Studies on Finger Coral Concrete, 3

Following from the previous studies, this paper describes the behavior of Finger Coral concrete. It was clarified that Finger Coral concrete has enough strength for structural use but its low qualities in workability and bleeding behavior make it not to use generally. Low quality in workability can be improved by use of AE agents, but bleeding quantity can not be reduced so much by the use of AE agents. "Ishigū" is a powderly soil of calcium carbonate and is yielded with lime stone in the main islands of Okinawa Prefecture. "Ishigū" is also-called coaral reef rock and much used as base-course materials in building roads. The auther has planned to use "Ishigū" as fine additives instead of a part of fine aggregate, because sea sand used in Okinawa commonly are suffering from shortage of very fine part in composition. "Ishigū" was used as a part of fine aggregate in proportionning concrete materials and following results are attained. 1) Bleeding behavior was much improved by the dosage of "Ishigu". 2) Bleeding quantity and ratio become reduced as increasing the dosage of "Ishigu". 3) "Ishigū" has much larger effect in reducing bleeding quantity or ratio than AE agents. 4) Finger coral concrete contained "Ishigu" has much larger compressive strength than concrete with no "Ishigū". 5) Finger Coral concrete with "Ishigū" also-exhibits higher Young's modulus than concrete with no "Ishigū", but the rate of increase in Young's modulus was not so large as the rate in strength. In this study, a lot of static and dynamic Young's moduli of Finger Coral concrete specimens were measured, and formulae computing the both moduli based on the values of compressive strength and unit weight of concrete are proposed