Nanostructure of hardened cement compacts cured under sealed and saturated curing conditions

Hydrated cement compacts were repeatedly prepared via capillary absorption. The chemical shrinkage was measured to characterize the hydration degree of the cement in the compacts. The fractal dimension was detected to distinguish the packing behavior of the nanoparticles of C-S-H gel by small-angel X-ray scattering (SAXS) technique. The fractal structure of hardened cement compacts cured under different conditions was investigated. The results show that the hydrated compacts cured under the saturated condition have the same hydration degree as that under the sealed condition at the age of 10 d. The fractal dimension of nanoparticles of C-S-H gel in the saturated compacts is less than that in the sealed compacts at 10 d. The dense packing of nanoparticles of C-S-H gel due to the auto-desiccation in the nanostructure of sealed compacts was found by synchrotron SAXS. This technique could provide some information for the research on the micro-mechanisms of autogenous shrinkage in cement based materials.