The Role of Al in C-S-H: NMR, XRD, and Compositional Results for Precipitated Samples

X-ray diffraction, compositional analysis, and 29Si and 27Al MAS NMR spectroscopy of Al-substituted tobermorite-type C�S�H made by precipitation from solution provide significant new insight into the structural mechanisms of Al-substitution in this important and complicated phase. Al occurs in 4-, 5-, and 6-coordination (Al[4], Al[5], and Al[6]) and plays multiple structural roles. Al[4] occurs on the bridging tetrahedra of the drierkette Al�silicate chains, and Al[5] and Al[6] occur in the interlayer and perhaps on particle surfaces. Al does not enter either the central Ca�O sheet or the pairing tetrahedra of the tobermorite-type layers. Al[4] occurs on three types of bridging sites, Q3 sites that bridge across the interlayer; Q2 sites that are charge balanced by interlayer Ca+2, Na+, or H+; and Q2 sites that are most likely charge balanced by interlayer or surface Al[5] and Al[6] through Al[4]�O�Al[5,6] linkages. Although the data presented here are for relatively well-crystallized tobermorite-type C�S�H with C/S ratios less than or equal to 1.2, comparable spectral features for hydrated white cement pastes indicate the presence of similar structural environments in the C�S�H of such pastes, and by implication OPC pastes.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00088846
• Supplemental Notes:
  • Abstract reprinted with permission from Elsevier.
• Authors:
  • Sun, G K
  • Young, J Francis
  • Kirkpatrick, R James
• Publication Date: 2006-1

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 18-29
• Serial:
  • Cement and Concrete Research
  • Volume: 36
  • Issue Number: 1
  • Publisher: Elsevier
  • ISSN: 0008-8846
  • Serial URL: http://www.sciencedirect.com/science/journal/00088846

Subject/Index Terms

• TRT Terms: Aluminates; Calcium silicate; Cement paste; Hydration; Nuclear magnetic resonance; Portland cement; Spectroscopy; Tobermorite
• Uncontrolled Terms: Calcium silicate hydrate
• Subject Areas: Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 01019350
• Record Type: Publication
• Files: TRIS
• Created Date: Mar 1 2006 9:04AM