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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

In-ground performance of two formulations of chlorothalonil after five years of exposure at three test sites in Australia
1996 - IRG/WP 96-30101
Sapwood specimens of Pinus radiata D. Don and Eucalyptus regnans F. Muell. were each treated to three retentions of each of two preservative formulations (chlorothalonil in oil; chlorothalonil plus chlorpyrifos in oil) and installed in-ground at three field test sites in Australia. Specimens were treated with each formulation to achieve 3.2, 6.4 and 12.8 kg/m³ of chlorothalonil a.i. and 3.2 + 0.2, 6.4 + 0.4 and 12.8 + 0.8 kg/m³ of chlorothalonil plus chlorpyrifos a.i. For comparison, specimens of each timber species, treated to a commercial in-ground retention of a copper-chromium-arsenic (CCA) formulation, were also installed. Treated specimens (including controls) have been rated for their condition annually for attack by subterranean termites and fungal decay using a scale ranging from 4 (sound) down to 0 (failed). After five years of exposure, mean termite and decay scores for replicate test specimens at each site reveal that the performance of all three retentions of each formulation, particularly the two highest retentions, is comparable to CCA.
J W Creffield, T L Woods, N Chew

Efficacy of anhydrides as wood protection chemicals - II. Performance against soft rot fungi
1998 - IRG/WP 98-30174
Pine sapwood modified with various anhydrides and with butyl isocyanate was tested for its resistance to soft rot decay. Small stakes were exposed for 20 months in unsterile soil in a fungal cellar test. Wood modified with butyl isocyanate performed better than any of the anhydrides tested, with a threshold level of protection (less than 3% weight loss) at 12% weight percent gain (WPG). Stakes acetylated to 15% WPG did not give complete protection against soft rot. Stakes modified with alkenyl succinic anhydride showed increasing resistance to soft rot with WPG up to about 10% WPG, above which no further improvements were evident. Succinic anhydride and phthalic anhydride treated stakes showed little or no noticeable protection.
S C Forster, M D C Hale, G R Williams

Short term preconditioning of preservative-treated wood in soil contact in relation to performance in field trials
2000 - IRG/WP 00-20185
The effect of pre-exposure to primary colonising micro-organisms on preservative-treated wood, prior to a basidiomycete decay test, was determined by preconditioning in two soil types. Scots pine EN 113 blocks treated with 3 model systems (a triazole, a copper quaternary compound and a copper boron triazole) were leached according to EN 84 and subjected to 6 weeks and 8 weeks burial in either John Innes no. 2 (a loam-based horticultural compost) or soil from the Simlångsdalen field site in Sweden. The samples were then tested according to the method described in EN 113. Selective isolations were also performed after soil exposure and compared with those from a longer term field trial. Preconditioning lowered the effectiveness of the 2 copper containing preservatives. Some effect of soil pre-exposure could be noted with the triazole but this was limited. The fungal isolations from preconditioned EN 113 blocks and field exposed stakes were a similar mixture of soft rot and mould fungi. Bacteria were commonly isolated from the preconditioned wood. The role of these micro-organisms in the modification of the preservatives is currently being investigated.
S Molnar, D J Dickinson

Decay resistance of resin treated wood
1999 - IRG/WP 99-30206
Selected natural resin systems were evaluated for their potential as wood protecting agents according to standard test procedures. As indicated by the European standard EN 599 both a Basidiomycete test according to EN 113 and a ENV 807 soil bed test were carried out. Six resin treatments were tested using 3 concentration or treatment levels. Using the biocidal activity criteria as usually applied for wood preservatives it became obvious that resin treatments do not comply to the standard requirements. None of the resin treatments tested allowed the establishment of toxic limits when all Basidiomycete fungi were considered. Four resin systems showed a clear impact of retention. The functional relationship of the percentage mass loss to the resin retention was examined. Based on this function the retention levels corresponding with specific mass loss levels were calculated for each fungus. Treatment levels are proposed taking into account the envisaged utilisation under European hazard class 3 (EN 335) and the mass loss criteria for wood species belonging to natural durability class 3.
J Van Acker, A J Nurmi, S M Gray, H Militz, C Hill, H Kokko, A O Rapp

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 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

Performance of treated spruce in Canadian field test sites
1989 - IRG/WP 3506
Spruce material under test in Canadian field test sites is performing better than anticipated. From the comparison of the performance of spruce treated with various preservatives, it appears that penetration may be far more important on durability performance than the preservative itself or the retention of preservatives in the wood. However, there is still insufficient data on the influence of penetration on the performance of treated spruce. As data for species other than white spruce and data for sawn material is also incomplete, spruce cannot be accepted by the Canadian standards at this time.
J P Hösli, E E Doyle

