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- Adamopoulos, Stergios, et al.
(author)
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Impregnation of timber and regulations applied to preservation practice in Greece
- 1998
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Conference paper (peer-reviewed)abstract
- The practice of wood preservation in Greece was started about 80 years ago and refer to creosote-treated timber used in ground contact (i.e. railway sleepers, poles). At present, three creosote impregnation plants and thirteen CCA or CCB units exist in Greece treating about 90.000 m3 of wood per year. Most of the research on wood preservation has been carried out in the last 15-20 years and refer to the application of creosote and water soluble preservatives (CCA, CCB) to native wood species. However, research on a number of specific topics of wood impregnation is lacking. Impregnation of wood is of great importance for Greece, a country with great wood deficit, and, for this reason, the elongation of wood durability is strongly desirable. On the other hand, the environmentally safe impregnation of timber and the use of preservatives in a non-hazardous manner to humans or animals are gaining an increasing importance. There are some national and EU regulations applied to the use of preservatives, while the Greek Organization of Standardization (ELOT) is responsible for approving European standards. The organizations of Greek Telecommunication, Electricity and Railway apply their own standards.
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| 3. |
- Carlsson, Peter, et al.
(author)
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Optimization, a tool with which to create an effective drying schedule
- 1998
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In: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 52:5, s. 530-540
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Journal article (peer-reviewed)abstract
- A method for defining effective schedules for kiln drying of wood is presented. The method is designed in such a way that it proposes an optimized variation of temperature and humidity which yields the minimum total drying time, with the condition that the moisture content and the deformation not exceed specified limits after the drying and that the stress not exceeds a specified level at any time during the drying process in order to avoid crack development. To demonstrate the capability of the optimization method numerical results are presented. It should be noted that ill this first approach, drying starts from moisture content corresponding to the fibre-saturation point, i.e. approximate to 30%).
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| 4. |
- Carlsson, Staffan, et al.
(author)
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Utvärdering av deplacementmetod med vatten för bestämning av träets torrdensitet.
- 1996
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Reports (other academic/artistic)abstract
- Evaluation of the deplacement method with water for determination of dry wood density.by Staffan Carlsson, Stephan Eskilander and Dick SandbergAbstractA new method (SP-method) for determination of wood density at 12 % moisture content has been developted at the Swedish National testing and Research Institute (SP). The method is a futher development of the deplacement method with water as. The volume of the specimens is determined with use of Archimeds principle. The specimen is immersed in water and a computer program compensate for errors in the measurement as a result of wateruptake in the specimen.This investigation describes the correlation between the dry density of wood, determined by the SP-method and a "traditional" method. Traditional method means that the dimensions of the specimen are measured with a slide-calliper in order to calculate the volume of the specimen. The test materials were taken from Scots pine and Norway spruce with dimension 40 x 60 x 120 mm.The results show a difference less than 3 % between dry density determined by the two methods. The correlation coefficient (R2) was 0.99 when linear regression was used. Repetition test showed mean deviation of 0.2 % when dry density for same specimens were determined two times with the SP-method.
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| 9. |
- Dahlblom, O., et al.
(author)
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Simulation of wood deformation processes in drying and other types of environmental loading
- 1996
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In: Annales des Sciences Forestieres. - : Elsevier. - 0003-4312 .- 1878-6545. ; 53:4, s. 857-866
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Journal article (peer-reviewed)abstract
- Deformation processes in wood exposed to drying and other types of environmental loading are simulated by use of the finite element method. In the material model applied, the orthotropic structure of the wood material is considered. The differences of properties in the longitudinal, radial and tangential directions for stiffness parameters as well as for moisture shrinkage parameters are taken into account. As an illustration of possible application areas, the deformation development of boards during drying is simulated. In the analyses, the influence of spiral grain and the variation of wood properties with the distance from the pith are considered. The simulation yields information about unfavourable deformations that develop during the drying process., Le processus de déformation du bois exposé au séchage et autres types de charges environnementales est simulé par la méthode des éléments finis. La structure orthotropique du bois est prise en considération sur le modèle de matériel utilisé. Les différences existant au niveau des propriétés des directions longitudinales, radiales et tangentielles sont prises en compte pour les paramètres de rigidité et de contraction par humidité. Une des possibilités du champ d'applications est illustrée par le fait que l'évolution de la déformation des planches pendant le séchage est simulée. À l'échelon des analyses, l'influence du grain spiral et la variation des propriétés du bois avec la distance depuis la moelle sont pris en compte. La simulation permet d'obtenir des informations concernant l'évolution des déformations défavorables pendant le processus de séchage.
