Tricky Concrete Technology Questions and Answers on “Defects Occurring During Construction”.
1. What is the moisture content in slurry for wet process?
a) 35-50%
b) 12%
c) 40-45%
d) 100%
Answer: a
Clarification: The moisture content in slurry for wet process is 35-50%. 12% is the moisture content for dry process.
2. The use of crushed aggregates may results in 10 to 20% higher compressive strength.
a) True
b) False
Answer: a
Clarification: The use of crushed aggregates may results in 10 to 20% higher compressive strength due to development of stronger aggregate-mortar bond.
3. Dry intervals in surface wetting leads to ____________
a) Cracking
b) Fogging
c) High strength
d) Good workability
Answer: a
Clarification: Dry intervals or patches can lead to crazing or cracking on the slab surface. The effect of surface wettability on the dynamics of crack formation and their characteristics are examined during the drying of aqueous colloidal droplets containing nano particles.
4. The rate of creep rapidly ___________ with time.
a) Increase
b) Decrease
c) Doesn’t affect
d) Depends on the temperature
Answer: b
Clarification: The rate of creep rapidly decreases with time. The time taken by a concrete structure to attained creep is 5 years.
5. The rate of creep generally ____________ with the ____________ of the size of aggregates.
a) Increase, increase
b) Decrease, decease
c) Increase, decrease
d) 2.5, 12mm
Answer: c
Clarification: The rate of creep generally decreases with the increase of the size of aggregates. Time rate of deformation of a material subject to stress at a constant temperature. It is the slope of the creep vs. time diagram obtained in a creep test.
6. Reduction in the volume due to shrinkage causes __________
a) Low volume
b) Volumetric strain
c) Volumetric stress
d) W/c ratio
Answer: b
Clarification: Reduction in the volume due to shrinkage causes volumetric strain in freshly hardened concrete.
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