RBI Assistant - Concrete Technology and Design 1000+ MCQ [Solved] PDF Download

1. If 50 kg of fine aggregates and 100 kg of coarse aggregates are mixed in a concrete whose water cement ratio is 0.6, the weight of water required for harsh mix, is
A. 8 kg
B. 10 kg
C. 12 kg
D. 14 kg
Answer : C

2. The diameter of the Vicat plunger is 10 mm and its length varies from
A. 20 mm to 30 mm
B. 30 mm to 40 mm
C. 40 mm to 50 mm
D. 50 mm to 60 mm
Answer : C

3. While designing an air entrained concrete
A. Water cement ratio is reduced
B. Proportion of aggregates is reduced
C. An allowance for the entrained air is made
D. All the above
Answer : D

4. Pick up the correct statement from the following:
A. Construction joints in columns are provided a few cm below the junction of beam
B. Construction joints in columns are provided at the bottom hunching
C. Construction joints in beams and slabs are provided within middle third
D. All the above
Answer : D

5. Expansion joints are provided if the length of concrete structures exceeds
A. 10 m
B. 15 m
C. 15 m
D. 45 m
Answer : D

6. For the construction of the retaining structures, the type of concrete mix to be used, is
A. 1 : 3 : 6
B. 1 : 2 : 4
C. 1 : 1 ½ : 3
D. 1 : 4 : 8
Answer : C

7. For a reinforced concrete section, the shape of shear stress diagram is
A. Wholly parabolic
B. Wholly rectangular
C. Parabolic above neutral axis and rectangular below neutral axis
D. Rectangular above neutral axis and parabolic below neutral axis
Answer : C

8. Pick up the correct statement from the following:
A. Insufficient quantity of water makes the concrete mix harsh
B. Insufficient quantity of water makes the concrete unworkable
C. Excess quantity of water makes the concrete segregated
D. All the above
Answer : D

9. If X, Y and Z are the fineness modulli of coarse, fine and combined aggregates, the percentage (P) of fine aggregates to combined aggregates, is
A. P = [(Z - X)/(Z - Y)] × 100
B. P = [(X - Z)/(Z - Y)] × 100
C. P = [(X - Z)/(Z + Y)] × 100
D. P = [(Z + X)/(Z - Y)] × 100
Answer : B

10. The property of the ingredients to separate from each other while placing the concrete is called
A. Segregation
B. Compaction
C. Shrinkage
D. Bulking
Answer : A

11. In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively
A. Compressive and tensile
B. Tensile and compressive
C. Both compressive
D. Both tensile
Answer : B

12. Finer grinding of cement
A. Affects only the early development of strength
B. Affects only the ultimate strength
C. Both (A) and (B)
D. Does not affect the strength
Answer : A

13. Cube strength of controlled concrete to be used for pre-tensioned and post-tensioned work respectively should not be less than
A. 35 MPa and 42 MPa
B. 42 MPa and 35 MPa
C. 42 MPa and 53 MPa
D. 53 MPa and 42 MPa
Answer : B

14. The commonly used material in the manufacture of cement is
A. Sand stone
B. Slate
C. Lime stone
D. Graphite
Answer : C

15. The compressive strength of 100 mm cube as compared to 150 mm cube is always
A. Less
B. More
C. Equal
D. None of the above
Answer : B

16. If the effective working time is 7 hours and per batch time of concrete is 3 minutes, the output of a concrete mixer of 150 litre capacity, is
A. 15,900 litres
B. 16,900 litres
C. 17,900 litres
D. 18,900 litres
Answer : D

17. In counterfort retaining walls, the main reinforcement in the stem at support is
A. Not provided
B. Provided only on inner face
C. Provided only on front face
D. Provided both on inner and front faces
Answer : B

18. The risk of segregation is more for
A. Wetter mix
B. Larger proportion of maximum size aggregate
C. Coarser grading
D. All the above
Answer : D

19. The grade of concrete M 150 means that compressive strength of a 15 cm cube after 28 days, is
A. 100 kg/cm2
B. 150 kg/cm2
C. 200 kg/cm2
D. 250 kg/cm2
Answer : B

20. Addition of pozzolana to ordinary port land cement, causes
A. Decrease in early strength
B. Reduction in chemical action with sulphates
C. Increase in shrinkage
D. All the above
Answer : D

21. The void ratio of
A. Single size coarse aggregate is roughly 0.45
B. Graded coarse aggregate is roughly 0.040
C. Fine aggregate is roughly 0.45
D. All the above
Answer : D

22. Which of the following R.C. retaining walls is suitable for heights beyond 6 m?
A. L-shaped wall
B. T-shaped wall
C. Counterfort type
D. All of the above
Answer : C

23. In a counterfort retaining wall, the main reinforcement in the stem at mid span is provided on
A. Front face only
B. Inner face only
C. Both front face and inner face
D. None of the above
Answer : A

24. Higher workability of concrete is required if the structure is
A. Made with cement concrete
B. Thick and reinforced
C. Thin and heavily reinforced
D. Thick and heavily reinforced
Answer : D

