Early age microstructure of hydrating cement with ultra-low water to cement ratio investigated by synchrotron SAXS

Synchrotron small angle X-ray scattering (SAXS) was applied for non-destructive measure of fractal structure of hydrating cement. Early age microstructure of the cement with ultra low water to cement ratio was investigated. Fractal structure of the hydration products indicates that nano C-S-H particles are packed randomly. Double fractal results from two types of structural self-similarity locating in the inner and outer hydration products respectively. Packing of the high density C-S-H within the inner hydration productions is dense, and packing density degrease with hydration, while packing of the low density C-S-H within the outer hydration productions is looser, and packing density also degrease with hydration. The densest packing of a layer of nano C-S-H particles is produced at the induction period of cement hydration. At acceleration period, packing density of the layer degreases with hydration of cement. However, evolution of packing density of the layer becomes flat after acceleration period of cement hydration.