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  • Autoclaved cellulose fibre reinforced cement: effects of silica fume

     Fernández Carrasco, Lucía; Claramunt Blanes, Josep; Ardanuy Raso, Monica
    Construction & building materials
    Vol. 66, p. 138-145
    DOI: 10.1016/j.conbuildmat.2014.05.050
    Date of publication: 2014-07-01
    Journal article

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    With the aim of developing vegetable-fibre cement composites free of portlandite and with short curing process, this study analyses the influence of the curing conditions and the addition of pozzolanic material on the hydration of Portland cement¿fibre matrices. Different specimens of cement composites with and without cellulose fibres and with and without silica fume were cured using autoclaving steam and normal curing. The hydration products and the microstructure of the resulting pastes were analysed by means of FTIR and BSE¿SEM and the degree of hydration was quantified with Image analysis. The results indicate that the hydration products and the hardness of the pastes depend on the three analysed factors: curing method, silica fume, and presence of fibres

    With the aim of developing vegetable-fibre cement composites free of portlandite and with short curing process, this study analyses the influence of the curing conditions and the addition of pozzolanic material on the hydration of Portland cement–fibre matrices. Different specimens of cement composites with and without cellulose fibres and with and without silica fume were cured using autoclaving steam and normal curing. The hydration products and the microstructure of the resulting pastes were analysed by means of FTIR and BSE–SEM and the degree of hydration was quantified with Image analysis. The results indicate that the hydration products and the hardness of the pastes depend on the three analysed factors: curing method, silica fume, and presence of fibres

  • A Force field for tricalcium aluminate to characterize surface properties, initial hydration, and organically modified interfaces in atomic resolution

     Mishra, Ratan K.; Fernández Carrasco, Lucía; Flatt, Robert J.; Heinz, Hendrik
    Journal of the Chemical Society. Dalton transactions
    Vol. 43, p. 10602-10616
    DOI: 10.1039/C4DT00438H
    Date of publication: 2014-04-22
    Journal article

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    Tricalcium aluminate (C3A) is a major phase of Portland cement clinker and some dental root filling cements. An accurate all-atom force field is introduced to examine structural, surface, and hydration properties as well as organic interfaces to overcome challenges using current laboratory instrumentation. Molecular dynamics simulation demonstrates excellent agreement of computed structural, thermal, mechanical, and surface properties with available experimental data. The parameters are integrated into multiple potential energy expressions, including the PCFF, CVFF, CHARMM, AMBER, OPLS, and INTERFACE force fields. This choice enables the simulation of a wide range of inorganic¿organic interfaces at the 1 to 100 nm scale at a million times lower computational cost than DFT methods. Molecular models of dry and partially hydrated surfaces are introduced to examine cleavage, agglomeration, and the role of adsorbed organic molecules. Cleavage of crystalline tricalcium aluminate requires approximately 1300 mJ m-2 and superficial hydration introduces an amorphous calcium hydroxide surface layer that reduces the agglomeration energy from approximately 850 mJ m-2 to 500 mJ m-2, as well as to lower values upon surface displacement. The adsorption of several alcohols and amines was examined to understand their role as grinding aids and as hydration modifiers in cement. The molecules mitigate local electric fields through complexation of calcium ions, hydrogen bonds, and introduction of hydrophobicity upon binding. Molecularly thin layers of about 0.5 nm thickness reduce agglomeration energies to between 100 and 30 mJ m-2. Molecule-specific trends were found to be similar for tricalcium aluminate and tricalcium silicate. The models allow quantitative predictions and are a starting point to provide fundamental understanding of the role of C3A and organic additives in cement. Extensions to impure phases and advanced hydration stages are feasible.

    Tricalcium aluminate (C3A) is a major phase of Portland cement clinker and some dental root filling cements. An accurate all-atom force field is introduced to examine structural, surface, and hydration properties as well as organic interfaces to overcome challenges using current laboratory instrumentation. Molecular dynamics simulation demonstrates excellent agreement of computed structural, thermal, mechanical, and surface properties with available experimental data. The parameters are integrated into multiple potential energy expressions, including the PCFF, CVFF, CHARMM, AMBER, OPLS, and INTERFACE force fields. This choice enables the simulation of a wide range of inorganic–organic interfaces at the 1 to 100 nm scale at a million times lower computational cost than DFT methods. Molecular models of dry and partially hydrated surfaces are introduced to examine cleavage, agglomeration, and the role of adsorbed organic molecules. Cleavage of crystalline tricalcium aluminate requires approximately 1300 mJ m-2 and superficial hydration introduces an amorphous calcium hydroxide surface layer that reduces the agglomeration energy from approximately 850 mJ m-2 to 500 mJ m-2, as well as to lower values upon surface displacement. The adsorption of several alcohols and amines was examined to understand their role as grinding aids and as hydration modifiers in cement. The molecules mitigate local electric fields through complexation of calcium ions, hydrogen bonds, and introduction of hydrophobicity upon binding. Molecularly thin layers of about 0.5 nm thickness reduce agglomeration energies to between 100 and 30 mJ m-2. Molecule-specific trends were found to be similar for tricalcium aluminate and tricalcium silicate. The models allow quantitative predictions and are a starting point to provide fundamental understanding of the role of C3A and organic additives in cement. Extensions to impure phases and advanced hydration stages are feasible.

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    Manual para la redacción de estudios de gestión de RCD en obras de edificación, rehabilitación y demolición  Open access

     Fernández Carrasco, Lucía
    Date of publication: 2014-06-20
    Book

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    Este Manual se ha desarrollado para dar soporte a los arquitectos, parejadores y project managers para la redacción e implantación de Plan de Gestión de Residuos de Construcción y Demolición y buenas prácticas gremiales, dando soporte a los contratistas a la hora de redactar e implantar Planes de Gestión de RCD.

    Este Manual se ha desarrollado para dar soporte a los arquitectos, parejadores y project managers para la redacción e implantación de Plan de Gestión de Residuos de Construcción y Demolición y buenas prácticas gremiales, dando soporte a los contratistas a la hora de redactar e implantar Planes de Gestión de RCD.

