The minimum compressive strength on 15 cm cubes of M 30 grade concrete at 7 days

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Question
The minimum compressive strength on 15 cm cubes of M 30 grade concrete at 7 days, should be a minimum of
Options
A. 7 N/mm²
B. 10 N/mm²
C. 20 N/mm²
D. 30 N/mm²

Correct Answer

20 N/mm²

Structural Design Specifications problems

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2. If the slenderness ratio of a column is more than 160, the compressive stress obtained by the secant formula is multiplied by a factor in which value of x is
Options
A. 0.9
B. 1.1
C. 1.2
D. 1.5
E. None of these.

4. If the ratio of effective span to overall depth of a simply supported beam is equal or greater than 1 but less than or equal to 2, the lever arm, is
Options
A. 0.2 (l + 2D)
B. 0.3 (l + 3D)
C. 0.2 (l + 3D)
D. 0.3 (l + 2D)

6. If D is the overall thickness of the slab, the diameter of the reinforcing bars should not exceed
Options
A.
B.
C.
D.
E.

7. The minimum pitch i.e., the distance between centres of rivet holes is not less than
Options
A. 1.5 times the hole diameter
B. 2.0 times the hole diameter
C. 2.5 times the hole diameter
D. 3.0 times the hole diameter
E. None of these.

9. For heavily reinforced concrete member, the nominal maximum size of the aggregates should be restricted to
Options
A. 5 mm less than the minimum clear distance between the main bars
B. 5 mm less than the minimum cover to the reinforcement
C. smaller of (a) and (b)
D. greater of (a) and (b)

10. The concrete is deemed not to comply with the strength requirements if the strength is less than the greater of
Options
A. characteristic strength minus 1.35 times the standard deviation
B. 0.8 times the characteristic strength
C. the average strength of all the samples is less than the characteristic strength plus times the standard deviation.
D. all the above.

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