Your search resulted in 154 documents. Displaying 25 entries per page.
New developments in wood preservation
1974 - IRG/WP 335
Most of the developments in wood preservation in recent years have been stimulated by changing circumstances, particularly the increasing interest in reducing hazards and environmental, pollution but also the serious difficulties that are now being encountered in obtaining economic supplies of established preservatives. There is perhaps a danger that new controls to reduce pollution dangers may be too severe.
B A Richardson
Social and economocal impact of an extension of service life resulting of an adequate preventive treatment. Application to wooden components used in urban areas with a high density of population
1993 - IRG/WP 93-50001-15
Le document évalue les problèmes rencontrés en zone urbaine pour le sauvetage des constructions: coordination de la lutte, délimination des chantieres et des périmètres d'investigation, nuisances causées par les interventions, risques pour la santé, risques pour l'environnement. Coûts. Comparaison socio-économique du traitement préventif et des interventions à posteriori. Cas particulier du détermitage.
A T De Lelis, G A C Lopez
Loss of preservatives from treated wood during service
1992 - IRG/WP 92-3734
During the 23rd IRG conference in Harrogate the matter of preservative losses from treated wood during service was raised. We were asked to collect information in this field and ask now for help from you. Many tests have been carried out at a laboratory scale to study fixation and leaching from wood treated with different preservatives. Very little, however, is reported on losses of preservatives during service. Since these values are of great relevance regarding environmental impact and the final disposal, reuse or recycling of treated wood, it is of great importance to get as much information as possible on the amount of active ingredients lost during service life. We are convinced there are quite a lot of analytical data and additional information available in many places all over the world. It appears to be rewarding to collect those data and put them together adequately to get an astimate of the losses of the different components based on a broad scale of in service situations. This work will be done as soon as information is available and it is intended to present the results on next IRG meeting.
M-L Edlund, D Rudolph
Problems caused by termites in buildings in the State of Sao Paulo
1976 - IRG/WP 150
Termites are the main insects attacking buildings in the State of Sao Paulo - Brazil. Their attack occurs in wood and wooden materials as well as paper, textile, leather and so on.
M S Cavalcante
Improved equipment and technique for high pressure sap displacement impregnation of natural round wood
1972 - IRG/WP 309
Hitherto the main problem in the practical application of high pressure sap displacement impregnation (HPSD) has been in devising a satisfactory cap. Such a cap must be easily fitted to different size log ends to give a leak proof seal. The present contribution describes a new type of cap and sealing system designed to meet these requirements.
C G W Mason, F B Shorland
Rates of emission from CCA-treated wood in the marine environment: measurement, modelling and requirements for further research
2001 - IRG/WP 01-50166-12
Accurate estimates of rates of emission of leachate from preservative treated wood are crucial for realistic predictions of the environmental impact of its use in maritime construction. Estimates are available for some commonly used preservatives, but these vary widely. Though variable, these measurements suggest that emission generally decreases exponentially with time. Part of the variation is due to differences in methodology employed. Physical and chemical characteristics of the seawater used (e.g. temperature, salinity, pH and oxygen content) affect emission rate. So too do the specifics of the treatment process especially the preservative formulation used, and pre- and post-treatment handling of the wood. The nature of the treated wood samples is also important, with misleadingly high estimates being obtained from samples with unrepresentatively high proportions of cross-cut surfaces. A suggested strategy for developing an informative and standardised methodology is discussed. To form useful models of impacts of leaching, emission rates need to be considered in conjunction with site-specific information regarding a) water exchange rates between the area where leaching occurs and the sea, and b) the extent of partitioning of leachate between the water column, biota and sediment. The risk of environmental impact may be reduced by modification to treatment procedures and by careful planning of installation.
S M Cragg, C J Brown, R A Albuquerque, R A Eaton
Nouvelles techniques de lutte anti-termites à faible impact environnemental
1995 - IRG/WP 95-50040-32
A summary of tests and practical experiences with the Pilodyn wood testing instrument
1980 - IRG/WP 282
This paper presents a summary of the reports, tests and practical experiences with the Pilodyn wood tester not only, however, concerning poles but also in other fields such as standing trees, sawn timber etc. The principle of the Pilodyn is a spring-loaded pin which is fired into the object and the depth to which the pin penetrates is correlated to physical and mechanical properties of the object.
