Concrete Technology and Design of Concrete Structures Multiple Choice Questions and Answers

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Concrete Technology and Design of Concrete Structures Multiple Choice Questions and Answers
1. To determine the modulus of rupture, the size of test specimen used is
a) 150 x150 x500 mm
b) 100 x100 x700 mm
c) 150 x150 x700 mm
d) 100 x100 x500 mm
Ans: c


2. The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called
a) segregation
b) bleeding
c) bulking
d) creep
Ans: b


3. Select the incorrect statement
a) Lean mixes bleed more as compared to rich ones.
b) Bleeding can be minimized by adding pozzuolana finer aggregate.
c) Bleeding can be increased by addition 'of calcium chloride.
d) none of the above
Ans: d


4. The property of the ingredients to separate from each other while placing the concrete is called
a) segregation
b) compaction
c) shrinkage
d) bulking
Ans: a


5. Workability of concrete is directly proportional to
a) aggregate cement ratio
b) time of transit
c) grading of the aggregate
d) all of above
Ans: c


6. Workability of concrete is inversely pro¬portional to
a) time of transit
b) 'vater-cement ratio
c) the air in the mix
d) size of aggregate
Ans: a


7. Approximate value of shrinkage strain in concrete, is
a) 0.003
b) 0.0003
c) 0.00003
d) 0.03
Ans: b


8. Air entrainment in the concrete increases
a) workability
b) strength
c) the effects of temperature variations
d) the unit weight
Ans: a


9. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by
a) tcr -rcs = tct
b) fcr>fcs>fc.
C) fcr
d) fc5>fcr>fC.
Ans: b


10. The approximate value of the ratio between direct tensile strength and flexural strength is
a) 0.33
b) 0.5
c) 0.75
d) 1.0
Ans: b


11. Strength of concrete increases with
a) increase in water-cement ratio
b) increase in fineness of cement
c) decrease in curing time
d) decrease in size of aggregate
Ans: b


12. The relation between modulus of rupturefcr and characteristic strength of concrete fck is given by
a) fcr=0.35Vf7
b) fcr=0.57f7
c) fcr=0.7Vf7
d) fcr=1.2Vf7
where fcr and fck are in N/mm2'
Ans: c

13. 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
Ans: b


14. According to IS : 456 -1978, the modulus of elasticity of concrete Ec (in N/mm2) can be taken as
a) Ec = = 5700
b) Ec = = 570
c) Ec = = 5700fck
d) Ec = where fck N/mm2 = 700 is the characteristic strength in
Ans: a

15. Increase in the moisture content in con-crete
a) reduces the strength
b) increases the strength
c) does not change the strength
d) all of the above
Ans: a

16. As compared to ordinary portland cement, use of pozzuolanic cement
a) reduces workability
b) increases bleeding
c) increases shrinkage
d) increases strength
Ans: c


17. Admixtures which cause early setting, and hardening of concrete are called
a) workability admixtures
b) accelerators
c) retarders
d) air entraining agents
Ans: b

18. 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
Ans: a


19. The percentage of voids in cement is approximately
a) 25%
b) 40%
c) 60%
d) 80%
Ans: b

20. The strength of concrete after one year as compared to 28 days strength is about
a) 10 to 15% more
b) 15 to 20% more
c) 20 to 25% more
d) 25 to 50% more
Ans: c

21. As compared to ordinary portland cement, high alumina cement has
a) higher initial setting time but lower final setting time
b) lower initial setting time but higher final setting time
c) higher initial and final setting times
d) lower initial and final setting times
Ans: a


22. Modulus of rupture of concrete is a measure of
a) flexural tensile strength
b) direct tensile strength
c) compressive strength
d) split tensile strength
Ans: a

23. In order to obtain the best workability of concrete, the preferred shape of aggregate is
a) rounded
b) elongated
c) angular
d) all of the above
Ans: a


24. The effect of adding calcium chloride in concrete is
i) to increase shrinkage
ii) to decrease shrinkage
iii) to increase setting time
iv) to decrease setting time
The correct answer is
a) (i) and (iii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans: b

25. Bulking of sand is maximum if moisture content is about
a) 2 %
b) 4%
c) 6%
d) 10%
Ans: b


26. 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
Ans: a

27. Poisson's ratio for concrete
a) remains constant
b) increases with richer mixes
c) decreases with richer mixes
d) none of the above
Ans: b

