QUIZ : CIVIL ENGINEERING (19-01-2021)

Quiz: CIVIL ENGINEERING
Exam: NPCIL-SCINTIFIC ASSISTANT(CIVIL)
Topic: MISCELLANEOUS

Each question carries 1 mark
Negative marking: No negative marking
Time: 10 Minutes

Q1. Consider the following oxides

  1. Al_2 O_3
  2. CaO
  3. SiO_2
    The correct sequence in increasing order of their percentage in an ordinary Portland cement is
    (a) 2, 1, 3
    (b) 1, 3, 2
    (c) 3, 1, 2
    (d) 1, 2, 3
    Q2. Consider the following statements:
    High early strength of cement is obtained as a result of
  4. fin grinding
  5. decreasing the lime content
  6. burning at higher temperatures
  7. increasing the quantity a gypsum
    Which of these statements are correct
    (a) 1 and 2
    (b) 1, 2 and 3
    (c) 2, 3 and 4
    (d) 1, 3 and 4
    Q3. The main function of a fish plate is
    (a) to join the two rails together
    (b) to join rails with the sleeper
    (c) to allow rail to expand and contract freely
    (d) None of the above
    Q4. The entrance and exit curves of a rotary have
    (a) equal radii and equal widths of pavement
    (b) equal radii but pavement width is more at entrance than at exit curve
    (c) equal pavement widths but radius is more at entrance curve than at exist curve
    (d) different radii and different width of pavement

Q5. Traffic flow equation for a section of road is u=80–0.7 K where ‘u’ is speed in kmph and ‘k’ is density in vpkm (vehicles per km). The maximum expected flow is
(a) 4572 vph
(b) 2286 vph
(c) 1143 vph
(d) 572 vph
Q6. The compensated gradient provided at the curve of radius 60 m with a ruling gradient of 6 percent is:
(a) 5.25%
(b) 4.75%
(c) 4.5%
(d) 3.75%
Q7. Road alignment is influenced by
(a) traffic requirements
(b) stability of hill slopes
(c) number of cross drainage works
(d) all of the above

Q8. The shape of the camber, best suited for cement concrete pavements, is
(a) Straight line
(b) Paraboilc
(c) Elliptical
(d) Combination of straight and parabolic

Q9. A soil has 28 g of soil solids, 10 cu cm of voids, 9 g of water and specific gravity of soil grains of 2.7 consider the following statements in this regard:

  1. The water content is 9/28×100%
  2. The void ratio is (10 × 2.7)/28
  3. Degree of saturation is 9/(10 ×2.7) × 100
  4. The porosity is (10 × 2.7)/((28+10×2.7))
    Of these statements :
    (a) 1, 2 and 3 are correct
    (b) 2, 3 and 4 are correct
    (c) 1, 3 and 4 are correct
    (d) 1, 2 and 4 are correct

Q10. In a falling head permeability test on a soil, the time taken for the head to fall from h_0 to h_1 is t. The test is repeated with same initial head h_0, the final head h’ is noted in time t/2. Which one of the following equations gives the relations between h’, h_0 and h_1 ?
(a) h’ = h_0/h_1
(b) h’ = √(h_0/h_1 )
(c) h’ = h_0 h_1
(d) h’ = √(h_0 h_1 )

Solutions

S1. Ans.(b)
Sol. Oxide Percentage
Lime 60-65%
Silica 17-25%
Alumina 3-8%
Iron oxide 0.5-6%
Magnesia 0.5-4
Sulphur trioxide 1-2
Alkalies 0.5-1.3

S2. Ans.(b)
Sol. On increasing finness setting time decreases. So early gain of strength with decrease in lime content quick setting takes place.
On increasing gypsum initial setting increases.

S3. Ans.(a)
Sol. The main function of a fish plate is to joint the two rail together.
The holes are drilled through the plates and the web of rail and then the fish bolts and nuts are provided in these holes. When the bolts and nuts are tightened up the rails are joined together and a continuous track is formed.

S4. Ans.(d)
Sol. Vehicle leaving the rotary would accelerate to the speed of the radiation roads hence the exit curves should be of larger radii than entry curve hence the pavement width at entrance curve will be higher than exit curve as the radius of the former is less than the later.

S5. Ans.(b)
Sol. Traffic flow equation
u = 80 – 0.7 k
Flow (q) = u.k
= 80 k – 0.7 k^2
For maximum flow :
d_q/d_k = 0
u = a – b.k
qmax = a^2/4b = (80)^2/(4×0.7) = 2286 Vph

S6. Ans.(b)
Sol. Percent grade compensation = (30 + R)/R
Maximum = 75/R
for R = 60 m
maxi grade compensation = 75/60 = 1.25%
grade compensation = (30+R)/R
= (30 + 60)/60
= 1.5
Compensated gradient = Rulling gradient – grade compensation
= 6 – 1.25
= 4.75%

S7. Ans.(d)
Sol. Factors which governs the alignment of roads are :
(i) Obligatory Points : These points either the road alignment has to pass or not have to pass.
(ii) Traffic : The new road to be aligned should keep in view the desired lines, traffic flow pattern and future trends.
(iii) Geometric Design :
(iv) Economy
(v) Stability of hill drainage and geometric standard of hill road.

S8. Ans.(a)
Sol. The camber is given a Parabolic elliptic or straight line shape in the cross section. Parabolic or elliptic shape is given so that the profile is flat at the middle and sleeper towards the edges, which is preferred by fast moving vehicles.

S9. Ans.(d)
Sol. Water content = W_w/W_s × 100
= 9/28 × 100
Void ratio = V_v/V_s = 10/(28/2.7) = (10 ×2.7)/28
Degree of saturation = V_w/V_v = 9/10 × 100
Porosity = V_v/V = 10/(28/2.7+ 10) = (10 × 2.7)/(28 + 10 × 2.7)
(1), (2) and (4) are correct.

S10. Ans.(d)
Sol. in falling head method
K = 2.3 aL/At log_10⁡(h_0/h_1 )
= 2.3 × aL/A(t/2) log_10⁡(h_0/h’)
= log_10⁡(h_0/h_1 ) = 2 log_10⁡(h_0/h’)
h_0/h_1 = (h_0/h’)^2
▭(h’= √(h_0 h_1 ))

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