  • Evaluation of the mechanical behavior of natural fiber nonwoven cement composites under flexural loading

     Ardanuy Raso, Monica; Claramunt Blanes, Josep; Ventura Casellas, Heura; Pares Sabates, Ferran; Fernández Carrasco, Lucía
    Congreso Nacional de Materiales
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    Use of coal mining waste as pozzolanic material in new blended cement matrixes  Open access

     Vigil de la Villa, Raquel; García Jiménez, Rosario; Ramírez Fernández, Mario; Rubio Fernández, Virginia; Frias Rojas, Moisés; Rodríguez Largo, Olga; Lahoz Ruiz, Eduardo; Martínez Ramírez, Sagrario; Fernández Carrasco, Lucía; Vegas, Iñigo
    European Conference on Composite Materials
    p. 1-8
    Presentation's date: 2014-06-26
    Presentation of work at congresses

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    Research and eco-innovation geared to obtain alternative sources of raw materials from waste constitute pathways for enhancing the competitiveness of resource-intensive industries. Cement and concrete manufacture calls for new sources of new, highly pozzolanic products to improve the mechanical properties and durability of the resulting matrices, while at the same time reducing production costs and environmental impact. Spanish coal mining wastes generated in the extraction and washing steps from a mine in the Castilla-León region were investigated. Mineralogically, these wastes are composed by kaolinite (20-30%), illite (45-70%) and quartz (5-15). This composition is very interesting in order to activate, by controlled thermal activation, the present kaolinite that generates metakaolin, a highly pozzolanic product. Morphological, textural and microstructural changes affect the activity and reactivity of activated wastes. These first studies open up a new research line, practically unknown to the international research community, and stand out the important economic and environmental benefits associated with the recycling of these wastes as supplementary cementing materials for future commercial blended cements.

    Research and eco-innovation geared to obtain alternative sources of raw materials from waste constitute pathways for enhancing the competitiveness of resource-intensive industries. Cement and concrete manufacture calls for new sources of new, highly pozzolanic products to improve the mechanical properties and durability of the resulting matrices, while at the same time reducing production costs and environmental impact. Spanish coal mining wastes generated in the extraction and washing steps from a mine in the Castilla-León region were investigated. Mineralogically, these wastes are composed by kaolinite (20-30%), illite (45-70%) and quartz (5-15). This composition is very interesting in order to activate, by controlled thermal activation, the present kaolinite that generates metakaolin, a highly pozzolanic product. Morphological, textural and microstructural changes affect the activity and reactivity of activated wastes. These first studies open up a new research line, practically unknown to the international research community, and stand out the important economic and environmental benefits associated with the recycling of these wastes as supplementary cementing materials for future commercial blended cements.

  • Effect of sulfate content on cement mixtures

     Torrens Martin, David; Fernández Carrasco, Lucía
    Construction & building materials
    Vol. 48, p. 144-150
    DOI: 10.1016/j.conbuildmat.2013.05.106
    Date of publication: 2013-07-13
    Journal article

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    Portland cement, calcium aluminate cement and calcium sulfate mixtures were investigated to determine the influence of sulfates and the effect of curing conditions on durability. This study focused on the richest mix of Portland cement. The PC/CAC ratio was kept constant at 5.67, and different proportions of calcium sulfate were added (0%, 1%, 3%, 5% and 10%). Samples were kept at 20 C and 97% relative humidity or immersed in water. The dimensional change and mineralogical composition of samples were evaluated. The results showed that the dimensional change of samples in the PC/CAC and PC=CAC=CS systems depended on the amount of sulfate added and on the curing conditions. The dimensional change was associated not only with amorphous ettringite formation, but also with the subsequent formation of a C-S-H gel.

    Portland cement, calcium aluminate cement and calcium sulfate mixtures were investigated to determine the influence of sulfates and the effect of curing conditions on durability. This study focused on the richest mix of Portland cement. The PC/CAC ratio was kept constant at 5.67, and different proportions of calcium sulfate were added (0%, 1%, 3%, 5% and 10%). Samples were kept at 20 °C and 97% relative humidity or immersed in water. The dimensional change and mineralogical composition of samples were evaluated. The results showed that the dimensional change of samples in the PC/CAC and View the MathML source systems depended on the amount of sulfate added and on the curing conditions. The dimensional change was associated not only with amorphous ettringite formation, but also with the subsequent formation of a C-S-H gel.

  • Raman spectroscopy of anhydrous and hydrated calcium aluminates and sulfoaluminates

     Torrens Martin, David; Fernández Carrasco, Lucía; Martínez Ramírez, Sagrario; Ibáñez, Jordi; Artús, Lluís; Matschei, Thomas
    Journal of the American Ceramic Society
    Vol. 96, num. 11, p. 3589-3595
    DOI: 10.1111/jace.12535
    Date of publication: 2013-10-04
    Journal article

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    Recent investigations have revealed the great potential of Raman spectroscopy for the characterization of clinker minerals and commercial Portland cements. The usefulness of this technique for the identification of anhydrous, hydrated, and carbonated phases in cement-based materials has been demonstrated. In the present work, the application of micro-Raman spectroscopy for the characterization of the main clinker phases of calcium aluminate cements and calcium sulfoaluminate cement is explored. The main stable hydrated phases as well as several important carbonated phases are investigated. Raman measurements on the following phases are reported: (i) pure, unhydrated phases: CA, C12A7, CA2, C2AS, cubic-C3A, C4AF, and C4A3inline image; (ii) hydrated phases: ettringite, monosulfoaluminate, and hydrogarnet (C3AH6); (iii) carboaluminate phases: hemicarboaluminate and monocarboaluminate. The present results, which are discussed in terms of the internal vibrational modes of the aluminate, carbonate, and sulfate molecular groups as well as stretching O¿H vibrations, show the ability of Raman spectroscopy to identify the main hydrated and unhydrated phases in the aluminate and sulfoaluminate cements. The Raman spectra obtained in this work provide an extended database to the existing data published in the literature.

