Concrete Technology MCQ – Aggregate MCQ

261. The development of hair-like cracks usually in an irregular pattern caused by the shrinkage of concrete surface is called as

  1. Blistering
  2. Cracking
  3. Crazing
  4. Laitance
  5. Grinning
Answer
Answer. c

262. ________ are used to finish concrete surfaces such as bridge floors, road slabs, station platforms, etc.

  1. Immersion vibrators
  2. Surface vibrators
  3. Form vibrators
  4. Internal vibrators
Answer
Answer. b

263. If creep coefficient for concrete at 7 days is K1 and 28 days is K2 then

  1. K1 > K2
  2. K1 < K2
  3. K1 = K2
  4. K1 ≤ K2
Answer
Answer. a

264. A concrete mix has entrapped air about 1% results in

  1. requires less quantity of water
  2. poor quality of concrete
  3. average quality of concrete
  4. improved quality of concrete
Answer
Answer. c

265. The ratio of modulus of rupture to direct tensile strength of concrete is

  1. 1
  2. 0.75
  3. 2
  4. 4
Answer
Answer. c

266. As per IS code of practice, concrete should be cured at

  1. 35°C
  2. 25°C
  3. 27°C
  4. 50°C
Answer
Answer. c

267. What is the amount of water required for a workable RC of mix 1 : 2 : 4 by weight when w/c ratio is 0.6 and unit weight of concrete is 2400 kg/m3?

  1. 165 L
  2. 205 L
  3. 245 L
  4. 285 L
Answer
Answer. b

268. Slump and compaction factor are two different measure of workability of concrete. For a slump of 0 to 20, what is the equivalent range of compaction factor?

  1. 0.4-0.7
  2. 0.7-0.9
  3. 0.7-0.8
  4. 0.6-0.8
Answer
Answer. c

269. Inadequate compaction during concrete casting results in

  1. Honey combing
  2. Bleeding
  3. Segregation
  4. Bleeding and Segregation
Answer
Answer. a

270. If characteristic compressive strength at 28 days is 40 N/mm2 and the standard deviation is 5 N/mm2, the target strength at 28 days for concrete mix proportioning

  1. 40 N/mm2
  2. 45 N/mm2
  3. 43.25 N/mm2
  4. 48.25 N/mm2
Answer
Answer. d
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