SSC-Junior Engineer (Civil & Structural) Online Exam 2018 (Part-IV)

Total Questions: 50

41. The process of maintaining the moisture and temperature conditions of concrete so that concrete develops hardened properties over time is called __________.

Correct Answer: B. curing
Solution:Curing is the maintenance of a satisfactory moisture content and temperature in concrete for a period of time immediately following placing and finishing so that the desired properties may develop.

The need for adequate curing of concrete cannot be overemphasized. Curing has a strong influence on the properties of hardened concrete; and proper curing will increase durability, strength, watertightness, abrasion resistance, volume stability, and resistance to freezing and thawing and deicers.

Exposed slab surfaces are especially sensitive to curing, as strength development and freeze-thaw resistance of the top surface of a slab can be reduced significantly when curing is defective.

42. A cantilever beam of span 'l' subjected to concentrated load 'W' at a distance 'a' from fixed end, the deflection under the point load is:

Correct Answer: C. Wa³/3EI
Solution:No explanation given in the book

43. Cast iron is manufactured by re-melting ________ with coke and limestone.

Correct Answer: C. pig iron
Solution:Cast Iron: The cast iron is obtained by remelting pig iron with coke and limestone in a furnace known as cupola. It is primarily an alloy of iron and carbon. The carbon contents in cast iron varies from 1.7 per cent to 4.5 per cent. It also contains small amounts of silicon, manganese, phosphorous and sulphur. The carbon in a cast iron is present in either of the following two forms:

1. Free carbon or graphite
2. Combined carbon or cementile.

44. Free settling of particles in the sedimentation process is also called:

Correct Answer: B. discrete settling
Solution:Types of Sedimentations:
  • Discrete Settling: It is also known as a free settling. This corresponds to the sedimen-tation of discrete particles in a suspension of low solids concentration. The particles have little tendency to flocculate or coalesce upon contact with each other.
  • Hindered Settling: This type of settling refers to rather dilute suspension of particles that coalesce or flocculate during sedimentation process. Due to flocculation, particles increase in mass and settle at a faster rate.
  • Zone Settling: This type of settling refers to flocculent suspension of intermediate concerntration. Interparticles force hold the particles together and hence the mass of the particles subside as whole.
  • Compression Settling: This refers to flocculent suspension of so high concentration that particles actually come in contact with each other, resulting in the formation of structure.

45. The spacing of stirrups in a beam:

Correct Answer: C. decreases near the support
Solution:
  • The spacing of vertical stirrups in a rectangular beam is minimum near the supports.
  • The centre to centre spacing of vertical stirrups in a rectangular beam, is increased towards the centre of the span of the beam.
  • A stirrup consists of 5 to 12 mm diameter mild steel bar bent round the tensile reinforcement.
  • According to IS: 456-1978, the spacing of stirrups shall not exceed a distance equal to the lever arm of the resisting moment.

46. Which type of particle has the least self-cleaning velocity?

Correct Answer: D. Fine clay and silt
Solution:To ensure that deposition of suspended solids does not take place, self-cleansing velocities using Shield's formula is considered in the design of sewers.

where, n = Manning's n
R = Hydraulic Mean Radius in m
Kₛ = Dimensionless constant with a value of about 0.04 to start motion of granular particles and about 0.8 for adequate self cleansing of sewers
Sₛ = Specific gravity of particle
dₚ = Particle size in mm

The above formula indicates that velocity required to transport material in sewers is mainly dependent on the particle size and specific gravity and slightly dependent on conduit shape and depth of flow.

Fine clay and silt have least self-cleansing velocity.

47. In masonry NO deduction is made for:

Correct Answer: D. opening each upto 1000 sq. cm
Solution:Brick masonry is measured in volume for thickness more than single bricks. For masonry with single bricks it is measured in square metres.
  • No deduction is made for following.
  • Opening each up to 1000 sq. cm (0.1 sq. meter).
  • Ends of beams rafters etc. up to 500 sq. cm or 0.05 sq. m in section.

48. Grade M20 has a nominal mix of:

Correct Answer: A. 1 : 1.5 : 3
Solution:Nominal Concrete Mix Ratios: In the past specifications for concrete prescribed the proportions of cement, fine and coarse aggregates. These mixes of fixed cement-aggregate ratio which ensures adequate strength are termed nominal mixes.

Nominal mixes offer simplicity and under normal circumstances, have a margin of strength above that specified. However, due to the variability of mix ingredients the nominal concrete for a given workability varies widely in strength, Nominal mix ratios for concrete are 1:2:4 for M15, 1:1.5:3 for M20 etc.

49. A property fetches ₹9,000 deducting all outgoings. If the rate of interest is 8% per annum the capitalized value of the property is _______.

Correct Answer: C. ₹ 1,12,500
Solution:Capitalized Value: The amount of money whose interest at the highest prevailing rate of interest will be equal to the net income or net return in per petuity (for specific period).

[Capitalised Value = Net Return × Year's Purchase]
The rent = ₹ 9000
Highest rate of interest = 8%
So, the capitalized value = 9000×1×100/8
[Capitalised value of property = ₹ 112500].

50. Cross slope given to the pavement for safe drainage of water is:

Correct Answer: C. camber
Solution:Cross-slope/camber: Camber is the transverse slope provided to the pavement surface to drain of rain water. It is provided by raising centre with respect to edges.

If no camber is provided,

(a) Water seepage occurs leading to unevenness.
(b) Stripping of bitumen from aggregates.
(c) Does not provide dry and skid resistant condition.
Required camber of a pavement depends on

(i) Type of pavement surface:

  • Flat camber (1.7%-2%) concrete or bituminous concrete
  • Steeper camber for water bound macadam

(ii) Amount of rainfall:

  • Flat camber if less rainfall area
  • Steep camber if more rainfall area.