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High-energy multiple impact (HEMI)-test – Part 2: A mechanical test for the detection of fungal decay
2006 - IRG/WP 06-20339
The suitability of the high-energy multiple impact (HEMI)-test for detection of early fungal decay was examined. The HEMI – test characterizes the treatment quality of thermally modified wood by stressing the treated material by thousands of impacts of pounding steel balls. This method differentiates between heat treatment intensities, which are expressed by structural changes of the wood. Similar changes of the wood structure are known for wood decayed by fungi. Pine (Pinus sylvestris L.) decayed by brown rot and beech (Fagus sylvatica L.) decayed by white rot were tested. Mass loss caused by fungal decay and the resistance to impact milling (RIM) determined in HEMI-tests were found to be highly correlated. Testing of non-degraded pine, beech, and ash (Fraxinus excelsior L.) showed only marginal effects of wood density on RIM. Furthermore, annual ring angles and RIM of spruce (Picea abies Karst.) were found to be not correlated. Accordingly, the detection of strength reduction of decayed wood is not masked by variations in density and orientation of the annual rings. Previous results showed no adverse effects of weathering on RIM. Thus, the detection of fungal decay with HEMI-tests is feasible, not only for laboratory purposes, but also for wood in outdoor applications, which was already weathered.
C R Welzbacher, C Brischke, A O Rapp
High-energy multiple impact (HEMI)-test – Part 1: A new tool for quality control of thermally modified timber
2006 - IRG/WP 06-20346
Thermal modification processes improve durability and dimensional stability of wood, but the strength properties, especially the dynamic ones, are compromised and need to be considered with respect to industrial quality control. Results from standard dynamic strength testing, such as impact bending tests, suffer from high variability, and therefore require a high number of replicates. To overcome this, a new test method named high-energy multiple impact (HEMI) was developed. In the present paper heat treated beech (Fagus sylvatica L.), spruce (Picea abies Karst.), silver fir (Abies alba Mill.), and larch (Larix decidua Mill.) were investigated. The HEMI method is based on crushing small specimens by thousands of impacts of pounding steel balls in a heavy vibratory mill. The level of destruction was determined by slit sieving and analysing the size distribution of the fragments. We calculated the resistance to impact milling (RIM) based on the mass of the size fractions. RIM showed a linear correlation with the decrease in mass of the wood by the thermal treatment. The HEMI-test method has the following advantages: small number of specimens, short time for specimen preparation, small variances, high reproducibility of the results, and applicability to timber out of service for a subsequent quality control.
C Brischke, A O Rapp, C R Welzbacher
Mechanical strength of wood from the Vasa shipwreck
2008 - IRG/WP 08-20381
Samples from three ancient ship wrecks (Vasa, Elefanten, and Gröne Jägaren) and recent oak samples as reference were examined with regard to mechanical strength using the high-energy multiple impact (HEMI) - test method, which delivers the resistance to impact milling (RIM) of a material. Adoption and optimisation of the test method for the particular sample size of the wooden drilling cores was necessary. After that optimisation the HEMI method proved to be suitable not only for cube like specimen but also for specimens from wooden drilling cores. The RIM of the different wreck samples was partly significantly different from the recent reference material. Low values indicated deterioration of some cores. Interestingly the wooden core with high iron content showed the highest RIM, even significantly higher than that of untreated recent oak.
A O Rapp, C Brischke, C R Welzbacher, T Nilsson, C Björdal
The effect of gamma radiation on selected wood properties
2008 - IRG/WP 08-40394
As an easy, fast, and effective sterilisation method, gamma irradiation changes molecular structures not only in pest’s living cells, but also in wooden cell walls. Radiation-induced depolymerisation causes significant changes in some properties of wood crucial for restoration and for laboratory testing of wood-preservative effectiveness. The influence of gamma radiation concerning total amount of water-soluble carbohydrates (TSC), maximum swelling (aMAX) and resistance to impact milling (RIM) were investigated. Cobalt (60Co) was used as gamma source and Scots pine sapwood (Pinus sylvestris L.) was irradiated with dosages of 30, 90 and 150 kGy. A strong linear correlation between TSC and the radiation dosage was found. Leached irradiated specimens had significantly greater TSC than non-irradiated controls. RIM decreased significantly and linearly with increasing radiation dosage. After leaching, the linearity between these parameters was improved. Gamma radiation had no significant effect on aMAX and the elapsed time after irradiation did not influence aMAX, RIM, and TSC.
