Construction Materials Flashcards
What is the building envelope?
sum of all the elements: - foundation - floor - walls - ceiling - windows - door - corridor - stair - toilet, ramp, fireplace etc (materials affects all aspects of the building envelope)
What are the initial impacts of materials?
- resources: depletion of renewable resources
- biodiversity: ruining habitats etc
- visual impacts
- CO2 emissions: effect on atmosphere due to large scale deforestation
- effect on soil stability due to large scale deforestation
- energy and CO2 emissions: transport and energy conversion
What are the long term impacts of materials?
- toxicity
- production of toxic wastes
- effect on health
- life span
- waste during the construction process
- destination at the end of its life
- potential for re-use
What does LCA stand for?
Life Cycle Assessment
What is the Life Cycle Assessment of materials?
Building materials life cycle…
extraction—> processing—> use /maintenance—> eventual disposal (back to extraction)
What are the processes relating to material use and what are their impacts?
processes:
exploration, mining, pre-processing transport, processing, transport, fabrication, discarding
impact: energy resource depletion, air pollution, water pollution, land disturbance (mining and solid waste generation)
What are two common materials that require a lot of energy to produce/extract?
concrete and aluminium
Why is concrete harmful to the environment?
cement in concrete is produced in an energy intensive process, and the chemical reaction produces CO2
What are the pros and cons to aluminium?
aluminium is produced in a highly energy intensive way (uses a lot of energy), but eminently recyclable. If systems are set up so this will happen, i is a good material. It is possible to obtain recycled aluminium products
What are the basic principles of material use?
- reduce
- reuse
- recycle
- consider the impact on health
What are primary building materials we use today?
- wood
- glass
- concrete
- brick
- steel
Why do you have an air cavity between walls?
- provides insulation
- to stop damp getting through
What does MMC stand for?
Modern Methods of Construction
What is significant about brick?
- most commonly used material to construct external walls
- generally made from clay
- modern bricks are modular in size
- manufactured to the same dimensions
What is a standard block?
2 bricks long and 3 bricks high (for rapid construction)
Why are bricks so stable?
the weight is distributed evenly
What is tension and what is compression?
tension = pulling/stretching
compression = compressing/squashing
(both tension and compression are essential as basic foundations in design)
What is the rule of thumb we use for determining the depth of a steel beam?
the depth of a steel beam is 1/20th of the span
In a beam with a force being applied onto it, where is the compression and tension force?
compression = top half of beam tension = bottom half of beam
How can we ‘reduce’ the impacts of materials?
- use lower embodied material
- travel distance (locally available materials)
- use materials efficiently
- use renewable resources
What are some examples of local materials?
stone and clay (for bricks)
What is significant about stone?
stone can damage the surroundings but is abundant, and if used locally it needs comparatively little energy to make it useable
What is significant about clay?
bricks use energy to produce, but local clays can be used, the transporting of large quantities of bricks long distances is not a sustainable approach
What is significant about timber?
a renewable resource, used for timber frames for houses
What are some examples of an efficient use of local timber?
- Earth centre, Doncaster - untreated roundwood
- Woodland enterprise centre - local coppiced chestnut
- Olivier theatre Bedales School - green oak frame with stainless steel joints, roof cladding larch, wall cladding Douglas fir
What does the FSC stand for?
Forestry Stewardship Council - who are responsible for making sure timber is sourced sustainably, they ensure that felled timber is replaced by new planting (you can specify that your wood has come from an FSC approved forest)
What is significant about straw?
straw and reed is used locally as a roofing material - a very good insulator, but a fire risk and not long lasting.
straw bales, suitably protected, are being used experimentally to provide cheap, well insulated, environmentally friendly walling.
How can hemp be used in construction?
- insitu wall construction (mixed with lime)
- pre-cast wall construction (mixed with lime)
- block insitu (mixed with lime)
What is a rammed earth wall?
a wall made from earth and mud compacted together (using heat) - helps to keep the building warm
What is significant about sheep wool?
sheep wool is a renewable resource and can be used economically to make non-toxic insulation
What percentage of materials that are used on UK building sites are wasted?
approx 20% of materials used on UK building sites is wasted - through bad design, poor storage, theft or damage during installation
What is good about aluminium?
although it is difficult and expensive to extract and produce, aluminium is eminently recyclable - the recycling of aluminium uses 95% less energy than the production of the material from raw form.
What happens at the end of a buildings life?
- most buildings are just demolished, with the majority of waste going to land fill sites
- land fill tax is reducing this as an economic option
- demolition waste needs to be sorted on site, and reused wherever possible
- there are specialist reclamation businesses that do this, and many materials from bricks through to sanitary fittings can be economically saved for reuse
What are some general rules in terms of materials and construction?
- use materials that are locally produced
- use materials with low environmental costs
- consider “cradle to grave” energy costs involved
- avoid using tropical hardwoods
- think about loading and associated impacts on structure, and type of material
What are the advantages of green roofs and green walls?
- improved appearance and accessibility/use
- designing for future climate - thermal insulation and heat island effect
- manage air quality
- sustainable urban drainage: rainwater runoff and attenuation
- increased/enhanced urban biodiversity