28. 1% of voids in a concrete mix would reduce its strength by about
a) 5%
b) 10 %
c) 15%
d) 20%
Ans: a


29. The fineness modulus of fine aggregate is in the range of
a) 2.0 to 3.5
b) 3.5 to 5.0
c) 5.0 to 7.0
d) 6.0 to 8.5
Ans: a


30. 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
Ans: b


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)
Ans: b


32. 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
Ans: c


33. 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
Ans: c


34. If a beam fails in bond, then its bond strength can be increased most economi-cally by
a) increasing the depth of beam
b) using thinner bars but more in number
c) using thicker bars but less in number
d) providing vertical stirrups
Ans: b


35. If nominal shear stress tv exceeds the design shear strength of concrete xc, the nominal shear reinforcement as per IS : 456-1978 shall be provided for carrying a shear stress equal to
a) xv
b) xc
c) xv - TC
d) Tv + Tc
Ans: c

36. If the depth of actual neutral axis in a beam is more than the depth of critical neutral axis, then the beam is called
a) balanced beam
b) under-reinforced beam
c) over-reinforced beam
d) none of the above
Ans: c


37. If the depth of neutral axis for a singly reinforced rectangular section is represented by kd in working stress design, then the value of k for balanced section
a) depends on as, only
b) depends on aCbC only
c) depends on both crst and acbc
d) is independant of both ast and acbc where d is the effective depth, ast is per-missible stress in steel in tension and ocbc is permissible stress in concrete in bend¬ing compression.
Ans: a

38. If the permissible stress in steel in tension is 140 N/mm2, then the depth of neutral axis for a singly reinforced rectangular balanced section will be
a) 0.35 d
b) 0.40 d
c) 0.45 d
d) dependent on grade of concrete also
Ans: b


39. Modulus of elasticity of steel as per IS : 456-1978 shall be taken as
a) 20 kN/cm2
b) 200 kN/cm2
c) 200kN/mm2
d) 2xl06N/cm2
Ans: c

40. Minimum grade of concrete to be used in reinforced concrete as per IS:456-1978 is
a) M15
b) M20
c) M 10
d) M25
Ans: a


41. For concreting of heavily reinforced sections without vibration, the workability of concrete expressed as compacting
factor should be
a) 0.75-0.80
b) 0.80-0.85
c) 0.85 - 0.92
d) above 0.92
Ans: d

42. Maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is
a) 28 litres
b) 30 litres
c) 32 litres
d) 34 litres
Ans: c

43. In case of hand mixing of concrete, the extra cement to be added is
a) 5%
b) 10%
c) 15%
d) 20%
Ans: b


44. For walls, columns and vertical faces of all structural members, the form work is generally removed after
a) 24 to 48 hours
b) 3 days
c) 7 days
d) 14 days
Ans: a

45. The individual variation between test strength of sample should not be more than
a) ±5% of average
b) ± 10% of average
c) ± 15% of average
d) ±20% of average
Ans: c


46. One of the criteria for the effecvve width of flange of T-beam is bf =-+ bw +6Df 6
In above formula, l0 signifies
a) effective span of T-beam
b) distance between points of zero mo-ments in the beam
c) distance between points of maximum moments in the beam
d) clear span of the T-beam
Ans: b


47. For a cantilever of effective depth of 0.5m, the maximum span to satisfy vertical deflection limit is
a) 3.5 m
b) 4 m
c) 4.5 m
d) 5 m
Ans: a

48. For a simply supported beam of span 15m, the minimum effective depth to satisfy the vertical deflection limits should be
a) 600 mm
b) 750 mm
c) 900 mm
d) more than 1 m
Ans: b


49. For a continuous slab of 3 m x 3.5 m size, the minimum overall depth of slab to satisfy vertical deflection limits is
a) 50 mm
b) 75 mm
c) 100 mm
d) 120 mm
Ans: b

50. According to IS : 456-1978, the fiexural strength of concrete is
a) directly proportional to compressive strength
b) inversely proportional to compressive strength
c) directly proportional to square root of compressive strength
d) inversely proportional to square root of compressive strength
Ans: c


51. According to IS : 456-1978, the cblumn 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
Ans: c

52. According to IS : 456- 1978, minimum slenderness ratio for a short column is
a) less than 12
b) less than 18
c) between 18 and 24
d) more than 24
Ans: a


53. Lap length in compression shall not be less than
a) 15 4>
b) 20 <}>
c) 24 (j)
d) 30 (j)
where (j) is diameter of bar
Ans: c

