The Application of Bounded Normal Distribution in Statistics of Concrete Strength
23,037 values of concrete compressive strength from construction sites were obtained from Beijing Building Construction Research Institute from 2009-2012 by standard cubes testing method. The mean values, standard deviations, coefficients of variations, maxima and minima were derived from the original strength values analyzed and compared with the data in 1989. The results make up for the lack in C25/C30 and the maxima/minima of every strength class of concrete of the former data. Both the coefficients of variations and mean values have increased in recent years. The log-normal distribution commonly used in concrete compressive strength statistics is not that suitable for strength modeling for it is unbounded. So a bounded normal distribution was given in this paper. By Geary's test, the goodness-of-fit of bounded normal distribution is better than log-normal distribution has been proved.