    Recent investigations have revealed the great potential of Raman spectroscopy for the characterization of clinker minerals and commercial Portland cements. The usefulness of this technique for the identification of anhydrous, hydrated, and carbonated phases in cement-based materials has been demonstrated. In the present work, the application of micro-Raman spectroscopy for the characterization of the main clinker phases of calcium aluminate cements and calcium sulfoaluminate cement is explored. The main stable hydrated phases as well as several important carbonated phases are investigated. Raman measurements on the following phases are reported: (i) pure, unhydrated phases: CA, C12A7, CA2, C2AS, cubic-C3A, C4AF, and C4A3inline image; (ii) hydrated phases: ettringite, monosulfoaluminate, and hydrogarnet (C3AH6); (iii) carboaluminate phases: hemicarboaluminate and monocarboaluminate. The present results, which are discussed in terms of the internal vibrational modes of the aluminate, carbonate, and sulfate molecular groups as well as stretching O–H vibrations, show the ability of Raman spectroscopy to identify the main hydrated and unhydrated phases in the aluminate and sulfoaluminate cements. The Raman spectra obtained in this work provide an extended database to the existing data published in the literature.

  • Conduction calorimetric studies of ternary binders based on Portland cement, calcium aluminate cement and calcium sulphate

     Torrens Martin, David; Fernández Carrasco, Lucía; Blanco Varela, Maria Teresa
    Journal of thermal analysis and calorimetry
    Vol. 114, num. 2, p. 799-807
    DOI: 10.1007/s10973-013-3003-9
    Date of publication: 2013-01-21
    Journal article

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    Different binders of Portland cement, calcium aluminate cement and calcium sulphate (PC/CAC/CS) have been investigated to determinate the in¿uence the CAC and CS amount in the reactions mechanism. Several mixtures were studied, ratios of 100, 85/15 and 75/25 of PC/CAC with 0, 3 and 5 % of CS. Conduction calorimetric technique was used to follow the hydration during 100 h. The XRD and FTIR techniques were used as support in the analysis of the hydration products. The results have shown that the studied ternary systems form an extra amount of ettringite, and changes in the reactions mechanism with respect to a PC. The reactions mechanism depends on the CAC and CS amount present in the different binders.

    Different binders of Portland cement, calcium aluminate cement and calcium sulphate (PC/CAC/CS) have been investigated to determinate the in¿uence the CAC and CS amount in the reactions mechanism. Several mixtures were studied, ratios of 100, 85/15 and 75/25 of PC/CAC with 0, 3 and 5 % of CS. Conduction calorimetric technique was used to follow the hydration during 100 h. The XRD and FTIR techniques were used as support in the analysis of the hydration products. The results have shown that the studied ternary systems form an extra amount of ettringite, and changes in the reactions mechanism with respect to a PC. The reactions mechanism depends on the CAC and CS amount present in the different binders.

  • Hydration of calcium aluminates and calcium sulfoaluminate studied by Raman spectroscopy

     Torrens Martin, David; Fernández Carrasco, Lucía; Martinez Ramirez, Sagrario
    Cement and concrete research
    Vol. 47, p. 43-50
    DOI: 10.1016/j.cemconres.2013.01.015
    Date of publication: 2013-05-01
    Journal article

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    The main hydration reaction product in the ternary system fly ash, calcium sulphate and calcium aluminate cement (40/20/40) at 20°C is a hydrated calcium sulfoaluminate compound, an AFt phase slightly different from ¿traditional ettringite¿. The carbonation of ettringite develops gypsum but in this case rapidcreekite is formed. For the first time it has been observed that carbonation of the mentioned calcium sulfoaluminate compound (AFt), an hydrated calcium sulphate carbonated phase (Ca2(SO4)(CO3)·4H2O) is formed with the replacement of an SO4 row in a (0 4 0) layer of the gypsum by CO3 groups. The developed carbonated phase has been studied and analyzed through XRD, FTIR, Raman spectroscopy, and scanning electron microscopy.

    The main hydration reaction product in the ternary system fly ash, calcium sulphate and calcium aluminate cement (40/20/40) at 20°C is a hydrated calcium sulfoaluminate compound, an AFt phase slightly different from “traditional ettringite”. The carbonation of ettringite develops gypsum but in this case rapidcreekite is formed. For the first time it has been observed that carbonation of the mentioned calcium sulfoaluminate compound (AFt), an hydrated calcium sulphate carbonated phase (Ca2(SO4)(CO3)·4H2O) is formed with the replacement of an SO4 row in a (0 4 0) layer of the gypsum by CO3 groups. The developed carbonated phase has been studied and analyzed through XRD, FTIR, Raman spectroscopy, and scanning electron microscopy.

  • Mezclas Ternarias de Cemento Portland Cemento de Aluminato de Calcio y Sulfato Cálcico: Mecanismos de Expansión  Open access

     Torrens Martin, David
    Universitat Politècnica de Catalunya
    Theses

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    El cemento Portland es el material constructivo más usado. Está compuesto principalmente por silicatos, también tiene en menor proporción aluminatos y sulfato cálcico. Su naturaleza hidráulica, genera que en su hidratación se formen nuevas fases que proporcionan propiedades (endurecimiento, resistencia...) muy útiles en el campo de la construcción.El cemento de aluminato de calcio está compuesto principalmente por aluminatos. Presenta un fraguado más rápido y un desarrollo de resistencias mayores que un cemento Portland. Su hidratación proporciona diferentes fases dependiendo de la temperatura a la que ocurra. Este hecho produce ciertas reacciones de conversión con una disminución del volumen provocando una disminución de las resistencias.Con el fin de generar nuevas propiedades o mejorar alguna de ellas, existe un gran número de materiales compuestos formados por uno o varios cementos con diversas adiciones. Las diferentes combinaciones de materiales, producen una variación en la producción de las fases hidratadas que conllevan cambios en las propiedades mecánicas de los materiales compuestos.Los sistemas ternarios formados por CP/CAC/CS ¯, se han venido usando para producir mezclas con propiedades de fraguado y endurecimiento diferentes a los que presentan los cementos constituyentes por separado. La demanda de este tipo de productos se ha visto incrementada, debido a la necesidad de una rápida puesta en servicio de ciertos sistemas constructivos. No obstante, dentro de los materiales de construcción sus aplicaciones, se han limitado a interiores debido a ciertos problemas de durabilidad.En este trabajo se estudia la zona rica en cemento Portland dentro de los sistemas ternarios CP/CAC/CS ¯. Observando la formación de fases hidratadas, en especial la etringita y relacionándolas con las variaciones dimensionales que se producen.De forma general se observa que un incremento en la formación de etringita produce una mayor variación dimensional. La formación de etringita es función de las relaciones CP/CAC y CAC/CS ¯. El contenido de aluminatos y sulfatos rige la formación de esta fase, si los sulfatos presentes no consumen todos los aluminatos, estos reaccionan con la etringita para formar monosulfoaluminato disminuyendo la expansión. Pero si el contenido en sulfato es alto la formación de etringita aumenta provocando grandes variaciones dimensionales, que para porcentajes superiores al 5% provocan fisuras llegando a la destrucción de probetas si se sube en exceso. Así se comprobó que el medio de curado también influye en la variación dimensional que se produce. Muestras con las mismas proporciones de cementos y sulfato cálcico sufren variaciones diferentes. Cuando se curan al aire se produce retracción, pero cuando se curan bajo agua se produce expansión. Esto se puede deber a diferencias en la intercapa del gel C-S-H desarrollado, siendo más voluminoso en las muestras sumergidas por la inclusión de moléculas de agua.

