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2. Potentialities of Different Materials from the Eastern Region of Cuba as Partial Cement Substitutes: A Comparison of Their Performance

Author

Almenares Reyes, Roger S., Alujas Díaz, Adrián, Leyva Rodríguez, Carlos A., Poll Legrá, Lisandra, Guerra González, Yosbel, Pérez García, Luis A., Betancourt Rodríguez, Sergio, Martirena-Hernandez, Jose Fernando, Martirena-Hernandez, Jose Fernando, editor, Alujas-Díaz, Adrian, editor, and Amador-Hernandez, Meylin, editor

Published
2020
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5. Potentialities of Different Materials from the Eastern Region of Cuba as Partial Cement Substitutes: A Comparison of Their Performance

Author

Almenares Reyes, Roger S., primary, Alujas Díaz, Adrián, additional, Leyva Rodríguez, Carlos A., additional, Poll Legrá, Lisandra, additional, Guerra González, Yosbel, additional, Pérez García, Luis A., additional, Betancourt Rodríguez, Sergio, additional, and Martirena-Hernandez, Jose Fernando, additional

Published
2019
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6. Aluminothermic synthesis of ceramics from the hercynite-alumina system, using mill scale and aluminum chips.

Author

Perdomo-González, Lorenzo, Quintana-Puchol, Rafael, Alujas-Díaz, Adrián, Ailin Perdomo-Gómez, Laura, Ruíz-Pérez, Roily, and Cruz-Crespo, Amado

Subjects
GRINDING wheels, IRON alloys, ALUMINUM, MANUFACTURING processes, X-ray diffraction, ROLLING-mills, CERAMICS
Abstract

Copyright of Dyna is the property of Universidad Nacional de Colombia, Medellin, Facultad de Minas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2023
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9. ESTUDIO CINÉTICO DE LA SORCIÓN DE IONES HIDRONIO EN ARCILLA DE LA REGIÓN DE MANICARAGUA, VILLA CLARA, CUBA.

Author

Prieto García, Julio Omar, Alujas Díaz, Adrián, Iturria Quintero, Pedro, Broche Galindo, María Hertha, Enríquez García, Mixary, and Mollineda Trujillo, Ángel

Subjects
*OXONIUM ions, *ADSORPTION (Chemistry), *ACTIVATION energy, *CLAY, *ENERGY consumption
Abstract

These research exposes the kinetic study results for the adsorption of hydronium ions in clay from Las Mozas deposit, in Manicaragua region, province of Villa Clara, Cuba. The main objective is to facilitate clay activation. Moreover, it is determined that the adsorption satisfies a pseudo first order kinetic model. The study evidences intraparticle diffusion and in liquid film too, for different temperatures. The low activation energy of adsorption process justifies the easiness in which the hydronium ion is adsorbed. The low value of the isosteric heat involved demonstrates the low energetic superficial heterogeneity. The activation process leads to an energy release. [ABSTRACT FROM AUTHOR]

Published
2019

10. Genesis and crystallinity as factors to consider during the quantification of clay mineral phases: case studies of Cayo Guam and Dumañuecos.

Author

García-Obregón, Livan, Alberto Pérez-García, Luis, Alujas-Díaz, Adrián, Eduardo Espinosa-Borges, Angel, and Kirsch, Astrid

Subjects
*CLAY minerals, *CRYSTALLINITY, *KAOLINITE, *X-ray diffraction, *WEATHER, *PARAGENESIS
Abstract

The study focused on the influence of geological genesis and degree of crystallinity on the quantification of mineral phases and amorphous content in Cuban clays. Two clay deposits with different geological genesis were taken and the samples were characterized using X-ray diffraction and techniques for analyzing the clay fraction. Dominant paragenesis were established for each deposit, dominated by kaolinite, and useful relationships were found between structural and particle size differences with geological genesis, which can affect proper quantification. It was determined that the level of weathering conditions the degree of crystallinity, which in turn has a strong relationship with factors that affect proper quantification. Finally, the fundamental elements for formulating a comprehensive methodology for the proper characterization and quantification of clay phases were established. [ABSTRACT FROM AUTHOR]

Published
2024

11. Estudio de la adición de arcillas calcinadas en la durabilidad de hormigones

Author

Castillo Lara, Rancés, Antoni, Mathieu, Alujas Díaz, Adrián, Scrivener, Karen, and Martirena Hernández, José Fernando

