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.