A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Pozzolanicity of Calcined Clay
Out of the three major clay mineral groups, viz, kaolin, smectite and palygorskite – attapulgite, the cement science primarily focuses on the first group to be used on calcination as a pozzolanic admixture. The general understanding is that the dehydroxylation of dehydrated kaolinite in the temperature range of 550 – 650 °C apparently yields an x-ray amorphous alumino-silicate phase which provides the pozzolanic property to clay. There is not much of information on how the highly crystalline kaolinite loses its long-range order in the lattice on account of dehydroxylation. Little data are available on the effect of cation exchange capacity on pozzolanicity. Further, in EN-197-1 the usability of a calcined clay as a pozzolana has been linked with the presence of minimum 25 per cent reactive silica in it. The test methods for determining the pozzolanic property of calcined clays are still in the realm of arbitrariness. The present paper is a brief crystallo-chemical disquisition of the above issues, based on the characterization of six different Indian clay samples.
Pozzolanicity of Calcined Clay
Out of the three major clay mineral groups, viz, kaolin, smectite and palygorskite – attapulgite, the cement science primarily focuses on the first group to be used on calcination as a pozzolanic admixture. The general understanding is that the dehydroxylation of dehydrated kaolinite in the temperature range of 550 – 650 °C apparently yields an x-ray amorphous alumino-silicate phase which provides the pozzolanic property to clay. There is not much of information on how the highly crystalline kaolinite loses its long-range order in the lattice on account of dehydroxylation. Little data are available on the effect of cation exchange capacity on pozzolanicity. Further, in EN-197-1 the usability of a calcined clay as a pozzolana has been linked with the presence of minimum 25 per cent reactive silica in it. The test methods for determining the pozzolanic property of calcined clays are still in the realm of arbitrariness. The present paper is a brief crystallo-chemical disquisition of the above issues, based on the characterization of six different Indian clay samples.
Pozzolanicity of Calcined Clay
RILEM Bookseries
Scrivener, Karen (editor) / Favier, Aurélie (editor) / Chatterjee, Anjan K (author)
2015-05-08
7 pages
Article/Chapter (Book)
Electronic Resource
English
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