54. The minimum cover in a slab should neither be less than the diameter of bar nor less than
a) 10 mm
b) 15 mm
c) 25 mm
d) 13 mm
Ans: b


55. For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than the diameter of bar nor less than
a) 15 mm
b) 25 mm
c) 30mm
d) 40 mm
Ans: d


56. The ratio of the diameter of reinforcing bars and the slab thickness is
a) 1/4
b) 1/5
c) 1/6
d) 1/8
Ans: d


57. According to IS: 456-1978, the maximum reinforcement in a column is
a) 2 %
b) 4%
c) 6 %
d) 8 %
Ans: c


58. The percentage of reinforcement in case of slabs, when high strength deformed bars are used is not less than
a) 0.15
b) 0.12
c) 0.30
d) 1.00
Ans: b


59. Which of the following statements is incorrect ?
a) Minimum cross sectional area of longitudinal reinforcement in a column is 0.8%.
b) Spacing of longitudinal bars measured along the periphery of column should not exceed 300 mm.
c) Reinforcing bars in a column should not be less than 12 mm in diameter.
d) The number of longitudinal bars pro-vided in a circular column should not be less than four.
Ans: d


60. Which of the following statements is incorrect ?
a) Higher Vee-Bee time shows lower workability.
b) Higher slump shows higher workability.
c) Higher compacting factor shows higher workability.
d) none of the above
Ans: d


61. Minimum pitch of transverse reinforce¬ment in a column is
a) the least lateral dimension of the member
b) sixteen times the smallest diameter of longitudinal reinforcement bar to be tied
c) forty-eight times the diameter of transverse reinforcement
d) lesser of the above three values
Ans: d


62. Maximum distance between expansion joints in structures as per IS : 456 - 1978 is
a) 20 m
b) 30 m
c) 45 m
d) 60 m
Ans: c


63. A continuous beam is deemed to be a deep beam when the ratio of effective span to
overall depth (1/D) is less than
a) 1.5
b) 2.0
c) 2.5
d) 3.0
Ans: c


64. Critical section for shear in case of flat slabs is at a distance of
a) effective depth of slab from periphery of column/drop panel
b) d/2 from periphery of column/capital/ drop panel
c) at the drop panel of slab
d) at the periphery of column
Ans:b


65. Minimum thickness of load bearing RCC wall should be
a) 50 mm
b) 100 mm
c) 150 mm
d) 200 mm
Ans:b


66. If the storey height is equal to length of RCC wall, the percentage increase in strength is
a) 0
b) 10
c) 20
d) 30
Ans: b


67. In reinforced concrete footing on soil, the minimum thickness at edge should not be less than
a) 100 mm
b) 150 mm
c) 200 mm
d) 250 mm
Ans:b


68. The slab is designed as one way if the ratio of long span to short span is
a) less than 1
b) between 1 and 1.5
c) between 1.5 and 2
d) greater than 2
Ans: d


69. Ratio of permissible stress in direct compression and bending compression is
a) less than 1
b) between 1 and 1.5
c) between 1.5 and 2.0
d) greater than 2
Ans: a


70. A higher modular ratio shows
a) higher compressive strength of con-crete
b) lower compressive strength of concrete
c) higher tensile strength of steel
d) lower tensile strength of steel
Ans:b


71. The average permissible stress in bond for plain bars in tension is
a) increased by 10% for bars in compression
b) increased by 25% for bars in compression
c) decreased by 10% for bars in compression
d) decreased by 25% for bars in com-pression
Ans:b


74. In working stress design, permissible bond stress in the case of deformed bars is more than that in plain bars by
a) 10%
b) 20%
c) 30%
d) 40%
Ans: d


75. The main reason for providing number of reinforcing bars at a support in a simply supported beam is to resist in that zone
a) compressive stress
b) shear stress
c) bond stress
d) tensile stress
Ans: c

76. Half of the main steel in a simply supported slab is bent up near the support at a
distance of x from the centre of slab bearing where x is equal to
a) 1/3
b) 1/5
c) 1/7
d) 1/10
where 1 is the span
Ans:c


77. When shear stress exceeds the permissible limit in a slab, then it is reduced by
a) increasing the depth
b) providing shear reinforcement
c) using high strength steel
d) using thinner bars but more in number
Ans: a

