Concrete Technology And Design Of Concrete Structures - Study Mode
[#71] Which of the following R.C. retaining walls is suitable for heights beyond 6 m?
Correct Answer
(C) Counterfort type
[#72] In T-shaped R.C. retaining walls, the main reinforcement in the stem is provided on
Correct Answer
(C) The inner face in one direction
[#73] Which of the following has high tensile strength?
Correct Answer
(B) Cold drawn wires
[#74] Minimum grade of concrete to be used in reinforced concrete as per IS: 456-1978 is
Correct Answer
(B) M20
Explanation
Solution: As per IS: 456-1978 , the minimum grade of concrete required for reinforced concrete (RC) structures is M20 . The M20 grade concrete has a characteristic compressive strength of 20 MPa after 28 days of curing. Lower grades like M15 and M10 are generally used for plain cement concrete (PCC) and are not suitable for reinforced structures. Higher grades such as M25 and above are used for structural members requiring higher strength . Hence, the correct answer is M20 (Option B).
[#75] The purpose of reinforcement in pre-stressed concrete is
Correct Answer
(C) To impart initial compressive stress in concrete