R Despot, M Hasan, A O Rapp, C Brischke, C R Welzbacher
Estimating the heat treatment intensity through various properties of thermally modified timber (TMT)
2009 - IRG/WP 09-40459
The suitability of different measures for prediction of the heat treatment intensity was investigated. Therefore, the resistance to impact milling (RIM), the lightness L*, the equilibrium moisture content (EMC), the anti swelling efficiency (ASE) and the total amount of soluble carbohydrates (TSC) of heat treated specimens were correlated with corresponding fungal resistance achieved by heat treatments. Heat treatment temperatures of 180°C, 200°C, 210°C, 220°C, and 240°C for various heat treatment durations from 0.25 to 72 h were applied. The results show, that the decrease in mass (dm) by heat treatments is a suitable measurand to describe the treatment intensity, which is a product out of treatment temperature and duration, where the impact of temperature is predominating the impact of time. The properties examined showed a strong reciprocally proportional relationship with the decrease in mass. Thus different correlations were found for the various treatment temperatures: The higher the temperature applied, the lower was the decrease in mass required for an equivalent improvement of certain wood properties, e.g. biological durability, EMC, and dimensional stability. However, mass loss by Poria placenta correlated well with the resistance to impact milling (RIM), lightness L*, EMC, ASE and TSC of the different heat treated specimens, depending on the heat treatment temperature. Consequently, a reliable estimation of improved fungal resistance of TMT, as well as the quality control of TMT in general, strongly requires certain process information.
C R Welzbacher, C Brischke, A O Rapp
Influence of heat treatment intensity on the structural integrity of 14 timber species
2012 - IRG/WP 12-40586
Thermally modified timber (TMT) is characterized by improved durability and dimensionally stability, but strength properties, especially the dynamic ones, are compromised at the same time. Because dynamic standard tests require high efforts and time, the high-energy multiple impact (HEMI) –test was developed for the fast and reliable characterisation of the structural integrity of TMT, showing a strong correlation of decreasing structural integrity with rising treatment intensity. Since the number of wood species subjected to this test method was limited up to now, 14 soft- and hardwoods were heat treated by ten different treatments at 180 and 220°C and used for determination of the structural integrity. The results showed temperature dependent strong correlations of decreasing structural integrity with increasing intensity for all species tested, pointing to the general applicability of the destructive HEMI-test in the frame of the post production quality control of TMT. In addition, the structural integrity is not affected by density, anatomical macro-defects like drying cracks, growth ring and fibre deflection or weathering impacts, which confirms its usage for implementation within a reliable factory production control to ensure constant product qualities.
C R Welzbacher, C Brischke, G Maier
Changes in mechanical and chemical properties of wood exposed outdoors
2014 - IRG/WP 14-20550
The aim of this study was to investigate differences in certain mechanical and chemical properties of three different wood species (common beach (Fagus sylvatica), Norway spruce (Picea abies), and copper-ethanolamine (CuE) impregnated Norway spruce (Picea abies)) that were exposed in use class 3 (CEN, 2006) for periods between 4 and 30 months. The results show, that changes in the investigated mechanical and chemical properties coincide, with first signs of fungal degradation after 12 to 18 months of outdoor exposure.
N Thaler, C Brischke, D Žlindra, V Vek, M Humar
The effect of preservative treatment on mechanical strength and structural integrity of wood
2015 - IRG/WP 15-30667
The use of wood for demanding construction applications is increasing in Europe. Wooden constructions are frequently designed of susceptible conifer wood, which is endangered by wood decay fungi in wet applications. Therefore in many cases treating wood with preservatives is unavoidable to ensure the desired service life. However, chemical treatment of wood can result in changes of its mechanical properties. There are contradictory results published in literature regarding the influence of the various impregnation agents on relevant mechanical properties. In order to elucidate mechanical properties of impregnated wood, Scots pine (Pinus sylvestris) sapwood and Norway spruce (Picea abies) wood were impregnated with a copper-ethanolamine based system, an aqueous solution of boric acid and a solvent based wood preservative. For comparison, wood samples were impregnated with deionised water. After conditioning, half of the samples were artificially aged according to the EN 84 leaching procedure. Afterwards, samples were oven dried, and their bending and compressive strength in axial and radial direction was determined. In parallel, structural integrity of the samples was determined in High-Energy Multiple Impact (HEMI) tests. The results clearly showed that treatment with wood preservatives does not have significant influence on the mechanical properties, with exception of non-aged copper-ethanolamine and boric acid treated wood that exhibited significantly lower structural integrity of wood. The negative effect on strength and structural integrity was found to be reversible through exposure to liquid water or high relative humidity.
