Basic study on relation between flatness of end of high strength concrete specimen and compressive strength

In this research, the relation between the flatness of the end of the high strength concrete specimen and its compressive strength was examined The results of the examination are shown as follows. (1) The flatness of the end of the specimen can be evaluated by measuring 17 points with a device shown in JIS A 5308. (2) Flatness of the end of the specimen will change with the time passing. Therefore, specimens should be ground just before the strength test. (3) Every flatness of the end of the grounded specimen was within the limits regulated in JIS A 1132. (4) In this experiment, compressive strength decreased as the roughness of the end of the specimen increased. (5) In this experiment, the influence of the flatness on the strength reduction rate increased with the rise of the compressive strength level.