Preservative treatment of Pinus elliottii
1987 - IRG/WP 3435
The treatment of Pinus elliottii with copper-chrome-arsenic preservative by four alternative seasoning and treatment methods is investigated. Steam conditioning followed by either alternating pressure method (APM) or 'Q' treatment resulted in inadequate preservative penetration. Air drying or high temperature drying followed by the Bethell process resulted in a high standard of treatment.
P Vinden, L Carter
Environmental impact of CCA poles in service
1997 - IRG/WP 97-50087
Soil samples from different depths and distances from CCA treated utility poles in Canada were analyzed for copper, chromium and arsenic content for a number of soil types, two wood species red pine (Pinus resinosa) and jack pine (P. banksiana) and different pole ages in service. A limited number of poles were equipped with water traps to collect rain water that dripped down the poles and where sufficient ground water was present, ground water samples from next to the pole were analyzed. The level of soil contamination dropped rapidly with distance from the pole, with soil levels approaching background levels within 0.25 from the pole. Generally, copper levels (above background) were highest, followed by arsenic and chromium, consistent with the known relative leaching tendencies of the three elements. Contaminant levels increased with age of the pole in service and were generally highest in wet organic soils, followed by sand loam soils and clay soils. Soil concentrations were highest at the ground line, adjacent to the poles. This suggested that a large source of the soil contamination was contaminated rain water that ran down the pole. Rain water trapped from the pole surfaces during rain events had significant concentrations of all three elements. There was no obvious drop in contaminant content in water that dripped down the poles with age of the poles. Ground water samples from next to the poles occasionally had detectable CCA components above aquatic and drinking water guidelines.
P A Cooper, Y T Ung, J-P Aucoin
Multiple-Phase Pressure (MPP) Process: One-stage CCA treatment and accelerated fixation process. 5. Treatment of Sitka spruce and Scots pine
1999 - IRG/WP 99-40136
The suitability of the MPP Process for CCA treatment and accelerated fixation of species other than Radiata pine was assessed by pilot plant trials on UK-grown Sitka spruce (Picea sitchensis) and Scots pine (Pinus sylvestris). Pressure and vacuum kickbacks of spruce (14 l/m3) and Scots' pine (122 l/m3) were both substantially lower than that generated during treatment of radiata pine (369 1/m). Total Organic Carbon (TOC) in kickback from spruce treatment (~ 750 ppm) was approximately half that in Scots pine kickback (~ 1400 ppm), and were substantially less than TOC generated during treatment of radiata pine (~ 2000 ppm). Extent of CCA fixation (spruce: 93%, Scots pine: 97%) was similar to that obtained with radiata pine (97%). To reduce post-treatment drippage, caused particularly by the refractory nature of spruce, a modified Bethell process was found most appropriate for MPP treatment rather than modified Lowry schedules used with radiata pine. Use of hot CCA solutions did not improve penetration into spruce and some collapse (washboarding) of early wood was a feature of its treatment.
M E Hedley, K Nasheri, G Durbin
Changed susceptibility of the chemically and thermally degraded spruce wood to its attack by the dry rot fungus Serpula lacrymans
1999 - IRG/WP 99-10322
In buildings, some intentional or unintended situations can occur at which some wood products are exposed to aggressive chemicals and also to higher temperatures. Occasional activity of fungi on such pre-attacked wood products can be either higher or lower. This paper deals with changes in the susceptibility of spruce wood (Picea abies L. Karst.) to attack by the dry rot fungus Serpula lacrymans, in such situations, when the wood samples 8.5x8.5x120 mm3 (RxTxL) were first pre-treated with 1% water solutions of selected acids (H2SO4, CH3COOH), bases (NaOH, NH4OH) or oxidizing agent (H2O2), or they were also exposed to a higher temperature (190°C/3h). The activity of S. lacrymans was totally restricted only in one situation, if the wood was pre-treated with sulphuric acid and then exposed to 190°C. On the other hand, specimens pre-treated with ammonium hydroxide were more susceptible to bio-attack (in both situations: without or with high temperature pre-treatment effect) than sound ones.