    Portland cement is the most widely used building material. Is mainly composed of silicates, also has lesser proportion of aluminates and calcium sulfate. Its hydraulic nature generates in its hydration, the formation of new phases which provide properties (hardness, resistance...) very useful in the field of construction. Calcium aluminate cement is mainly composed of aluminate. Present a faster setting and resistance development higher than Portland cement. Its hydration provides different phases depending of the temperature. This fact provides conversion reactions with a volume decrease causing a resistance decrease. For generate a new properties or improve some of them, exist a wide range binders materials formed for one o few cements with diverse additions. The different combinations provide a variation in the hydrated phases produced which generate changes in the mechanical properties of binders materials. Ternary systems formed by CP/CAC/CS, have been used to produce mixtures with different setting and hardened properties than separately cements. However, within of building materials, the applications of these systems are limited at insides due to durability problems. This work studies the Portland cement rich zone within of ternary systems. Noting the hydrated phases formation, in special ettringite and relationship with dimensional variations which be produced. Generally is observed which an increase in the ettringite formation provides a higher dimensional variation. Ettringite formation is function of CP/CAC and CAC/CS ratios. The amount of aluminates and sulfates control the formation of this phase, if the sulfate present do not consumed all aluminates, these reacts with the ettringite to form monosulfoaluminate decreasing the expansion. In the contrary the amount of sulfate is high the ettringite formation higher and provides higher dimensional variation, that percentages up to 5% generates fissures. Also was verified that environmental of cured have influence in the dimensional variation. Samples with the same cement proportion and calcium sulfate have a different variation. When are cured at air be produced retraction, but when is cured under water be produced expansion. This fact may due at differences in the interlayer of the C‐S‐H, being more voluminous in the samples submerged per the inclusion of water molecules.

    El cemento Portland es el material constructivo más usado. Está compuesto principalmente por silicatos, también tiene en menor proporción aluminatos y sulfato cálcico. Su naturaleza hidráulica, genera que en su hidratación se formen nuevas fases que proporcionan propiedades (endurecimiento, resistencia...) muy útiles en el campo de la construcción. El cemento de aluminato de calcio está compuesto principalmente por aluminatos. Presenta un fraguado más rápido y un desarrollo de resistencias mayores que un cemento Portland. Su hidratación proporciona diferentes fases dependiendo de la temperatura a la que ocurra. Este hecho produce ciertas reacciones de conversión con una disminución del volumen provocando una disminución de las resistencias. Con el fin de generar nuevas propiedades o mejorar alguna de ellas, existe un gran número de materiales compuestos formados por uno o varios cementos con diversas adiciones. Las diferentes combinaciones de materiales, producen una variación en la producción de las fases hidratadas que conllevan cambios en las propiedades mecánicas de los materiales compuestos. Los sistemas ternarios formados por CP/CAC/CS, se han venido usando para producir mezclas con propiedades de fraguado y endurecimiento diferentes a los que presentan los cementos constituyentes por separado. La demanda de este tipo de productos se ha visto incrementada, debido a la necesidad de una rápida puesta en servicio de ciertos sistemas constructivos. No obstante, dentro de los materiales de construcción sus aplicaciones, se han limitado a interiores debido a ciertos problemas de durabilidad. En este trabajo se estudia la zona rica en cemento Portland dentro de los sistemas ternarios. Observando la formación de fases hidratadas, en especial la etringita y relacionándolas con las variaciones dimensionales que se producen. De forma general se observa que un incremento en la formación de etringita produce una mayor variación dimensional. La formación de etringita es función de las relaciones CP/CAC y CAC/CS. El contenido de aluminatos y sulfatos rige la formación de esta fase, si los sulfatos presentes no consumen todos los aluminatos, estos reaccionan con la etringita para formar monosulfoaluminato disminuyendo la expansión. Pero si el contenido en sulfato es alto la formación de etringita aumenta provocando grandes variaciones dimensionales, que para porcentajes superiores al 5% provocan fisuras llegando a la destrucción de probetas si se sube en exceso. Así se comprobó que el medio de curado también influye en la variación dimensional que se produce. Muestras con las mismas proporciones de cementos y sulfato cálcico sufren variaciones diferentes. Cuando se curan al aire se produce retracción, pero cuando se curan bajo agua se produce expansión. Esto se puede deber a diferencias en la intercapa del gel C‐S‐H desarrollado, siendo más voluminoso en las muestras sumergidas por la inclusión de moléculas de agua.

