This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Types of Shrinkage”.
1. What is plastic shrinkage?
a) It is not a result of any change in the concrete production process. Rather, it is a result of certain environmental conditions which occurs in the Central Missouri area
b) It is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile
c) It is an important phenomenon in young concrete. At low w/c ratios, less than about 0.42, all the water is rapidly drawn into the hydration process and the demand for more water creates very fine capillaries
d) It occurs when the concrete is exposed to air containing carbon dioxide
View Answer
Explanation: It is not a result of any change in the concrete production process. Rather, it is a result of certain environmental conditions which occurs in the Central Missouri area.
2. What is drying shrinkage?
a) It is not a result of any change in the concrete production process. Rather, it is a result of certain environmental conditions which frequently occur in the Central Missouri area
b) It is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile
c) It is an important phenomenon in young concrete. At low w/c ratios, less than about 0.42, all the water is rapidly drawn into the hydration process and the demand for more water creates very fine capillaries
d) It occurs when the concrete is exposed to air containing carbon dioxide
View Answer
Explanation: It is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile.
3. What is autogenous shrinkage?
a) It is not a result of any change in the concrete production process. Rather, it is a result of certain environmental conditions which frequently occur in the Central Missouri area
b) It is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile
c) It is an important phenomenon in young concrete. At low w/c ratios, less than about 0.42, all the water is rapidly drawn into the hydration process and the demand for more water creates very fine capillaries
d) It occurs when the concrete is exposed to air containing carbon dioxide
View Answer
Explanation: It is an important phenomenon in young concrete. At low w/c ratios, less than about 0.42, all the water is rapidly drawn into the hydration process and the demand for more water creates very fine capillaries.
4. What is carbonation shrinkage?
a) It is not a result of any change in the concrete production process. Rather, it is a result of certain environmental conditions which frequently occur in the Central Missouri area
b) It is defined as the contracting of a hardened concrete mixture due to the loss of capillary water. This shrinkage causes an increase in tensile
c) It is an important phenomenon in young concrete. At low w/c ratios, less than about 0.42, all the water is rapidly drawn into the hydration process and the demand for more water creates very fine capillaries
d) It occurs when the concrete is exposed to air containing carbon dioxide
View Answer
Explanation: It occurs when the concrete is exposed to air containing carbon dioxide.
5. ACI 305.R.91 specifies Evaporation rate __ kg/hr/m2 should be avoided to prevent plastic cracking.
a) <.5
b) =0.5
c) >.5
d) Not equal to .5
View Answer
Explanation: ACI 305.R.91 specifies Evaporation rate >0.5 kg/hr/m2 should be avoided to prevent plastic cracking.
6. Carbonic Acid + Ca(OH)2 ⇨ X. What is the main compound in X?
a) CaCO2
b) CO2
c) CaCO3
d) H2O
View Answer
Explanation: It is a chemical reaction. It causes contraction of concrete which is known as Carbonation shrinkage.
7. If there is continuous supply of H2O to the concrete during hydration, concrete expands due to absorption of water by the cement gel.
a) True
b) False
View Answer
Explanation: If there is continuous supply of H2O to the concrete during hydration, concrete expands due to absorption of water by the cement gel and it is known as swelling.
8. Reduction in the volume due to shrinkage causes _____
a) Low volume
b) Volumetric strain
c) Volumetric stress
d) W/c ratio
View Answer
Explanation: Reduction in the volume due to shrinkage causes volumetric strain in freshly hardened concrete.
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