Performance of chromated copper arsenate-treated aspen fence posts installed in Forintek's Eastern test plot from 1951 to 1963
1984 - IRG/WP 3272
Aspen poplar fence posts were pressure treated by the full cell process using three formulations of copper chrome arsenate wood preservative. A total of one hundred and fifty nine of the posts were installed in service in Forintek's Chalk River post plot from 1951 to 1962. During the 1982 general inspection of the post plot all 159 posts were still in service. A groundline inspection was carried out on the material to determine the extent to which decay had progressed during this period. Samples were taken from the surface of tanalith C treated posts and subsequent microscopic examination revealed that soft rot attack was present in the outer portion of posts. The groundline area of posts treated with (K 33), CCA type B and (greensalt) CCA type A were in generally good condition after 22 years and 31 years respectively. Rate of decay was highest for CCA-C tanalith treated posts at 0.3 mm per year with a retention of 3.04 kg/m³ oxides.
C D Ralph

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

Ground contact performance of wood treated by the MSU process
1990 - IRG/WP 3609
Environmental concerns have prompted a renewed interest in accelerated fixation schemes for CCA-treated wood. Results from stake tests of southern pine (Pinus sp.) treated using a conventional Bethell cycle are compared with matched stakes treated using the MSU Process. The effects of adding boric acid to the preservative formulation are also discussed. Differences among test plots are discussed.
H M Barnes, T L Amburgey, R W Landers

Performance of treated and untreated sawn fence posts of Scots pine and Norway spruce
2000 - IRG/WP 00-30247
Sawn fence posts are a rather important product and the objective of this trial was to assess their durability. In 1985 a field trial with treated and untreated fence posts of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) was set out at the test field in Ultuna, Uppsala, Sweden. The posts had a dimension of 75 x 100 x 1400 mm3. The preservatives applied were a CCA, an ammoniacal copper and a creosote. In 1991 fence posts of the same species and size were set out at the test field in Simlångsdalen, Sweden and the preservatives used were a CCA and an ammoniacal copper quaternary compound. The assessment showed that all treated fence posts were attacked very little (mean rating 0 - 0.5) during the first 3 - 4 years at the two test sites. After 7 to 8 years the mean ratings were around 1.0 (slight decay). In Ultuna, after 13 years of exposure, the mean ratings are around 2.0 (moderate decay). The mean service life of untreated Scots pine was 10.2 years in Ultuna and 5.4 years in Simlångsdalen and for untreated Norway spruce 7.5 and 3.2 years, respectively.
Ö Bergman

Performance if internal remedial treatments to arrest fungal attack in poles and large timbers
2018 - IRG/WP 18-40834
Internal remedial treatments have been used to arrest internal fungal attack in utility poles and other large timbers. Water diffusible systems and volatile fumigants have both been used for this purpose. While both work, it is important to understand the performance attributes of each system. This paper reviews the literature on both systems and makes recommendations for future research.
J J Morrell

Relative performances of DNBP and CCA wood preservatives in accelerated decay tests
1988 - IRG/WP 3496
The effectiveness of 2-sec-butyl-4,6-dinitrophenol (DNBP) was compared with that of CCA. Test blocks of Pinus patula and Eucalyptus grandis were impregnated to precisely known retentions of approximately 3, 6, and 10 kg/m³ CCA and solvent-borne DNBP respectively. They were then challenged in decay tests comprising soil burial and exposure to monocultures of Chaetomium globosum, Coriolus versicolor and Coniophora puteana. Decay was monitored by determining weight losses produced in the blocks over 15 weeks. Overall, DNBP performed more successfully than CCA. Specifically, a toxic threshold of 7.4 kg/m³ DNBP was shown in soil-buried Eucalypt, whereas this wood failed in soil even when treated to 10.43 kg/m³ CCA. A mycocidal effect of DNBP on Coniophora puteana was detected. Comparing costs, effective wood preservation using DNBP was cheaper than using CCA, and such costs would be significantly lowered with the advent of less toxic water-borne DNBP.
W H Schnippenkoetter, L D Abraham, A A W Baecker