    El ciment Portland és el material constructiu més usat. Està compost principalment per silicats, també té en menor proporció aluminats i sulfat càlcic. La seva naturalesa hidràulica genera que a la seva hidratació es formin noves fases que proporcionen propietats (enduriment, resistència...) molt útils en el camp de la construcció. El ciment d’aluminat de calci es composa principalment per aluminats. Presenta un fraguat mes ràpid i un desenvolupament de resistències majors que el ciment Portland. La seva hidratació proporciona diferents fases depenent de la temperatura a la que es produeixi. Aquest fet produeix certes reaccions de conversió amb una disminució del volum provocant una disminució de les resistències. Amb la finalitat de generar noves propietats o millorar alguna d’elles, existeix un gran nombre de materials compostos formats per un o més ciments amb diversos afegits. Les diferents combinacions de materials produeixen una variació a la producció de fases hidratades que porten canvis a les propietats mecàniques dels materials compostos. Els sistemes ternaris formats per CP/CAC/CS , s’han utilitzat per a produir mescles amb propietats de fraguat i enduriment diferents als que presenten els ciments constituents per separat. La demanda d’aquest tipus de productes s’ha vist incrementada degut a la necessitat d’una ràpida posada en servei de certs sistemes constructius. No obstant, dins dels materials de construcció les seves aplicacions s’han limitat a interiors degut a certs problemes de durabilitat. En aquest treball s’estudia la zona rica en ciment Portland dins dels sistemes ternaris, observant la formació de fases hidratades, en especial la etringita i relacionant‐les amb les variacions dimensionals que es produeixen. De forma general s’observa que un increment en la formació d’etringita produeix una major variació dimensional. La formació d’etringita es funció de les relacions CP/CAC y CAC/CS. El contingut d’aluminats i sulfats regeix la formació d’aquesta fase: si els sulfats presents no consumeixen tots els aluminats, aquests reaccionen amb l’etringita per a formar monosulfoaluminat disminuint l’expansió. Però si el contingut de sulfat és alt la formació d’etringita augmenta provocant grans variacions dimensionals, que per a percentatges superiors al 5% provoquen fissures arribant a la destrucció de provetes si puja en excés. Així es va comprovar que el mitjà de crat també influeix en la variació dimensional que es produeix. Mostres amb les mateixes proporcions de ciments i sulfat càlcic pateixen variacions diferents. Quan es curen a l’aire es produeix retracció, però quan es curen sota l’aigua es produeix expansió. Això pot ser degut a diferències en l’intercapa del gel C‐S‐H desenvolupat, essent mes voluminosos a les mostres submergides per la inclusió de molècules d’aigua.

  • Materials a l'arquitectura

     Fernández Carrasco, Lucía
    Date of publication: 2013-11-29
    Book

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  • Effects of curing conditions and silica fume content on the hydration degree of vegetable fiber reinforced cement composites

     Claramunt Blanes, Josep; Ardanuy Raso, Monica; Fernández Carrasco, Lucía
    European and Exhibition Congress on Advanced Materials and Processes
    p. 1
    Presentation's date: 2013-09-10
    Presentation of work at congresses

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  • Influencia de las condiciones de curado y contenido en humo de sílice en las propiedades de matrices cementíceas reforzadas con fibras vegetales

     Claramunt Blanes, Josep; Fernández Carrasco, Lucía; Ardanuy Raso, Monica
    Congreso Nacional de Materiales Compuestos
    p. 311-316
    Presentation's date: 2013-07-04
    Presentation of work at congresses

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    El objetivo del presente trabajo es desarrollar compuestos de cemento reforzados con fibras vegetales que presenten una mayor durabilidad y que puedan curarse con tiempos cortos. Para ello se analizan la influencia de las condiciones de curado ¿ en autoclave o en cámara estándar¿ y la adición de humo de sílice y fibras de sisal en la hidratación y resistencia de matrices de cemento portland.

  • Els materials que fem servir a l'Arquitectura

     Fernández Carrasco, Lucía
    Competitive project

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    Infrared spectroscopy in the analysis of building and construction materials  Open access

     Fernández Carrasco, Lucía; Torrens Martin, David; Morales Martinez, Laura Maria; Martinez Ramirez, Sagrario
    Date of publication: 2012-03-30
    Book chapter

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  • Carbonation of ternary cement systems

     Martinez Ramirez, Sagrario; Fernández Carrasco, Lucía
    Construction & building materials
    Vol. 27, num. 1, p. 313-318
    DOI: 10.1016/j.conbuildmat.2011.07.043
    Date of publication: 2012-02
    Journal article

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    The main hydration reaction product in the ternary system fly ash, calcium sulphate and calcium aluminate cement (40/20/40) at 20°C is a hydrated calcium sulfoaluminate compound, an AFt phase slightly different from ¿traditional ettringite¿. The carbonation of ettringite develops gypsum but in this case rapidcreekite is formed. For the first time it has been observed that carbonation of the mentioned calcium sulfoaluminate compound (AFt), an hydrated calcium sulphate carbonated phase (Ca2(SO4)(CO3)·4H2O) is formed with the replacement of an SO4 row in a (0 4 0) layer of the gypsum by CO3 groups. The developed carbonated phase has been studied and analyzed through XRD, FTIR, Raman spectroscopy, and scanning electron microscopy.

    The main hydration reaction product in the ternary system fly ash, calcium sulphate and calcium aluminate cement (40/20/40) at 20°C is a hydrated calcium sulfoaluminate compound, an AFt phase slightly different from “traditional ettringite”. The carbonation of ettringite develops gypsum but in this case rapidcreekite is formed. For the first time it has been observed that carbonation of the mentioned calcium sulfoaluminate compound (AFt), an hydrated calcium sulphate carbonated phase (Ca2(SO4)(CO3)·4H2O) is formed with the replacement of an SO4 row in a (0 4 0) layer of the gypsum by CO3 groups. The developed carbonated phase has been studied and analyzed through XRD, FTIR, Raman spectroscopy, and scanning electron microscopy.

  • Carbonation of ternary building cementing materials

     Fernández Carrasco, Lucía; Torrens Martin, David; Martinez Ramirez, Sagrario
    Cement & concrete composites
    Vol. 34, num. 10, p. 1180-1186
    DOI: 10.1016/j.cemconcomp.2012.06.016
    Date of publication: 2012-11
    Journal article

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    The carbonation processes of ettringite and calcium aluminate hydrates phases developed by hydration of calcium aluminate cement, fly ash and calcium sulphate ternary mixtures have been studied. The hydrated samples were submitted to 4% of CO2 in a carbonation chamber, and were analysed, previous carbonation and after 14 and 90 days of carbonation time, by infrared spectroscopy and X-ray diffraction; the developed morphology was performed with the 14 days carbonated samples. The results evidenced that ettringite reacts with CO2 after 14 days of exposition time and evolves totally at 90 days; the developed hydrated phases C3AH6 in samples with major CAC content, also reacts with CO2. Due to carbonation, calcium carbonate ¿ mainly vaterite but also aragonite-, depending on the initial formulation, aluminium hydroxide and gypsum were detected.