78. If the size of panel in a flat slab is 6m x 6m, then as per Indian Standard Code, the widths of column strip and middle strip are
a) 3.0 m and 1.5 m
b) 1.5 m and 3.0 m
c) 3.0 m and 3.0 m
d) 1.5 m and 1.5 m
Ans:c


79. 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
Ans: a


80. 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
Ans: a


81. The limits of percentage p of the longitudinal reinforce-ment 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%
Ans: c


82. The minimum diameter of longitudinal bars in a column is
a) 6 mm
b) 8 mm
c) 12 mm
d) 16 mm
Ans:c


83. The minimum cover to the ties or spirals should not be less than
a) 15 mm
b) 20 mm
c) 25 mm
d) 50mm
Ans: c

84. The load carrying capacity of a helically reinforced column as compared to that of a tied column is about
a) 5% less
b) 10% less
c) 5% more
d) 10% more
Ans:c


86. The diameter of ties in a column should be
a) more than or equal to one fourth of diameter of main bar
b) more than or equal to 5 mm
c) more than 5 mm but less than one-fourth of diameter of main bar
d) more than 5 mm and also more than one-fourth of diameter of main bar
Ans: d

87. Due to circumferential action of the spiral in a spirally reinforced column
a) capacity of column is decreased
b) ductility of column reduces
c) capacity of column is decreased but ductility of column increases
d) both the capacity of column and ductility of column increase
Ans: d


88. Maximum percentage reinforcement in case of slabs is limited to
a) 2
b) 4
c) 6
d) 8
Ans: b


89. Which of the following R.C. retaining walls is suitable for heights beyond 6m?
a) L-shaped wall
b) T-shaped wall
c) counterfort type
d) all of the above
Ans: c

90. For the design of retaining walls, the minimum factor of safety against overturning is taken as
a) 1.5
b) 2.0
c) 2.5
d) 3.0
Ans: b


91. In counterfort type retaining walls
i) the vertical slab is designed as a continuous slab
ii) the heel slab is designed as a conti¬nuous slab
iii) the vertical slab is designed as a cantilever
iv) the heel slab is designed as a cantilever
The correct answer is
a) (i) and (ii)
b) (i)and(iv)
c) (ii) and (iii)
d) (iii) and (iv)
Ans:a


92. A T-shaped retaining wall mainly conssits of
a) one cantilever
b) two cantilevers
c) three cantilevers
d) four cantilevers
Ans: c

93. In T-shaped R C. retaining walls, the main reinforcement in the stem is provided on
a) the front face in one direction
b) the front face in both directions
c) the inner face in one direction
d) the inner face in both directions
Ans:c


94. The main reinforcement in the toe of a T- shaped R C. retaining wall is provided on
i) top face parallel to the wall
ii) top face perpendicular to the wall
iii) bottom face paralleUo the wall
iv) bottom face perpendicular to the wall
The correct answer is
a) only (ii) is correct
b) (i) and (ii) are correct
c) (iii) and (iv) are correct
d) only (iv) is correct
Ans: d

95. 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
Ans: d


96. The main reinforcement in the heel of a T-shaped R.C. retaining wall is provided on
a) top face perpendicular to wall
b) bottom face perpendicular to wall
c) both top and bottom faces perpendi-cular to wall
d) none of the above
Ans: a

97. In a counterfort retaining wall, the main reinforcement is provided on the
i) bottom face in front counterfort
ii) inclined face in front counterfort
iii) bottom face in back counterfort
iv) inclined face in back counterEort
The correct answer is
a) (i) and (ii),
b) (ii) and (iii)
c) (i) and (iv)
d) (iii) and (iv)
Ans: c


98. 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
Ans: b


99. In the design of a front counterfort in a counterfort retaining wall, the main reinforcement is provided on
i) bottom face near counterfort
ii) top face near counterfort
iii) bottom face near centre of span
iv) top face near centre of span The correct answer is
a) only (i)
b) only (ii)
c) both (i) and (iv)
d) both (ii) and (iii)
Ans: c

100. 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
Ans: a


101. The depth of footing for an isolated column is governed by
i) maximum bending moment
ii) shear force
iii) punching shear The correct answer is
a) only (i)
b) (i)and(ii)
c) (i) and (iii)
d) (i), (ii) and (iii)
Ans: d

102. If the foundations of all the columns of a structure are designed on the total live and dead load basis, then
a) there will be no settlement of columns
b) there will be no differential settlement
c) the settlement of exterior columns will be more than interior columns
d) the settlement of interior columns will be more than exterior columns
Ans:c


