote’s use. Life cycle assessments (LCA) have shown that in some applications alternatives to creosote treated products do not have less environmental impacts. Searching for alternatives to creosote, tall-oil-based preservatives have been of interest; in this regard, a LCA study has therefore been performed to compare the creosote and tall oil treated products according to their impacts on global warming potential (GWP). There are several approaches to include the removal and release of biogenic carbon in LCA. Under current end-of-life scenarios for treated wood, the different approaches give the same total impact on GWP when the whole life cycle is included. However, if carbon capture and storage is implemented at end-of-life of treated wood, the different approaches have large differences in the results. Tall oil treated wood has been shown in this study to have a relatively large contribution to GWP compared to creosote treated wood from a cradle-to-gate perspective. When the whole life cycle is included, the tall oil has a relatively lower contribution to GWP. This is because tall oil is from a renewable resource and that the combustion at end-of-life thus has a significantly lower impact than fossil-based creosote.
L G F Tellnes, U Hundhausen


Long service life or cascading? The environmental impact of maintenance of wood-based materials for building envelope and their recycling options
2018 - IRG/WP 18-50336
A major restraint in choosing bio-based materials (i.e. wood-based) for external use, is the lack of confidence that architects, designers and customers have toward these materials. In particular, the limit state of bio-based materials, which defines the frequency of maintenance operations, might be reached earlier for wood than for other materials (i.e. concrete). On the other hand, resource and energy scarcity together with increasing concern for climate change consequences are raising the demand for competitive bio-based materials in the built environment as substitutes for other energy-intensive materials. Therefore, novel and traditional protective treatments are used to improve the performance of woody materials for outdoor use. Nonetheless, the environmental and economic burden of such treatments is often unknown. The number of LCA (life cycle assessment) studies on the topic is low, with geographically sparse data and non-uniform assessment protocols. This study provides a novel approach to assess the in-service performance, maintenance requirements and end-of-service-life options for over one hundred bio-based materials for façades. The protection techniques of the materials under examination include: chemical modification, thermal treatment, impregnation, hybrid treatments, and surface treatments (bio-film, coating and nanocoating). Natural, untreated wood and composite materials such as wood-plastic composites are included as well. The in-service environmental performance is analysed by considering the amount of material, energy, water and waste that are used and/or produced to maintain one square meter of façade. The options for end-of-service-life include: panel manufacturing, pelletizing, animal bedding, liquefaction, insect conversion, fungal conversion, combustion, incineration, gasification and pyrolysis, anaerobic digestion, fermentation, composting and landfilling. For each material group, the possibility for cascading use is assessed. The overall goal is to increase the confidence in bio-based building materials by tackling environmental issues related to wood modification processes.
M Petrillo, J Sandak, P Grossi, A Kutnar, A


Conversion by insects – alternative method for wood waste up-cycling
2018 - IRG/WP 18-50337
Building industry is a major consumer of materials and waste generator in Europe. The bio-based building materials are considered as interesting alternative in modern building sector due to their low environmental impact. However, in order to increase confidence for bio-based materials application, they should present satisfying performance during service life allowing at the same time their cascade use, material and/or energy recovery and recycling. New development in the wood modification offer well-performing solutions even in severe environments. However, the advantage of the high resistance against biological degradation can become a restraining factor at the end of their service life. Presented research is a part of the BIO4ever project, where beside of modelling of service life performance, alternative end-of-life solutions for novel facades biomaterials are investigated. The efficiency and ability of insects to convert different categories of materials was investigated during 24 weeks of laboratory tests with selected termite species. Considering discriminatory choice of termites, it can be stated that at least some of the materials category might be converted into valuable protein source at their end-of-life. The investigated termite species Reticulitermes flavipes was recently classified among edible insects. Proposed solution might therefore contribute to the global problem of nutrient deficiency by providing recommendation of the use of building biomaterial wastes as an alternative feedstock for further transformation into proteins.
A Sandak, J Sandak, M Kutnik, I Paulmier, C Brunet, M Petrillo, P Grossi


Is cascading of harvested wood products really an environmentally beneficial strategy in Finland and Norway?
2020 - IRG/WP 20-50364
The role of cascading wood waste in the bioeconomy is highlighted in the several strategic documents. The European Waste Framework Directive describes a waste hierarchy where re-use and recovery are considered more favourable options compared with energy recovery, and applies strict re-use and recycling targets to household waste and non-hazardous construction and demolition waste. It is not fully clear if setting such targets will result in a positive environmental benefit. The assumption is generally made that cascading of bio-materials is good and incineration is bad. But how true is this assumption and is it universally applicable? This paper discusses the methodology to be used in order to determine the best strategy for the use of end of life wood waste in Norway and Finland. The scenario considered is that of the cascading of wood at the end of life into different product categories as counterfactuals compared to the incineration of wood with energy recovery. The paper considers both the LCA aspects by comparison of the global warming potential of different scenarios, as well as the storage of atmospheric carbon in the materials. Knowledge gaps that need to be covered in order to determine the best approach to utilising wood waste from an environmental perspective have been identified.
C A S Hill, G Alfredsen, M Hughes, L R Gobakken