    The carbonation processes of ettringite and calcium aluminate hydrates phases developed by hydration of calcium aluminate cement, fly ash and calcium sulphate ternary mixtures have been studied. The hydrated samples were submitted to 4% of CO2 in a carbonation chamber, and were analysed, previous carbonation and after 14 and 90 days of carbonation time, by infrared spectroscopy and X-ray diffraction; the developed morphology was performed with the 14 days carbonated samples. The results evidenced that ettringite reacts with CO2 after 14 days of exposition time and evolves totally at 90 days; the developed hydrated phases C3AH6 in samples with major CAC content, also reacts with CO2. Due to carbonation, calcium carbonate – mainly vaterite but also aragonite-, depending on the initial formulation, aluminium hydroxide and gypsum were detected.

  • Estudio de los cementos anhidros e hidratados a través de espectroscopía Raman

     Martinez Ramirez, Sagrario; Fernández Carrasco, Lucía
    Cemento hormigón : fabricación, investigación y aplicaciones del cemento y del hormigón
    num. 942, p. 4-8
    Date of publication: 2011-01
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  • Recycling silicon solar cell waste in cement-based systems

     Fernández Carrasco, Lucía; Ferrer, R.; Aponte Hernandez, Diego Fernando; Fernández, P.
    Solar energy materials and solar cells
    Vol. 95, num. 7, p. 1701-1706
    DOI: 10.1016/j.solmat.2011.01.033
    Date of publication: 2011-03-03
    Journal article

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    This is a study of the recycling of crystalline solar cells by incorporating them in cement matrices. The hydration process of a mixture of calcium aluminate cement (CAC) and solar photovoltaic cell waste was researched and analyzed. The nature of the hydration products of various compositions of these mixtures was evaluated at a temperature of 20 1C by analyzing the samples through X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The total porosity and mechanical strength development of these materials were also determined. It was revealed that the presence of a solar cell residue of up to 5% in the cement matrices does not result in new hydration products that are different from those derived from the normal hydration of the CAC cement. Moreover, the material developed can be considered as an expansive cement blend because it releases H2 at early stages. The presence of waste causes a decrease in the mechanical strength and an increase in the total porosity of this material, but it can be used for applications such as thermal insulation.

    This is a study of the recycling of crystalline solar cells by incorporating them in cement matrices. The hydration process of a mixture of calcium aluminate cement (CAC) and solar photovoltaic cell waste was researched and analyzed. The nature of the hydration products of various compositions of these mixtures was evaluated at a temperature of 20 1C by analyzing the samples through X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The total porosity and mechanical strength development of these materials were also determined. It was revealed that the presence of a solar cell residue of up to 5% in the cement matrices does not result in new hydration products that are different from those derived from the normal hydration of the CAC cement. Moreover, the material developed can be considered as an expansive cement blend because it releases H2 at early stages. The presence of waste causes a decrease in the mechanical strength and an increase in the total porosity of this material, but it can be used for applications such as thermal insulation

  • Mezclas ternarias basadas en cemento Portland, cemento de aluminato de calcio y sulfato de calcio.

     Fernández Carrasco, Lucía; Martinez Ramirez, Sagrario; Fernandez, Pedro
    Cemento hormigón : fabricación, investigación y aplicaciones del cemento y del hormigón
    Vol. MARZO/ABRIL, num. 943, p. 245-253
    Date of publication: 2011-02-15
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    Evolution to carbonated compounds of phases developed on ternary systems materials  Open access

     Fernández Carrasco, Lucía; Torrens Martin, David; Morales Martinez, Laura Maria; Martinez Ramirez, Sagrario; Fernández, Pedro
    International Congress on the Chemistry of Cement
    p. 345-352
    Presentation's date: 2011-07-15
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    The incorporation of supplementary cementitious materials to the cement industry is an alternative to reduce consume of large amounts of raw materials and gives up a huge spectrum of blended cements that have been noted not only for its properties of reducing energy consumption and CO2 emission but also for its well known durability properties. In this research work we evaluate ternary systems from CAC/FA/C$ mixtures, focusing on their durability. Selected formulations in the ternary system CAC/FA/C$ hydrated and carbonated have been studied at 14 and 90 days of carbonation time. The carbonation process of ettringite phases and calcium aluminate hydrates proceeded from different formulations, i.e. calcium aluminate cement, fly ash predominance, and calcium sulphate is analysed and discussed by means of infrared spectroscopy, x-ray diffraction but also mechanical properties of samples. The analysis of the results have shown that developed hydrated compounds depend on formulation; after carbonation process, the ettringite decomposition can promote metastable calcium carbonate polymorphs (aragonite and vaterite) due to inorganic compounds (aluminium hydroxide, gypsum, etc) presence. Long term carbonation of the blended samples analysis by Raman spectroscopy allows the identification of a new hydrated phase with carbonate, sulphate and calcium ions in its structure.

    Originality This paper describes for the first time a study of the durability of different selected formulations in the ternary system CAC/FA/C$ which substitutes the Portland cement by by-products. On the hydrates characterization, the Infrared and Raman spectroscopies allow the identification of differentiate ettringite structures.

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    Raman spectroscopy: applycation to cementitious systems  Open access

     Martinez Ramirez, Sagrario; Fernández Carrasco, Lucía
    Date of publication: 2010-12-13
    Book chapter

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    Raman scattering was discovered by Krisma and Raman in 1928. Until approximately 1986, the Raman literature was dominated by physical and structural investigations, with relatively few reports of Raman spectroscopy applied to chemical analysis due to several technical and fundamental problems, such as weak intensity, fluorescence interference, and inefficient light collection and detection. When the introduction of Fourier transform (FT)-Raman, charge-coupled devices, small computers and near-infrared laser, the major impediments were solved and resulted in a Raman renaissance in the chemical analysis context. Spectroscopic techniques have proved to be appropriate tools for studying cement hydration; however, fluorescence effect in anhydrous cement can give anomalous results. With the micro-Raman technique, spectra can be obtained for surface samples just a few microns thick and with minimal interference from the surrounding water. On such a scale, the interference from fluorescence, so often a problem when working with bulk cement slurry is also minimized. Spectra can be obtained rapidly and extensive sample preparation is not needed.

