Question

If concrete is exposed to repeated freezing and thawing after the final set, the final qualities of the concrete may also be __________

(a) Impair

(b) Aid

(c) Improve

(d) Extend

I had been asked this question in unit test.

Enquiry is from Factors Affecting PIC, Cold Weather Concreting in section Special Concrete and Concreting Methods of Concrete Technology

Answer 1

Correct answer is (a) Impair

For explanation: If concrete is exposed to repeated freezing and thawing after the final set and during the hardening period, the final qualities of the concrete may also be impaired.