Danish wood preservatives approval system with special focus on assessment of the environmental risks associated with industrial wood preservatives
2001 - IRG/WP 01-50166-01
The following is a description of the procedure used by the Danish Environmental Protection Agency to assess the environmental risks associated with preservatives used in the pressure impregnation of wood. The risk assessment covers issues considered to be of significance for the environment and which are adequately documented so as to allow an assessment. Such issues are persistence and mobility in soils, bioaccumulation and the impact on aquatic and terrestrial organisms. Unless required in special circumstances, the assessment does not apply to birds and mammals as the normal use of preservative treated wood is not expected to involve any noteworthy exposure of these groups. Approval of wood preservatives will be based on a general assessment of the environmental risk associated with the normal use of wood treated with the preservative in a realistic worst case situation. The assessment may address other aspects such as disposal and total life cycle.
J Larsen


The applicability of life cyle analysis and alternative methods in the wood preservation industry
1994 - IRG/WP 94-50023
In the Netherlands, several case studies have been performed using the life cycle analysis method (LCA). This type of research is aimed at an inventory and classification (sometimes including also evaluation) of the environmental impacts of a product, from the raw material to waste stage ("cradle to grave" approach). In a LCA each environmental impact is assessed in terms of, for example, mass of raw material use (kg), energy consumption (MJ), emissions (COx, NOX, SOx, etc.) and final waste (in kg). The critical point in an LCA is the definition of comparable "functional units" for similar products made of different materials with different service lifes. As the LCA method has often proved to be very complex, lime-consuming, expensive and difficult to interpret and translate into practically usefull results, alternative methods are developed. Three methods are described and compared on the basis of various examples. It is hoped that this may be of use as a starting point for further discussion on the suitability of applying the LCA on (preservative treated) timber products.
P Esser, J Cramer


How to Document the Performance of Super-Critical Treated Wood in above Ground Situations?
2005 - IRG/WP 05-20316
The paper presents practical experiences from the preparation of a new preservative treated wood product for introduction to the market. The product in question is Superwood™, which is treated with organic biocides using CO2 in a supercritical state as a solvent. The question is how to evaluate the performance of a new product such as Superwood™ in order to get an acceptance on the market and fulfil the formal requirements. In the European Union countries, the EN 599-1 is the standard that needs to be complied when approving a new product for the market, but it only focuses on the toxic limit against representative decay fungi according to EN 113. However, decay test, above ground and other forms of field tests are optional, this is not in line with the traditional test philosophy in the Scandinavian countries. The open question is to which extent treatment to the level of the toxic threshold value also ensures a long service life and expected performance of the treated commodity. Superwood™ is evaluated using a strategy, in which basic laboratory tests are done to get the toxic value (according to EN 599-1) and in addition a number of field tests are done including accelerated testing in the tropics. These tests are focussed on the evaluation of the performance criteria such as durability and service life and maintenance requirements. These questions must be answered by the producer without having a full record of performance test for their new products. A short status on the test performed on super-critical treated wood (Superwood™) is presented. Based on a comparison between field test in Scandinavia and in the tropical Malaysia a service life of more than 25 years for a specific supercritical treated product is estimated. It is stated that the existing European standardisation system is insufficient when it comes to service life prediction. A number of important questions need to be addressed by the European standardisation system as soon as possible because the market and the public opinion change quickly due to environmental concern.
N Morsing, A H H Wong, F Imsgard, O Henriksen


Extending the useful life of creosoted electricity distribution poles in service
1993 - IRG/WP 93-50001-16
Creosoted transmission poles have provided good service over many decades in a whole range of environments. The use of save biocides for secondary treatments has the potential to extend the life of such poles. These techniques, together with a full understanding of the modes of failure, make it possible to establish new strategies to further improve the environmental benefits of treated wooden poles.
D J Dickinson, B Calver


Effect of a penta emulsion on the service life of Douglas fir, heartwood posts
1978 - IRG/WP 3112
C S Walters


An approach to testing the preventive effectiveness of preservative treatments for wooden joinery
1981 - IRG/WP 2156
The ecological sequence established in field trial samples exposed out of ground contact has shown the need for outdoor exposure in testing potential joinery preservative pretreatments. A system of exposure of L-joint units is proposed. Data obtained by examining samples destructively show promise as the basis for predicting service life after relatively short exposure periods (within 2 years).
J K Carey, A F Bravery, J G Savory


