SSC-JUNIOR ENGINEER (Civil & Structural) Online Exam 2020 (Exam held on 23/03/2021) (Part-IV)

GENERAL ENGINEERING CIVIL AND  STRUCTURAL

Total Questions: 50

41. An old building has a future life of 15 years. The rate of interest on capital is 7%. If the coefficient of annual sinking fund is 0.43, then what will be value of year's purchase?

Correct Answer: A. 2
Solution:

42. The determination of shear strength of a soft saturated clay deposit in the field can be done by:

Correct Answer: B. the vane shear test
Solution:Vane shear test is used to determine the undrained shear strength of soils especially soft clays. This test can be done in laboratory or in the field directly on the ground. Vane shear test gives accurate results for soils of low shear strength (less than 0.3 kg/cm²).

The Vane shear test:

Used to determine undrained shear strength of soft clays.

The test can be conducted in the field/laboratory.

when both ends partake in shearing.

when only bottom end partake in shearing.

c = undrained cohesion
D = overall diameter of vane
H = Height of vane, as per IS recommendation,
H = 2d.

The sensitivity of soil can be conveniently determined by this test.
This test is not suitable when clay contains sand or silt laminations or fissured clay.

43. As per IS 456:2000, the minimum grade of concrete to be used for plain concrete and reinforced concrete, respectively, in concrete works exposed directly along the sea coast are:

Correct Answer: A. M20 and M30
Solution:Concrete in sea-water or exposed directly along the sea-coast shall be at least M20 Grade in the case of plain concrete and M30 in case of reinforced concrete. The use of slag or pozzolana cement is advantageous under such conditions
ExposureMinimum grade of Plain ConcreteMinimum grade of Reinforced Concrete
Mild–M20
ModerateM15M25
SevereM20M30
Very severeM20M35
ExtremeM25M40

44. Which of the following compounds of cement is responsible for early strength?

Correct Answer: A. C₃S
Solution:Properties of cement compounds:

These compounds contribute to the properties of cement in different ways-

  • Tricalcium silicate, C₃S: This compound hydrates and hardens rapidly. It is largely responsible for Portland cement's initial set and early strength gain.
  • Dicalcium silicate, C₂S: C₂S hydrates and hardens slowly. It is largely responsible for strength gain after one week.
  • Tricalcium aluminate, C₃A: It liberates a lot of heat during the early stages of hydration, but has little strength contribution. Gypsum slows down the hydration rate of C₃A Cement low in C₃A is sulphate resistant.
  •  Tetracalcium alumino Ferrite, C₄AF: This is a fluxing agent which reduces the melting temperature of the raw materials in the kiln (from 1650°C to 1450°C). It hydrates rapidly but does not contribute much to the strength of the cement paste. By mixing these compounds appropriately, manufacturers can produce different types of cement to suit several construction environments.

45. Sewers must be checked for minimum velocities at their minimum hourly flows which is equal to:

Correct Answer: B. 1/3 average daily flows
Solution:Variations in Sewage Flow:
  • For moderate areas, such involved for branch sewers, the following maximum flow may be assumed

Maximum daily flow

= 2 × Average daily flow.

Maximum hourly flow
= 1.5 × Maximum daily flow
= 3 × Average daily flow

  •  Sewers are designed for carrying the maximum hourly flow running ¾ full.

Minimum daily flow
= ⅔ × Average daily flow

Minimum hourly flow
= ½ × Minimum daily flow
= ⅓ × Average daily flow

  • Sewers must be checked for minimum velocities at their minimum hourly flow.

46. An airport runway fill needs 8,50,000 m³ of soil compacted to void ratio of 0.7. The required soil is to be taken from a borrow pit having an in situ void ratio of 0.8. If the transportation cost is ₹10 per m³ estimated cost for the filling work is (in):

Correct Answer: D. 90,00,000
Solution:Here, volume of solid will remain constant From formula, volume of solid

47. The annual or periodical payment for repayment of the capital amount invested on a property for a specified period is known as:

Correct Answer: B. annuity
Solution:An annuity is a series of payments made at equal intervals. Examples of annuities are regular deposits to a savings account, monthly home mortgage payments, monthly insurance payments and pension payments. Annuities can be classified by the frequency of payment dates. The payments (deposits) may be made weekly, monthly, quarterly, yearly or at any other regular interval of time. Annuities may be calculated by mathematical functions known as "annuity functions".

48. Which of the following methods is NOT used for the calculation of depreciation of a structure?

Correct Answer: C. Geometric projection method
Solution:Depreciation is the gradual exhaustion of the usefulness of a property. This may be defined as the decrease or loss in the value of a property due to structural deterioration, life wear and tear, decay and obsolescence.

Four methods for calculating depreciation

1. Straight line method
2. Constant percentage method
3. Sinking fund method
4. Quantity survey method

The formula for finding depreciation using straight line method is given below.

Annual depreciation (D)

= (Original cost – Scrap value)/(Life in year)
= (C – S)/n

where,

  • C = original cost
  • S = scrap value
  • n = life of property in years
  • D = annual depreciation
    and

The formula of finding annual depreciation using constant percentage method is given below.

Annual depreciation (D) = 1 – (S/C)¹⁄ⁿ

Where,

  • C = original cost
  • S = scrap value
  • n = life of property in years
  • D = annual depreciation

49. Kor watering in irrigation is defined as:

Correct Answer: A. the first watering which is given to a crop when the crop is a few centimetres high
Solution:Kor watering: The first watering which is given to a crop, when the crop is a few centi-meters high, is called kor watering. It is usually the maximum single watering followed by other waterings at usual intervals, as required by drying of leaves.

The kor period for a Rabi crop = 4 weeks
The kor period for a Kharif crop = 2-3 weeks

50. Pigment volume concentration (PVC) of paint is defined as:

Correct Answer: B.
Solution:PVC (Pigment Volume Concentration): The ratio of the volume of pigment to the volume of total non-volatile material present in a coating. The figure is usually expressed as a percentage.

The non-volatile material, the material in the dried film, is represented by pigment and binder. Solvents and other materials not present in the dried film must not be included in the denominator.

PVC = volume of pigment / volume of total solids