Multifractal analysis of calcium silicate hydrate (C-S-H) mapped by X-ray diffraction microtomography

An investigation of Calcium Silicate Hydrate (C-S-H) topological distribution and modes of precipitation is performed by combining X-ray powder diffraction tomography, performed on an ordinary Portland cement sample, with a numerical scheme that simulates C-S-H precipitation. C-S-H distribution maps obtained both experimentally and numerically are analyzed by means of a quantitative method based on the principles of multifractal systems. The combination of these methods allows C-S-H spatial distribution and modes of precipitation and aggregation to be assessed quantitatively. In particular, the multifractal spectra obtained from the digital images of the cement paste microstructure, act as a structural probe, which is able to quantify the tendency of C-S-H to form clusters. The results of this combined approach suggest that a multifractal network forms by aggregation of C-S-H clusters heterogeneously nucleated on clinker grains and preexisting clusters that are partly homogeneously nucleated in the porous space.