M Humar, D Kržišnik, C Brischke
Impact of decay and blue stain causing fungi on the structural integrity of wood
2009 - IRG/WP 09-10699
The potential influence of diverse decay patterns caused by different brown rot provoking basidiomycetes on the structural integrity of wood was investigated. Additionally the potential impact of blue stain on the structural integrity was examined. Therefore decayed Norway spruce (Picea abies Karst.) specimens representing a wide range of mass loss, caused by four different brown-rot fungi and one white-rot fungus, were applied to a high-energy multiple impact (HEMI) -test series. The relationship between the resistance to impact milling (RIM) and the mass loss by fungal decay could be subdivided in three areas: 1. Prior to measurable mass loss a strength reduction was detectable due to the depolymerisation of wood cell wall components. 2. Between 0 and 25-30% mass loss RIM decreased with increasing mass loss. 3. Above 30% mass loss RIM increased again due to gluing effects of the fungal mycelium. The influence of the different brown rot fungi on the structural integrity of the wood differed slightly, but partly significantly. According to preliminary results blue stain caused by Aureobasidium pullulans and Sydowia polyspora was found to have no significant impact on RIM.
C Brischke, C Welzbacher, T Huckfeldt, F Schuh
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
Sequential exposure of borate treated Douglas-fir to multiple Formosan subterranean termite colonies in a 40-week field test
1993 - IRG/WP 93-10006
Douglas-fir boards (ca. 74.5 g) pressure-treated with disodium octaborate tetrahydrate (DOT) retentions of 0 (controls), 0.88, 1.23, 1.60, or 2.10% (weight/weight) DOT were sequentially exposed to four active field colonies of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in an above-ground field test. Samples were placed in contact with each colony for 10 weeks, with oven-dry weight losses determined between exposures, for a total termi exposure period of 40 weeks. Feeding activity differed among termite colonies, with the control wood samples having mean weight losses of 1.3-15.1% of their initial weight during each individual 10-week termite exposure. The two lower borate retentions (0.88 and 1.23% DOT) were virtually equal efficacy, with mean wood weight losses during each individual 10-week exposure ranging from 1.2-4.6%. Feeding was negligible at the two higher borate retentions, with mean wood weight losses from termite feeding during each 10-week period ranging from 0.7-1.3% with 1.60% DOT, and 0.3-0.9% with 2.10% DOT. Total cumulative wood weight losses over the 40 week exposure were: 10.2% (0.88% DOT), 8.7% (1.23% DOT), 3.6% (1.60% DOT), and 2.4% (2.10% DOT).
J K Grace, R T Yamamoto
Experiences from a Danish large scale test by means of a new method of treatment by attack of true dry rot fungus (Serpula lacrymans) in buildings
1994 - IRG/WP 94-10064
Experiences from a new and epoch-making method of treatment in connection with the repair of attack of the true dry rot fungus, Serpula lacrymans (Fr.) S.F. Gray, are described. The paper presents the background of a large scale test comprising repair of more than 150 Danish buildings over a period of approximate 5 years. The method being both gentle to the building and presenting savings of at least 70% compared with the traditionally known repairing methods is based on thorough recording of the extent of attack and examination of the vitality of the fungal attack combined with a changed chemical and constructive treatment including treatment by means of a newly developed heat treatment based on high frequency radio waves. Continuous controls have confirmed the applicability in practice of the method. Beyond the method, the paper discusses the consequences as regards security, possibilities of insurance and obtaining a mortgage loan.
