Building Material (Part-II) (GENERAL ENGINEERING) (SSC JE)

Total Questions: 50

21. Three main chemical constituents of wood are [BPSC AE (GEN. ENGG.) 11.11.2022]

Correct Answer: (c) cellulose 40% - 50%, hemicellulose 20% - 35%, lignin (phenyl group) 15% - 35%
Solution:Wood–Wood is a natural resource and one of the most attractive materials because of its multidimensional assembly and its extensive exhibition on Global.

• Wood is made up of cellulose, hemicellulose and lignin to make their multifaceted structure which is biologically originated.

• The chemically modified or monomer incorporation of three cell wall.

• The main objective of chemical modification or monomer impregnation of wood to revolute its properties and to increase its performance.

• Cellulose content ranges from (40 to 50%) and hemi celluloses range from (25 to 35%) lignin range from (15 to 35)%.

22. The approximate composition of Portland cement is [BPSC AE (GEN. ENGG.) 11.11.2022]

Correct Answer: (b) tricalcium silicate 45%, dicalcium silicate 30%, tricalcium aluminate 10%, tetracalcium aluminoferrite 8% and other bonding agents 7%
Solution:The approximate composition of Portland cement is–

Then it fuses and following four major compounds are formed–

Principal mineralCompoundAvgSymbol function
Tri-calcium silicate (Alite)3CaO·SiO₂ (C₃S)40%7 days strength and hardness, best cementing material
Dicalcium silicate (Belite)2CaO·SiO₂ (C₂S)32%Ultimate strength (1 year strength)
Tricalcium aluminate (Celite)3CaO·Al₂O₃ (C₃A)10%Flash set, initial setting time
Tetracalcium alumina (Felite)4CaO·Al₂O₃Fe₂O₃ (C₄AF)8%Poorest cementing value

23. The fire clay contains pure [BPSC AE (GEN. ENGG.)-2006]

Correct Answer: (c) hydrated aluminium silicate
Solution:Fire clay–The main component of refractory fire clay is hydrated aluminium. Silicates with tiny amounts of other mineral. The geological formation of fire clays depended on rock from the earth's crust being weathered by wind, rain cheat, cold and abrasion.

24. Plywood is obtained from : [RRB JE 27.08.2015 (Shift-II)]

Plywood is made from

Correct Answer: (c) teak wood only
Solution:Plywood is made from teak wood only. Plywood is a construction material made from thin sheets of wood venier glued together. This is consisting of sheets of wood glued together with the grains of adjacent layer arranged at right angle.

25. The most fire resistant paints are [BPSC AE (GEN. ENGG.)-2006 ]

Correct Answer: (c) asbestos paints
Solution:Asbestos paints–Asbestos was very inexpensive and was used as filler in many different products in different industries. The most fire resistant paint are asbestos paints.

Enamel paints–It contain vehicle (binding material) like a styrene, polyvinyl lactate, alkyl resin etc.

Cement paints– The cement paint is water based paint is used to preventing water penetrating redemptions of drift collection prevent fungal and algal growth on interior and exterior walls.

26. Bullet proof glass is made of thick glass sheet sandwiched by a layer of [BPSC AE (GEN. ENGG.)-2006]

Correct Answer: (c) high strength plastic
Solution:Bullet proof glass is made of thick glass sheet sandwiched by a layer of high strength plastic. Bullet proof glass is constructed using layer of plate glass and vinyl resin plastic. The thickness of outer layer is small as compared to inner layer.

27. Laterite is found in [BPSC AE (GEN. ENGG.)-2006]

Correct Answer: (e) Kerala
Solution:Laterite is found in area with high temperature and heavy rainfall. These soils are mainly found in Karnataka, Kerala, Tamil Nadu and hilly areas of Odisha and Assam.

28. Stones used for the construction of retaining walls must be [BPSC AE (GEN. ENGG.)-2006]

Correct Answer: (d) heavy
Solution:Stones used for the construction of retaining walls must be heavy. Retaining wall is used to create a transition from one level of ground to another.

Heavy stone = Retaining wall

Hard stone = Masonary structure

Fire expose = Compressed sand stone

29. The compressive strength of a good Portland cement and standard sand mortar after 3 days of curing should not be less than [BPSC AE (GEN. ENGG.)-29.03.2019]

Correct Answer: (b) 11.5 MN/m²
Solution:Compressive strength test–This test is carried out on standard cubes made of a good "Portland Cement" and standard motor (in 1:3 ratio) to determine the compressive strength of cement. According to Indian standard specifications, the average compressive strength for three cubes should not be less than 11.5 N/mm² and 17.5 N/mm² after 3 and 7 days of curing respectively

30. Eminently hydraulic lime is one in which the percentage of silica, alumina and iron oxide is [BPSC AE (GEN. ENGG.)-29.03.2019]

Correct Answer: (c) 25% – 30%
Solution:Hydraulic lime–It is the lime which has small quantities of silica, alumina and iron oxide, which are in chemical combination with calcium oxide. It can set and become hard even in the absence of carbon dioxide and can set under water.

The hydraulic lime, depending upon the percentage of clayey impurities in the form of silica, alumina and iron oxide, are classified into the following three groups–

(a) Feebly hydraulic lime - 5 to 10%

(b) Moderately hydraulic lime - 10 to 25%

(c) Eminently hydraulic lime - 25 to 30%