Calcined Illitic Clays as Portland Cement Replacements

摘要

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 (FTTR) and thermal analysis (TG). Clays are calcined at 300,600 and 950 °C and ground until 85 % mass passed through a 45 um 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.