Materials Flashcards
What is the effect of seasoning on timber?
as cells moisture evaporates the timber will being to shrink, leaving gaps or causing warping. Moisture content calculated as percentage of dry weight.
What are the performance characteristics of timber?
Strength: high strength to weight ratio. Good in tension and compression.
Good insulator
Fire performance varies in proportion to size
Durability can be enhanced with privatives
sustainability credentials good as timber acts as a carbon sink and is biodegradable.
What is aluminium typically used for?
windows, door frames, curtain walling, cladding, profiled sheeting and rain water goods.
What are the performance characteristics of steel?
Good under tension
ductile and therefore prone to bend and signal failure prior to catastrophic failure.
high embodies carbon but 100% recyclable.
Can be prone to corrosion
Become brittle in fire
What is the difference between hot and cold rolled steel?
Hot rolled steel has a scaled surface, is cheaper to produce and used where dimensional tolerances are important
Cold roles steel has been further processed to achieve more exact dimensions and a smooth surface.
What is concrete?
A mixture of cement, fine aggregates such as sand, coarse aggregates such as gravel, crushed rock and water, combined in the correct proportions to form a mass resembling stone.
What are the performance characteristics of concrete?
Strength - high compressive strength but weak in tension.
Durability - where exposed its porosity needs to be minimised.
Fire resistance - generally good.
Thermal insulation - can be improved using lightweight aggregate.
High embodies carbon.
What is cement?
A powder of alumina, silica, lime, iron oxide, and magnesium oxide burned together in a kiln and finely pulverized and used as an ingredient of mortar and concrete
What are the performance characteristics of bricks?
Compression: generally good
Water absorption: dependent on the method of manufacture
Thermal conductivity: generally high, and thus a poor insulation value.
Fire resistance: good.
Sustainability: high embodied energy
What are the performance characteristics of blocks?
Compressive strength: high
Water absorption: relatively porous
Durability: similar to that of clay bricks
Blocks are more porous than bricks and are therefore it is usual to select brick for external wall construction and blocks for internal wall construction.
Thermal conductivity: due to porous composition and use of hollow construction, they have relatively good thermal resistance.
What do the different colours of plasterboard denote?
Pale green - moisture resistant
pink - fire board
White - thermal
Blue - sound
