The shrink-swell behavior of active clays in response to changes in physico-chemical conditions creates challenges for management of agricultural and natural resources as well as for construction of geotechnical barriers for hazardous waste isolation. Initiation and evolution of desiccation cracks in active clays are strongly dependent on the physico-chemical boundary conditions. To investigate effects of bentonite content and mineralogy, solution chemistry, drying rate and soil additives such as polyacrylamide on cracking behavior, we conducted well-controlled dehydration experiments and applied X-ray Computed Tomography (CT) to visualize and quantify topological and geometrical features of evolving crack networks. Mathematical Morphology operations were applied to analyze 3-D reconstructed X-ray CT images. The analyzed crack network parameters include crack porosity, specific surface area, aperture distribution, tortuosity, crack depth, and connectivity.