31. Maximum strain in an extreme fibre in concrete and in the tension reinforcement (Fe-415 grade and E_s = 200 kN/mm²) in a balanced section at limit state of flexure are respectively

1. 1. 0.0035 and 0.0038

   
   
   

   2. 0.002 and 0.0018

   
   
   

   3. 0.0035 and 0.0041

   
   
   

   4. 0.002 and 0.0031

   
   
   

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1. View Hint View Answer Discuss in Forum

   Max strain in steel
   

   = 0.002 +	0.87 fy
   	Es

   
   

   = 0.002 +	0.87 × 415	= 0.0038
   	200 × 103

   
   For concrete max strain = 0.0035

   Correct Option: A

   Max strain in steel
   

   = 0.002 +	0.87 fy
   	Es

   
   

   = 0.002 +	0.87 × 415	= 0.0038
   	200 × 103

   
   For concrete max strain = 0.0035

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32. As per provisions of IS 456-2000, in the limit state method for design of beams, the limiting value of the depth of neutral axis in a reinforced concrete beam of effective depth ‘d’ is given as

1. 1. 0.53 d

   
   
   

   2. 0.48 d

   
   
   

   3. 0.46 d

   
   
   

   4. any of the above depending on the different grades of steel.

   
   
   

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1. View Hint View Answer Discuss in Forum

   Limiting value of depth of neutral axis depends on grade of concrete.

   Correct Option: D

   Limiting value of depth of neutral axis depends on grade of concrete.

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33. As per the provisions of IS 456-2000, the (short-term) modulus of elasticity of M 25 grade concrete (in N/mm²) can be assumed to be

1. 1. 25000

   
   
   

   2. 28500

   
   
   

   3. 30000

   
   
   

   4. 36000

   
   
   

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1. View Hint View Answer Discuss in Forum

   E_C = 5000 √25
   = 25000 MPa

   Correct Option: A

   E_C = 5000 √25
   = 25000 MPa

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34. Match the information related to tests on aggregates given in Group-I with that in Group-II
    Group-I
    P. Resistance to impact
    Q. Resistance to wear
    R. Resistance to weathering action
    S. Resistance to crushing
    Group-II
    1. Hardness
    2. Strength
    3. Toughness
    4. Soundness

1. 1. P-1, Q-3, R-4, S-2

   
   
   

   2. P-3, Q-1, R-4, S-2

   
   
   

   3. P-4, Q-1, R-3, S-2

   
   
   

   4. P-3, Q-4, R-2, S-1

   
   
   

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1. View Hint View Answer Discuss in Forum

   Resistance to impact – Toughness
   Resistance to wear – Hardness
   Resistance to weathering action – Soundness
   Resistance to crushing – Strength

   Correct Option: B

   Resistance to impact – Toughness
   Resistance to wear – Hardness
   Resistance to weathering action – Soundness
   Resistance to crushing – Strength

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35. Consider the following statements for air-untrained concrete:
    (i) Air-entertainment reduces the water demand for a given level of work ability
    (ii) Use of air-untrained concrete is required in environments where cyclic freezing and thawing is expected
    Which of the following is TRUE?

1. 1. Both (i) and (ii) are True

   
   
   

   2. Both (i) and (ii) are False

   
   
   

   3. (i) is True and (ii) is False

   
   
   

   4. (i) is False and (ii) is True

   
   
   

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1. View Hint View Answer Discuss in Forum

   Both statements are true

   Correct Option: A

   Both statements are true

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