Abstract:Coarse aggregate size distribution is important for the research on concrete strength analysis. Usually it can not be obtained without cutting a part of concrete down. A new method based on conditional probabilistic method is introduced. Application of “estimation of three-dimensional size distribution from two-dimensional section” is presented to direct estimation of three-dimensional size distribution. Analysis for a two-dimensional section using digital images is compared with the test of conventional mechanical sieving. The study demonstrates that this new method is a convenient and accurate technique for particle size distribution analysis.