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| 16. |
- Hameed, Mahmood, 1967-, et al.
(author)
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Über die Benetzbarkeit von Splint- und Kernholz der Kiefer, Douglasie und Lärche : [On the Wettability of sapwood and heartwood of various woods pieces (Pine, Douglas fir and Larch)]
- 1999
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In: European Journal of Wood and Wood Products. - : Springer Science and Business Media LLC. - 0018-3768 .- 1436-736X. ; 57:4, s. 287-293
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Journal article (peer-reviewed)abstract
- On the wettability of sapwood and heartwood of various woodspecies (Pine, Douglas fir and larch) Results have established that the wettability of sapwood from three woodspecies (Pine, Douglas ®r and Larch) on the cross, radial and tangential section with water and various glues (UF-resins, PF-resins, MUPF-resins and PMDI-adhesive) is better than that of heartwood. In most cases, the tangential section in sapwood and heartwood was less wettable than radial and cross sections. Using alkaline phenolic resins which cause wood to swell, wettability in the tangential direction was improved.
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| 19. |
- Holmberg, Hans, 1963-, et al.
(author)
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Kvistars frekvens, form och beskaffenhet i trekantprofil av furu (Pinus silvestris L) och gran (Picea abies Karst).
- 1995
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Reports (other academic/artistic)abstract
- Frequency and Character of Knots in Triangular Profiles of Pine (Pinus silvestris L) and Spruce (Picea abies Karst).byHansHolmberg Dick SandbergAbstractThis report describes the structure and amount of knots in triangular profiles from StarSawing of pine (Pinus silvestris L) and spruce (Picea abies Karst). The yield of blanks is determined mainly with a defined knot structure and the fibre aberration around knots. In addition a minor investigation of the amount of pitch pockets has been carried out.The specimens comprise of butt logs from three different areas in Sweden. The specimens are taken from normal grown pine, and both normal and fast grown spruce.Large amounts of the knots found in triangular profiles from butt logs are unacceptable for further refinement. Thus, the knots have to be removed. When producing blanks free from knots there is a volume decrease of 8 and 21 percent in average for pine and spruce respectively, referring to the original volume. Further refinement including fibre aberration increases the volume loss by another 5 percent for pine and 6 percent for spruce. The length of the refined blanks varies between 2 and 500 centimetres for pine and between 2 and 400 centimetres for spruce.Measurement results are included in the report for calculating the volume yield of blanks free from knots, with or without fibre aberration. The distributions of lengths of blanks and corresponding volume yields are shown in different graphs.
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| 22. |
- Holmberg, Hans, 1963-, et al.
(author)
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Utvärdering av en ny ströläggningsmetod för stjärnsågad trekantprofil.
