Tutorials and Sustainability

Question 1

Sustainable development requires materials that minimize what?

Answer 1

Social, environmental and economic impact of development

Question 2

Define sustainable development

Answer 2

Meets the needs of the present without compromising the ability of future generations to meet their needs

Question 3

What parameters can control to support sustainability?

Answer 3

Choice of materials, their source, durability, mode of construction, design choices, energy use choices, maintenance

Question 4

What are the 3 Rs in order of importance?

Answer 4

Reduce, reuse, recycle

Question 5

Name and describe the three components of energy footprint

Answer 5

1) indirect: extraction, material transportation, processing and manufacturing
2) direct: transportation and construction of infrastructure
3) recurring: repair, maintenance, refurbishment, replacement

Question 6

How bad is cement for environment?

Answer 6

Production of cement produces 8% of greenhouse gas emissions. Building operations contribute 17% of GHG emissions.

Question 7

Name the 4 types of engineering materials

Answer 7

Metals and alloys, polymers, ceramics and glass, composites

Question 8

Name the properties of metals and alloys

Answer 8

• Homogenous and recurring microstructure
• crystalline
• conductive electrically
• alloys are combos of 2 or more materials and their properties depend on proportion

Question 9

Name the properties of ceramics and glasses (also what is glass made of)

Answer 9

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

Question 10

Name the properties of polymers and plastics

Answer 10

• Chains of self repeating molecules
• Composed of hydrocarbons
• Some possible cross linking
• High degree of plasticity (shape and mouldable)
• Electrically insulating

Question 11

Name the properties of composite materials

Answer 11

• 2+ engineering materials
• Huge variation in macroscopic properties
• Eg. reinforced concrete and fibre reinforced polymers

Question 12

Stress vs Force?

Answer 12

Stress is force divided by area! Stresses can be applies in different axes (uni axial and triaxial, shear and normal)

Question 13

What is elasticity and what is the name of the law associated with it?

Answer 13

Hooke’s Law
It’s the ability of the material to deform and return to its unreformed state

Question 14

What is plastic deformation?

Answer 14

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

Question 15

What is strain rate and how does it affect materials?

Answer 15

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.

Question 16

How does temperature affect materials?

Answer 16

At higher temperature, materials are more ductile. Lower = brittle duh

Question 17

How does the degree of triaxiality affect materials?

Answer 17

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

Question 18

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?

Answer 18

Slide 45-46 of same lecture

Question 19

What does fatigue failure look like?

Answer 19

Microscopic defects that are loaded cyclically form cracks and eventually fail suddenly

Question 20

What are crack intuition and crack propagation?

Answer 20

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.

Question 21

Describe fatigue limit for ferrous alloys (eg. steel)

Answer 21

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.

Question 22

What is the equation for how much percentage of life you have left?

Answer 22

Sum of cycles/cycles to failure. If >= 1 then specimen will fail. Called the Palmgren-miner hypothesis

Question 23

What is creep?

Answer 23

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.

Question 24

What are the stages of creep (4)?

Answer 24

Initial elastic strain, primary creep, secondary (steady state) creep, tertiary creep

Question 25

What are the three hardened concrete phases?

Answer 25

Hydrated cement paste, interfacial transition zone, and aggregates.

Question 26

What are the growth rates of steel aluminium cement plastics and wood? From 1970-2004

Answer 26

Steel -1.6
Cement -3.5
Aluminium -3.0
Plastics -6.83
Wood -1.27

Question 27

What does the teacher say about service life cost?

Answer 27

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.

Question 28

What does the teacher say about asphalt?

Answer 28

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

Question 29

What are the 8 sustainable construction characteristics?

Answer 29

• 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)
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Question 30

Issues of concern for the concrete industry?

Answer 30

Accounting for all three: profitability, compliance to standards and sustainability

Question 31

What is the only thing we consume more of than concrete?

Answer 31

Water

Question 32

What are the negative impacts of climate concrete and steel production?

Answer 32

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.

Question 33

What are 6 co2 emission sources in the concrete industry?

Answer 33

Manufacture of material and concrete, construction, repair and rehabilitation, demolition and recycling, transportation

Question 34

What is the traditional linear flow of building materials?

Answer 34

Material extraction -> manufacture and processing -> materials used in buildings -> landfill disposal

Question 35

Why is reducing hard in today’s house society? What is the biggest soliton?

Answer 35

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!

Question 36

How is reusing done in construction?

Answer 36

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.

Question 37

How is recycling as the solution to sustainability?

Answer 37

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

Question 38

How can the concrete industry become more sustainable?

Answer 38

• 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

Question 39

What are we doing to enhance our environment? And what are the four time scales?

Answer 39

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

Question 40

What are the three states of development (time frames)?

Answer 40

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)

Question 41

What are the 5 stages of life cycles of products?

Answer 41

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