Shape assessment of particles in concrete technology: 2D image analysis and 3D stereological extrapolation

A survey is given of stereology-based two-dimensional (2D) and three-dimensional (3D) approaches to shape assessment of embedded or non-embedded particles. Firstly, the development is outlined of global parameters characterizing geometric structure of cementitious materials. Secondly, these parameters are combined to yield effective shape estimators to be applied to section images of embedded particles or to projection images of non-embedded particles. This application can be just 2D, denoted as quantitative image analysis, giving information on what is displayed of the particle(s) in the section or projection image plane only. However, the researcher should strive for geometrical–statistical (stereological) extrapolation of the 2D observations to the real world’s third dimension. This is demonstrated superior over the 2D approach, however, requires a careful sampling strategy for providing representative information on structure.