A fixation model, based on the temperature dependence of CCA-C fixation
2000 - IRG/WP 00-40163
A model was prepared for the fixation of 1% CCA-C in red pine that allows the prediction of extent of fixation based on the temperature history of the treated wood following pressure treatment. The reaction kinetics of the rapid initial reaction and the slower main reaction were characterized using the Van t'Hoff equation. The initial reaction could be represented by a 10th order chemical reaction and the main reaction by a first order chemical reaction. The main reaction zone in red pine starts once approximately 47% of the total Cr VI in the impregnated CCA-C solution is fixed on wood matrix and is much slower so it controls the fixation rate. The rate constants for the two zones were estimated at a range of fixation temperatures and the temperature dependence defined by the Arrhenius equation. The rate equation and the temperature dependence were combined in a single model for each fixation zone providing an equation that related extent of fixation to the time/temperature history following fixation. The model accurately predicted fixation rate of pine poles exposed to variable temperature conditions following treatment in most cases, although slight changes in the reaction and Arrhenius constants due to natural variability in wood density and other properties could result in relatively large errors in some cases.
P A Cooper, K M F Kazi, Jianbin Chen, Y T Ung
Fully impregnated poles for a minimum environmental impact: Eucalyptus poles
2005 - IRG/WP 05-50224-24
The classical processes for preservation of wooden poles (vacuum-pressure and Boucherie processes) allow the impregnation of the sapwood only. The new radial-axial injection process has been applied to Eucalyptus poles, and has led to impregnation of both sapwood and heartwood. Further more; preserving product is injected both through the groundline area and through the bott end. This allows the two entrances to benefit from a very high retention of antiseptic.
Radio frequency heating times for sterilization radiata pine solid piles
2017 - IRG/WP 17-40815
In this work was sterilized wood packaging material of radiata pine, stacked as solid piles without stickers, for determining the heating times using radiofrequency treatment. The experiments were performed in a radio frequency semi-industrial equipment. The results showed that the radio frequency heating times increases with wood volume and that radio frequency treatments were faster than conventional vapour heat treatment.
H Esquivel, V Sepúlveda, J Torres, L Salvo, R A Ananías
Life cycle analysis: Assessing environmental impact
1994 - IRG/WP 94-50034
Environmental impact assesment is a major issue that faces every nation today. However, consistently and objectively measuring the environmental impact is difficult. During the past two decades, a process called life cycle analysis was developed that tried to make consistent and objective environmental assessments. The Society of Environmental Toxicology and Chemistry broadened the concept to not only incude the inventory, as previously considered in life cycle analysis, but also the environmental impact and improvement phases. The Society of Environmental Toxicology and Chemistry defines life cycle assessment as "an objectice process to evaluate the environmental burdens associated with a product, process or activity by identifying and quantifying energy and materials used and wastes released to the environment, to assess the impact of those energy and materials uses and releases on the environment, and to evaluate and implement opportunities to affect environmental improvements." Life cycle assessment (LCA) has received both positive and negative feedback on its utility as a process to evaluate environmental impact. This paper provides a brief history and overview of life cycle assessment, illustrating how it has been used and misused, listing the benefits and limitations, and outlining its possible applications to the wood preservation industry. Life cycle assessment provides an opportunity to quantify some environmental impacts of various wood preservation techniques and treatments; however, the process must be appropriately applied to gain the full benefit.
S L LeVan
Decay resistance of high performance biocomposites based on chemically modified fibres
1998 - IRG/WP 98-40120
Different partners within the framework of a European research project produced high performance biocomposites aiming at the utilisation of board materials as durable products both in dimensional and biological degrading circumstances. This paper summarises test data, which indicate the potential of board materials produced with modified fibre material. The chemical modifications applied cover a range of technologies, which were selected for scaling up experiments. Acetylation, as well as alternative methods like maleiation, phthalylation, succinylation, oxidation and silylation were investigated. Fibre source, density variation and the use of several types of glues were parameters of the total set-up. Basidiomycete testing was carried out using specific methodology for board materials elaborated in CEN standardisation committees.
