Building Material (GENERAL ENGINEERING) (SSC JE)

Total Questions: 50

31. Which one of the following does not belong to endogenous trees? [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (a) Teak
Solution:Types of trees based on growth–

(i) Exogeneous trees

Example–Chir, deodar, pine, spruce, babul, mahagony, teak, sal, oak etc.

(ii) Endogenous trees

• These are the types of trees which grows in bulk in inward direction and fibrous mass can be seen across their longitudinal section.

•  Wood obtained from these tree have limited engineering application.

Example–Bamboo, cane, palm, coconut etc.

32. Alumina in brick earth gives the brick's [BPSC AE (GEN. ENGG.) 15.09.2018 ]

Correct Answer: (c) plasticity
Solution:Ingredients of good brick earth–
IngredientsQuantity
Silica50–60%
Alumina20–30%
Lime2 to 5%
Iron oxides5 to 6% (not > 7%)
Magnesia< 1%

Alumina-

• It absorbs water and imparts plasticity to the bricks earth, have helps in its moulding.

• If it is in excess it produces cracks on drying.

• Clays have excess of alumina are likely to be very refractory.

33. Pallet board is used [BPSC AE (GEN. ENGG.) 15.09.2018 ]

Correct Answer: (c) for table moulding of brick
Solution:Table moulding– The bricks are moulded on stock boards nailed on the moulding table. Stock boards have the projection for forming the frog. The process of filling clay in the mould is the same as explained above. After this a thin board called pallet is placed over the mould. The mould containing the brick is then smartly lifted off the stock board and inverted so that the moulded clay along with the mould rests on the pallet.

34. When fat lime is slaked, its volume [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (c) increases by 2 to 2.5 times
Solution:Fat lime or pure limes–

• Fat lime is pure lime that is made by burning a pure limestone rock like chalk, shell or coral.

• It contains approximate 90% to 95% of calcium oxides.

• Fat lime absorbs carbon dioxide when itis exposed in air and gets transferred into calcium carbonate.

• Fat lime has the following properties–

(i) Fat lime hardens very slowly.

(ii) Fat lime has very high degree of plasticity.

(iii) Fat lime slakes vigorously

(iv) Colour of fat lime is pure white

(v) Fat lime sets very slowly if exposed to air.

• Fat lime slakes rapidly when water is added giving out considerable heat and making hissing and cracking noise and increase 2 to 3 times its original volume.

• Used in white washing and plastering of wall.

35. The process of adding water to quicklime in order to convert it into hydrated lime is known as [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (d) slaking
Solution:The process of adding water to quicklime in order to convert it into hydrated lime is known as slaking.

36. Rotary kiln used in manufacturing cement rotates at a speed of [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (a) 1 r.p.m. – 3 r.p.m.
Solution:• A rotary kiln is a pyro-processing device used to raised materials to a high temperature (calcinations) in a continuous process.

• The rotary kiln rotates at the speed of 1-5 rpm as per the requirement of the process.

37. Match List-I with List-II and select the correct answer using the codes given below the Lists : [BPSC AE (GEN. ENGG.) 15.09.2018]

List-I (Parts of exogenous tree)List-II (Character)
a. Cambium layer1. Youngest
b. Pith2. Innermost part
c. Heart wood3. Thin layer of fresh sap
d. Sap wood4. Portion surrounding pith

Codes:

abcd
1234
3241
4132
1324
Correct Answer: (b)
Solution:
PartDescription
Cambium layerThin layer of fresh sap
PithInnermost part
HeartwoodPortion surrounding pith
SapwoodYoungest wood in tree

38. By calcining and smelting iron ores, a crude and impure form of iron obtained is known as [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (d) pig iron
Solution: Pig iron–

• The iron ore in dressed by crushing it to about 50 mm cubes. The impurities are knocked off and the ore is then calcined to drive off moisture. The calcined are is smelted in blast furnace. •

Pig iron contains 3-4% carbon, 0.5-3.5% silicon, 0.5- 2% manganese.

39. The compressive strength of high duty bricks should be more than [BPSC AE (GEN. ENGG.) 15.09.2018]

Correct Answer: (a) 40 N/mm²
Solution:Heavy duty bricks (IS:2180)–

• The burnt clay bricks having a compressive strength of more than 40 N/mm2 are known as heavy duty bricks.

• It is used in masonary in heavy engineering works such as bridges, industrial foundations and multistoreyed building.

• The water absorption of these bricks is limited to 5%.

40. According to I.S. specifications, the compressive strength of ordinary Portland cement (33 grade) after three days should not be les than : [MPSC AE PRE -27.03.2021]

Correct Answer: (c) 16 MPa
Solution:As per I.S. 269 : 2015–

• The compressive strength of ordinary portland cement grade-33 after 3 days should not be less than 16 N/mm2 and 7 days compressive strength of OPC grade-33 should not be less than 22 MPa.

• The compressive strength of OPC grade 33 after 28 days should not be less than 33 N/mm².