Chapter 47. Microstructure and Nanoporosity of as-Set Geopolymers

  1. Rajan Tandon,
  2. Andrew Wereszczak and
  3. Edgar Lara-Curzio
  1. W. M. Kriven,
  2. J. L. Bell and
  3. M. Gordon

Published Online: 27 MAR 2008

DOI: 10.1002/9780470291313.ch47

Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 27, Issue 2

Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 27, Issue 2

How to Cite

Kriven, W. M., Bell, J. L. and Gordon, M. (2006) Microstructure and Nanoporosity of as-Set Geopolymers, in Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 27, Issue 2 (eds R. Tandon, A. Wereszczak and E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291313.ch47

Author Information

  1. Department of Materials Science and Engineering University of Illinois at Urbana–Champaign, Urbana, IL 61801, USA

Publication History

  1. Published Online: 27 MAR 2008
  2. Published Print: 1 JAN 2006

ISBN Information

Print ISBN: 9780470080528

Online ISBN: 9780470291313

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Keywords:

  • porosimetry;
  • nanoparticulate;
  • nanoporous;
  • biomodal;
  • hydrogen

Summary

The microstructure and porosity of as–cured and crushed sodium–based geopolymers has been examined by electron microscopy (SEM, TEM, STEM), mercury intrusion porosimetry (MIP) and specific surface area measurements, respectively. These techniques indicate that that the intrinsic microstructure is nanoporous and nanoparticulate (< 5 run in size). When made from natural metakaolin, geopolymers have an average pore radius of∼3.4 nm, and the porosity constitutes 41 % by volume of the material. When the geopolymer is made from a pure, synthetic alumino–silicate metakaolin in which the Al atom is in five–fold co–ordination, the average pore size decreases to ∼0.8 nm, and the pores again constitute ∼40% of the volume. The porosity can be varied by selection of Na+ or K+ charge balancing cation, where the latter produces a relatively homogeneous dispersion of fine, sub–micron sized pores distributed in the nanoporous body. A biomodal pore size distribution yielding pores of∼50 μum in diameter can be achieved by synthesis with hydrogen peroxide solution in a closed pressure vessel.