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 economically 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 bending 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