Compressive Strength of Concrete

Q. In limit state design of reinforced concrete, deflection is computed by using

1. initial tangent modulus
2. secant modulus
3. tangent modulus
4. short-and long-term values of Young's modulus

Q. As per $\text{IS 456-2000,}$ which one of the following correctly expresses the modulus of elasticity of concrete? (read with the relevant units)

1. $E_c=0.7\sqrt{f_{ck}}$
2. $E_c=500\sqrt{f_{ck}}$
3. $E_c=5000\sqrt{f_{ck}}$
4. $E_c=5700\sqrt{f_{ck}}$

Q. Consider the following statements:

1. Modulus of Elasticity of concrete increases with increase in compressive strength of concrete.
2. Brittleness of concrete increases with decrease in compressive strength of concrete.
3. Shear strength of concrete increases with increases in compressive strength of concrete.

Which of the above statements are correct?

1. 1 and 2 only
2. 1, 2 and 3
3. 1 and 3 only
4. 2 and 3 only

Q. If ${\sigma }_{cbc}$ is permissible compressive stress in flexural compression in $N/m{m}^2$ in service, the modular ratio is of the order of

1. $\frac{280}{3{\sigma }_{cbc}}$
2. $\frac{280}{4{\sigma }_{cbc}}$
3. $19$
4. $13$

Q. Find the compressive strength below which 50% test results are expected to fall for M20 concrete

1. 20
2. 26.6
3. 13.4
4. 30

Q. Consider the following statements:

1. In reinforced cement concrete, modular ratio is defined by the ratio (modulus of elasticity of steel)/(Modulus of elasticity of concrete).
2. Modulus of rupture of cement concrete is a function of its characteristic compressive strength.
3. The characteristic compressive strength of M 20 grade cement concrete at 7 days is $20N/m{m}^2.$

1. 1, 2 and 3
2. 1 and 2 only
3. 2 and 3 only
4. 1 and 3 only

Q. Consider the following statements:

1. Modulus of elasticity of concrete increases with the increase in compressive strength of concrete.
2. Shear strength of concrete increases with the increase in compressive strength of concrete.

Which of these statements is/are correct?

1. Neither 1 nor 2
2. Both 1 and 2
3. 1 only
4. 2 only