Material and elastic properties of Al-tobermorite in ancient roman seawater concrete

Marie D. Jackson, Juhyuk Moon, Emanuele Gotti, Rae Taylor, Sejungrosie Chae, Martin Kunz, Abdul-Hamid M. Emwas, Cagla Meral, Peter Guttmann, Pierre E. Levitz, Hans Rudolf Wenk, Paulo José Meleragno Monteiro

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

The material characteristics and elastic properties of aluminum-substituted 11 Å tobermorite in the relict lime clasts of 2000-year-old Roman seawater harbor concrete are described with TG-DSC and 29Si MAS NMR studies, along with nanoscale tomography, X-ray microdiffraction, and high-pressure X-ray diffraction synchrotron radiation applications. The crystals have aluminum substitution for silicon in tetrahedral bridging and branching sites and 11.49(3) Å interlayer (002) spacing. With prolonged heating to 350°C, the crystals exhibit normal behavior. The experimentally measured isothermal bulk modulus at zero pressure, K0, 55 ±5 GPa, is less than ab initio and molecular dynamics models for ideal tobermorite with a double-silicate chain structure. Even so, K0, is substantially higher than calcium-aluminum-silicate-hydrate binder (C-A-S-H) in slag concrete. Based on nanoscale tomographic study, the crystal clusters form a well connected solid, despite having about 52% porosity. In the pumiceous cementitious matrix, Al-tobermorite with 11.27 Å interlayer spacing is locally associated with phillipsite, similar to geologic occurrences in basaltic tephra. The ancient concretes provide a sustainable prototype for producing Al-tobermorite in high-performance concretes with natural volcanic pozzolans. © 2013 The American Ceramic Society.
Original languageEnglish (US)
Pages (from-to)2598-2606
Number of pages9
JournalJournal of the American Ceramic Society
Volume96
Issue number8
DOIs
StatePublished - May 28 2013

ASJC Scopus subject areas

  • Materials Chemistry
  • Ceramics and Composites

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