Durability of concrete

Question 1

Mechanisms defining deterioration of concrete.

Answer 1

Corrosion of reinforcement, chemical attack, physical attack.

Question 2

Stages of carbonation induced corrosion.

Answer 2

1. CO2 present in atmosphere diffuses into concrete.
2. Reaction of CO2 with pore fluids leading to formation of carbonic acid.
3. reaction with carbonic acid with alkaline constitutes of concrete to form carbonates

Question 3

Carbonation formula

Answer 3

Ca(OH)2 + CO2 = CaCO3 + 2H20

Question 4

factors influencing carbonation

Answer 4

concrete characteristics, environmental conditions

Question 5

measures to minimize carbonation

Answer 5

1. Sufficient concrete between exterior and steel
2. Reduce w/c ratio
3. Use high PC content to maximize calcium hydroxide levels
4. Use FA,GGBS,MK,CSF,LS
5. use a surface treatment(membrane)

Question 6

What causes chloride induced corrosion?

Answer 6

1. Chlorides present in de-icing salts
2. In the sea water
3. Chemical admixtures

Question 7

Measure to minimize chloride-induced corrosion

Answer 7

same as for the other one gus is tired

Question 8

Mechanisms of chemical attack on concrete

Answer 8

Sulfate, Acid, Alkali-aggregate rectors, seawater attacks.

Question 9

Mechanisms of sea water attacks

Answer 9

Atmospheric zone, splash zone, tidal zone, submerged zone.

Question 10

How do physical attacks occur?

Answer 10

Expansion of concrete
variations in environmental conditions
direct physical attacks

Question 11

What is freeze thaw attack?

Answer 11

Ask gus again

Question 12

Freeze/thaw attack influencing factors

Answer 12

1. Environmental conditions
2. air content in concrete
3. aggregate type and size

Question 13

Types of physical attrition of concrete

Answer 13

1. Abrasion ( Interaction between concrete and object)
2. Erosion
3. caviation