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CaCl2-Accelerated Hydration of Tricalcium Silicate: A STXM Study Combined with Si-29 MAS NMR

Title
CaCl2-Accelerated Hydration of Tricalcium Silicate: A STXM Study Combined with Si-29 MAS NMR
Author
배성철
Keywords
X-RAY MICROSCOPY; C-S-H; CALCIUM-CHLORIDE; EDGE XANES; CEMENT; SPECTROSCOPY; MECHANISM; PRODUCTS; MODEL; PASTE
Issue Date
2015-11
Publisher
HINDAWI PUBLISHING CORPORATION
Citation
JOURNAL OF NANOMATERIALS, Page. 1-10, Article Number: 215371
Abstract
The effect of calcium chloride (CaCl2) on tricalcium silicate (C3S) hydration was investigated by scanning transmission Xray microscopy (STXM) with Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra and Si-29 MAS NMR. STXM is demonstrated to be a powerful tool for studying the chemical composition of a cement-based hydration system. The CaL3,2-edge NEXAFS spectra obtained by examining C3S hydration in the presence of CaCl2 showed that this accelerator does not change the coordination of calcium in the calcium silicate hydrate (C-S-H), which is the primary hydration product. O K-edge NEXAFS is also very useful in distinguishing the chemical components in hydrated C3S. Based on the CaL3,2-edge spectra and chemical component mapping, we concluded that CaCl2 prefers to coexist with unhydrated C3S instead of C-S-H. In Si K-edge NEXAFS analysis, CaCl2 increases the degree of silicate polymerization of C-S-H in agreement with the Si-29 CP/MAS NMR results, which show that the presence of CaCl2 in hydrated C3S considerably accelerates the formation of middle groups (Q(2)) and branch sites (Q(3)) in the silicate chains of C-S-H gel at 1-day hydration.
URI
https://www.hindawi.com/journals/jnm/2015/215371/http://hdl.handle.net/20.500.11754/28807
ISSN
1687-4110; 1687-4129
DOI
10.1155/2015/215371
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > ARCHITECTURAL ENGINEERING(건축공학부) > Articles
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