Inspection results of preservative treated stakes, maximum 33 years in field
1992 - IRG/WP 92-3690
Since in 1958, we have undertaken field experiments in Japan. For these field experiments, we used sapwoods of Japanese cedar called Sugi (Cryptomeria japonica) because of majority of plantation forest soft wood species in Japan. For some preservatives, we added sapwood of Japanese beech called Buna (Fagus crenata), a main Japanese hard wood species. Dimensions of these specimens were 30 x 30 x 600 mm³ (T x R x L). About 30 preservatives mainly water born but 20% of oil born preservatives included, were examined for this test. We checked the damage rating every year by the observation. The service life of the preservative treated stakes were estimated at the period when the average damage rating of stakes were reached beyond 2.5 . Creosote oil, creosote oil mixed heavy oil (75:25 and 50:50) and creosote oil mixed coal tar (75:25 and 50:50) are still sound conditions for 33 years. CCA (JIS K 1554 Type 1) 2% and Tancas C 2% are still sound conditions for 28 years. Because of soft rot, the treated Buna specimens were shorten as ones of treated Sugi.
K Suzuki, K Yamamoto, M Inoue, S Matsuoka


Local preservation with difluoride pills: Life-time of preservative
1998 - IRG/WP 98-40127
A brief history of the situation in the Netherlands with respect to the preservation of joinery is given. Already in the eighties in the Netherlands many spruce window frames were treated with difluoride pills. One of the possible disadvantages of this kind of diffusing preservatives is the high leaching rate found in laboratory situations. The leaching rate in practice is influenced by many factors of which the condition of the paint systems and the condition of the glue in the joint are the most important. In this research the difluoride content in wood was analysed in samples which were taken from several buildings. An estimation of the remaining difluoride content leached is given. Related to these figures the remaining life of the protecting agent can be calculated. The results show that even in situations with open joints of paint damage the remaining amount of difluoride is still very high after 10 years. This suggests that in practice the leaching of difluorides is of minor importance.
W J Homan, C Blom, B W Holleboom


Scientific development for prolonging the service life of timbers by impregnating with creosote or organic solvent type preservatives in which additive has been incorporated
1977 - IRG/WP 382
Chemically impregnated wood has played a prominent part in the Telephone and Electricity Distribution Industry during the past century and there is no doubt that it will play an equally prominent part in the future. The reasons why wood poles and wooden, structures predominate, are that when adequately chemically impregnated with a recognised timber preservative to ensure the expected service life for the purpose envisaged, the timber is then fully protected against the ravages of wood destructive organisms. Furthermore, wood is endowed with many natural characteristics that make it a favourite pole and structural material. Its high strength, light weight, ability to absorb impact or shock from loads suddenly applied and ability to resist overloading for brief periods plus its well-known insulating qualities - all are important basic reasons for its predominance in pole line structure. The use of chemically impregnated timber often makes it possible to carry out a given construction programme at less cost, or to erect more structures for a given sum of money, than when more expensive construction materials are employed.
P R B D De Bruin


Reliability-based service life prediction methodology for assessment of water protection efficiency for coatings on wood
2003 - IRG/WP 03-20268
Assessment of water protection efficiency according to EN 927-5 has been shown to give significant differences in water absorption values for different types of coatings on wood. It is shown that the combination of EN 927-5 and an artificial weathering procedure gives more information regarding expected durability and long-term performance than a single measurement of water absorption on fresh, unweathered wood. A combination of water absorption measurement and artificial weathering could become a useful tool in product development as well as in benchmarking. Together with statistical tools, such as reliability-based service life prediction methodologies for prediction of the service life of coating systems a reduction in testing time may be achieved. The predicted service life can then be the input to integrated life cycle assessment of products for wood protection.
J Ekstedt


The performance of glue laminated railway ties after 40 years of service in the main line track
1989 - IRG/WP 2325
Two series of horizontally glue laminated ties made of a softwood body and topped with a hardwood lamination were creosoted and installed in 1947 in a tangent and a curved main line track. The tests are now 40 years old and the excellent condition of the ties of these two series suggest that a service life of 50-60 years can be expected.
J P Hösli, E E Doyle, C P Bird, T Lee


36 years of wood preservative tests in Tanzania
1992 - IRG/WP 92-3731
The performanee of major wood presevatives which are used widely commereially are given. These include creosote, CCA's and 5% Pentachlorophenol dissolved in heavy industrial diesel. Tests are conducted at three ecologically different using pine stakes. Results show that the striking performance of creosote and CCA's is noticeable at above 128 kg/m³ and 16 kg/m³ respectively.
K K Murira, P F Nangawe


