X-ray dark-field contrast imaging of water transport during hydration and drying of early-age cement-based materials

The results show that such approach provides higher sensitivity to local water content changes and higher temporal and spatial resolutions as compared to standard X-ray attenuation contrast imaging. In this work, we assessed both qualitatively and quantitatively the roles of key drivers of such water displacements in the evolving microstructure: capillary force gradients created by the spatial heterogeneity in the pore size distribution and by evaporative drying. This was accomplished by correlating the dark-field contrast imaging results with information about the system's pore space features, obtained by attenuation contrast X-ray micro-tomography and respective 3D image analysis. Such correlative analysis provides new evidence of the existence of strong couplings between pore-scale water displacements and the microstructure formation in cement-based materials at early ages.