Wood Flashcards
(25 cards)
What is the central, spongy core of a tree called?
Pith
The pith is the weakest part of the tree.
What is the function of heartwood in a tree?
Provides strength and is more resistant to decay
Heartwood is dense and dark-colored, consisting of inactive core material.
What does sapwood do?
Transports water and nutrients
Sapwood is the outer living wood layer.
What is the cambium layer responsible for?
Producing new xylem and phloem
The cambium is a thin growth layer between bark and sapwood.
What do rays in tree anatomy do?
Transport nutrients laterally
Rays are horizontal cells radiating from the center of the tree.
What are the two main types of wood based on microstructure?
Softwood and Hardwood
Softwoods are mostly coniferous, while hardwoods are typically deciduous.
What is the primary load-bearing component of wood?
Cellulose
Cellulose makes up 40-50% of wood’s chemical composition.
What is hemicellulose?
An amorphous component that surrounds and bonds microfibrils
Hemicellulose comprises 20-25% of wood’s chemical composition.
What role does lignin play in wood?
Acts as glue and provides compressive strength and stiffness
Lignin constitutes 20-30% of wood’s chemical composition.
Define anisotropy in the context of wood.
Direction-dependent properties due to fiber alignment
This means that wood behaves differently under stress depending on the direction of the fibers.
What is the moisture content formula?
MC (%) = (Wet weight - Dry weight) / Dry weight × 100
This formula is used to calculate the moisture content in wood.
What is the Fiber Saturation Point (FSP)?
Approximately 25-30% MC
Above FSP, water is only in cell cavities.
What happens to wood when it is dried below the Fiber Saturation Point?
Increases strength and stiffness; causes dimensional changes and shrinkage
This process can lead to warping and cracking.
What is the target moisture content for construction wood?
Approximately 15%
This moisture content helps ensure stability and strength in wood products.
What is the tensile strength of wood parallel to the grain?
70-100 MPa
This indicates the strength of wood when pulled along the grain.
What is the compressive strength of wood perpendicular to the grain?
5-10 MPa
Wood is much weaker when force is applied perpendicular to the grain.
True or False: Moisture weakens wood.
True
Increased moisture content can lead to a decrease in wood strength.
What are the two main types of biological degradation in wood?
Fungi and Insects
Fungi require moisture, while insects like termites and carpenter ants can damage wood.
What does brown rot do to wood?
Degrades cellulose
Brown rot fungi primarily affect the structural integrity of wood.
What is the term for cracks that occur through the section of wood?
Splits
Splits can significantly weaken the structural integrity of timber.
What is plywood made of?
Veneer sheets glued in alternating grain directions
This construction method enhances strength and stability.
What is the purpose of engineered wood products?
Maximize strength, uniformity, stability; minimize defects
Engineered wood products include types like plywood, glulam, and LVL.
List two applications of wood in construction.
- Structural Framing
- Heavy Timber Construction
Wood is widely used in various construction methods due to its favorable properties.
What is one advantage of using wood as a building material?
Renewable and biodegradable
Wood has a low carbon footprint and is a sustainable resource.