O Munck, H Sundberg
Quality of timber impregnated with preservatives of class AB
after three years in service
2002 - IRG/WP 02-20241
Quality of impregnated timber is most often expressed by penetration and retention of the preservative used. Relatively less information is available about the performance of the final product, e.g. decks, panels etc. regarding product’s surface checks, deformations and overall appearance. Together with the timber durability, the above mention features are of esthetical importance in the above ground performance of timber. A comprehensive Nordic project dealing with pre-treatment, impregnation, durability and performance of Scots pine timber impregnated with copper-based preservatives for above ground use (class AB) was recently finished. The results from an above ground trail concerning the quality of timber are presented. The timber was dried in a conventional progressive, batch and high temperature kiln prior to impregnation. A significantly better quality regarding checks, deformations and deviation of the final moisture content, was achieved after conventional batch and high temperature dryings. Three preservatives (Kemwood ACQ 1900, Tanalith E and Wolmanit CX-8) were impregnated. The high temperature drying ensured the best penetration of all preservatives, but the retention was lower compared to conventional progressive and batch kiln dried timber. A part of the planks were conventionally kiln dried after the impregnation, the second part was air dried. Two decks with planks covering the variations in primary drying and preservative used were exposed; the former deck was in the open, the later one was under a shelter. After three years in service the planks were assessed regarding checks, deformations and moisture content. All three preservatives showed satisfactory appearance and no indication of decay was found. The deformations were comparable to those measured directly after final drying; the type of exposure had effect on the checks and moisture content of timber.
Tropical In-Ground Durability of Structural Sarawak Hardwoods Impregnated to High Retention with CCA-salts, CCA-oxide and FCAP after 20 Years Exposure
2005 - IRG/WP 05-30384
Statistical analysis (ANOVA) was conducted on durability (termite and decay combined) rating data collected over 20 years exposure period of over 140 species of Sarawak timbers with altogether 30,000 stake specimens, at the Forest Department’s Sibu “graveyard” stake test sites from 1977. About 20 replicated stakes were pressure-treated to refusal with 10% g/ml concentration of up to 3 CCA-salt formulations and 1 CCA-oxide product and FCAP were visually evaluated every 6 months according to the 5-point ASTM D1758 durability rating scale, and the treated durability results reported in this paper are between 5 and 20 years exposure. The analysis was confined to 7 relatively high density hardwood species that are regarded suitable for in-ground structural use (ie, basic density >600 kg/m3), and had achieved a minimum preservative retention of 16 kg/m3 (as required for CCA-salts) but up to 48 kg/m3 retention. The results revealed that the in-ground durability of treated wood decreased usually after 5 years to poor-to-moderately durable levels with CCA-salts, moderate-to-high durability with CCA-oxide, but failed with FCAP after 20 years. CCA-oxide treated hardwoods out-perform the CCA-salt treated counterparts despite their relatively similar retention and “over-treatment factor”. The non-leach-resistant FCAP is clearly unsuitable as an industrial used in-ground wood protectant.
Wang Choon Ling, A H H Wong
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
Impact of climate change on wood deterioration - Challenges and solutions for cultural heritage
2010 - IRG/WP 10-20441
Deterioration of wood in cultural assets follows the same physiological mechanisms as in modern structures. Therefore rules and data for prediction of service life derived from old wooden structures can be used to model the service life of recent wooden structures and vice versa. The latter is done in this paper: From experimental test set ups in the field spread over Europe, climatic data, wood temperature, wood moisture content, and decay rates recorded for several years were correlated and used for mathematic modelling of decay. On that data basis a first attempt is made to quantify the influence of global warming on wood decay rates for different regions and scenarios, valid for both: wood in modern and historic structures. Against this background conservation of cultural heritage is increasingly challenging and methods are sought to allow historic structures to survive without severe modifications in design, but also with limited use of preservatives. How moisture monitoring can contribute to this purpose is shown on the example of the Echo pavilion in Maksimir Park, Zagreb, Croatia.
C Brischke, A O Rapp, M Hasan, R Despot
Performance of Wood Protection Systems at Multiple Field Test Sites Using the Ground Proximity Test Method
2012 - IRG/WP 12-20499
A series of preservative systems were used to treat southern pine ground proximity test samples which were then exposed at a range of test sites located throughout the world. The sites were chosen on the basis of having vastly different Scheffer Climate decay indices. After almost 14 years exposure, distinct differences are apparent in how different preservative systems perform at the different sites, as well as how their relative performance is impacted at different retentions.