Subjects
durabilidad, porosidad, porosity, Arcillas calcinadas, capillary absorption, absorción capilar, Calcined clays, durability, hydration products, productos de hidratación
Abstract

Actualmente son bien conocidas las ventajas económicas y medioambientales de la sustitución del clínker de cemento por otros materiales cementicios suplementarios. Las arcillas calcinadas en forma de metacaolín han recibido por ejemplo especial atención en años recientes. Se conoce que estas adiciones, cuando se añaden a morteros y hormigones, mejoran tanto su resistencia mecánica como su durabilidad. El objetivo de este trabajo es evaluar el comportamiento de las propiedades físico-mecánicas y la durabilidad en microhormigones, empleando arcillas calcinadas y molidas como material sustituyente del 30% en peso del cemento Pórtland ordinario (CPO). Para ello se utilizó una tierra arcillosa, compuesta principalmente por mineral caolín de bajo grado de pureza, para la obtención de arcillas calcinadas como minerales cementicios suplementarios. Los mejores resultados se resistencia a la compresión a los 28 días se obtuvieron para la arcilla sedimentada y calcinada, la cual posee mayor contenido de mineral caolín debido a un proceso de purificación por sedimentación de la materia prima acometido sólo para esta adición. Sin embargo, los ensayos de absorción de agua por capilaridad arrojaron los mejores resultados para el suelo arcilloso calcinado, el cual posee una elevada finura en comparación al resto de los materiales estudiados. Los menores valores mostrados por esta adición, tanto de porosidad capilar como de sorptividad, indican que existió un predominio del fenómeno de la compacidad e impermeabilidad, lograda en la matriz cementicia al usar un material tan fino, por encima del efecto de la reacción puzolánica. Estudios en la microestructura del gel de C-S-H, usando energía dispersiva por rayos-X (EDX), demostraron como el empleo de arcillas calcinadas en sustitución del CPO favorece la formación de productos de hidratación más estables, principalmente monosulfos del tipo hemicarbo y monocarbo, lo cual es conveniente para el hormigón ante la posible acción de diferentes mecanismos de degradación. Currently economical and environmental advantages of cement clinker replacement by other supplementary cementious materials are well known. For example calcined clays, such as metakaolin, have drawn special attention during recent years. It is well known that these admixtures added to mortars and concretes improve mechanical strength as well as durability. The purpose of this study is to evaluate the behavior of physical-mechanical properties and durability in micro-concretes, by employing calcinated and grinded clays as replacement material, by 30% of ordinary Portland cement (OPC). Therefore, clay soil was employed, which is mainly composed by low-purity-kaolin mineral, so as to obtain calcined clays to be used as supplementary cementious minerals. Best results for compressive strength at 28 days were obtained by sedimentary calcined clays, which have higher content of kaolin mineral thanks to a purification process by means of raw material sedimentation conducted on this admixture only. Nevertheless, capillary water absorption tests delivered best results for calcined clay soil, which finesse is quite high. Lower values showed by this admixture, as much for capillary porosity and sorptivity, revealed there was a predominance of compaction and impermeability phenomena achieved by cementious matrix using such fine material, over the effect of puzzolanic reaction. Micro-structure studies on C-S-H gel, employing energy dispersive x-ray (EDX) technique, demonstrated that the use of calcined clays as replacement of RPC favors the creation of quite stable hydration products, mainly monosulfos of hemicabo and monocarbo types, which is convenient for concrete against possible deterioration actions from different mechanisms.

Published
2011

12. Productos De La Reducción Carbotérmica De Cromita Refractaria A Baja Temperatura, Una Fuente Alternativa En El Tratamiento Cromodifusivo De Aceros

Author

Alujas Díaz, Adrián, Quintana Puchol, Rafael, Arniella Orama, Abel, Díaz Aguila, Carlos, and Reguera, Edilso

Subjects
cromita refractaria, reducción carbotérmica, carbothermic reduction, thermodifusive treatment, tratamiento termodifusivo, refractory chromite
Abstract

