Morphological quantification of hierarchical geomaterials by X-ray nano-CT bridges the gap from nano to micro length scales
Chae, R. S.
Monteiro, P. J. M.
KAUST Grant NumberKUS-11-004021
MetadataShow full item record
AbstractMorphological quantification of the complex structure of hierarchical geomaterials is of great relevance for Earth science and environmental engineering, among others. To date, methods that quantify the 3D morphology on length scales ranging from a few tens of nanometers to several hun-dred nanometers have had limited success. We demonstrate, for the first time, that it is possible to go beyond visualization and to extract quantitative morphological information from X-ray images in the aforementioned length scales. As examples, two different hierarchical geomaterials exhibiting complex porous structures ranging from nanometer to macroscopic scale are studied: a flocculated clay water suspension and two hydrated cement pastes. We show that from a single projection image it is possible to perform a direct computation of the ultra-small angle-scattering spectra. The predictions matched very well the experimental data obtained by the best ultra-small angle-scattering experimental setups as observed for the cement paste. In this context, we demonstrate that the structure of flocculated clay suspension exhibit two well-distinct regimes of aggregation, a dense mass fractal aggregation at short distance and a more open structure at large distance, which can be generated by a 3D reaction limited cluster-cluster aggregation process. For the first time, a high-resolution 3D image of fibrillar cement paste cluster was obtained from limited angle nanotomography.
SponsorsThis publication was based on work supported in part by ANR program M POMODIM, the CNRS-CPR "Porosity, transport, and resistance" program and Award No. KUS-11-004021, made by King Abdullah University of Science and Technology (KAUST). We thank M. Thiery and V. Baroghel-Bouny at IFFSTAR (Paris) for providing the two-year-old cement paste. Small-angle and wide-angle X-ray scattering experiments were carried out on beamline A2 at Hasylab (flocculated clays) and at SOLEIL on beamline SWING (cement paste). This work is dedicated to the memory of Olivier Coussy (1952-2010).