Journal of Materials Science

, Volume 44, Issue 17, pp 4668–4676 | Cite as

Crystalline phase formation in metakaolinite geopolymers activated with NaOH and sodium silicate

  • Bo ZhangEmail author
  • Kenneth J. D. MacKenzie
  • Ian W. M. Brown


The effect of the NaOH content and the presence of sodium silicate activators on the formation of crystalline phases from metakaolinite-based geopolymers were studied by X-ray powder diffraction (XRD), Rietveld quantitative XRD, solid-state MAS NMR and SEM in samples synthesized with varying NaOH contents and different curing times at 40 °C. Geopolymers activated with NaOH alone with Si/Na ratios of 4/4 or less formed the crystalline zeolite Na–A (Na96Al96Si96O384·216H2O), but at ratios >4/4 nanosized crystals of another zeolite (Na6[AlSiO4]6·4H2O) were formed. The Si/Na ratio of 4/4 produces a product of greatest crystallinity. The addition of sodium silicate in addition to NaOH significantly reduces crystallite formation. The network units of all the materials containing NaOH and sodium silicate are essentially the same, namely, tetrahedral [SiO4] units coordinated through four bridging oxygens to four aluminium atoms [denoted as Q4 Si(4Al) units]. A templating function of the various silicate units of the sodium silicate molecules is suggested to occur in geopolymerization, which differs from the reaction route operating when NaOH alone is used as the activator. This templating function is responsible for the suppression of crystallization and the increase in strength of the geopolymers activated with sodium silicate.


Zeolite Geopolymer Sodium Silicate Sodium Silicate Solution Metakaolinite 



We are indebted to Martin Ryan for his assistance with the XRD quantitative analysis.


  1. 1.
    Rocha J, Klinowski J (1991) J Chem Soc Faraday Trans 87:3091CrossRefGoogle Scholar
  2. 2.
    Benharrats N, Belbachir M, Legrand AP, D’espinose De La Caillerie J-B (2003) Clay Miner 38:49CrossRefGoogle Scholar
  3. 3.
    Heller-Kallai L, Lapides I (2007) Appl Clay Sci 35:99CrossRefGoogle Scholar
  4. 4.
    Engelhardt G, Fahlke B, Mägi M, Lippmaa E (1985) Zeolites 5:49CrossRefGoogle Scholar
  5. 5.
    Lippmaa E, Mägi M, Samoson A, Tarmak M, Engelhardt G (1981) J Am Chem Soc 103:4992CrossRefGoogle Scholar
  6. 6.
    Thomas JM, Fyfe CA, Ramdas S, Klinowski J, Gobbi GC (1982) J Phys Chem 86:3061CrossRefGoogle Scholar
  7. 7.
    Engelhardt G, Fahlke B, Mägi M, Lippmaa E (1983) Zeolites 3:292CrossRefGoogle Scholar
  8. 8.
    Singh PS, Bastow T, Trigg M (2005) J Mater Sci 40:3951. doi: CrossRefGoogle Scholar
  9. 9.
    Singh PS, Trigg M, Brugar I, Bastow T (2005) Mater Sci Eng A 396:392CrossRefGoogle Scholar
  10. 10.
    Barbosa VFF, MacKenzie KJD, Thaumaturgo C (2000) Int J Inorg Mater 2:309CrossRefGoogle Scholar
  11. 11.
    Fletcher RA, MacKenzie KJD, Nicholson CL, Shimada S (2005) J Eur Ceram Soc 25:1471CrossRefGoogle Scholar
  12. 12.
    Weng L, Sagoe-Crentsil K (2007) J Mater Sci 42:2997. doi: CrossRefGoogle Scholar
  13. 13.
    Sagoe-Crentsil K, Weng L (2007) J Mater Sci 42:3007. doi: CrossRefGoogle Scholar
  14. 14.
    Provis JL, Lukey GC, van Deventer JSJ (2005) Chem Mater 17:3075CrossRefGoogle Scholar
  15. 15.
    MacKenzie KJD, Smith ME (2002) Multinuclear solid-state NMR of inorganic materials. Pergamon Materials Series, vol 6. Pergamon-Elsevier, OxfordGoogle Scholar
  16. 16.
    Felche J, Luger S, Baerlocher C (1986) Zeolites 6:367CrossRefGoogle Scholar
  17. 17.
    Duxson P, Lukey GC, Separovic F, van Deventer JSJ (2005) Ind Eng Chem Res 44:832CrossRefGoogle Scholar
  18. 18.
    Duxson P, Lukey GC, van Deventer JSJ (2007) J Non-Cryst Solids 353:2186CrossRefGoogle Scholar
  19. 19.
    Duxson P, Fernández-Jiménez A, Provis JL, Lukey GC, Palomo A, van Deventer JSJ (2007) J Mater Sci 42:2917. doi: CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Bo Zhang
    • 1
    Email author
  • Kenneth J. D. MacKenzie
    • 1
  • Ian W. M. Brown
    • 1
  1. 1.Industrial Research Ltd.Lower HuttNew Zealand

Personalised recommendations