The performance of CCA treatment in bamboo against decay fungi
1993 - IRG/WP 93-30027
Samples of culm wall material from young (< 6 month age) and mature (> 3 years age) culms of the bamboo, Phyllostachys virideglaucescens were treated to equivalent% w/w retentions of a CCA preservative. After fixation and leaching the treated samples were exposed to decay by Chaetomium globosum FPRL S70K, Coriolus versicolor FPRL 28A and Coniophora puteana FPRL 11E. Thin section samples of untreated and CCA treated bamboo were also exposed to Chaetomium globosum PPRL S70K for visual assessment of decay. The results indicated that CCA could control all three decay types in the mature culm but, in the young material, no dose response to the treatment was found at%w/w retentions equivalent to those in the mature culm. The results are discussed with respect to the development of bamboo cell walls and suggest a significant role for the presence of lignin in determining CCA effectiveness.
O Sulaiman, R J Murphy

A Soil Bed Test of the Effect of CCA Penetration on the Performance of Hem-fir Plywood
2004 - IRG/WP 04-30332
An accelerated decay test was set up to compare the performance of CCA-treated Western hemlock/amabilis fir plywood treated to meet the preserved wood foundation (PWF) retention standard with various patterns of preservative penetration. Short lengths of treated plywood and comparable untreated material were installed in a soil bed. After eleven years of exposure, the CCA treatments were all sound regardless of penetration, while the untreated material had failed due to decay within three years.
P I Morris, J K Ingram

Calculation of preformance index of Bardac 20 (an alkylammonium compound) evaluated in a field stake test
1982 - IRG/WP 3206
Bardac 20 treated stakes have been in test for three years at the Westham Island test site near Vancouver, B.C. The Performance Index for the preservative was calculated and found to be 0.009 which infers that, at the standard retention, Bardac 20 added 0.9 y to the life of the stake. It may be concluded that when tested using a standard field stake test using ponderosa pine (Pinus ponderosa Laws) sapwood at a standard retention of 6.35 kg/m³ Bardac 20 did not fulfil the expectations indicated from the laboratory screening test conducted earlier. Studies are in progress to determine the cause of this discrepancy in performance with a view to improving this class of compound as a wood preservative for use in ground contact situations.
J N R Ruddick

Comparative performance of several ammoniacal copper preservative systems
1997 - IRG/WP 97-30151
The efficacy of several ammoniacal copper-based wood preservative systems was evaluated in this study. The selection of potential co-biocides was based on the results of an agar plate test. Following this, the most promising systems were evaluated in a standard field stake test. Good correlation was found between the agar plate and field stake test results. Of the preservative systems tested, copper/tribromophenol, copper/naphthenic acid, copper/DDAC, and copper/propiconizole were found to be superior against copper tolerant fungi in comparison to the other systems tested after three years of field ground-contact exposure. The performance of copper/benzoic acid was mediocre. Copper/citric acid was ineffective against copper-tolerant fungi, with its performance being no better than copper alone.
D D Nicholas, T Schultz

Performance of boron and fluoride based rods as remedial treatments in Douglas-fir poles
1995 - IRG/WP 95-30070
Boron and fluoride are widely used for remedial internal treatments, but their use in North America has been limited. Recently, however, interest in these chemicals has increased as the result of concerns about the risks of fumigant usage. The performance of boron or a boron/fluoride combination was assessed in Douglas-fir poles over 1 to 3 year periods. Both chemical formulations diffused well through the wetter, groundline zone of the poles, although the initial release rate of the boron in the fused borate rods was somewhat slower than that found with the combination. Chemical levels in the groundline zone remain above those required for control of active fungal attack. Chemical levels above the groundline varied widely reflecting the moisture variations present and highlighting the need for adequate moisture to produce uniform diffusion.
J J Morrell, P F Schneider

A serial exposure technique for estimating probable service life of treated timber
1978 - IRG/WP 2111
This paper briefly describes part of our preliminary work aimed at developing a test procedure that culd be adopted as a standard method. A detailed version of the work has been submitted for formal publication. In both papers, the aim is to promote interest in extended laboratory testing of wood preservatives. It is believed that this work may provide the basis of a laboratory test procedure from which predictions of field performance could be made. The results of the experiment showed that (a) decay of treated blocks increased with successive soil-jar exposure, and (b) the progressive increase in decay was greatest in blocks to the lower retention of CCA.
J A Butcher

L-joint trials: Part 2: The relationship between colonisation by decay fungi and long-term performance
2002 - IRG/WP 02-20251
Many of the L-joint trials conducted at BRE were assessed during the early stages to establish the rate of colonisation by fungi, principally basidiomycetes. At that time, a system of assessment incorporating colonisation studies was proposed for inclusion within the European Standard EN 330 but was rejected for the final version of the standard. The long-term trials associated with the colonisation studies have now reached a stage where direct comparisons can be made between the incidence of colonisation by basidiomycetes and the rate of progress of visible decay. The procedures used were not totally reliable in isolating all decay fungi from L-joints. The correlation between the time decay fungi were first isolated from preservative treated L-joints and the onset of visible decay was poor but there was much better correlation between the total number of L-joints which yielded isolates of decay fungi during the first five years of exposure and the onset of visible decay. It is suggested that isolations made from a greater number of replicates, perhaps after 5 years of exposure, could be used to predict minimum performance life.
J K Carey

