Building Material (GENERAL ENGINEERING) (SSC JE)

Total Questions: 50

41. The minimum compressive strength for rapid hardening Portland cement after 72 hours should be

Correct Answer: (b) 28 N/mm²

42. The average life of Class I timber is [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (c) 120 months
Solution:Classification of timber on the basis of average life.

1. Class I → > 120 months

2. Class II → > (60-120) months

3. Class III → > < 60 months

43. A good stone should have water absorption less than [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (b) 0.6
Solution:A good stone should have water absorption less than 0.6% for road construction and 5% for building construction.

• If water absorption is more than 10% then stone is not used for construction work in buildings.

44. The minimum crushing strength of brick should be [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (a) 35 kg/cm²
Solution:The required minimum compressive strength of building bricks as recommended by IS 1077-1957 and 1970 is–

Class vs Average Compressive Strength

Class (not)Average Compressive Strength (not less than) (N/mm²)
3535.0
3030.0
2525.0
2020.0
17.517.5
1515.0
12.512.5
1010.0
7.57.5
55.0
3.53.5

45. The ingredient which imparts hardness and colour to cement is [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (c) magnesia
Solution:Magnesia–It imports hardness and colour to cement.

Alkali–Impurities imparts efflorescence if present in excess.

Alumina–Responsible for setting of cement.

Sulphur–Makes cement unsound and soundness due to excess of sulphur cannot be determined.

46. Which one of the following is responsible for red colour of brick? [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (a) Iron oxide
Solution:Iron oxide → Responsible for red colour

Magnesia → Excess of magnesia imparts yellowish tint

Silica → Imparts strength and hardness

Alumina → Imparts plasticity

47. Enamel paint is prepared by adding [BPSC AE (GEN. ENGG.) 16.09.2018 ]

Correct Answer: (a) white lead or zinc
Solution:Enamel paints–These paints are obtained by adding white lead or zinc white as a base material to a vehicle. These paints have better chemical resistance, water proofing and great appearance.

48. Pigments are added to [BPSC AE (GEN. ENGG.) 16.09.2018 ]

Correct Answer: (a) give colour to paint
Solution:Pigments are used to provide colour to the points for better appearance. Ex.–

1. Iron oxides

2. Chromium dioxide

3. Ultramarines

4. Manganese violet

5. Iron blue 6. Titanium dioxide

49. The base material of distemper is [BPSC AE (GEN. ENGG.) 16.09.2018 ]

Correct Answer: (c) chalk
Solution: Distemper–It is made with base as white chalk and thinner as water. They are available in powder and paste forms and are substantially cheaper than paints. They are most suitable for plastered surface as well as white washed surface of interior walls.

50. Plywood is identified by [BPSC AE (GEN. ENGG.) 16.09.2018]

Correct Answer: (a) thickness
Solution:Plywood–A wood panel glued under pressure from an odd number (usually 3 to 13) of layers/piles of veneers is known as plywood. The outer most veneers sheet in a plywood panel are called faces. Plywood may be classified upon direction of grains in the plies and on the type of adhesive used

Normally, the alternate plies are oriented at 30º or 60º in star plywood. The faces are arranged with the grain at 45º to that of the centers in diagonal plywood. It is identified by its thickness.