Heated Montmorillonite: Structure, Reactivity, and Dissolution

  • Nishant GargEmail author
  • Jørgen Skibsted
Conference paper
Part of the RILEM Bookseries book series (RILEM, volume 10)


The dehydroxylated form of the principal 1:1 clay, kaolinite, known as metakaolin, has been widely studied in terms of its structure and reactivity. However, detailed information on the dehydroxylation of the abundant 2:1 clay, montmorillonite, is lacking in this respect. Three montmorillonites, calcined at various temperatures have been characterized by solid-state 29Si MAS NMR. The dehydroxylation (600 – 800 °C) results in progressive distortion of the SiO4 tetrahedra, followed by crystallization of inert, stable phases at higher temperatures. The dissolution kinetics of a structurally pure montmorillonite, SAz-2, calcined at two different temperatures are found to be in good agreement with its pozzolanic reactivity established in an earlier study. It is also found that SAz-2, calcined at its optimum calcination temperature of 800 °C, undergoes incongruent dissolution reaching a molar Si/Al ratio of 3.7 in a 0.1 M NaOH solution after one day of dissolution. It has been reaffirmed that both the degree of dehydroxylation and the type of structural phases (Q3/Q4) have a significant impact on the reactivity of the calcined montmorillonite. The clear identification of inert phases and reactive sites by solid-state NMR may have major implications in the utilization of not only montmorillonites but also other calcined clays.


Dissolution Kinetic Octahedral Sheet Supplementary Cementitious Material Incongruent Dissolution Optimum Calcination Temperature 
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The Danish National Advanced Technology Foundation is acknowledged for the financial support to the SCM project.


  1. 1.
    Lothenbach, B., Scrivener, K., Hooton, R.D.: Supplementary cementitious materials. Cem. Concr. Res. 41(12), 1244–1256 (2011)CrossRefGoogle Scholar
  2. 2.
    He, C., Osbaeck, B., Makovicky, E.: Pozzolanic reactions of six principal clay minerals: activation, reactivity assessments and technological effects. Cem. Concr. Res. 25(8), 1691–1702 (1995)CrossRefGoogle Scholar
  3. 3.
    Fernandez, R., Martirena, F., Scrivener, K.L.: The origin of the pozzolanic activity of calcined clay minerals: a comparison between kaolinite, illite and montmorillonite. Cem. Concr. Res. 41(1), 113–122 (2011)CrossRefGoogle Scholar
  4. 4.
    Bergaya, F., Theng, B.K.G., Lagaly, G.: Handbook of Clay Science. Elsevier, Amsterdam (2011)Google Scholar
  5. 5.
    Garg, N., Skibsted, J.: Thermal activation of a pure montmorillonite clay and its reactivity in cementitious systems. J. Phys. Chem. C 118(21), 11464–11477 (2014)CrossRefGoogle Scholar
  6. 6.
    Garg, N., Skibsted, J.: Manuscript in preparation, (2015)Google Scholar
  7. 7.
    Snellings, R.: Solution-controlled dissolution of supplementary cementitious material glasses at pH 13: the effect of solution composition on glass dissolution rates. J. Am. Ceram. Soc. 96(8), 2467–2475 (2013)CrossRefGoogle Scholar
  8. 8.
    Mermut, A., Cano, A.: Baseline studies of the clay minerals society source clays: chemical analyses of major elements. Clays Clay Miner. 49(5), 381–386 (2001)CrossRefGoogle Scholar

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© RILEM 2015

Authors and Affiliations

  1. 1.Department of Chemistry and Interdisciplinary Nanoscience, Center (iNANO)Aarhus UniversityAarhus CDenmark

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