Considerations in image analysis as applied to investigations of the ITZ in concrete

A number of considerations are discussed with regard to the study of the Interfacial transition zone (ITZ) in concrete by image analysis of backscatter SEM images. These include selection and sampling of the concrete, selection of individual aggregates for the ITZ measurements, and design and positioning of individual sampling units around the chosen aggregates. Emphasis is placed on the importance of analyzing the lateral variation in properties around the aggregate as well as variation in mean composition with distance from the aggregate. Statistical considerations that can be applied to the interpretations of the results are illustrated