UPSC ESE PrelimsExam Question Paper Detailed Solutions

UPSC ESE PrelimsExam Question Paper Detailed Solutions

ESE 2020 civil engineering paper WITH DETAILED SOLUTIONS

1. When the deposit of efflorescence is more than 10% but less than 50% of the exposed area of the brick, the presence of efflorescence is ?
(a) Moderate 
(b) Slight
(c) Heavy 
(d) Serious



Ans. (a) (Moderate )


NIL negligible
SLIGHT  ≤ 10%
MODERATE   10 – 50%
HEAVY/HIGH   > 50%
SERIOUS   > 50% and accompanied by powdering or flacking of exposed surface.


2. Mohs scale is used for stones to determine ?
(a) Flakiness index 
(b) Durability
(c) Strength 
(d) Hardness




Ans. (d) (Hardness)


3. Which of the following conditions are recommended for using sulphate resisting cement?
1. Concrete to be used in foundation and basement, where soil is not infested with sulphates.
2. Concrete used for fabrication of pipes which are likely to be buried in marshy region or sulphate bearing soils.
3. Concrete to be used in the construction of sewage treatment works.
(a) 2 and 3 only 
(b) 1 and 2 only
(c) 1 and 3 only 
(d) 1, 2 and 3




Ans. (a) (2 and 3 only )


4. Which one of the following cements is a deliquescent?
(a) Quick setting Portland cement 
(b) White and Coloured cement
(c) Calcium Chloride cement 
(d) Water Repellent cement






Ans. (c) (Calcium Chloride cement )



5. Consider the following data for concrete with mild exposure
Water-cement ratio = 0.50 Water = 191.6 litre
The required cement content will be
(a) 561 kg/m3 
(b) 472 kg/m3
(c) 383 kg/m3 
(d) 294 kg/m3






Ans. (c) (383 kg/m3 )

W/C (By mass) = 0.5
C =W/0.5

Volume of water = 191.6 litre = 0.1916 m3
Mass of water = 0.1916 × 103 = 191.6 kg

C =191.6/0.5

= 383.2 kg

UPSC ESE PrelimsExam Question Paper Answer Key And Detailed Solutions

6. The strength of a fully matured concrete sample is 500 kg/cm2. When cured at an average temperature of 20°C in day, 10°C in night, datum temperature T0 is –11°C. If Plowman

constants A is 32 and B is 54, the strength of identical concrete at 7 days will be nearly

(a) 333 kg/cm2 

(b) 312 kg/cm2

(c) 272 kg/cm2 

(d) 243 kg/cm2

Ans. (a)  (333 kg/cm2 )

solutions-

M = (20 – (–11)) × 12 × 7 + (10 – (–11)) × 12 × 7

= 2604 + 1764

= 4368°C –  Hrs

Strength, 

f = a + b log10 (M × 10^–3)

= 32 + 54 log10 (4368 ×  10^–3)

= 66.57%

Strength of concrete at 7 days = 0.6657 × 500

= 332.85 kg/cm^2

= 333 kg/cm^2

7. A sample of concrete is prepared by using 500 g of cement with water cement ratio of 0.55 and 240 N/mm2 intrinsic strength of gel. The theoretical strength of concrete on full hydration will be nearly ?

(a) 148 N/mm2 

(b) 126 N/mm2

(c) 104 N/mm2 

(d) 82 N/mm2

Ans. (c) (104 N/mm2 )

Weight of cement = 500 gm

W/C= 0.55

Weight of water = 500 × 0.55 = 275 gm

Volume of water = 275 ml

Gel space ratio =(0.657C /0.319C+W) =

 =

(0.657×500 /0.319× 500+ 275)

 328.5/434.5 = 0.756

Theoretical strength of concrete = 240 (0.756)^3 = 103.71 N/mm2

8. The cement and water slurry coming on the top and setting on the surface is called ?

(a) Crazing 

(b) Efflorescence

(c) Sulphate deterioration 

(d) Laitance

Ans. (d) ( Laitance)

9. Polymer concrete is most suitable for ?

(a) Sewage disposal works

(b) Mass concreting works

(c) Insulating exterior walls of an air-conditioned building

(d) Road repair works

Ans. (d) ( Road repair works)

10. Which one of the following limes will be used for finishing coat in plastering and white washing?

(a) Semi Hydraulic lime 

(b) Kankar lime

(c) Magnesium/Dolomitic lime 

(d) Eminently Hydraulic lime

Ans. (c) (Magnesium/Dolomitic lime)

11. Which one of the following light weight element will be added to enhance the protective properties for X-ray shielding mortars?

(a) Sodium 

(b) Potassium

(c) Lithium 

(d) Calcium

Ans. (c) (Lithium )

12. Which one of the following stone is produced by moulding a mixture of iron slag and Portland cement?

(a) Imperial stone 

(b) Garlic stone

(c) Ransom stone 

(d) Victoria stone

Ans. (b) (Garlic stone)

13. When a round bar material with diameter of 37.5 mm, length of 2.4 m, Young’s modulus of 110 GN/m2 and shear modulus of 42 GN/m2 is stretched for 2.5 mm, its Bulk modulus will be nearly ?

(a) 104 GN/m2 

(b) 96 GN/m2

(c) 84 GN/m2 

(d) 76 GN/m2

Ans. (b) (96 GN/m2)

E = (9KG/3K +G)

3KE + EG = 9KG

9KG – 3KE = EG

K =(EG/9G −3E)

((110×42)/(9×42 − 3×110))

= 96.25 GN/m2

14. A punch of 20 mm diameter is used to punch a hole in 8 mm thick plate. If the force required to create a hole is 110 kN, the average shear stress in the plate will be nearly ?

(a) 410 MPa 

(b) 320 MPa

(c) 220 MPa 

(d) 140 MPa

  

Ans. (c) (220 MPa )

Shear stress, τ =P/A = P/πdt

= (110× 10^3)/(π ×20×8)

= 219 MPa 

= 220 MPa (Approx)

15. A reinforced concrete circular section of 50,000 mm2 cross-sectional area carries 6 reinforcing bars whose total area is 500 mm2. If the concrete is not to be stressed more than 3.5 MPa and modular ratio for steel and concrete is 18, the safe load the column can carry will be nearly ?

(a) 225 kN 

(b) 205 kN

(c) 180 kN 

(d) 160 kN

Ans. (b) (205 kN)


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