25. To prevent segregation, the maximum height for placing concrete, is
A. 100 cm
B. 125 cm
C. 150 cm
D. 200 cm
Answer : A

26. Pick up the correct statement from the following:
A. Segregation is necessary for a workable concrete
B. Consistency does not affect the workability of concrete
C. If the concrete mix is dry, the slump is maximum
D. None of these
Answer : D

27. The light weight aggregates are obtained from
A. Sedimentary rocks
B. Metamorphic rocks
C. Igneous rocks
D. Volcanic source
Answer : D

28. For the construction of thin R.C.C. structures, the type of cement to be avoided, is
A. Ordinary Portland cement
B. Rapid hardening cement
C. Low heat cement
D. Blast furnace slag cement
Answer : D

29. Slump test is done for
A. Clay
B. Sand
C. Lime
D. Concrete
Answer : D

30. The process of proper and accurate measurement of concrete ingredients for uniformity of proportion, is known
A. Grading
B. Curing
C. Mixing
D. Batching
Answer : D

31. Examine the following statements: (i) Factor of safety for steel should be based on its yield stress, (ii) Factor of safety for steel should be based on its ultimate stress, (iii) Factor of safety for concrete should be based on its yield stress, (iv) Factor of safety for concrete should be based on its ultimate stress. The correct statements are
A. (i) and (iii)
B. (i) and (iv)
C. (ii) and (iii)
D. (ii) and (iv)
Answer : B

32. The most commonly used admixture which prolongs the setting and hardening time is
A. Gypsum
B. Calcium chloride
C. Sodium silicate
D. All of the above
Answer : A

33. For construction of structures in sea water, the cement generally preferred to, is
A. Portland-pozzolana cement
B. Quick setting cement
C. Low heat Portland cement
D. Rapid hardening cement
Answer : A

34. A concrete using an air entrained cement
A. Has strength less than 10% to 15%
B. Has more resistance to weathering
C. Is more plastic and workable
D. Is free from segregation and bleeding
Answer : C

35. Normally pre-stressing wires are arranged in the
A. Upper part of the beam
B. Lower part of the beam
C. Center
D. Anywhere
Answer : B

36. Pick up the correct statement from the following:
A. The concrete gains strength due to hydration of cement
B. The concrete does not set at freezing point
C. The strength of concrete increases with its age
D. All the above
Answer : D

37. For given water content, workability decreases if the concrete aggregates contain an excess of
A. Thin particles
B. Flat particles
C. Elongated particles
D. All the above
Answer : D

38. The most useless aggregate is one whose surface texture is
A. Smooth
B. Granular
C. Glassy
D. Honey combed and porous
Answer : C

39. While compacting the concrete by a mechanical vibrator, the slump should not exceed
A. 2.5 cm
B. 5.0 cm
C. 7.5 cm
D. 10 cm
Answer : B

40. Pick up the incorrect statement from the following. While performing preliminary test on concrete
A. Proportions of the material and water should be the same as to be used at the work site
B. Cement should be mixed by hand in order to maintain uniformity
C. Concrete mix should be stored in air-tight containers
D. Concrete ingredients should be kept at a temperature of 37° ± 2°C
Answer : D

41. Approximate value of shrinkage strain in concrete, is
A. 0.003
B. 0.0003
C. 0.00003
D. 0.03
Answer : B

42. Maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is
A. 28 liters
B. 30 liters
C. 32 liters
D. 34 liters
Answer : C

43. Admixtures which cause early setting and hardening of concrete are called
A. Workability admixtures
B. Accelerators
C. Retarders
D. Air entraining agents
Answer : B

44. Pick up the incorrect statement applicable to the field test of good cement.
A. When one thrusts one's hand into a bag of cement, one should feel warm
B. The colour of the cement is bluish
C. By rubbing cement in between fingers, one should feed rough
D. All the above
Answer : D

45. Vicat apparatus is used for
A. Fineness test
B. Consistency test
C. Test for setting time
D. Test for tensile strength
Answer : B

46. Curing of pavements, floors, roofs and slabs, is done by
A. Membrane method
B. Ponding method
C. Covering surface with bags
D. Sprinkling water method
Answer : B

47. Segregation is responsible for
A. Honey-combed concrete
B. Porous layers in concrete
C. Surface scaling in concrete
D. All the above
Answer : D

48. Permissible compressive strength of M 150 concrete grade is
A. 100 kg/cm2
B. 150 kg/cm2
C. 200 kg/cm2
D. 250 kg/cm2
Answer : C

49. According to Water-Cement Ratio Law, the strength of workable plastic concrete
A. Depends upon the amount of water used in the mix
B. Does not depend upon the quality of cement mixed with aggregates
C. Does not depend upon the quantity of cement mixed with aggregates
D. All the above
Answer : D

50. The following proportion of the ingredients of concrete mix, is not in conformation to arbitrary method of proportioning
A. 1 : 1 : 2
B. 1 : 2 : 4
C. 1 : 3 : 6
D. 1 : 4 : 10
Answer : D