C3 Assignment Flashcards
Timber
- Cellulose (C₆H₁₀O₅)ₙ: An organic compound polysaccharide forming the
structural component of cell walls, providing rigidity and strength. - Hemicellulose: A complex carbohydrate organic molecule that binds with
cellulose to enhance structural integrity. - Lignin: An organic polymer that imparts rigidity and resistance to microbial
attack. - Extractives: Compounds such as resins and tannins that influence colour,
odour, and decay resistance.
Cellulose (C₆H₁₀O₅)ₙ
An organic compound polysaccharide forming the
structural component of cell walls, providing rigidity and strength.
Hemicellulose:
A complex carbohydrate organic molecule that binds with
cellulose to enhance structural integrity.
Lignin
An organic polymer that imparts rigidity and resistance to microbial
attack.
Extractives:
Compounds such as resins and tannins that influence colour,
odour, and decay resistance.
Structural Properties of timber:
- Strength-to-Weight Ratio: Timber has a high strength-to-weight ratio,
making it efficient for load-bearing applications. - Elasticity: Exhibits good elasticity, allowing it to absorb shocks and stresses
without permanent deformation. - Thermal Insulation: Provides natural thermal insulation due to its porous
structure
Pros of using timber:
- Renewable Resource: Sustainably sourced timber is renewable and can
reduce carbon emissions in construction. - Carbon Sequestration: Trees absorb CO₂ during growth, and this carbon
remains stored in timber products. - Aesthetic Appeal: Offers a natural and warm appearance, enhancing
architectural designs.
Cons of using timber:
- Durability Concerns: Susceptible to decay, pests, and moisture if not properly
treated. - Fire Risk: Combustible material requiring treatment to improve fire resistance.
- Dimensional Stability: Prone to expansion and contraction with changes in
humidity.
Steel Chemical Composition:
Steel is an alloy predominantly composed of iron (Fe) with varying amounts of carbon
(C) and other elements
Steel Carbon Content
Typically between 0.2% and 2.1%, influencing hardness and
strength.
Alloying Elements:
Elements such as manganese (Mn), chromium (Cr), and
nickel (Ni) are added to enhance specific properties.
Structural Properties of steel:
- High Strength: Offers exceptional tensile and compressive strength.
- Ductility: Capable of significant deformation before failure, allowing for
flexibility in design. - Uniformity: Manufactured under controlled conditions, ensuring consistent
quality.
Pros of steel use:
- Durability: Resistant to pests, rot, and fire, contributing to longevity.
- Recyclability: Steel is 100% recyclable without degradation of properties.
- Structural Efficiency: Enables the construction of large spans and open
spaces without excessive material use.
Cons of timber use:
- Corrosion Susceptibility: Prone to rust when exposed to moisture and oxygen,
necessitating protective measures. - High Embodied Energy: Production involves significant energy consumption
and CO₂ emissions. - Thermal Conductivity: High thermal conductivity can lead to energy
inefficiencies if not properly insulated.
Concrete is a composite material consisting of:
- Cement: A binder, typically Portland cement, composed of ionic compounds
calcium silicates and aluminates. - Aggregates: Sand, gravel, or crushed stone providing bulk and strength.
- Water: Initiates the chemical reaction (hydration) that hardens the mixture.
Structural Properties of concrete:
- Compressive Strength: Excellent resistance to compressive forces.
- Low Tensile Strength: Requires reinforcement (e.g., steel rebar) to withstand
tensile stresses. - Thermal Mass: High thermal mass enables it to absorb and release heat
slowly, aiding in temperature regulation.
Pros of concrete:
- Versatility: Can be molded into various shapes and sizes for diverse
applications. - Fire Resistance: Inherently non-combustible, enhancing building safety.
- Local Availability: Constituent materials are widely available, reducing
transportation impacts.
Cons of concrete:
- Environmental Impact: Cement production is a significant source of CO₂
emissions. - Brittleness: Prone to cracking under tensile loads if not properly reinforced.
- Weight: High density increases the load on foundations and may limit design
options.
Timber tackles climate change
Timber is the only major building material
that tackles climate change. It is both a
naturally renewable and abundant resource.
Growing trees remove carbon dioxide from
the atmosphere in a process known as
carbon sequestration.
The carbon absorbed by the growing tree –
about half the weight of dry timber -
remains in the wood until it is either burnt
or decomposed.
In addition, the production and processing
of wood uses much less energy – known as
embodied carbon – than other more
carbon-intensive materials like concrete and
steel, giving wood a significantly lower
carbon footprint. Wood is a low-emission
substitute for materials that require larger
amounts of fossil fuels to be produced.
