Tutorials and Sustainability Flashcards
Sustainable development requires materials that minimize what?
Social, environmental and economic impact of development
Define sustainable development
Meets the needs of the present without compromising the ability of future generations to meet their needs
What parameters can control to support sustainability?
Choice of materials, their source, durability, mode of construction, design choices, energy use choices, maintenance
What are the 3 Rs in order of importance?
Reduce, reuse, recycle
Name and describe the three components of energy footprint
1) indirect: extraction, material transportation, processing and manufacturing
2) direct: transportation and construction of infrastructure
3) recurring: repair, maintenance, refurbishment, replacement
How bad is cement for environment?
Production of cement produces 8% of greenhouse gas emissions. Building operations contribute 17% of GHG emissions.
Name the 4 types of engineering materials
Metals and alloys, polymers, ceramics and glass, composites
Name the properties of metals and alloys
- Homogenous and recurring microstructure
- crystalline
- conductive electrically
- alloys are combos of 2 or more materials and their properties depend on proportion
Name the properties of ceramics and glasses (also what is glass made of)
Silicate
- non-metallic inorganic material
- insulating
- brittle
- homogeneous microstructure
Not highly crystalline hence brittle and clear (for glass). In fact, when making glass, we are ruining the crystalline microstructure of sand
Name the properties of polymers and plastics
- Chains of self repeating molecules
- Composed of hydrocarbons
- Some possible cross linking
- High degree of plasticity (shape and mouldable)
- Electrically insulating
Name the properties of composite materials
- 2+ engineering materials
- Huge variation in macroscopic properties
- Eg. reinforced concrete and fibre reinforced polymers
Stress vs Force?
Stress is force divided by area! Stresses can be applies in different axes (uni axial and triaxial, shear and normal)
What is elasticity and what is the name of the law associated with it?
Hooke’s Law
It’s the ability of the material to deform and return to its unreformed state
What is plastic deformation?
When deformation becomes permanent. Energy is lost destructively. Unloading could occur but the specimen won’t return to its undeformed shape. Brittle materials break without being plastic
What is strain rate and how does it affect materials?
It’s the rate of external applied loading. Material is constantly trying to get into equilibrium with the application of the forces. At fast rates, material has less time to adjust and so it’s more brittle and has less plastic deformation.
How does temperature affect materials?
At higher temperature, materials are more ductile. Lower = brittle duh
How does the degree of triaxiality affect materials?
Higher degree = more brittle because of negation of poisson effect. The material has no room to expand because loaded from every side and therefore it becomes brittle and has to break. With lower degree of triaxiality, poisson effect can take into place and allow deformation
Go to tutorial lecture 2, slide 42 and name each point on stress-strain curve. Also what is difference between Eng curve and true curve?
Slide 45-46 of same lecture
What does fatigue failure look like?
Microscopic defects that are loaded cyclically form cracks and eventually fail suddenly
What are crack intuition and crack propagation?
Crack initiation occurs at localized places where material cannot withstand load (usually at discontinuities and surface flaws). Crack propagation occurs from gradual widening of the crack due to cyclic loading. In fatigue, this creates beach patterns.
Describe fatigue limit for ferrous alloys (eg. steel)
Some stresses will never reach fatigue limit and thus will never fail. You can have an infinite number of cycles as long as you stay below the fatigue limit stress-cycle curve.
What is the equation for how much percentage of life you have left?
Sum of cycles/cycles to failure. If >= 1 then specimen will fail. Called the Palmgren-miner hypothesis
What is creep?
Long term plastic and permanent deformation under constant sustained loads below the the yield point. Creep is time dependent and there is more creep at higher temperatures and at higher loads.
What are the stages of creep (4)?
Initial elastic strain, primary creep, secondary (steady state) creep, tertiary creep
What are the three hardened concrete phases?
Hydrated cement paste, interfacial transition zone, and aggregates.
What are the growth rates of steel aluminium cement plastics and wood? From 1970-2004
Steel -1.6
Cement -3.5
Aluminium -3.0
Plastics -6.83
Wood -1.27
What does the teacher say about service life cost?
Making a building sustainable for infinite amount of time takes a lot of money. If a residential is occupied on average for 18 years will the owner spend money on making its service infinitely long? We want to consider long-term owners eg. religion and government.
What does the teacher say about asphalt?
Sustainable when they stop using asphalt. It requires a lot of upkeep and costs more than concrete despite the cheap installation. Rains and temp are bad for asphalt. Government only thinks in 4 year timeframes! They think making more highways is what impresses people
What are the 8 sustainable construction characteristics?
- durable
- local/regional extraction
- contain recycled materials (not ideal for concrete because we don’t want second hand concrete)
- reusable (we like steel)
- manufactured w minimal pollution
- do not pollute
- minimum amount of energy required to produce
- renewable (only wood)
Dulocrecypolenerenew.
Issues of concern for the concrete industry?
Accounting for all three: profitability, compliance to standards and sustainability
What is the only thing we consume more of than concrete?
Water
What are the negative impacts of climate concrete and steel production?
Enormity of resources used. Generation of large amounts of CO2 (heat and power, transportation and cement production). However no know replacement. Wood cannot supply 8 billion people.
What are 6 co2 emission sources in the concrete industry?
Manufacture of material and concrete, construction, repair and rehabilitation, demolition and recycling, transportation
What is the traditional linear flow of building materials?
Material extraction -> manufacture and processing -> materials used in buildings -> landfill disposal
Why is reducing hard in today’s house society? What is the biggest soliton?
Family size decreases but the average size of a house increases. Lots of empty space. Biggest solution is to improve durability so you need to rebuild less!
How is reusing done in construction?
Salvaging building materials from existing buildings and renovating instead of demolition. Bolted connections instead of welds, fasteners instead of adhesives, homogeneous materials instead of composites. We get rid of landfill disposal in the linear flow.
How is recycling as the solution to sustainability?
It’s the least efficient since a lot of energy is used to process the original material in the new needed form. New form is usually of lower quality. Can be applied to steel concrete (not really) wood and polymers. Still requires the manufacturing process in the linear flow
How can the concrete industry become more sustainable?
- manufacture efficiency
- waste materials as fuel and inside the cement
- using high performance concretes
- durability
- recycled concrete as aggregates
- capturing, storing and utilizing CO2 emissions
- improving structural designs and building codes
- good maintenance and repair strategies
What are we doing to enhance our environment? And what are the four time scales?
Paying attention to what the industry does. Creating awareness of issues amount the public. We have four time scales: the past (remedial), present (compliance and prevention), future (how design processes are dictated by today), far future (50+ planned changes to current designs). Engineers have more impact on future
What are the three states of development (time frames)?
Industrial revolution -> immediate action -> longer term vision.
We require a certain lifespan of buildings but we have no way to check if they actually work (we die)
What are the 5 stages of life cycles of products?
1: resource extraction performed by supplies and production of materials
2: manufacturing
3: packaging, shipping and installation, done by corporations
4: consumption, customer use
5: refurbishment or discarding, customer is no longer satisfied
