Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5437149 | Cement and Concrete Research | 2017 | 9 Pages |
Meso- and micro-scale structural changes in matured hardened cement paste dried slowly for 1.5 years at different relative humidities (RHs) are evaluated by small-angle X-ray scattering profiles covering a q range of 0.017 nmâ 1-30 nmâ 1 with a fractal disc-shaped particle analysis and Guinier approximation. The fractal disc-shaped particle analysis revealed that calcium-silicate-hydrate (C-S-H) agglomerations are very thin (~ 2.5 nm) and of relatively large width (~ 35 nm) under high RH conditions. However, the agglomerations are segmented (in width) into ~ 10 nm below an RH of 40%. The Guinier approximation found the possibility that the scattering profiles in the range of 2 nmâ 1-8 nmâ 1 correspond to a spacing between C-S-H monolayers and it showed stepwise changes at 40%-50% RH. The stepwise behavior of the distance between C-S-H monolayers may explain a kink in water vapor desorption at around 40% RH.