Question

Consider the following statements:
Entrainment of air in concrete is done so as to
1. increase the workability.
2. increase the strength.
3. increase the resistance to freezing and thawing.
Which of these statements is/are correct?

• A. 1, 2, and 3
• B. 1 only
• C. 1 and 3 only
• D. 3 only

Answer 1

The correct option is C 1 and 3 only

Air-entrainment improves durability, workability and plasticity but it has an adverse effect on the strength of concrete. The decrease in strength is usually proportional to the amount of entrained air. For each percent increase in air content, the compressive strength reduces approximately by 1.4 MPa.