Wood based products

• Wood-based products: Particel or fibres —> subsequent assembly

  • Glued laminated timber

  • Veneer laminates

  • Particle boards

  • Composite panels

  • Fibreboards

• Solid wood: round timber, sawn timber

• Wood + Binding agent + Additives

• Binding agent: synthetic adhesives, mineral binding agents, connectors

• Additives: Paraffing, fire retardants

• lower strength

• higher homgenity, isotropy, thermal insulation, suface finish

• solid wood products

• Veneer based products

• Particle based products

• Fibere based products

• Composite materials

Products substitution of solid wood in construction

• low for sawn timber and plywood

• Higher for OSB, particle boards and so on

• Plate shaped (Cross laminated timber)

• Bar shaped (Glued laminated timber)

• Composite elements

• nailed or dowled

• glued or dovetail

• Compression/adhesive content

• Veneer-particle materials: Parallam

• Fibre orientation in veneer layers:

  • parallel

  • at angle of 90° = plywood

  • 15°: star plywood

• Rotary cut veneer production using soft or hardwoods

• Keep wood at high moisture content

• Steaming: colors, release of stress

• 13mm wide strips up to 2.5m long

• Gluing an compression to beam elements

• Can be shaped in wet state

• Reason: H-bonding and Van-der-Waals forces in cell walls are disrupted

• Delignification time increases with sample dimensions

• Impregnation time increases

• Material flexibility

• Particle type

• Cross section structure

• Bulk density

• Adhesive binder

• Fomraldehyde emission

• Production process

• Surface

• Resistance

1. Production of chips

2. Drying

3. Gluing

4. Sheet formation

5. Pre-press

6. Press

• Homogeneous

• Clear differentation betwenn top and middle lamella

• Little differentation

• Depends on density

• Increase with density

• Thicknes swelling higher than of solid wood

• Swelling is irreversible

• Oriented Strand Board (OSB): long chips

• Waferboard: large chips

• LSL: Similar to OSB, extremly long chips

• Wet process (high density)

• Dry process (insulation boards, MDF)

Higher density —> higher conductivity

The higher the resin content the lower the swelling

Higher density —> higher bending strength