WOOD SCIENCE WORKBOOK
VERSION 2
Guidelines
This is not an assessment but can be used as a reference document for the Timed Assignment required for this subject. You may also be required to submit this workbook with you assessment
References
• Toi-Ohomai power point presentations
Outcome 5 Explain key physical, chemical and mechanical properties of wood as a raw material and discuss
the relationship between wood properties and wood utilisation.
1 Define basic density as a physical property of wood and discuss how will affect the potential end use.
2 Rank the following exotic and native timbers in terms of their density (lowest-highest)
Exotic timbers: Douglas fir, Radiata pine, Redwood, Macrocarpa, Eucalyptus species
Native timbers: Rimu, Kauri, Black Maire, Rata, Totara
Exotic timbers
Native timbers
3 Compare hardwoods and softwoods generally using any two of the following wood properties :
wood density, fibre length, cell wall thickness, microfibril angle (MFA), wood strength, moisture content, shrinkage and stability on drying
Wood property
Softwoods Hardwoods
1
2
4 Compare heartwood and sapwood within a tree using any four of the following wood properties : wood density, fibre length, cell wall thickness, microfibril angle (MFA), wood strength, moisture content, shrinkage and stability on drying
Wood property
Sapwood Heartwood
1
2
3
4
5 Compare Radiata pine corewood and outerwood using any three of the following wood properties: wood density, fibre length, cell wall thickness, microfibril angle (MFA), wood strength, moisture content, shrinkage and stability on drying
Wood property Corewood Outerwood
1
2
3
6 Compare earlywood and latewood within a growth ring in terms of any three of the following wood properties : wood density, fibre length, cell wall thickness, microfibril angle (MFA), wood strength, moisture content, shrinkage and stability on drying
Wood property Earlywood Latewood
1
2
3
7 For hardwoods list three major cell types present in their anatomy and define the function of each
Hardwood cell type Function
1
2
3
8 For softwoods list two major cell types present in their anatomy and define the function of each
Softwood cell type Function
1
2
9 Describe four key factors that can impact on the wood density of radiata pine timber grown in New Zealand
Factors influencing wood density Description
1
2
3
4
10 Define the moisture content of wood, and describe how the strength and elasticity of wood changes as it dries out
Moisture content is
Changes to strength and elasticity as wood dries out
•
•
11 Describe two end uses of wood where the following wood properties are critical for wood in service
Wood property
Describe two end uses where this is critical for wood in service
low moisture content
1
2
High durability
1
2
Good strength
1
2
Good stability
1
2
12 Identify and describe the four main chemical components of heartwood and sapwood, and describe the function of each in terms of wood properties.
Chemical component of heartwood and sapwood
Description Function of each in terms of wood properties
1
2
3
4
13 Define the following terminology in relation to the mechanical testing of wood.
Modulus of rupture (MOR)
Modulus of elasticity (MOE)
14 Describe how the following growth characteristics can impact on the strength of wood in service.
Factors Describe effect on wood strength
Density
Moisture Content
Knots
Pith
15 Describe how each of the following growth characteristics can impact on the stability of wood in service
Growth characteristic Describe effect on wood stability
Compression/tension wood
Corewood/outerwood
Spiral grain
High MFA
16 Define durability in terms of wood in service
17 Rank the following exotic and native timbers in terms of their natural durability (lowest-highest)
Exotic timbers: Douglas fir, Radiata pine, Redwood, Macrocarpa, Eucalyptus species
Native timbers: Rimu, Totara, Red beech, Matai
Exotic timbers
Native timbers
18 Describe one process of timber preservative treatment for Radiata pine and discuss the impact that this has on expected wood durability
Description of timber preservative treatment process
Impact on expected wood durability
19 Complete the following table in relation to reconstituted and laminated wood products.
Reconstituted wood products
Describe manufacturing process Advantages and disadvantages Describe one end use
Particle board
Medium density fibre board
(MDF)
Laminated wood products
Describe manufacturing process Advantages and disadvantages Describe one end use
Glue laminated beams
Laminated Veneer Lumber
(LVL)
Structural Plywood
Cross laminated timber (CLT)
20 Discuss three advantages and two disadvantages of using wood as a building product compared to concrete or steel
Wood as a building product compared to concrete or steel
Three advantages
Two disadvantages
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