103. To minimise the effect of differential settlement, the area of a footing should be designed for
a) dead load only
b) dead load + live load
c) dead load + fraction of live load
d) live load + fraction of dead load
Ans: c

104. The critical section for finding maximum bending moment for footing under masonry wall is located
a) at the middle of the wall
b) at the edge of the wall
c) halfway between the middle and edge of the wall
d) at a distance equal to effective depth of footing from the edge of the wall
Ans: c

105. In a pile of length /, the points of suspen¬sion from ends for lifting it are located at
a) 0.207 1
b) 0.25 /
c) 0.293 /
d) 0.333 /
Ans: a


106. During erection, the pile of length / is supported by a crane at a distance of
a) 0.207 /
b) 0.293 /
c) 0.7071
d) 0.793 /
from the driving end of pile which rests on the ground
Ans: c

107. While designing the pile as a column, the end conditions are nearly
a) both ends hinged
b) both ends fixed
c) one end fixed and other end hinged
d) one end fixed and other end free
Ans: c


108. The recommended value of modular ratio for reinforced brick work is
a) 18
b) 30
c) 40
d) 58
Ans: c

109. According to ISI recommendations, the maximum depth of stress block for balanced section of a beam of effective depth d is
a) 0.43 d
b) 0.55 d
c) 0.68 d
d) 0.85 d
Ans: a


110. Assertion A : The load factor for live load is greater than that for dead load.
Reason R : The live loads are more uncertain than dead loads.
Select your answer based on the coding system given below :
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.
Ans: a

111. The centroid of compressive force, from the extreme compression fibre, in limit state design lies at a distance of
a) 0.367 xu
b) 0.416 xu
c) 0.446 xu
d) 0.573 xu
where xu is the depth of neutral axis at the limit state of collapse
Ans: b


112. The design yield stress of steel according to IS: 456-1978 is
a) 0.37 fy
b) 0.57 fy
c) 0.67 fy
d) 0.87 fy
where fy is the characteristic yield strength of steel
Ans: d

113. According to Whitney's theory, ultimate strain of concrete is assumed to be
a) 0.03%
b) 0.1%
c) 0.3%
d) 3%
Ans: c


114. 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[ES 2k]
Ans: b

115. The load factors for live load and dead load are taken respectively as
a) 1.5 and 2.2
b) 2.2 and 1.5
c) 1.5 and 1.5
d) 2.2 and 2.2
Ans:b


116. As per Whitney's theory, the maximum moment of resistance of the balanced section of a beam of width b and effective
depth d is given by
a) ^acybd2
b) ^acybd2
c) 0.185acybd2
d) 0.43acybd2
where acy is the cylinder compressive strength of concrete
Ans: b

127. 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
Ans: b


128. Shrinkage of concrete depends upon
i) humidity of atmosphere
ii) passage of time
iii) stress The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) only (iii)
d) All (i), (ii) and (iii)
Ans: a


129. Due to shrinkage stresses, a simply supported beam having reinforcement only at bottom tends to
a) deflect downward
b) deflect upward
c) deflect downward or upward
d) none of the above
Ans: a


130. 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
Ans: b


131. A beam curved in plan is designed for
a) bending moment and shear
b) bending moment and torsion
c) shear and torsion
d) bending moment, shear and torsion
Ans: d


132. In a spherical dome subjected to concentrated load at crown or uniformly distributed load, the meridional force is
always
a) zero
b) tensile
c) compressive
d) tensile or compressive
Ans: c


133. Sinking of an intermediate support of a continuous beam
i) reduces the negative moment at support
ii) increases the negative moment at support
iii) reduces the positive moment at centre of span
iv) increases the positive moment at centre of span The correct answer is
a) (i) and (iii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans: b


134. The maximum value of hoop compression in a dome is given by
a) wR / 4d
b) wR/2d
c) wR/d
d) 2wR/d
where, w = load per unit area of surface of dome R = radius of curvature d = thickness of dome
Ans: b

135. In a spherical dome the hoop stress due to a concentrated load at crown is
a) compressive everywhere
b) tensile everywhere
c) partly compressive and partly tensile
d) zero
Ans:b


136. In a ring beam subjected to uniformly distributed load
i) shear force at mid span is zero
ii) shear force at mid span is maximum
iii) torsion at mid span is zero
iv) torsion at mid span is maximum The correct answer is
a) (i) and (iii)
b) (i)and(iv)
c) (ii) and (iii)
d) (ii) and (iv)
Ans:a