- 1995
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Reports (other academic/artistic)abstract
- En ny typ av ströläggning för trekantprofiler har undersökts. Profilema har torkats i buntar om tre där man alltid har lagt de tangentiella sidoma inåtvända för att minska risken för sprickbiIdning.Trekantprofilema som undersökts hade sidomåttet 120 mm. Torken som använts var en kammartork som styrs med ett torkschemat anpassat för furu med tjockleken 100 mm. Slutfuktkvoten var avsedd att bli 18 % om man torkat 100 mm virke.Efter torkning har prover tagits i rot, mitt och topp för att mata fuktkvotsgradienten i virket. I samband med fuktkvotsmätningen har även densiteten för virket bestämts. Resultaten visar att furu erhåller en större fuktkvotsgradient an gran för det parti som undersökts. Medelfuktkvoten för furn var efter torkning 15,8 % medan gran erhöll en medelfuktkvot på 13,0 %. Fuktkvotsskillnaden mellan torraste och fuktigaste parti i tvärsnittet var för furu 6,4 % och för gran 2,1 %.I undersökningen jämfördes trekantprofilemas slutfuktkvot med avsseende på placering i grupperna och med avseende på densitet. Med ett 95 % konfidensintervall kan man inte säkerställa att det finns skillnad mellan de olika placeringama i gruppen. Det går vidare inte att finna några samband mellan densiteten för virket och dess slutfuktkvot.En undersökning av ungefär tio kubikmeter virke visar att cirka 15 % av de torkade trekantprofilerma hade lättare angrepp av mögelsvampar. Mindre an 5 % av det genomgångna virket hade angrepp av blånad. Tryckskador fran strön förekom på två tredjedelar av virket och dessa skador kan i många fall härledas till dåIig måttnoggrannhet på profilema.
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| 23. |
- Holmberg, Hans, 1963-, et al.
(author)
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Volym- och kvalitetsutbyte vid stjärnsågning.
- 1996
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Reports (other academic/artistic)abstract
- Volume yield and quality of timber when using Star-sawing techniquebyHans Holmberg and Dick SandbergAbstractVolume yield and quality are investigated when starsawing logs of pine (Pinus silvestris L) and spruce (Picea abies Karst). Topdiameters of timber were for pine sorted in two classes 260-300 rnm and 300-340 mm. Spruce timber were sorted in one class with top diameters between 290 and 340 mm.The investigation shows a volume yield considerably higher for starsawing compared to conventional techniques. This investigation, carried out on a simple testplant, yields 68 %calculated from top volume of log. Volume yield calculated from a cone with top and root diameters is 56 %. With sideboards included these numbers will incerease with one percent. The triangular profiles is 47 % of the total volume and the rest 53 % are quarter sawn boards.The volume yield of spruce is about one percent higher than for pine. The difference is assumed to depend on more pronounced taper of the log in spruce, wich allows easier positioning of the log.Quality is determined with a method developed especially for quarter sawn timber.
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| 24. |
- Holmberg, Hans, 1963-, et al.
(author)
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Volymutbyte vid tillverkning av furulimfog från stjärnsågad trekantsprofil.
- 1997
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Reports (other academic/artistic)abstract
- Volume yield in manufacturing gluelam board of Scots pine from star-sawn triangular profiles.byH.HolmbergD. SandbergAbstractTriangular profiles from star-sawing have been used to produce knot free gluelam boards with radial surfaces and a length of 2.1 m. The volume yield has been evaluated in two different gluelam qualities. One was with finger joints and the other one without finger joints. The material used was 7.78 m3 triangular profiles of pine. The quality and dimension was sawfallen. The manufacture of the profiles has been carried out in five steps:Removal of knots and defects.Finger jointing of cut pieces.Planing of triangular profiles.Clueing of triangular profiles into blocks.Splitting the blocks into gluelam boards and finishing the surface.The measurements comprises all steps except splitting and final finishing. These steps have been simulated theoretically.The total volume yield was 53.8 %. In the process three operations were found to be critical for the result. They are: removal of knots and defects, planing and splitting of blocks and finishing. These operations account for more than 93 % of the total loss during manufacturing.Removal of knots and defects resulted in 12,8 % loss of volume. 13 % of the manufactured blocks were without knots, defects and finger joints. The average length of the pieces after cutting was 0,41 m.
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