1000+ Concrete Technology and Design MCQ for SSC Scientific Assistant [Solved]

1. 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

2. Workability improved by adding
A. Air-entraining agent
B. Foaming agent
C. Oily-agent
D. All the above
Answer : D

3. The relation between modulus of rupture f_cr, splitting strength f_cs and direct tensile strength f_cl is given by
A. f_cr - f_cs = f_cl
B. f_cr > f_cs > f_cl
C. f_cr < f_cs < f_cl
D. f_cs > f_cr > f_cl
Answer : B

4. The surface where two successive placements of concrete meet, is known as
A. Contraction joint
B. Expansion joint
C. Construction joint
D. Both (a) and (b)
Answer : C

5. If P, Y and Z are the weights of cement, fine aggregates and coarse aggregates respectively and W/C is the water cement ratio, the minimum quantity of water to be added to first batch, is obtained by the equation
A. 0.1P + 0.3Y + 0.1Z = W/C × P
B. 0.3P + 0.1Y + 0.01Z = W/C × P
C. 0.4P + 0.2Y + 0.01Z = W/C × P
D. 0.5P + 0.3Y + 0.01Z = W/C × P
Answer : B

6. The grade of concrete not recommended by I.S. : 456, is
A. M 100
B. M 200
C. M 300
D. M 500
Answer : D

7. Water required per bag of cement, is
A. 7 kg
B. 14 kg
C. 21 kg
D. 35 kg
Answer : D

8. The permissible diagonal tensile stress in reinforced brick work is
A. About 0.1 N/mm²
B. Zero
C. 0.3 N/mm² to 0.7 N/mm²
D. About 1.0 N/mm²
Answer : A

9. During erection, the pile of length l is supported by a crane at a distance of
A. 0.207 l
B. 0.293 l
C. 0.707 l
D. 0.793 l From the driving end of pile which rests on the ground
Answer : C

10. Separation of water or water sand cement from a freshly concrete, is known
A. Bleeding
B. Creeping
C. Segregation
D. Flooding
Answer : A

11. An ideal ware house, is provided
A. Water proof masonry walls
B. Water proof roof
C. Few windows which remain generally closed
D. All the above
Answer : D

12. For a slab supported on its four edges with corners held down and loaded uniformly, the Marcus correction factor to the moments obtained by Grashoff Rankine's theory
A. Is always less than 1
B. Is always greater than 1
C. Can be more than 1
D. Can be less than 1
Answer : A

13. Minimum grade of concrete to be used in reinforced concrete as per IS: 4561978 is
A. M 15
B. M 20
C. M 10
D. M 25
Answer : A

14. 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

15. According to Whitney's theory, depth of stress block for a balanced section of a concrete beam is limited to
A. 0.43 d
B. 0.537 d
C. 0.68 d
D. 0.85 d Where d is effective depth of beam
Answer : B

16. In case of hand mixing of concrete, the extra cement to be added is
A. 5 %
B. 10 %
C. 15 %
D. 20 %
Answer : B

17. A flaky aggregate is said to be elongated if its length is
A. Equal to the mean size
B. Twice the mean size
C. Thrice the mean size
D. Four times the mean size
Answer : B

18. Pick up the correct statement from the following:
A. An increase in water content must be accompanied by an increase in cement content
B. Angular and rough aggregates reduce the workability of the concrete
C. The slump of the concrete mix decreases due to an increase in temperature
D. All the above
Answer : D

19. Allowable shear strength of concrete, depends upon
A. Shear strength
B. Tensile strength
C. Compressive strength
D. None of these
Answer : A

20. 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

21. The temperature reinforcement in the vertical slab of a T-shaped R.C. retaining wall is
A. Not needed
B. Provided equally on inner and front faces
C. Provided more on inner face than on front face
D. Provided more on front face than on inner face
Answer : D

23. Pre-stress loss due to friction occurs
A. Only in post-tensioned beams
B. Only in pre-tensioned beams
C. In both post-tensioned and pre-tensioned beams
D. None of the above
Answer : A

24. The limits of percentage p of the longitudinal reinforcement in a column is given by
A. 0.15% to 2%
B. 0.8% to 4%
C. 0.8% to 6%
D. 0.8% to 8%
Answer : C

25. The ratio of the length to breadth of a wooden float, is
A. 4.5
B. 5.5
C. 6.5
D. 7.5
Answer : D

26. C.R.R.I. charts are used to obtain a relationship between strength of concrete and
A. Water cement ratio
B. Workability
C. Grading of aggregate
D. Fineness modulus
Answer : A