V Rijckaert, J Van Acker, M Stevens
Less environmental impact of wood preservatives by considering the risk of attack in addition to the hazard class system
1995 - IRG/WP 95-50040-10
Hazard classes, which are standardized in Europe in EN 335, are most useful to direct chemical wood preservation towards the organisms which may attack wood in the various fields of utilisation. However, hazard only signifies the fact that an attack may occur without considering the actual risk to attack. To minimize the application of chemicals with respect of less environmental impact it is necessary to consider both, the hazard of attack and the risk which implies the probability, how often attack may occur and how important this will be. In addition, also the consequences of the failure of a wooden commodity will influence the need of chemical wood preservation. It is therefore proposed to combine the hazard classes as specified in EN 335 or in similar non European regulations with a risk assessment including time assessment as a basis for the requirement on chemical wood preservation. For this, details are given in the paper.
Exterior wood stains
1980 - IRG/WP 3135
Experience has shown that conventional paints cannot now be relied upon to provide a complete seal against water entry, that in practice water can often circumvent the film and that the paint, far from serving to keep water out will seal it in. Moreover present-day paints are often subject to localised and premature failure out of doors and consequently entail high maintenance costs. Problems of wood decay and premature paint failure reached a high level during the 1960s, and led to the acceptance of the need for the preservative treatment of softwood joinery and cladding. The question remains however, whether, in the light of changes in the quality of timber and how it is used, the traditional approach of attempting to seal the outer surface of the wood is still valid, or should be abandoned in favour of using different types of finish which are more permeable to moisture and prevent it accumulating in the timber. One of the reasons for the remarkable success of semi-transparent exterior wood stains is that they met the demand for finishes of increased water vapour permeability for timber which was susceptible to decay. They also possessed two other important attractions: they provided natural finishes for exterior timber which were without the technical problems of clear varnish; and their mode of breakdown by erosion reduced the preparation work in maintenance and hence the overall maintenance costs. These are valid commendations for stains and remain important factors encouraging their use. Stains offer the architect additional design freedom and, used effectively, can make a pleasing contribution to the appearance of modern buildings. They do reduce average moisture levels in the timber and are simple to maintain, though these advantages may be offset to some extent if more frequent maintenance is necessary and if the higher permeability creates problems from dimensional movement.
E R Miller
Resin bleed after light organic solvent preservative treatment - the effect of drying method and process type
1986 - IRG/WP 3378
The effects of drying method and treatment process type on resin bleed were investigated. High-temperature drying of resinous radiata pine (Pinus radiata D. Don) heartwood resulted in improved wood permeability, higher preservative uptake, and greater resin bleed when treated by the Rueping process. Resin bleed was reduced substantially when timber was treated by the Lowry process, and totally eliminated when Bethell-treated. The incorporation of 2% wax into the preservative formulation may control resin bleed after Rueping treatment.
Observations on the uptake and penetration of various liquids in clear heartwood and sapwood of Pinus radiata D.Don
1983 - IRG/WP 3224
Volumetric uptake of water (aqueous copper-chrome-arsenic (CCA)) or methanol, applied by bulk hydrostatic pressure to air dried clear heartwood specimens of Pinus radiata D. Don, far exceeds that of a wide variety of polar and non-polar solvents. In air dried sapwood, the volumetric uptake of CCA tends to be less than that achieved for most solvents including methanol. No comprehensive explanation of the penetration mechanism in these two substrates can yet be offered. High temperature drying effects a significant increase of volumetric uptake of all liquids by heartwood, but not by sapwood, possibly because air dried material is nearly saturated after pressure treatment.
J E Barnacle
The effect of high temperature and long pressing time on the dimensional stability and decay resistance of OSB
2002 - IRG/WP 02-40237
The exterior use of OSB is restricted because when it is exposed to wet conditions swelling, loss of internal bond strength (IB) and decay occur. In this study an alternative process of pressing which results in the production of dimensionally stable and a more decay resistant strandboard was investigated. Boards were pressed at elevated temperatures for prolonged pressing cycles and their physical (thickness swelling and water absorption after 2 and 24 hours soak), mechanical properties (IB, MOR, MOE) and decay resistance were assessed. Analysis of variance (ANOVA, p=0.005) between pressing time/temperature and each property tested were used for the assessment of the results. The decay resistance of the boards was tested according to a draft European standard (DD ENV 12038: 1996) with a slight modification to the sample size. Boards were tested against Coniophora puteana, Postia placenta, Trametes versicolor and Pleurotus ostreatus. The results of this study showed that the increase of pressing time and temperature resulted in significant reductions in the thickness swelling and water absorption of the boards. The treatment had little effect on board mechanical properties. The resistance to fungal biodegradation was significantly improved at the higher temperature / pressing time combinations tested. The results of this study show that the production of a dimensionally stable and a more decay resistant OSB is possible without excessive use of preservative chemicals. If adopted these findings may lead to the development of new wood-based panel products (non-preserved dimensional stable and decay resistant hazard class 3-OSB) which may replace preservative treated plywood and solid wood for many exterior construction applications.