137. In prestressed concrete
a) forces of tension and compression change but lever arm remains unchanged
b) forces of tension and compressions remain unchanged but lever arm changes with the moment
c) both forces of tension and compres-sion as well as lever arm change
d) both forces of tension and compres-sion as well as lever arm remain unchanged
Ans: b


138. The purpose of reinforcement in prestressed concrete is
a) to provide adequate bond stress
b) to resist tensile stresses
c) to impart initial compressive stress in concrete
d) all of the above
Ans: c


139. Normally prestressing wires are arranged in the
a) upper part of the beam
b) lower part of the beam
c) centre
d) anywhere
Ans: b


140. Most common method of prestressing used for factory production is
a) Long line method
b) Freyssinet system
c) Magnel-Blaton system
d) Lee-Macall system
Ans:a


141. Select the incorrect statement
a) The loss of prestress is more in pre-tensioning system than in post-tensioning system.
b) Pretensioning system has greater certainty about its durability.
c) For heavy loads and large spans in buildings or bridges, post-tensioning system is cheaper than pretensioning system
d) none of the above
Ans:d

142. Which of the following losses of prestress occurs only in pretensioning and not in post-tensioning ?
a) elastic shortening of concrete
b) shrinkage of concrete
c) creep of concrete
d) loss due to friction
Ans: a


143. Prestress loss due to friction occurs
a) only in post-tensioned beams
b) only in pretensioned beams
c) in both post-tensioned and preten-sioned beams
d) none of the above
Ans:a

145. Which of the following has high tensile strength ?
a) plain hot rolled wires
b) cold drawn wires
c) heat treated rolled wires
d) all have same tensile strength
Ans: b


146. High carbon content in the steel causes
a) decrease in tensile strength but increase in ductility
b) increase in tensile strength but decrease in ductility
c) decrease in both tensile strength and ductility
d) increase in both tensile strength and ductility
Ans:b

147. Stress strain curve of high tensile steel
a) has a definite yield point
b) does not show definite yield point but yield point is defined by 0.1% proof stress
c) does not show definite yield point but yield point is defined by 0.2% proof stress
d) does not show definite yield point but yield point is defined by 2% proof stress,
Ans: c


148. Select the correct statement
a) Elastic modulus of high tensile steel is nearly the same as that of mild steel.
b) Elastic modulus of high tensile steel is more than that of mild steel.
c) Carbon percentage in high carbon steel is less than that in mild steel.
d) High tensile steel is cheaper than mild steel.
Ans:a

149. Cube strength of controlled concrete to be used for pretensioned 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
Ans: b


150. Ultimate strength of cold drawn high steel wires
a) increases with increase in diameter of bar
b) decreases with increase in diameter of bar
c) does not depend on diameter of bar
d) none of the above
Ans: b


151. Prestressing losses in post-tensioned and pre-tensioned beams are respectively
a) 15% and 20%
b) 20% and 15%
c) 15% and 15%
d) 20% and 20%


152. In concrete, use of angular crushed aggregate in place of natural rounded gravel affects
a) direct tensile strength
b) split tensile strength
c) flexural tensile strength
d) compressive strength


153. Ratio of compressive strength to tensile strength of concrete
a) increases with age
b) decreases with age
c) remains constant
d) none of the above


154. According to Indian Standards, the grad¬ing of fine aggregates is divided into
a) two zones
b) three zones
c) four zones
d) five zones


155. Assertion A : Lightweight concrete exhi¬bits higher shrinkage than normal weight concrete.
Reason R : Modulus of elasticity of light-weight concrete is lower, than that of normal weight concrete. Select your answer according to the coding system given below :
a) Both A and R are true and R is the correct explanation of A
b) Both A.and R are true but R is not the correct explanation of A
c) A is true but R is false
d) A is false but R is true


156. Endurance limit of mild steel is approximately equal to,
a) 0.3
b) 0.5
c) 0.7
d) 0.8
Endurance limit is defined as the maxi-mum value of the ratio of maximum stress to short time static strength, below which no failure occurs.


