A4- Exposure Conditions & Chemical Degradation

Question 1

What are the 6 exposure conditions?
1.
2.
3.
4.
5.
6.

Answer 1

Weathering.
Freeze thaw.
Thermal ageing.
Creep.
Humidity.
Condensation.

Question 2

What occurs during thermal ageing?
A repetitive cycle of heating and cooling.
This causes __________.

Answer 2

cracks

Question 3

What are the 4 types of chemical degradation?
1.
2.
3.
4.

Answer 3

Acid rain.
Alkali.
Sulphates.
Leaching.

Question 4

What is an example of corrosion in metals?

Answer 4

Oxidation.

Question 5

What is a simpler term for oxidation in metals (such as iron and steel)?

Answer 5

Rust.

Question 6

What material do sulphates react with that produces the ettringite mineral?

This mineral is more solid than the material, so it causes internal stress and degradation.

Answer 6

Portland cement.

Question 7

Name 1 place where are sulphates present:

Answer 7

Sewage.

Question 8

Name 1 material where high alkali levels may be present:

Answer 8

Cement.

Question 9

What material does an alkali react with to cause cracks in its internal structure.

Answer 9

Concrete.

Question 10

A hardwood deck is degraded by being exposed to wet conditions from _______, making it susceptible to __________.

Answer 10

rain
wet rot