(Sandstrom, 1995). The method is suited for calculating size distribution of aggregates in concrete or mortar. The analysis is performed on thin sections or face ground specimens. The calculation of the three-dimensional distribution is based on the probability distribution for the two-dimensional intersection. Correction is made for edge effects since broad distributions are studied (0.03 up to about 30 mm for concrete). The edge effect here means that the probability of large objects being on the edge of the image frame is greater than for small objects.