SSC-JUNIOR ENGINEER (Civil & Structural) Online Exam 2016 (Part-II)

Total Questions: 50

21. The test most suitable for concrete of very low workability is _______.

Correct Answer: C. Vee-Bee test
Solution:Vee-Bee test is a good laboratory test suitable for stiff concrete mixes having low and very low workability. It consists of a vibrating table, a metal pot, a sheet of metal cone and a standard iron rod.

In this test, Slump test is performed by placing the slump cone inside the sheet metal cylindrical pot. Then the vibration is started and the time on a stop watch is noted. The time taken by the concrete to take cylindrical shape after the conical shape disappears is noted. This time recorded is known as Vee. Bee Degree or Vee-Bee seconds.

22. The design shear stress in reinforced cement concrete depends on:

(a) Characteristic strength of concrete

(b) Percentage of longitudinal tensile reinforcement

(c) Characteristic strength of steel

Correct Answer: D. Both (a) and (b)
Solution:Recent laboratory experiments confirmed that reinforced concrete in beams has shear strength even without any shear reinforcement. This shear strength (τc) depends on the grade of concrete and the percentage of tension steel in beams. On the other hand, the shear strength of reinforced concrete with the reinforcement is restricted to some maximum value тстах depending on the grade of concrete.

23. The strength and quality of concrete depends on:

Correct Answer: D. All options are correct
Solution:All above options are required but there are many other factories affect the concrete strength and quality because aggregate is only one component of the concrete which also contains cement, water and additive, also there are many other factories may affect like the patch plant type.

24. In the conventional pre-stressing, the diagonal tension in concrete __________.

Correct Answer: B. decreases
Solution:The prestressing of concrete has several advantages as compared to traditional reinforced concrete without prestressing. A fully prestressed concrete member is usually subjected to compression during service life. This rectifies several deficiencies of concrete. Serviceability and Strength

1. Reduced occurrence of cracks.

2. Freezing and thawing durability is higher than non prestressed concrete.

3. Section remains uncracked under service loads.

4. Reduction of steel corrosion.

5. Increase in durability.

6. Full section is utilized.

7. Higher moment of inertia (higher stiffness)

8. Less deformations (improved serviceability),

9. Increase in shear capacity.

10. Diagonal tension in concrete decreases.

25. The approximate allowable stress in axial compression in reinforced concrete is _______.

Correct Answer: A. 0.25 f꜀ₖ
Solution:No explanation given in the book

26. The tensile strength of concrete to be used in the design of reinforced concrete members is ________.

Correct Answer: C. 0.7 √f꜀ₖ
Solution:No explanation given in the book

27. The minimum quantity of cement content that is needed in 1 m³ of a reinforced concrete which is not directly exposed to weather is about (in kg) _________.

Correct Answer: B. 250
Solution:Minimum cement contents, maximum water-cement ratio and minimum grade of concrete for different exposures with normal weight aggregates of 20 mm nominal maximum size

28. The allowable tensile stress in high yield strength deformed steel stirrups used in reinforced cement concrete is (in N/mm²) __________.

Correct Answer: A. 140
Solution:Permissible stresses in steel reinforcement.
Type of stress in steel reinforcementMild steel bars, Fe 250 (N/mm²)High yield strength deformed bars, Fe 415 (N/mm²)
Tension (σₛ or σₛt)
(a) Up to and including 20 mm diameter140230
(b) Over 20 mm diameter130230
Compression in column bars (σₛc)130190

29. M 10 grade of concrete approximates _________ mix.

Correct Answer: A. 1 : 3 : 6
Solution:Recommended Mixes of Concrete

The concrete as per IS 456 : 2000, the grades of concrete lower than M20 are not to be used in RCC work.

30. The process of proper and accurate measurement of concrete ingredients for uniformity of proportion is known as ________.

Correct Answer: A. batching
Solution:A proper and accurate measurement of all the materials used in the production of concrete is essential to ensure uniformity of proportions and aggregate grading in successive batches. All the materials should be measured to the tolerance indicated in Table.

Table: Batching tolerances

MaterialAccuracy of Measurement
Aggregates, cement and water± 3 per cent of batch quantity
Admixtures± 5 per cent of batch quantity