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Title: Influence of Calcite on the Pozzolanic Reaction of Kaolinite

Author(s): Isabel Sánchez, Marina Casas Angulo, Mario Ramírez, Raquel Vigil de la Villa, Rosario García-Giménez, Isabel Sonsoles de Soto García, Moisés Frías and Antonio Zapardiel

Publication: Symposium Paper

Volume: 349


Appears on pages(s): 418-431

Keywords: activation thermically, calcite, cement, hydrated phases, kaolinite, pozzolanic reaction, kaolinite

DOI: 10.14359/51732762

Date: 4/22/2021

The use of kaolinite as a pozzolanic activator in the hydration of cement is widely established. The optimum calcination conditions and the scientific basis of the reaction kinetics for the systems metakaolinite (MK)/lime, used as a standard system, and metakaolinite (MK)/cement have been set. These treatments reach their maximum effectiveness in the presence of non-altered calcite. The objective of this research is to determine the influence that calcite has on the pozzolanicity of the kaolinite, in order to do so, different mixtures kaolinite (K)/calcite (Ca) thermally activated at 600ºC and 750ºC for 2 hours were prepared. The products obtained in the pozzolanic reaction were studied with XRD and SEM/EDX analysis. The calcite addition generated an inhibitor effect in the reactivity of natural kaolinite (K) when the thermic activation is at 750°C for 2 hours. The optimal calcination conditions regardless of the proportion of calcite are 600°C/2 hours.