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

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• 作者：Ippei Maruyama^a ; ^{ippei@dali.nuac.nagoya-u.ac.jp} ; Naoki Sakamoto^b ; ^{sakamoto.ng@om.asahi-kasei.co.jp} ; Kunio Matsui^c ; ^{matsui.kj@om.asahi-kasei.co.jp} ; Go Igarashi^d ; ^{go.igarashi@archi.tohoku.ac.jp}
• 关键词：Drying (A) ; Calcium&ndash ; silicate&ndash ; hydrate (C&ndash ; S&ndash ; H) (B) ; Small-angle X-ray scattering (B) ; Microstructure (B) ; Adsorption (C)
• 刊名：Cement and Concrete Research
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：91
• 期：Complete
• 页码：24-32
• 全文大小：1163 K
• 卷排序：91

文摘

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.