Using Fractal Geometry to Recover the 3D Air Void, Scale-Independent, Microstructure Information From 2D Sections of Mortars
Résumé
Advances in digital image analysis have allowed for rapid and detailed investigations of the microstructural topography of cementitious materials, and recent theoretical and analytical work have allowed for recovery of 3D information from 2D analyses. However, measurements of parameters such as the entrained air void size distribution and number density obtained from digital images of concrete are sensitive to the resolution of the image. To address this, an analytical model for recovering 3D information from 2D sections was applied to images of air-entrained mortar at different resolutions, and the results were interpreted in terms of fractal geometry. It is shown that there exists a “cutoff” resolution for scale independence, which is crucial for viewing stereological measurements in an absolute sense rather than relative to the resolution of the instrument used to acquire them. For the analysis of entrained air void structure, this cutoff resolution is around 3200 DPI; for such analyses, it is recommended that images be acquired at this resolution. Furthermore, the same analytical model was validated against full 3D X-ray microtomographic images.