L-joint trials: Part 3: Relative performance of a range of preservative products
2002 - IRG/WP 02-30292
Long-term trials using the L-joints described in BS EN 330 and AWPA Standard E9-97 have been in progress at BRE since 1982. This paper records the current assessments of decay of L-joints in trials started between 1982 and 1994 with treatments applied to both Scots pine sapwood (Pinus sylvestris) and spruce (Picea sp.). Data are provided on a range of active ingredients including TnBTO, PCP, acypetacs zinc, azoles, isothiazolones, IPBC and disodium octaborate tetrahydrate.
J K Carey

L-joint trials: Part 1: Observations on the process of colonisation and decay
2002 - IRG/WP 02-20250
The first trials using the small L-joint, later adopted for use in BS EN 330 and AWPA Standard E9-97 were exposed at BRE in 1975 but all were assessed destructively during the early stages of exposure. The longest running trial which included replicates for long-term exposure will have been exposed for 20 years in July 2002. This paper provides an overview of the results of testing during that period. Data are presented which show the variation in the rates of decay found in both untreated and treated replicates. In all cases, there is a period of protection before visible decay is present, followed by a decay period during which decay develops until the point of failure is reached. In preservative treated L-joints, the length of the decay period depends on the type of active ingredient, the concentration of active ingredient and the formulation. Different products also exhibit different modes of failure. For all these reasons, it is clear that there is no simple relationship in field trials between long-term performance and the length of the period of protection prior to visible decay.
J K Carey

Effect of kerfing on performance of Douglas-fir utility poles in the Pacific Northwest
1990 - IRG/WP 3604
Preservative treatment produces an external layer of protection in Douglas-fir poles, but the development of deep checks as the wood dries after treatment can permit entry by fungi and insects. A variety of remedial treatments can arrest this decay; however, it is far more efficient to prevent checking. Kerfing represents one potential method for limiting the development of deep checks. In previous studies, examination of kerfed poles after 20 years in service revealed that only 2% contained viable decay fungi in the kerfed zone, while over 20% of similar non-kerfed poles contained viable decay fungi. Recently, over 5,000 kerfed and non-kerfed Douglas-fir poles ranging from 0 to 25 years in age were inspected. The presence of internal decay in these poles was generally low in comparison with previous reports. Several explanations are proposed for these differences.
J J Morrell

Non-destructive stress wave measurement of decay and termite attack in experimental wood units
1986 - IRG/WP 2256
The purpose of this study was to determine if stress wave analysis could be used to monitor the degradation of wood specimens exposed to the brown-rot decay fungi (Gloeophyllum trabeum) and of wood specimens subjected to attack by subterranean termites. One hundred fifty 3/4 by 3/4 by 12 in. Southern pine specimens were used for exposure to brown-rot decay fungi and two hundred twenty-five 3/4 by 3/4 by 12 in. Southern pine specimens were used for attack by subterranean termites. Lots containing twenty five specimens each were subjected to either brown-rot decay fungi or monocultures of subterranean termites for various lengths of time in order to produce a gradient series of wood degradation. The specimens were then stress waved and statically tested to failure in compression. Stress wave modulus of elasticity and stress wave time provided useful correlation coefficients when used to estimate the ultimate compression stress of the degraded wood specimens. For the brown-rot decay specimens, a correlation coefficient of 0.892 was achieved using stress wave modulus of elasticity, as calculated with original specific gravity and exposed stress wave time values, to predict ultimate compression stress. Stress wave time by itself provided a correlation coefficient of 0.729. For the termite attacked specimens, correlation coefficients ranged from r = 0.90 for the control specimens, to r = 0.79 for the attacked specimens. In this case however, stress wave time by itself was not affected by the degradation of the wood due to the fact that the termites devoured the early wood but not the late wood of each annual ring. Changes in stress wave modulus of elasticity and stress wave time values reflected changes in ultimate compression stress values during early periods of decay. From the results it appears that stress wave analysis can be used to accurately monitor the strength degradation of wood specimens exposed to brown-rot decay fungi. Similar results were found in the termite attacked specimens with stress wave modulus of elasticity but not with stress wave time alone.
R F Pellerin, R C De Groot, G R Esenther

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