157. With the increase in rate of loading during testing, compressive strength of concrete
a) increases
b) decreases
c) remains same
d) none of the above


158. For a given aggregate content, increasing the water-cement ratio in concrete
a) increases shrinkage
b) decreases shrinkage
c) does not change shrinkage
d) none of the above


159. Assertion A : The net loss of strength due to air entrainment of a richer mix is higher than that of a leaner mix. Reason R : Effect of air entrainment on improving workability is smaller in richer mix than in a leaner mix. Select your answer based on the coding system given below
a) Both A and R are true and R is the correct explanation of A
b) Both A and R are true but R is not the correct explanation of A
c) A is true but R is false
d) A is false but R is true


160. The bond strength between steel rein-forcement and concrete is affected by i) steel properties ii) concrete properties iii) shrinkage of concrete The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) (i) and (iii)
d) (i), (ii) and (iii)


161. The bond strength between steel and concrete is due to
a) friction
b) adhesion
c) both friction and adhesion
d) none of the above


162. Impact strength of concrete increases by using
i) smaller maximum size of aggregate
ii) aggregate with high modulus of elasticity
iii) aggregate with low poisson's ratio The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) (i) and (iii)
d) (i), (ii) and (iii)


163. Impact strength of concrete is greater for
i) water stored concrete than for dry concrete
ii) angular crushed aggregates
iii) rounded aggregates The correct answer is
a) (i) and (ii)
b) (i) and (iii)
c) only (i)
d) only (ii)


164. If the contributions of tricalcium silicate, dicalcium silicate, tricalcium aluminate
and terra calcium alumino ferrite to the 28 days strength of hydrated ordinary Portland cement are respectively W, X, Y
and Z, then
a) W>.X>Y>Z
b) X>W>Y>Z
c) W>X>Z>Y
d) W>Y>X>Z

165. The initial and final setting times for ordinary portland cement are approxi¬
mately related as
a) T = 530 + t
b) T = 270 + t
c) T = 90+1.2t
d) T = 600-1.2t


where T and t are respectively final and initial setting times in minutes. * 166 Assertion A : The presence of tricalcium aluminate in cement is undesirable. Reason R : Tricalcium aluminate in ce¬ment contributes very little to strength of cement.
Select your answer based on the coding system given below
a) Both A and R are true and R is the correct explanation of A
b) Both A and R are true but R is not the correct explanation of A
c) A is true but R is false
d) A is false but R is true


167. Amount of gypsum required to be added to the clinker depends on the following contents of cement i) tricalcium silicate ii) dicalcium silicate iii) tricalcium aluminate iv) alkali The correct answer is
a) (i) and (ii)
b) (ii) and (iii)
c) (iii) and (iv)
d) (i)and(iv)


168. The diameter of needle used in Vicat's apparatus for the determination of initial
setting time is prescribed as
a) 0.5 mm
b) 1 mm
c) 5 mm
d) 10mm


169. The heat of hydration of cement can be reduced by
a) reducing the proportions of C3A and C3S
b) increasing the proportions of C3A and C3S
c) increasing the fineness of cement
d) both (a) and (c)


171. Assertion A : Rapid hardening cement is generally not used in mass concrete construction.
Reason R : The rate of heat development is low in rapid hardening cement. Select your answer based on the coding system given below
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.


172. If the angularity number of an aggregate is increased, then the workability of the concrete using this aggregate will
a) increase
b) decrease
c) not change
d) none of the above


173. If W,, W2, W3 and W4 are the weights of sand in oven dry, air dry, saturated but
surface dry and moist conditions respectively, then the moisture content of sand is
a) W3 - W,
b) W4-W2
c) W4-W3
d) W3-W2

174. The ordinate of grading curve of an aggregate represents
a) cumulative percentage passing each sieve plotted on normal scale
b) cumulative percentage passing each sieve plotted on logarithmic scale
c) sieve size plotted on normal scale
d) sieve size plotted on logarithmic scale


175. Increase in fineness modulus of aggregate indicates
a) finer grading
b) coarser grading
c) gap grading
d) none of the above


176. Weight of an oven dry sand and air dry sand are 500 gm and 520 gm respectively.
If the weight of the same sand under saturated but surface dry condition is 525 gms, then the water absorption of sand is
a) 1%
b) 4%
c) 4.76%
d) 5%


177. Soundness test of cement by Le-Chatelier's apparatus gives unsoundness due to
a) free lime only
b) magnesia only
c) both free lime and magnesia
d) none of the above


178. Maximum permissible limit of magnesia content in ordinary Portland cement is
a) 4%
b) 6%
c) 8%
d) 10%

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