A Zahora, A Preston, L Jin
Impact of water holding capacity and moisture content of soil substrates on the moisture content of wood in terrestrial microcosms
2019 - IRG/WP 19-20662
Terrestrial microcosms (TMC) are frequently used for testing the durability of wood and wood-based materials as well as the protective effectiveness of wood preservatives. In contrary to experiments in soil ecology sciences, the experimental set-up is usually rather simple. However, for service life prediction of wood exposed in ground, it is of immanent interest to better understand the different parameters defining the boundary conditions in TMC. This study focussed therefore on the soil-wood-moisture interactions and their potential effect on durability testing in TMC. TMC were prepared from the same compost substrate with varying water holding capacity (WHC) and soil moisture content (MCsoil). Wood specimens were made from English oak, Beech, Douglas fir, and Scots pine sapwood and exposed to in total 48 different TMC and wood moisture content (MCwood) was studied as well as its distribution within the specimens. For this purpose the compost substrate was mixed with sand and turf and its WHC was determined using two methods in comparison, i.e. the ‘Droplet counting method’ and the ‘Cylinder sand bath method’ in which the latter turned out advantageous over the other. MCwood increased generally with rising MCsoil, but WHC was often negatively correlated with MCwood. Instead, the degree of water saturation Ssoil could serve as a more predictive measure for MCwood in soil exposure scenarios. With increasing Ssoil the MCwood increased, but followed wood species-specific curves with differently steep increase and a plateau at Ssoil = 0 %. In addition, Ssoil from which MCwood increased most intensively was found to be wood-species specific and might therefore require further consideration in soil-bed durability testing and service life modelling of wooden components in soil contact.
C Brischke, F L Wegener
Impact of fungal decay on the bending properties of wood
2020 - IRG/WP 20-20671
Wood used outdoors is generally prone to fungal degradation, and its impact on the structural integrity of wood is an immanent factor for service life planning with timber. Wood decayed to very small mass losses can suffer from a significant reduction in mechanical strength and elastic properties. Hence, the latter are preferred indicators to detect decay in wood durability studies. Numerous previous studies suggested, for instance, modulus of elasticity (MOE) measurements for decay detection since they outperform mass loss in terms of sensitivity. However, literature reports on the topic are not always consistent and partly contradictory. Therefore, this study aimed at 1.) comparing different methods for decay detection with respect to their sensitivity to decay and transferability to each other, and at 2.) quantifying the effect of white and brown rot decay on bending properties of wood. Generally, with increasing mass loss (ML) due to fungal decay bending properties were negatively affected, and brown rot caused more severe damage to elasto-mechanical properties than white rot decay. The elasto-mechanical bending properties were more sensitive to fungal decay than ML but suffered from remarkably high variation. Temporal and spatial distribution of decay affected the structural stability of wood, which became manifested in MOE and MOR (modulus of rapture). Particularly, decay pockets and end-grain decay led to significant ML but had little to no effect on bending properties of the specimens. The quality of correlation between auxiliary quantities such as ML and the underlying target properties strongly depends on the experimental set-up. In the study at hand, wood specimens were placed directly on fully developed mycelium and the total specimen volume was subjected to fungal degradation. The transferability of decay assessment data from one method to the other appeared rather limited. The ML, MOE loss and MOR loss data obtained from recent tests should be considered preliminary but may serve to better define limit states which are essential for decay modelling and service life planning.
S Bollmus, P B van Niekerk, C Brischke
Durability against fungal decay of sorbitol and citric acid (SorCA) modified wood
2022 - IRG/WP 22-40928
Most European-grown wood species are susceptible to biological degradation, specifically, they suffer from a poor resistance against wood-destroying fungi. Therefore, prior to outdoor exposure, wood has to be treated either by applying a protective coating on its surface or by full-volume impregnation with antifungal chemicals. However, due to environmental and health concerns, the most frequently chosen solution, the use of biocidal preservatives, has become limited and new non-biocidal methods to protect wood against wood-destroying organisms are investigated. Recently, chemical wood modification via in-situ esterification of sorbitol and citric acid (SorCA) has been reported to result in a significant increase of the biological durability, specifically an increased resistance against wood-destroying basidiomycetes. However, none of these studies have investigated the resistance of SorCA treated wood against decay fungi by performing a full EN 113-2 (2021) procedure yet, i.e. following the standard incubation time and sample size. Therefore, a series of Scots pine sapwood (Pinus sylvestris L.) specimens was treated with aqueous solutions of SorCA at different solid content levels (10, 20, 30 and 50%). All treated collectives plus untreated reference samples were then exposed to brown rot (Coniophora puteana, Rhodonia placenta) and white rot (Trametes versicolor) fungi according to EN 113-2 (2021). After 16 weeks of incubation, wood decay was assessed on the basis of the loss in dry mass (ML %) and the decay protection threshold (ML ≤ 5 %) for SorCA-modified wood was established depending on the tested fungi. Post decay testing, the structural integrity of specimens characterized by various ML values was analysed by high-energy multiple impact (HEMI) tests and correlated with the ML resulting from decay by brown and white rot fungi. Basically, the structural integrity decreased with increasing ML in specimens being incubated with brown rot fungi, which was not observed after white rot incubation. The latter might be attributed to the narrow range of ML values measured after white rot incubation, indicating higher efficacy of SorCA modifications against white rot fungi. Thus, further work is needed to understand the difference in decay resistance between tested brown rot fungi and of course between brown and white rot fungi.