  • DURABILIDAD DE MEZCLAS TERNARIAS BASADAS EN CEMENTO PORTLAND, ALUMINATOS DE CALCIO Y SULFATOS DE CALCIO: MECANISMOS DE EXPANSION

     Torrens Martin, David; Morales Martinez, Laura Maria; Fernández Carrasco, Lucía
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    Stabilization of photovoltaic panels cell wastes in building material matrices  Open access

     Fernández Carrasco, Lucía; Ferrer, Rober; Aponte Hernandez, Diego Fernando; Martínez-Ramírez, Sagrario
    Spanish National Conference on Advances in Materials Recycling and Eco- Energy
    p. 189-192
    Presentation's date: 2009-11-13
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    This is a study about the hydration process of a mixture of Portland cement and solar photovoltaic cells waste. The nature of the hydration products of different compositions of these mixtures have been evaluated, at 20º C of temperature, by means of the analysis of samples throughout x- ray diffraction and infrared spectroscopy. The total porosity and mechanical strength development of those materials was also determined. It was revealed that the presence of solar cell residue –up to 5%- in the cement matrices do not induce to the develop of new hydration products different of those from the normal hydration of the Portland cement. However, the presence of the waste induces to a reduction of the mechanical strength and an increase in the total porosity is evidenced.

  • Reactions of fly ash with calcium aluminate cement and calcium sulphate

     Fernández Carrasco, Lucía; Vazquez Ramonich, Enric
    Fuel (Guildford)
    Vol. 88, num. 9, p. 1533-1538
    DOI: 10.1016/j.fuel.2009.02.018
    Date of publication: 2009-09
    Journal article

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    The hydration processes in the ternary system fly ash/calcium aluminate cement/calcium sulphate (FA/CAC/C$) at 20 °C were investigated; six compositions from the ternary system FA/CAC/C$ were selected for this study. The nature of the reaction products in these pastes were analysed by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). At four days reaction time, the main hydration reaction product in these pastes was ettringite and the samples with major initial CAC presented minor ettringite but calcium aluminates hydrates. The amount of ettringite developed in the systems has no direct relation with the initial components.

    The hydration processes in the ternary system fly ash/calcium aluminate cement/calcium sulphate (FA/CAC/C$) at 20 °C were investigated; six compositions from the ternary system FA/CAC/C$ were selected for this study. The nature of the reaction products in these pastes were analysed by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). At four days reaction time, the main hydration reaction product in these pastes was ettringite and the samples with major initial CAC presented minor ettringite but calcium aluminates hydrates. The amount of ettringite developed in the systems has no direct relation with the initial components.

  • Calcium aluminate cements with supplementary cementitious materials: fly ashes

     Fernández Carrasco, Lucía
    CALCIUM ALUMINATE CEMENTS- THE CENTENARY CONFERENCE.
    p. 475-483
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  • Formacion de etringita en mezclas ternarias

     Fernández Carrasco, Lucía
    Congreso Nacional de Materiales
    p. 979-982
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  • Microstructural characterization of fly ash blended with calcium aluminates and calcium sulphate

     Fernández Carrasco, Lucía; Rius, J.
    Cement and concrete research
    Vol. -, num. -, p. 1-2
    Date of publication: 2008-01
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  • Supercritical carbonation of calcium aluminate cement

     Fernández Carrasco, Lucía; Miravitlles, C; Rius, J.
    Cement and concrete research
    Vol. 38, num. 8-9, p. 1033-1037
    DOI: 10.1016/j.cemconres.2008.02.013
    Date of publication: 2008-08
    Journal article

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    The microstructural changes occurring during supercritical carbonation (scCO2) of calcium aluminate cement (CAC) and changes to its strength have been investigated. Cylindrical specimens of CAC cured at different temperatures were prepared and then subjected to scCO2. It is shown that CAC carbonation in supercritical conditions is accelerated with a positive effect on the compressive strength. Due to the scCO2 treatment, both conversion and alkaline hydrolysis are avoided. The best behaviour of the studied specimens was attained for samples cured at 25 °C. The residual compounds after the scCO2 process, i.e. monocalcium aluminate, calcium carbonate and aluminium hydroxide are durable in normal ambient conditions. Complete carbonation of CAC is particularly important for the reinforcement of CAC with polymer fibres to improve its mechanical strength.

    The microstructural changes occurring during supercritical carbonation (scCO2) of calcium aluminate cement (CAC) and changes to its strength have been investigated. Cylindrical specimens of CAC cured at different temperatures were prepared and then subjected to scCO2. It is shown that CAC carbonation in supercritical conditions is accelerated with a positive effect on the compressive strength. Due to the scCO2 treatment, both conversion and alkaline hydrolysis are avoided. The best behaviour of the studied specimens was attained for samples cured at 25 °C. The residual compounds after the scCO2 process, i.e. monocalcium aluminate, calcium carbonate and aluminium hydroxide are durable in normal ambient conditions. Complete carbonation of CAC is particularly important for the reinforcement of CAC with polymer fibres to improve its mechanical strength.

  • Expansion mechanisms in binary and ternary high sulphate blends

     Fernández Carrasco, Lucía
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  • Alkali activation of "Pozzolan-calcium aluminate cement" mixtures

     Fernández Carrasco, Lucía
    12th International Congress on the Chemistry of Cements
    Presentation's date: 2007-07-11
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    Alkali activation of "Pozzolan-calcium aluminate cement" mixtures  Open access

     Fernández Carrasco, Lucía; Fernández-Giménez, A; Palomo, A
    12th International Congress on the Chemistry of Cements
    Presentation of work at congresses

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  • Low pH calcium aluminate cement. Supercritical carbonation.

     Fernández Carrasco, Lucía
    Advances in Cement and Concrete: Sustainability
    Presentation's date: 2006-07-04
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  • Synthesis and crystal structure determination of hydrated potassium dawsonite from powder diffraction data

     Fernández Carrasco, Lucía
    European journal of mineralogy
    Vol. 18, num. 1, p. 99-104
    Date of publication: 2006-02
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  • Synthesis and crystal structure solution of potassium Dawsonite : an intermediate compound in the alkaline hydrolysis of calcium aluminate cements

     Fernández Carrasco, Lucía; Puertas, F; Blanco-Varela, M T; Vázquez, T; Rius, J.
    Cement and concrete research
    Vol. 35, num. 4, p. 641-646
    DOI: 10.1016/j.cemconres.2004.04.018
    Date of publication: 2005-04
    Journal article

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    Potassium dawsonite is formed as an intermediate compound during the alkaline hydrolysis (AH) in calcium aluminate cements (CACs). A synthesis method of potassium dawsonite has been developed. The crystal structure of potassium dawsonite KAl(CO3)(OH)2 has been solved by direct methods from X-ray powder diffraction data and refined with the Rietveld method. It crystallises in the orthorhombic Cmcm space group with unit cells parameters a=6.3021(3) Å, b=11.9626(5) Å, c=5.6456(3) Å and Z=4. The structure consists of carboaluminate chains, formed by the basic unit [Al2(OH)4(CO3)2]2- arranged along the c axis. The carbonate groups are placed in an alternate manner at both sides of the carboaluminate chains. The carboaluminate chains are also held together by the K+ cations that are located in the middle of three such chains. Finally, the chemical reactions explaining the AH process in CACs are postulated.

