Abstract
The probability distribution of compressive strength class of any kinds of concrete was definied as normal distribution in quality control even in structure concrete. It is clear that the peak of distribution is higher than the mean value of strength in high strength concrete, nevertheless the mean value is equal to the peak of distribution in ordinary strength class of concrete. In this report, it was clarified that the shape of probability distribution of compressive strength of core specimens in high strength concrete structures was not normal distribution. So, if the probabilistic property of concrete strength is assumed to follow a normal distribution in quality control, it makes the strength lower than the design strength in structure concrete.
