Microstructural changes in white Portland cement paste under the first drying process evaluated by WAXS, SAXS, and USAXS

Ippei Maruyama, Naoki Sakamoto, Kunio Matsui, Go Igarashi

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

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 nm− 1–30 nm− 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 nm− 1–8 nm− 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.

Original languageEnglish
Pages (from-to)24-32
Number of pages9
JournalCement and Concrete Research
Volume91
DOIs
Publication statusPublished - 2017 Jan 1

Keywords

  • Adsorption (C)
  • Calcium–silicate–hydrate (C–S–H) (B)
  • Drying (A)
  • Microstructure (B)
  • Small-angle X-ray scattering (B)

ASJC Scopus subject areas

  • Building and Construction
  • Materials Science(all)

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