En este trabajo se discute la obtención y caracterización de un producto prerreducido carbotérmicamente a partir de un concentrado de cromita refractaria cubana, con vistas a valorar las posibilidades de su utilización del producto reducido como componente alternativo de mezclas saturantes para la obtención de capas de carburos de cromo en aceros mediante un tratamiento termodifusivo. La reducción se lleva a cabo para mezclas con alto grado de compactación y a una temperatura de 1000 ° C. En la caracterización del concentrado mineral se hallo que este, por su composición química y fásica, puede actuar simultáneamente como elemento portador del componente activo y del aditivo termorrefractario en una mezcla termodifusiva, con una relación cromo / silicio dentro de los niveles recomendados para la saturación con cromo. En la caracterización de las mezclas reducidas mediante Espectroscopía Infrarroja, Espectroscopía Mössbauer y Difracción de Rayos-X, se encontró la presencia de varios carburos metálicos ( (Cr,Fe)23 C6 , (Cr,Fe)7 C3) capaces de actuar como difusores del elemento cromo, y característicos de una etapa avanzada del proceso reductivo. Se encontró que la adición de CaCO3 a la mezcla a reducir permite alcanzar mejores condiciones de reducción, a la temperatura establecida. In this work is presented a method for the obtention and characterization of a carbothermical prereduced product, using as base material a concentrate of cuban refractory chromite. The study of the reduced mixture is carried out to explore the possibilities of use of the reduction products as suitable components of mixtures for the obtaining of chromium carbides layers in steels through the thermodifusion method. The reduction is carried out for a mixture with high compactation degree and to a temperature of 1000 ° C. In the characterization of the chromite concentrate it was found that by its chemical and structural composition it can act simultaneously as carrier of the active component and of the thermorefractory additives in the chromodifusive mixture, with a chromium / silicon relation in correspondence with the recomended values for chromodifusion mixtures. In the characterization of the prereduced mixtures by Infrared Spectroscopy, Mössbauer Spectroscopy and X-Ray Difraction techniques, the presence of metallic carbides ( (Cr,Fe)23 C6 , (Cr,Fe)7 C3 ) was detected, characteristic of advanced stages of the reduction process and with possibilities to act as chromium difusors. It was found tahat the addiction of CaCO3 to the mixture allow better reduction conditions.

Published
2003

13. Evaluación de arcillas caoliníticas de Moa para la producción de cemento de base clínquer–arcilla calcinada–caliza (LC3).

Author

Almenares-Reyes, Roger S., Alujas-Díaz, Adrián, Poll-Legrá, Lisandra, Bassas-Noa, Pedro R., Betancourt-Rodríguez, Sergio, Martirena-Hernández, José F., and Leyva-Rodríguez, Carlos A.

Subjects
*KAOLINITE, *CLAY, *POZZOLANIC reaction, *LIMESTONE, *ALKALINE solutions, *CEMENT composites
Abstract

Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (ATG). These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1), although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C. [ABSTRACT FROM AUTHOR]

Published
2016

15. Valoración química, fásica y calorimétrica de un material puzolánico obtenido mediante aluminotermia asistida por arco eléctrico utilizando escoria de cubilote.

Author

Laura Pérez-González, Leidys, Quintana-Puchol, Rafael, Alujas-Díaz, Adrián, and Alejo-Sánchez, Daniellys

Subjects
*POZZOLANIC reaction, *ALUMINOTHERMY, *CUPOLA furnaces, *ELECTRIC arc, *CHEMICAL elements, *CHEMICAL reactions, *METALLIC oxides, *CALORIMETRY
Abstract

The purpose of this study was to evaluate the chemical, phasic and calorimetric evaluation of a pozzolanic material obtained by electric arcassisted aluminothermy using cupola slag to provide criteria on its pozzolanic nature. Chemical characterization of cupola slag and synthesized pozzolanic material (MPS) was performed by using analytical methods such as volatilization gravimetry, complex formation volumetry, UV-VIS spectrophotometry, atomic absorption spectrometry, and phase characterization using semi quantitative analysis by XRD. The pozzolanic character of cupola slag and MPS was evaluated by means of alkaline solubility tests and isothermal calorimetry in Ca(OH)2-Puzolana and Portland Cement (CP)-Pozzolan paste systems. Cupola slag does not contain more than 70% of SiO2, Al2O3 and Fe2O3 as indicated in NC TS 528: 2007 for its use as pozzolan and has 60% amorphism, while the MPS complies with the provisions of the standard and presents a 30% amorphism. The highest values of the Si and Al contents in the cupola slag respect to MPS and the zeolite studied are associated with the predominance of a non-periodic distribution of these chemical elements in the amorphous domains. Higher pozzolanic reactivity of the MPS respect to cupola slag obtained by isothermal Ca(OH)2-Pozolana and CP-Pozzolan calorimetry is attributed to a combination of amorphous character with the increasing of reactive phases result from chemical and phase modifications by using aluminothermy in an electric arc furnace. [ABSTRACT FROM AUTHOR]

Published
2020

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