MAT2600 EXAM LATEST UPDATE
Use the Zachariasen model to explain the concept of a disordered material - Answer The
structure is random, the atoms have bonded in the place they are in rather than moving
to become organised. Glass is an example of a disordered material.
Why does rapid cooling give a glass in some cases, while slow cooling gives an ordered
structure? - Answer Rapid cooling doesn't allow the structure to organise itself whereas
during slow cooling the particles will take the path of least resistance- an ordered
structure.
Float glass is prepared using a bath of liquid tin. What key property does this give to the
glass? - Answer It makes the glass very flat/smooth.
Why can glass rarely achieve more than 1% of its theoretical strength? - Answer The
structure is disorganised so the theoretical strength will never be realistic.
Explain why toughened glass is able to resist impacts better than many other forms of
glass - Answer The outer surface of toughened glass is in compression while the centre
is in tension therefore to break toughened glass you have to get through the outer layer
to the centre.
Why is bullet-proof glass often laminated? - Answer The lamination stops the glass from
shattering/ holds the broken glass in place
Why does a double-glazed window need the same thickness of glass on the inside and
outside panes? - Answer To prevent shearing forces occurring in the glass.
What is the importance of fine aggregate? - Answer Very important for characteristics of
concrete, if you don't have fine aggregates you will get separation issues.
Give three reasons why aggregate is added to concrete - Answer - Stops overheating
- Fills space
- Can reduce cost
Give three reasons why adding excessive water to concrete can be undesirable -
Answer - The added water will increase the no of pores which means less strength
- Makes it more difficult to pour
- Stops the concrete hardening properly
Describe the characteristic engineering properties of two non-Portland cements (one
based on a clinker and one without a clinkerisation process) - Answer Calcium
Aluminate: Has a lot of strength but loses this over time, therefore isn't used in many
structural applications
, Geopolymer Cement: 60-90% less co2 emissions, require an alkaline solution (the main
drawback)
Describe the process of plastic settlement - Answer Solid aggregate particles can sink
through the paste leaving water pockets under aggregates and reinforcing bars. Cracks
caused by this can extend from the surface to reinforcing bars, causing major durability
issues.
Does more steel reinforcement always make for 'better' concrete? - Answer Not always
if the steel is too congested the concrete won't fill the gaps which means it won't be
structurally sound, this tends to happen in beam to column joints.
What is the difference between pre-tensioning and post-tensioning? - Answer Pre
happens prior to the concrete being poured and consists of the bottom face concrete
member being held in compression with steel cables. Post is when pouring the concrete
ducts are created through the member which once the concrete has hardened steel
cables are used to create tension.
Is prestressing of concrete used to enhance resistance to flexural or compressive
loads? - Answer Mainly about flexural elements.
What is a passivating film in the context of concrete durability? - Answer A passivating
film is a layer of Fe oxides that sits on the steel reinforcement in concrete, once this
breaks down the steel will begin to corrode and can cause failure.
Is plastic settlement more likely to cause defects on the top or bottom of a concrete
element? - Answer Plastic settlement is more likely in the bottom although it can occur
on either side of the element.
Using the Pourbaix diagram, explain why chloride can cause corrosion problems in
reinforced concretes - Answer You can see in the Pourbaix diagram that the presence of
chlorine reduces the area of passivity and enlarges the region of corrosion.
Give two key differences between a masonry block and a brick - Answer The main
difference is that the blocks are bigger and often hollow. Generally blocks are made
with lighter weight materials.
What is the difference between structural masonry and a veneer? - Answer Veneer is
used to achieve a masonry look while using another structural material while structural
masonry is used to build the entire structure.
Which is more expensive, a dry pressed brick or a soft mud process brick? - Answer Dry
pressed bricks are more expensive but have a better finish.
Which is more porous, soft mud or dry pressed bricks? - Answer Soft mud process
bricks, they have more water in.
