Abstract
In order to clarify the extensibility of fresh concrete with fly ash of type IV that substitute for sea sand, visual inspection and ultrasonic method of nondestructive testing are performed to evaluate width and depth of settlement cracks of normal concrete and concrete with fly ash of type IV. As results of this experimental study, it is observed that the average of settlement crack width of concrete with fly ash of type IV become as half as one of normal concrete in same covering. It is confirmed that settlement cracks penetrate relatively closer at the position of reinforcement bar, as covering thickness become thinner regardless of the season placing concrete, the sort of cement and the replacement ratio of fly ash.