    Potassium dawsonite is formed as an intermediate compound during the alkaline hydrolysis (AH) in calcium aluminate cements (CACs). A synthesis method of potassium dawsonite has been developed. The crystal structure of potassium dawsonite KAl(CO3)(OH)2 has been solved by direct methods from X-ray powder diffraction data and refined with the Rietveld method. It crystallises in the orthorhombic Cmcm space group with unit cells parameters a=6.3021(3) Å, b=11.9626(5) Å, c=5.6456(3) Å and Z=4. The structure consists of carboaluminate chains, formed by the basic unit [Al2(OH)4(CO3)2]2− arranged along the c axis. The carbonate groups are placed in an alternate manner at both sides of the carboaluminate chains. The carboaluminate chains are also held together by the K+ cations that are located in the middle of three such chains. Finally, the chemical reactions explaining the AH process in CACs are postulated.

  • Crystal structure solution of the low and high temperature forms of potassium dawsonite: An intermediate compound in the alkaline hydrolysis of calcium aluminate cements.

     Fernández Carrasco, Lucía
    European Crystallographic Meeting
    Presentation's date: 2004-08-23
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  • Potassium dawsonite structures in calcium aluminate cement solved from X-ray diffraction and refined with the Rietveld method

     Fernández Carrasco, Lucía
    XV Symposium del Grupo Especializado de Cristalografía
    Presentation's date: 2004-08-21
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  • Nuevos desarrollos cristalográficos basados en la "modulus sum function."

     Rius Pajeiro, Jordi; Fernández Carrasco, Lucía
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  • Microstructural development in hydrated and carbonated calcium aluminate cement: influence of alkalis and strength behaviour

     Fernández Carrasco, Lucía
    11th International Congress on the Chemistry of Cement.
    Presentation's date: 2003-05-16
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  • Microstructural development in hydrated and carbonated calcium aluminate cement: influence of alkalis and strength behaviour

     Fernández Carrasco, Lucía
    11th International Congress on the Chemistry of Cement.
    Presentation's date: 2003-05-16
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  • Technological development and innovation in material science in the Spanish system

     Fernández Carrasco, Lucía
    Materials technology
    Vol. 16, num. 4, p. 228-229
    Date of publication: 2001-04
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  • Potassium dawsonite formation in calcium aluminate cements

     Fernández Carrasco, Lucía
    International conference on calcium aluminate cements
    Presentation's date: 2001-07-01
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    Carbonatación de pastas de cemento de aluminato de calcio  Open access

     Fernández Carrasco, Lucía; Puertas, F; Blanco, M T; Vázquez, T
    Materiales de construcción (Madrid)
    Vol. 51, num. 263-264, p. 127-136
    DOI: 10.3989/mc.2001.v51.i263-264.358
    Date of publication: 2001-07
    Journal article

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    En el presente trabajo se discuten los resultados obtenidos en los ensayos acelerados llevados a cabo para investigar los efectos de diferentes métodos de curado sobre la carbonatacion de pastas del cemento de aluminato de calcio (CAC). Se estudió la composición mineralógica de las muestras hidratadas y carbonatadas. Además, se determinaron las resistencias mecánicas a compresión y la porosidad de las probetas. Los resultados indican que la vaterita y el aragonito son las polimorfías del CaCO3 que se forman al carbonatar los aluminatos cálcicos hidratos, tanto los de naturaleza hexagonal como cúbica. El polimorfo del carbonato cálcico formado no depende del proceso de curado. La velocidad de carbonatación de los hidratos hexagonales es mayor que la de los cúbicos. Los resultados obtenidos en el presente trabajo han evidenciado que como consecuencia del proceso de carbonatación sobre pastas de CAC, en las condiciones realizadas, se produce un incremento en las resistencias mecánicas.

    En el presente trabajo se discuten los resultados obtenidos en los ensayos acelerados llevados a cabo para investigar los efectos de diferentes métodos de curado sobre la carbonatacion de pastas del cemento de aluminato de calcio (CAC). Se estudió la composición mineralógica de las muestras hidratadas y carbonatadas. Además, se determinaron las resistencias mecánicas a compresión y la porosidad de las probetas. Los resultados indican que la vaterita y el aragonito son las polimorfías del CaCO3 que se forman al carbonatar los aluminatos cálcicos hidratos, tanto los de naturaleza hexagonal como cúbica. El polimorfo del carbonato cálcico formado no depende del proceso de curado. La velocidad de carbonatación de los hidratos hexagonales es mayor que la de los cúbicos. Los resultados obtenidos en el presente trabajo han evidenciado que como consecuencia del proceso de carbonatación sobre pastas de CAC, en las condiciones realizadas, se produce un incremento en las resistencias mecánicas.

  • New theories on the "alkaline hydrolysis in high alumina cement

     Fernández Carrasco, Lucía
    5th CANMET/ACI International Conference on Durability of Concrete
    Presentation's date: 2000-06-04
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  • Hydration of high alumina cement in presence of alkalis

     Fernández Carrasco, Lucía
    Advances in cement research
    Vol. 12, p. 141-152
    Date of publication: 2000-06
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  • Síntesis y caracterización del compuesto K 4Al 6(CO ) 3 11-x (OH) 2x(H 2O)y

     Fernández Carrasco, Lucía
    VI Reunión Nacional de Materiales
    Presentation's date: 1999-06-22
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  • A Discussion of the paper "Hydration reactions of nonstoichiometric Barium orthoaluminates" by T.R.N. Kutty and M. Nayak

     Fernández Carrasco, Lucía
    Cement and concrete research
    Vol. 29, num. 10, p. 1697-1698
    DOI: 10.1016/S0008-8846(99)00125-8
    Date of publication: 1999-02
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