Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcina...Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.展开更多
基金financial support for the research and for the publication costs of the articlesupported by Santa Catarina State Research Support Foundation(FAPESC)National Council for Scientific and Technological Development(CNPq no 302903/2023-2).
文摘Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.
