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Evaluation of Calcined Clays from Boyaca-Colombia Containing Alunite as Supplementary Cementitious Materials
Abstract The goal of this study was to understand the behavior of clays from Iza, Boyaca, Colombia and their potential to be used in blended cement after calcination as pozzolan. The materials were characterized before and after thermal treatment by XRF, XRD, TGA and SEM. The performance in mortar was evaluated by compressive strength of mortar. The XRD analysis showed that the main minerals present in the raw materials were Kaolinite, Alunite, Quartz, Opal and Feldspars, each one with different behavior after activation. The performance of mortar was investigated by measuring the compressive strength according to ASTM C109. The produced blended cements were done with 30% of SCM and 70% of Ordinary Portland Cement (OPC). The optimization of the calcination temperature has been carried out using Thermal Gravimetric Analysis (TGA) as well as with X Ray Diffraction (XRD). After the calcination and depending on the temperature, both the Kaolinite as well as Alunite show structural changes with different effects on the performance. While kaolinite dehydroxylation significantly improves the performance, alunite decomposition into the new reactive phases KAl(SO4)2 and amorphous Al2O3 have strong effect on the early age of hydration, decreasing the workability, increasing the initial temperature of the mortar. This can nevertheless be controlled by optimizing the gypsum content.
Evaluation of Calcined Clays from Boyaca-Colombia Containing Alunite as Supplementary Cementitious Materials
Abstract The goal of this study was to understand the behavior of clays from Iza, Boyaca, Colombia and their potential to be used in blended cement after calcination as pozzolan. The materials were characterized before and after thermal treatment by XRF, XRD, TGA and SEM. The performance in mortar was evaluated by compressive strength of mortar. The XRD analysis showed that the main minerals present in the raw materials were Kaolinite, Alunite, Quartz, Opal and Feldspars, each one with different behavior after activation. The performance of mortar was investigated by measuring the compressive strength according to ASTM C109. The produced blended cements were done with 30% of SCM and 70% of Ordinary Portland Cement (OPC). The optimization of the calcination temperature has been carried out using Thermal Gravimetric Analysis (TGA) as well as with X Ray Diffraction (XRD). After the calcination and depending on the temperature, both the Kaolinite as well as Alunite show structural changes with different effects on the performance. While kaolinite dehydroxylation significantly improves the performance, alunite decomposition into the new reactive phases KAl(SO4)2 and amorphous Al2O3 have strong effect on the early age of hydration, decreasing the workability, increasing the initial temperature of the mortar. This can nevertheless be controlled by optimizing the gypsum content.
Evaluation of Calcined Clays from Boyaca-Colombia Containing Alunite as Supplementary Cementitious Materials
Perez, Ariam Lozano (author) / Antoni, Mathieu (author)
2017-10-28
7 pages
Article/Chapter (Book)
Electronic Resource
English
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| DataCite | 2023
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