Vakgebied Houtbiologie en - technologie Vakgroep Bos- en Waterbeheer Coupure Links 653, 9000 Gent Tel: +32 (0)9/ Fax: +32 (0)9/

Transcription

1 Vakgebied Houtbiologie en - technologie Vakgroep Bos- en Waterbeheer Coupure Links 653, 9000 Gent Tel: +32 (0)9/ Fax: +32 (0)9/

2 Variation in poplar timber properties - visual grading Titel doctoral thesis: Potential and possibilities of technological improvement of native light weighted hardwoods for the use as constructive materials Ir. Lieven De Boever COST E53 WG3 Strength, stiffness and appearance grading Hamburg May

3

4 OUTLINE (Dis)advantages of proposed wood species Density, Stability Predicting properties Drying modification Attempt of grading Current publications and future research Acknowledgement

5 Integrated schematic of thesis Closed Forestry- Wood chain Policy- Forestry Wood Technology Economics

6 (Dis)advantages Light weighted hardwoods = pionier tree species with rapid growth. Poplar, willow, alder, birch, Disadvantages Dimensional stability Tension wood and false heartwood (wetwood) Juvenile wood and its consequences Natural durability No specific approach in standards ( softwood) Advantages Specific strength treatability

7 Basic wood properties Density and stability Colour (classification veneers, discoloration, selection of clones, ) Anatomy (tension wood, fibre characteristics, ) Mechanical properties MOE, MOR, MOE = f(time, moisture, load, ) Non-destructive testing

8 North South Heartwood proportion Tension wood proportion (a) Strength properties 20x20x500 mm EN 408 (b) Heartwood and Tension wood proportions (c) Density and dime nsional stability 20x20x20 mm

9 ROBUSTA 20 m GHOY 15 m 10m 5m North Central Axe South North Central Axe South GAVER 20 m GIBECQ 15 m 10 m 5 m North Central Axe South North Central Axe South [kg/m³]

10 Density [kg/m³] ,00 4,50 4,00 3,50 3,00 2,50 2,00 1,50 1,00 0,50 Shrinkage [%] 200 North Pith South 0,00 Density at 90%RH Radial shrinkage (90-60%RH) Density at 60%RH Tangential shrinkage (90-60%RH)

11 Environmental impact Early assessment Impact of changing climate (CO 2 ) Impact of diseases (Erwinia sp.) How translating characteristics of young trees (3-5 years) to economic mature trees for processing (20-25 years)

12 POPFACE Physical properties thin samples Image analysis + weighing + determining thickness Micro-tensile strength

13 POPFACE maceration(clone 5HB03) Fibre length distribution (mm), different positioning within annual ring (mm)

14 POPFACE Fibre and vessel length (mm) as function of within tree ring position (mm) radial distance (mm)

15 POPFACE anatomy Vessel anatomy as function of 2D-position within annual ring Vessel frequenty Vessel conductivity Radial distance (mm)

16 Density (g/cm³) radial distance (mm)

17 75 60 MOR (N/mm²) radial distance (mm)

18 MOE (N/mm²) radial distance (mm)

19 Drying of poplar wood easy to remove water because of open structure Pressence of growth stresses Drying deformations Wet pocket occurence Discoloration (more for willow)

20

21

22 Modification potential Classic chemical treatment Retention and fixation Spatial pattern? Thermal treatment Durability versus mechanical properties Joints! (shear and splitting) Possibilities of using non-destructive evaluation? Natural durability of products in service life Gap between theoretic approach and service life

23

24 4(a) Retention Parameter Heartwood Transition wood Sapwood Duncan Test Uptake solution [kg/m³] aab Uptake solution [kg/m²] aab Uptake solution [%] aab Uptake dry salt [kg/m³] aab 4(b) Penetration Parameter Heartwood Transition wood Sapwood Duncan Test Impregnated area RT plane [%] Penetration depth RT plane [mm] Impregnated area RL plane [%] Penetration depth RL plane [mm] aab aab aab aab