27. If fineness modulus of sand is 2.5, it is graded as
A. Very fine sand
B. Fine sand
C. Medium sand
D. Coarse sand
Answer : B

28. Water cement ratio is
A. Volume of water to that of cement
B. Weight of water to that of cement
C. Weight of concrete to that of water
D. Both (a) and (b) of the above
Answer : D

29. The cement becomes useless if its absorbed moisture content exceeds
A. 1 %
B. 2 %
C. 3 %
D. 5 %
Answer : D

30. Bulking of sand is maximum if moisture content is about
A. 2 %
B. 4 %
C. 6 %
D. 10 %
Answer : B

31. The maximum percentage of chemical ingredient of cement is that of
A. Magnesium oxide
B. Iron oxide
C. Silica
D. Lime
Answer : D

32. The top diameter, bottom diameter and the height of a slump mould are:
A. 10 cm, 20 cm, 30 cm
B. 10 cm, 30 cm, 20 cm
C. 20 cm, 10 cm, 30 cm
D. 20 cm, 30 cm, 10 cm
Answer : A

33. Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is
A. 30 %
B. 40 %
C. 50 %
D. 60 %
Answer : A

34. Modulus of rupture of concrete is a measure of
A. Flexural tensile strength
B. Direct tensile strength
C. Compressive strength
D. Split tensile strength
Answer : A

35. For a cantilever of effective depth of 0.5 m, the maximum span to satisfy vertical deflection limit is
A. 3.5 m
B. 4 m
C. 4.5 m
D. 5 m
Answer : A

36. According to IS: 4561978, the maximum reinforcement in a column is
A. 2 %
B. 4 %
C. 6 %
D. 8 %
Answer : C

37. For ensuring quality of concrete, use
A. Single sized aggregates
B. Two sized aggregate
C. Graded aggregates
D. Coarse aggregates
Answer : C

38. The shuttering of a hall measuring 4 m × 5 m, can be removed after
A. 5 days
B. 7 days
C. 10 days
D. 14 days
Answer : B

39. M10 grade of concrete approximates
A. 1 : 3 : 6 mix
B. 1 : 1 : 2 mix
C. 1 : 2 : 4 mix
D. 1 : 1.5 : 3 mix
Answer : A

40. Pick up the incorrect statement from the following:
A. A rich mix of concrete possesses higher strength than that a lean mix of desired workability with excessive quantity of water
B. The strength of concrete decreases as the water cement ratio increases
C. Good compaction by mechanical vibrations, increases the strength of concrete
D. None of these
Answer : A

41. The effect of creep on modular ratio is
A. To decrease it
B. To increase it
C. Either to decrease or to increase it
D. To keep it unchanged
Answer : B

42. According to IS: 4561978, the column or the strut is the member whose effective length is greater than
A. The least lateral dimension
B. 2 times the least lateral dimension
C. 3 times the least lateral dimension
D. 4 times the least lateral dimension
Answer : C

43. The dimensions of a 35 litre forma for measuring aggregates by volume, are:
A. Length 30 cm, breadth 25 cm, height 30 cm
B. Length 39 cm, breadth 25 cm, height 32 cm
C. Length 27 cm, breadth 27 cm, height 48 cm
D. Length 220 cm, breadth 25 cm, height 40 cm
Answer : C

44. An aggregate which passes through 25 mm I.S. sieve and is retained on 20 mm sieve, is said to be flaky if its least dimension is less than
A. 22.5 mm
B. 18.5 mm
C. 16.5 mm
D. 13.5 mm
Answer : D

45. Diagonal tension in a beam
A. Is maximum at neutral axis
B. Decreases below the neutral axis and increases above the neutral axis
C. Increases below the neutral axis and decreases above the neutral axis
D. Remains same
Answer : C

46. I.S. Sieve Nos. 10 mm and 4.75 mm are generally used for grading of
A. Coarse aggregates
B. Fine aggregates
C. Neither (a) nor (b)
D. Both (a) and (b)
Answer : D

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

48. The factor of safety for
A. Steel and concrete are same
B. Steel is lower than that for concrete
C. Steel is higher than that for concrete
D. None of the above
Answer : B

49. Pick up the correct statement from the following:
A. Water enables chemical reaction to take place with cement
B. Water lubricates the mixture of gravel, sand and cement
C. Strength of concrete structure largely depends upon its workability
D. All the above
Answer : D

50. The aggregate containing moisture in pores and having its surface dry, is known as
A. Moist aggregates
B. Very dry aggregates
C. Dry aggregates
D. Saturated surface dry aggregate
Answer : D