Formulation of blended cement: Effect of process variables on clay pozzolanic activity

Chemical, physical and mineralogical properties of crude and calcined local kaolinitic clay were studied in detail in order to use it as an artificial pozzolan. The aim of this study was to investigate and optimize the properties of mortars in which calcined clay is employed as a pozzolan. A three v...

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Bibliographic Details
Published in:Construction & building materials 2009-03, Vol.23 (3), p.1365-1373
Main Authors: Chakchouk, Ahlem, Trifi, Lotfi, Samet, Basma, Bouaziz, Samir
Format: Article
Language:English
Subjects:
Calcination
Cement
Cement industry
Central composite design
Clay
Clay minerals
Crystals
Desirability
Ethylene glycol
Lime
Mechanical properties
Nuclear magnetic resonance spectroscopy
Silicates
Structure
Sulfates
Zeolites
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Summary:Chemical, physical and mineralogical properties of crude and calcined local kaolinitic clay were studied in detail in order to use it as an artificial pozzolan. The aim of this study was to investigate and optimize the properties of mortars in which calcined clay is employed as a pozzolan. A three variable (calcination time: X1, calcination temperature: X2 and % of calcined clay in the blended cement: X3) rotatable orthogonal composite design was set up. It was concluded that the compressive strengths were governed by the calcination temperature and the percentage of the calcined clay in the blended cement. It was proven that the strengths could be improved by increasing simultaneously the percentage of incorporation and the calcination temperature of the clay. It was also demonstrated that at temperatures lower than 700 °C, the increase of the calcination time, improved the compressive strength, while above 700 °C, the opposite effect was observed. Finally, a blended cement composition has been formulated and optimized using the desirability functions. The optimized blended cement contains 25% of calcined clay, heated for 3 h at a temperature of 750 °C.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2008.07.015