ANS:C - 7 days

In the case of lime concrete, the curing starts after 24 hours and is done for a minimum of 7 days period. Hence, the masonry works can only be done on the foundation after a minimum of 7 days.

In the case of cement concrete, the curing starts after 3-48 hours to ensure the initial and final setting time of concrete.

The curing is done for a minimum period of 7 days or up to the period at which the strength of concrete becomes 70% of the characterized strength.