Which has a better resistance to freeze-thaw damage, soft mud or dry pressed bricks? -
Answer Dry pressed bricks because they are less porous and have less water to begin
Use the Zachariasen model to explain the concept of a disordered material - Answer The
structure is random, the atoms have bonded in the place they are in rather than moving
to become organised. Glass is an example of a disordered material.
Why does rapid cooling give a glass in some cases, while slow cooling gives an ordered
structure? - Answer Rapid cooling doesn't allow the structure to organise itself whereas
during slow cooling the particles will take the path of least resistance- an ordered
structure.
Float glass is prepared using a bath of liquid tin. What key property does this give to the
glass? - Answer It makes the glass very flat/smooth.
Why can glass rarely achieve more than 1% of its theoretical strength? - Answer The
structure is disorganised so the theoretical strength will never be realistic.
Explain why toughened glass is able to resist impacts better than many other forms of
glass - Answer The outer surface of toughened glass is in compression while the centre
is in tension therefore to break toughened glass you have to get through the outer layer
to the centre.
Why is bullet-proof glass often laminated? - Answer The lamination stops the glass from
shattering/ holds the broken glass in place
Why does a double-glazed window need the same thickness of glass on the inside and
outside panes? - Answer To prevent shearing forces occurring in the glass.
What is the importance of fine aggregate? - Answer Very important for characteristics of
concrete, if you don't have fine aggregates you will get separation issues.
Give three reasons why aggregate is added to concrete - Answer - Stops overheating
- Fills space
- Can reduce cost
Give three reasons why adding excessive water to concrete can be undesirable -
Answer - The added water will increase the no of pores which means less strength
- Makes it more difficult to pour
- Stops the concrete hardening properly
Describe the characteristic engineering properties of two non-Portland cements (one
based on a clinker and one without a clinkerisation process) - Answer Calcium
Aluminate: Has a lot of strength but loses this over time, therefore isn't used in many
structural applications
, Geopolymer Cement: 60-90% less co2 emissions, require an alkaline solution (the main
drawback)
Describe the process of plastic settlement - Answer Solid aggregate particles can sink
through the paste leaving water pockets under aggregates and reinforcing bars. Cracks
caused by this can extend from the surface to reinforcing bars, causing major durability
issues.
Does more steel reinforcement always make for 'better' concrete? - Answer Not always
if the steel is too congested the concrete won't fill the gaps which means it won't be
structurally sound, this tends to happen in beam to column joints.
What is the difference between pre-tensioning and post-tensioning? - Answer Pre
happens prior to the concrete being poured and consists of the bottom face concrete
member being held in compression with steel cables. Post is when pouring the concrete
ducts are created through the member which once the concrete has hardened steel
cables are used to create tension.
Is prestressing of concrete used to enhance resistance to flexural or compressive
loads? - Answer Mainly about flexural elements.
What is a passivating film in the context of concrete durability? - Answer A passivating
film is a layer of Fe oxides that sits on the steel reinforcement in concrete, once this
breaks down the steel will begin to corrode and can cause failure.
Is plastic settlement more likely to cause defects on the top or bottom of a concrete
element? - Answer Plastic settlement is more likely in the bottom although it can occur
on either side of the element.
Using the Pourbaix diagram, explain why chloride can cause corrosion problems in
reinforced concretes - Answer You can see in the Pourbaix diagram that the presence of
chlorine reduces the area of passivity and enlarges the region of corrosion.
Give two key differences between a masonry block and a brick - Answer The main
difference is that the blocks are bigger and often hollow. Generally blocks are made
with lighter weight materials.
What is the difference between structural masonry and a veneer? - Answer Veneer is
used to achieve a masonry look while using another structural material while structural
masonry is used to build the entire structure.
Which is more expensive, a dry pressed brick or a soft mud process brick? - Answer Dry
pressed bricks are more expensive but have a better finish.
Which is more porous, soft mud or dry pressed bricks? - Answer Soft mud process
bricks, they have more water in.
Which has a better resistance to freeze-thaw damage, soft mud or dry pressed bricks? -
Answer Dry pressed bricks because they are less porous and have less water to begin
