Atomic and nano-scale characterization of a 50-year-old hydrated C{sub 3}S paste

Journal Article · Sun Nov 15 04:00:00 EST 2015 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2015.06.010· OSTI ID:22696528

Geng, Guoqing; Taylor, Rae; Bae, Sungchul ^[1]; Hernández-Cruz, Daniel ^[2]; Kilcoyne, David A. ^[3]; Emwas, Abdul-Hamid ^[4]

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1. Department of Civil and Environmental Engineering, University of California at Berkeley (United States)
2. Facultad de Ingeniería, Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas 29050 (Mexico)
3. Advanced Light Source-Lawrence Berkeley National Laboratory, Berkeley, CA (United States)
4. NMR Core lab, King Abdullah University of Science and Technology, 23955 Thuwal (Saudi Arabia)

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C–S–H fibers are composed of particles that are 1.5–2 nm thick and several tens of nanometers long. {sup 29}Si NMR shows 47.9% Q{sub 1} and 52.1% Q{sub 2}, with a mean SiO{sub 4} tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C{sub 3}S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L{sub 3,2}-edge indicates that Ca{sup 2+} in C–S–H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO{sub 4}{sup 4−} tetrahedron chain.

• OSTI ID: 22696528
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 77; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
ABSORPTION SPECTROSCOPY
FINE STRUCTURE
HYDRATION
NUCLEAR MAGNETIC RESONANCE
POLYMERIZATION
SILICATES
SILICON 29
SILICON OXIDES
X RADIATION
X-RAY SPECTROSCOPY