K Kurkowiak, L Emmerich, H Militz
Biological assessment of bio-based phase change materials in wood for construction applications
2022 - IRG/WP 22-40935
Solid wood can serve multi-functionality for energy savings in buildings. The study reveals the results of bio-deterioration and degradation of solid Scots pine wood used to incorporate single or multicomponent fatty acid mixtures as bio-based phase change materials (BPCMs). The sapwood samples were impregnated with capric acid (CA), methyl palmitate (MP), lauryl alcohol (LA) and a mixture of coconut oil fatty acids and linoleic acid (CoFA-LA). The samples were tested against subterranean termites by an Italian species (Reticulitermes lucifugus), the wood boring beetle Hylotrupes bajulus and mould through a discoloration test. Tested against termites, the impregnated samples were significantly less susceptible to the attack than the controls, i.e. the tested BPCMs were resistant to R. lucifugus. The only test with MP terminated at the moment against H. bajulus showed positive results with no larvae survived. The mould discoloration test revealed that the wood impregnated with CoFA-LA was identically susceptible to mould discoloration when compared to the control, non-impregnated samples. This pioneer study verifies that solid wood employed for encapsulation of BPCMs for building purposes can serve identically or somewhat better than similar wooden building elements regarding attacks of the above microorganisms and insects. Such multifunctional building elements will be tested further in a pilot scale building to characterize better the durability aspects of the new materials.
S Palanti, A Temiz, G Köse Demirel, G Hekimoğlu, A Sari, M Nazari, J Gao, M Jebrane, T Schnabel, N Terziev
Programme section 2, Test methodology and assessment
1997 - IRG/WP 97-20126
Progress report on co-operative research project on L-joint testing
1983 - IRG/WP 2192
A F Bravery, D J Dickinson, M Fougerousse
A comparison of soft rot, white rot and brown rot in CCA, CCP, CCF, CCB, TCMTB and benzalkonium chloride treated Pinus radiata IUFRO stakes, after 9-15 years exposure at five test sites in New Zealand
1991 - IRG/WP 1485
The aim of this study was to determine if decay type varies significantly between five field trial test sites of different soil type, aspect and climate in 9-15 year old, replicate CCA, CCF, CCP. CCB, TCMTB and AAC treated IUFRO stakes. A visual on-site assessment of decay type on every test stake was made and observations confirmed by microscopical examination. Regression analyses were used to determine significant differences of percentage frequency of occurrence of each rot type between sites and preservatives. Large differences in percentage frequency of occurrence of rot type were evident between sites. One site was dominated by brown rot (85%) and two were dominated by soft rot (99 and 91%). The fourth site had intermediate proportions of brown rot (40%) and soft rot (71%) but had the second highest occurrence of white rot (32%) (highest = 37%; lowest = 11%). The fifth site was distinct in that a large proportion of stakes (69%) had both well established brown rot and soft rot. Stakes at the other four sites tended to have only one rot type. Some highly significant preservative effects were also found. Possible causes of these differences are discussed in terms of inter-site soil type, climate and other differences.
R N Wakeling
Wood preservatives: Field tests out of ground contact. Brief survey of principles and methodology
1976 - IRG/WP 269
This paper contains the following spots: 1.: The general need for field tests. 2.: Interests and limits of field tests in ground contact. 3.: Various methods in use for out-of-ground contact field tests. 4.: Fungal cellar tests are they an alternative to above-ground decay exposure tests? 5.: Conclusions.