G J Goroyias, M D C Hale
Distribution of cellulases in the body of Coptotermes formosanus and the probability that the termite uses glucose as an energy and carbon sources
1997 - IRG/WP 97-10202
We assayed extracts of the digestive system and of the whole body of Coptotermes formosanus to determine where the various cellulases, glucose, and related substances were concentrated and to detect pyruvate dehydrogenase activity in the hindgut-removed body in order to verify its full cellulolytic system. About 20%, 18% and 36% of the total exo-1,4-ß-glucanase activity of C. formosanus were detected in the salivary glands, midgut, and hindgut, respectively. About a third of the total endo-1,4-ß-glucanase activity in the termite was detected in the salivary glands (34.5%) whereas the activities in the midgut and hindgut were 21.1% and 18.2%, respectively. About 75% of the total ß-D-glucosidase activity in the termite was detected in the midgut. Thus all the necessary cellulases for hydrolysis of natural cellulose to glucose were present in the region ranging from the salivary glands to the midgut in significant amounts. Most of the glucose and trehalose detected in the termite existed in the gutted-body. Most of the glucose detected in the gut existed in the midgut. Pyruvic acid was directly converted to acetyl-CoA in the presence of NAD+ by a crude extract of the gutted-body. These results suggest that natural cellulose ingested by the termite is hydrolyzed to oligosaccharides in the region of the foregut and midgut as well as in the hindgut, that oligosaccharides are hydrolyzed to glucose predominantly in the midgut, and that the resultant glucose is absorbed through the midgut wall into the tissues to be used as important energy and carbon sources.
S Itakura, H Tanaka, A Enoki
Comparative environmental impact analysis of telecommunication utility poles: Treated wood and fibreglass
1999 - IRG/WP 99-50136
This study is aimed at providing the information necessary to assess the main environmental implications of different materials utilised in construction of utility poles. The study was performed on fibreglass and CCA treated poles timber. The work has been carried out by identifying and quantifying energy and materials used and wasted released during the entire life of the pole. The interactions with the environment have been analysed, estimated and evaluated for their respective production, lifeservice and disposal phase, on the basis of the principles defined by the United Nations Conference on Environment and Development (Rio de Janeiro 1992), as sustainable development, precautionary approach, best available technology. According to those principles, results show that quite significantly better performances can be reached with CCA treated poles in terms of processing energy use (about 2 kWh/pole against the 580 kWh/pole necessary for the fibreglass); even the lifeservice extension of the fibreglass product (not really yet known and estimated 40 years in comparison with the 25 - 35 years of a wood treated pole) is not sufficient to compensate for its extremely unfavourable energetic aspect. Otherwise, considering both the material at the end of their use life, a remarkable role is played from fibreglass poles for its wide possibilities of recycling (grinding, gasification, burning, pyrolysis and fluidized bed combustion); even if concrete possibilities of reuse and detoxification are actually adopted for wood products as well. In the assessment of environmental impacts the in-service effects on soil and surrounding water, the CCA leaching can represent a limit to the utilisation of treated wood poles. Studies around the poles have shown amount of CCA components released into the soil of maximum 4,6% by weight of the original salt retention in a treated pole. In conclusion the comparison between the two materials shows a more favourable performance towards the environment for the treated wood products.
A Cugliandolo, M Onofrio, A Quaglino
Vapour boron treatment of wood based panels: Mechanism for effect upon impact resistance
1994 - IRG/WP 94-40036
Samples of medium density fibreboard, chipboard and oriented strandboard (OSB) were treated to two retentions of boric acid by a vapour phase treatment. The results of a range of mechanical tests were reported by Hashim et al. (1992, 1993) in which a small reduction in impact resistance was observed. Several investigations were carried out to study how and where this loss in impact resistance occured. Possible mechanisms for the loss in impact resistance are discussed.
R Hashim, R J Murphy, D J Dickinson, J Dinwoodie