Emmanuel K. Attiogbe

Correction of window size distortion of crack distributions on plane sections

The scanning electron microscope (SEM) has been used to measure crack distributions on the surfaces of cement paste and mortar. However, true distributions of cracks (or straws, needles, etc.) on a plane section may not be obtained directly if only a portion of the plane section is visible within the field of view (window), as is the case with an SEM. The procedures used to estimate the true distributions are presented. These procedures are based on the concepts of geometrical probability and statistics. Relationships are established between the observed and the true distributions, and iterative techniques are employed to estimate the true distributions. For a given window height, a guideline is provided to determine if the window size distortion needs to be corrected. It is shown that the total length of cracks per unit area on a plane section is not affected by the window size.