RRB JE exam Civil Engineering Building Materials Important MCQs – 5

41. A first class brick when immersed in cold water for 24 hours should not absorb water more than
a) 15%
b) 20%
c) 22%
d) 25%
Correct Option: b

42. Crushing strength of a first class​​ brick should not be less than
a) 3.5 N/mm2
b) 7.0 N/mm2
c) 10.5 N/mm2
d) 14.0 N/mm2
Correct Option: c

43. The main function of alumina in brick earth is
a) to impart plasticity
b) to make the brick durable
c) to prevent shrinkage
d) to make the brick impermeable
Correct Option: a

44. The percentage of alumina in a good brick earth lies between
a) 5 to 10%
b) 20 to 30%
c) 50 to 60%
d) 70 to 80%
Correct Option: b

45. Excess of alumina in brick earth makes the brick
a) impermeable
b) brittle and weak
c) to lose cohesion
d) to crack and warp on drying
Correct Option: d

46. The nominal size of the modular brick is
a) 190 mm x 90mmx 80 mm
b) 190 mm x 190 mm x 90 mm
c) 200 mm x 100 mm x 100 mm
d) 200 mm x 200 mm x 100 mm
Correct Option: c

47. Percentage of silica in a good brick earth lies between
a) 5 to 10%
b) 20 to 30%
c) 50 to 60%
d) 70 to 80%
Correct Option: c

48. Excess of silica in brick earth results in
a) cracking and warping of bricks
b) loss of cohesion
c) enhancing the impermeability of bricks
d) none of​​ the above
Correct Option: b

49. Which of the following ingredients of the brick earth enables the brick to retain its shape ?
a) alumina
b) silica
c) iron
d) magnesia
Correct Option: b

50. Which of the following pairs gives a correct combination of the useful and harmful constituents respectively of a
good brick earth ?
a) lime stone and alumina
b) silica and alkalies
c) alumina and iron
d) alkalies and magnesium
Correct Option: b