This set of Repair and Rehabilitation of Structures Multiple Choice Questions & Answers (MCQs) focuses on “Causes of Distress and Deterioration of Concrete”.
1. Damage due to accidental loadings cannot be prevented when compared to other damages.
a) True
b) False
View Answer
Explanation: Damage due to accidental loadings cannot be prevented when compared to other damages because the causes are not in the way they are expected and it seems to be difficult to prepare for it.
2. When acid attacks concrete it affects __________ property of cement.
a) spalling
b) hydration
c) slump
d) bleeding
View Answer
Explanation: When acid attacks concrete it affects the hydration property of cement and their products especially the product calcium silicate hydrate is adversely affected leading to the failing of concrete structures.
3. ___________ weakens the concrete.
a) Hydrochloric acid
b) Sulfuric acid
c) Nitric acid
d) Acetic acid
View Answer
Explanation: Sulfuric acid weakens the concrete and, in some cases, it affects the rebars leading to corrosion which in turn affects the strength of concrete.
4. Which of the following can provide protection against mild acid exposure?
a) Low slump
b) High slump
c) Low water cement ratio
d) High water cement ratio
View Answer
Explanation: Low water cement ratio can prevent a mild acid attack on concrete because in that case, the concrete becomes dense leading to less effects of acid on them which could be further rectified.
5. Low concentration of dissolved minerals in water leads to an aggressive water attack.
a) True
b) False
View Answer
Explanation: Low concentration of dissolved minerals in water leading to leaching of calcium from cement or aggregates leading to rough concrete and causing aggressive water attack.
6. The diameter of the conduit installed in concrete should not be greater than _______ of the overall thickness of the concrete slab.
a) 2/3rd
b) 1/3rd
c) 3/4rd
d) 3/2rd
View Answer
Explanation: The diameter of the conduit installed in concrete should not be greater than 2/3rd of the overall thickness of the concrete slab so as to prevent the bulging of the conduit into the outer atmosphere.
7. ___________ examination can be used to identify the presence of alkali carbonate reaction.
a) Visual
b) Petrographic
c) High resolution
d) Joint inspection
View Answer
Explanation: Petrographic examination can be used to identify the presence of alkali carbonate reaction and steps could be taken to identify the defects and rectify them.
8. Impure dolomitic aggregates result in alkali carbonate reaction.
a) True
b) False
View Answer
Explanation: Impure dolomitic aggregate results in alkali carbonate reaction which results in map or pattern cracking and now concrete will look swelling.
9. Concrete that contains less than 0.60% alkalis allows pattern cracking to occur.
a) True
b) False
View Answer
Explanation: Concrete that contains less than 0.60% alkalis allows pattern cracking thereby giving swelling appearance leading to alkali silica reaction.
10. Conduit that is embedded in concrete should be spaced at a minimum distance which is equal to not less than ______ times the diameter of the conduit installed.
a) 3
b) 2
c) 4
d) 5
View Answer
Explanation: Conduit that is embedded in concrete should be spaced at a minimum distance which is equal to not less than 3 times the diameter of the conduit installed to avoid damage to the conduit that is exposed to the external atmosphere.
11. Sulphate attack on concrete occurs from naturally occurring sulfates of sodium.
a) True
b) False
View Answer
Explanation: Sulphate attack on concrete occurs from naturally occurring sulfates of sodium, potassium, calcium or magnesium and it mainly causes the corrosion of rebars.
Sanfoundry Global Education & Learning Series – Repair and Rehabilitation of Structures.
To practice all areas of Repair and Rehabilitation of Structures, here is complete set of Multiple Choice Questions and Answers.
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