Image-based characterization of fracture surface roughness

Analysis of images from SEM, optical and confocal microscopes provides insight into the roughness of fracture surfaces of cement-based materials. Several techniques including 3D surface reconstruction and 2-D vertical contour analysis are compared. Roughness parameters and fractal dimensions are computed to describe the degree of tortuosity of the fracture surface. The tortuosity of the surface (i.e. crack path) is an aspect that has not been adequately integrated into fracture mechanics models of cement-based materials. Topographic maps from confocal microscopy reveal orientation of the crack front throughout the fracture process, allowing analysis of mixed-mode character of nominally mode I fracture. These techniques allow quantification of microstructural parameters to be linked to material properties.