A method of predicting the average life of field tests on preservative-treated stakes
1977 - IRG/WP 297
The paper presents an analysis of the results of completed field stake tests on untreated and preserved timber, and develops a method of predicting the average life of incomplete stake tests on wood preservatives from the failures that have occurred so far.
D F Purslow


Estimation of service life of durable timber species by accelerated decay test and fungal cellar test
2002 - IRG/WP 02-20249
Many kinds of durable wood species for outdoor uses has been imported from all over the world to Japan. However information on the natural durability of these species is not sufficient to estimate the service life of them in the climate of Japan. Highly durable species such as Jarrh, Teak, Ipe, Ekki, Selangan batu, Red wood, Western red cedar showed no significant percent mass losses by accelerated decay test according to the JIS Z2101, but some of them are degraded during fungal cellar test for 4 years . The decay rating (0:sound to 5:totally decayed) of them after 4 years exposure was 1.0, 2.0, 0.0, 1.0, 0.0, 2.3, 5.0 respectively. This results indicated that the conventional accelerated decay test could not evaluate the natural durability of these highly durable species at all. Solid wood specimens treated with boiling water at 120? for one hour are subjected to the same JIS test, and the obtained percent mass losses of these species are 1.2, 2.9, 1.9, 3.8, 4.7, 17.5, 0.0 % by a brown rot fungus, Fomitopsis palustris, and 17.5, 14.3, 3.3, 8.2, 4.2, 0.0, 18.3 % by a white rot fungus, Trametes versicolor respectively. Pre-treatment of solid wood specimens for removal of heartwood extractives before a accelerated decay test would be an effective way to evaluate the natural durability of highly durable species in a laboratory.
K Yamamoto, I Momohara


Regulatory and Consumer Challenges Facing Timber Preservation and Durability Interests in New Zealand and Australia
2003 - IRG/WP 03-20282
Timber preservation and durability interests in Australia and New Zealand are facing many challenges and threats arising from regulation and standards changes, to direct competition from competitive materials producers. Industry can address these challenges by pro-active initiation of sound, holistic, research, that addresses the performance needs of the regulators and specifiers and the expectations of consumers. Opportunities do exist for producers of treated timber particularly related to termite management, CCA alternatives and bushfire protection.
C MacKenzie


Thirty-four year test of on-site preservative treatments to control decay in wood above ground
1993 - IRG/WP 93-30015
This research was initiated in 1958 to investigate efficacy of various preservatives and treating methods for new lumber going into exterior structures of buildings. Post-rail units (2x4 inches) constructed of Southern Pine sapwood, Douglas-fir heartwood, and mill run western hemlock were dip- or brush-treated before or after assembly. Units were trested with pentachlorophenol in various petroleum solvents or with copper napthenate in mineral spirits. Both painted and unpainted units were exposed on a test fence in Madison, WI. Most of the painted untreated pine units (controls) failed by 34 years. Surprisingly, painting completely protected the untreated Douglas-fir units from decay and afforded substantial protection to untreated hemlock. Significant decay in painted units was present only in lightly treated pine units (2-second dip after assembly or brush treated). Copper napthenate (1% copper) was markedly less effective than the penta treatments on unpainted pine and hemlock units. There was no evidence that type of oil carrier or incorporation of a water repellent improved effectiveness of treatment. Three or 15-minute dips in penta were equally effective. Penta-grease applied to unit ends only was effective.
T L Highley, T C Scheffer


The effect of service life and preservative treatment on the hardness of wooden poles
1989 - IRG/WP 3537
The surface hardness of utility poles is an important parameter which effects the acceptability of the pole as being safe to climb during line maintenance. The current investigation was designed to evaluate how the surface hardness of preservative treated utility poles is effected by the type of preservative, and the age of the poles. Chromated-copper-arsenate (CCA) treated red pine and jack pine poles which had been in place for up to forty years were located in Bell Canada's system in Ontario, and screened for use in the project. A survey of poles in three locations was made, and data collected on surface hardness using a 6-Joule Pilodyn. Other information recorded included the wood species identified by the brand, and the moisture content (using a resistance type moisture meter). Core samples were removed from each pole for subsequent measurement of preservative retention. The CCA retentions were determined using an X-ray analysis.
E B Jonsson, E M A Nilsson, J N R Ruddick


HCB - a new preservative combination for wood pole maintenance
1996 - IRG/WP 96-30122
New combination of heavy creosoted boron (HCB) applied on hardwood and softwood logs at different moisture content revealed successful diffusion of boron in all sapwoods within 7 days and in all sapwoods plus hardwoods within 15 days. The new cost effective paste sterilizes wood through diffusion and suitable for pole maintenance at groundline and above groundline e.g. cut ends, drilled holes, woodpecker's holes etc.
A K Lahiry


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