Calcined Illitic Clays as Portland Cement Replacements
Different illitic clays (Buenos Aires Province, Argentine) were selected to study their potential pozzolanic activity. Clays were characterized by X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FTIR) and thermal analysis (TG). Clays are calcined at 300, 600 and 950 °C and ground until 85 % mass passed through a 45 µm sieve. The pozzolanic activity was evaluated by the Frattini test and the strength activity index (SAI) at 2, 7 and 28 days on blended cements containing 25 % by weight of calcined clay. Results indicates that calcined illitic clays are suitable as raw material to prepare calcined clay pozzolan when they are fired at 950 °C as revels the Frattini test and they have a SAI from 0.75 to 0.94 at 28 days depending the amount of clayed minerals in the raw shale-stone. Secondary clay minerals don’t change significantly the pozzolanic behavior of illitic calcined clays.
KeywordsCompressive Strength Clay Mineral Blended Cement Pozzolanic Activity Buenos Aires Province
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The authors would like to thank Eng. Monica Trezza for their assistance in carrying out the FTIR analysis, the CIC for the student-fellowship for Roxana Lemma and the ANPCYT for providing funding for the work under the PICT 0160-12.
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