25 First grading attempts Based on destructive measurement of glulam Based on nondestructive measurement of lamella I: homogenuous strong material II: homogenuous moderate strong material III: Strong material at tension and compression side and a core of weak material

26 Started work Non-destructive testing (Vibration) Product control Applying to solid wood and wood based materials Implementation in fundamental research Time-depending Elastic behaviour Specific for poplar and willow wood Influence of juvenile structures and presence of tension wood Different ranges of moisture content, loading, Implementing this knowledge on engineered products (thermal treated, veneer based products)

27 Conclusions Light weigthed hardwoods have a high potential BUT using this material requires adapted grading with attention for the large variability in physical and mechanical properties Laminated structures are possible More information needed on long-term behaviour.

28 Current publications DE BOEVER,L., VANSTEENKISTE, D., VAN ACKER,J. & STEVENS,M. End-use related physical and mechanical properties of selected fast-growing poplar hybrids (Populus trichocarpa x P. deltoides). Annals of Wood Science (2007) DE BOEVER,L., VANSTEENKISTE, D., VAN ACKER,J. & STEVENS,M. Wood technological potential of selected Belgian poplar clones (Populus deltoides x P. nigra) used in structural applications. Annals of Wood Science (2006,submitted) DE BOEVER,L., VANSTEENKISTE, D., VAN ACKER,J. & STEVENS,M. Low temperature drying of poplar wood (P. euramericana). Part 1: New methodology for evaluating wet pocket occurrence. Wood Material Science and Engineering (2006,submitted) DE BOEVER,L., VANSTEENKISTE, D., VAN ACKER,J. & STEVENS,M. Low temperature drying of poplar wood (P. euramericana). Part 2: Drying distortions related to tension wood and heartwood proportions, density and moisture distribution. Wood Material Science and Engineering (2006,submitted) DE BOEVER,L., VAN ACKER,J., VANSTEENKISTE, D. & STEVENS,M. Preservative treatment of willow wood (Salix alba): product retention and spatial distribution. Wood Research (2006,submitted)

29 DE BOEVER,L., VANSTEENKISTE, D., VAN ACKER,J. & STEVENS,M. Variability in density and dimensional stability in genetically related willow clones (S. alba, S. fraglis and S. x rubens). To be submitted to Holzforschung. DE BOEVER,L., VANSTEENKISTE,D., VAN ACKER,J., EVANS,S., CEULEMANS, R., GIELEN,B., SCARASCIA-MUGNOZZA, G. & CALFAPIERTRA,C. Effects of Free-Air Carbondioxide Enrichment (FACE) on intra-ring microdensity variations and micromechanical properties of juvenile poplar trees (Populus nigra L.). To be submitted to Global Change Biology. VANSTEENKISTE, D., DE BOEVER,L., VAN ACKER,J., ZICHE, D., OVERDIECK, D., EVANS,S., CEULEMANS,R., GIELEN,B., SCARASCIA-MUGNOZZA, G. & CALFAPIERTRA,C. Cell length distributions of juvenile poplars (Populus nigra L.) modified by Free- Air Carbondioxide Enrichment (FACE). To be submitted to Trees: Structure and Function.

30 COST E34: Bonding of Timber COST E44: Wood Processing Strategy COST E53: wood products Quality control for wood and COST E55: Modelling of the performance of timber structures IPC (Internationel Poplar Commission) NPC (National Poplar Commission) European project Pamuceaf, Mefyque, Popface, Plybiotest National project on Wood Quality in Flanders

31 Future research Thermally treated poplar wood Modelling of Product uptake Mechanical behaviour (FEM) Understaning tree growth and relation to early assessment (MEFYQUE SBO) Extending to willow, birch, eucalypt, Implementing non-destructive measurements Implementing time depending mechanical behaviour (Rheology)

32 MANY THANKS!