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Moises Frias - One of the best experts on this subject based on the ideXlab platform.
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influence of zno on the activation of kaolinite based coal waste pozzolanic activity and mineralogy in the pozzolan lime system
Applied Clay Science, 2018Co-Authors: Rosario Garciagimenez, Lucia Fernandezcarrasco, S Martinezramirez, Vigil R De La Villa, Moises FriasAbstract:Abstract One inconvenience presented by the thermal activation of kaolinite-based wastes is their low content of metakaolinite, a highly pozzolanic product listed in current standards for the manufacture of commercial cements. The addition of a chemical activator during the thermal activation process is a priority line of research to increase the reactivity of the recycled metakaolinite. In this paper, an additional chemical activator, ZnO, is studied and its effect on both pozzolanic properties and the evolution of mineralogical phases in the thermal activation of coal waste with a reaction time of up to 90 days in the pozzolan/lime system. To do so, activation temperatures of between 550 °C/650 °C were selected and additions of chemical activator (ZnO) in percentages of between 0.0% and 3.0% by weight of coal waste, because it is an activator with a positive effect on a 100% natural kaolinite. The results showed that the incorporation of ZnO inhibited the reactivity of the recycled metakaolinite and in consequence, the capacity of the metakaolinite to react with the surrounding lime; even more so when the content of added chemical activator was raised, albeit with some exceptions, in the samples activated at 550 °C and 650 °C with 0.5% of chemical activator. In none of the cases under analysis was the chemical activator able to improve the properties of the metakaolinite in comparison with the properties of the reference sample activated only with temperature. The Hydrated phases that appeared in the pozzolanic reaction were tetracalcium Aluminate Hydrate, stratlingite, monosulfoAluminate Hydrate and LDH (phyllosilicate/carbonate).
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mineralogical study of calcined coal waste in a pozzolan ca oh 2 system
Applied Clay Science, 2015Co-Authors: Rosario Garcia, Olga Rodriguez, Moises Frias, Raquel Vigil De La Villa, S Martinezramirez, Lucia Fernandezcarrasco, I S De Soto, E VillarcocinaAbstract:Abstract Activated carbon mining waste influences the formation of Hydrated phases, their saturation indexes and mineral stability fields during pozzolanic reactions. The behavior of these reactions is predicted in this study by examining the influence of carbon waste at 600 °C over 2 h, by means of a thermodynamic model running on a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations (PHREEQC program: pH - RE dox- Eq uilibrium in Program C ). Experimental analysis of the solid phases shows early formation of monosulfoAluminate Hydrate, C–S–H phases and subsequent precipitation of laminar minerals, tetracalcium Aluminate Hydrate, layered double hydroxide compounds (phyllosilicate/carbonate) (LDH) and stratlingite. MonosulfoAluminate Hydrate was formed on day one of the reaction for samples with activated coal mining waste. The thermodynamic calculations confirmed the experimental observations.
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Chemical and mineral transformations that occur in mine waste and washery rejects during pre-utilization calcination
International Journal of Coal Geology, 2014Co-Authors: R. Vigil De La Villa, Rosario García Giménez, Moises Frias, Sagrario Martínez-ramírez, Lucía Fernández-carrascoAbstract:Abstract The mineralogical content of coal mine waste consists primarily of inorganic compounds which can be converted into a metakaolin-based product under controlled activation conditions that is also a highly pozzolanic material. Activation temperatures ranging from 500 to 900 °C over 2 h retention time affect the mineralogy of coal mine waste, as well as the formation and evolution of the Hydrated phases that form during the pozzolanic reaction. The Hydrated phases formed during the pozzolanic reaction in the activated coal mine waste (ACMW)/Ca(OH) 2 system were C–S–H gels, stratlingite, tetracalcium Aluminate Hydrate, LDH compounds (phyllosilicate/carbonate) and monosulfoAluminate. Low temperatures (600 °C) favored the formation of LDH compounds and stratlingite; whereas monosulfoAluminate formed during the Hydrated phase at higher temperatures (900 °C) during the first day of the pozzolanic reaction, and tetracalcium Aluminate Hydrate appeared as the dominant crystalline phase at 7 and 28 days.
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mineral phases in an activated kaolinitic waste blended cement system
Applied Clay Science, 2010Co-Authors: Vigil R De La Villa, Olga Rodriguez, Rosario Garcia, Moises FriasAbstract:Abstract Addition of pozzolans to blended cements is well known to have a positive effect due to the pozzolanic reaction. For some pozzolanic materials such as clays, the activation temperature plays an important role in the mineralogy and in the pozzolanic reaction. This paper reports the influence of the activation conditions (700 to 800 °C for 2 or 5 h in a furnace) of a clay waste on the mineralogy of a 20% blended cement matrix at 28 days of normalised curing. The mineralogical composition changes were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) — energy dispersive X-ray spectroscopy (EDX). The presence of an unstable LDH-like compounds (without magnesium) and the presence of tetracalcium Aluminate Hydrate (C 4 AH 13 ) and calcium hydroxide, and the persistence of alite (Portland cement compound), was identified.
Morten Daugaard Andersen - One of the best experts on this subject based on the ideXlab platform.
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a new aluminium Hydrate species in Hydrated portland cements characterized by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2006Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:Abstract Recent 27 Al MAS NMR studies of Hydrated Portland cements and calcium-silicate-Hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known Aluminate species in Hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different Hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered Aluminate Hydrate which contains Al(OH) 6 3− or O x Al(OH) 6- x (3+ x )− units. The formation of the new Aluminate Hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70–90 °C. From the experiments in this work it is proposed that the new Aluminate Hydrate is either an amorphous/disordered Aluminate hydroxide or a calcium Aluminate Hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed.
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characterization of white portland cement hydration and the c s h structure in the presence of sodium Aluminate by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2004Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Joergen SkibstedAbstract:Abstract The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium Aluminate (NaAlO2) at 5 and 20 °C are investigated by 27Al and 29Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO2 accelerates the hydration of alite and belite and results in calcium-silicate-Hydrate (C-S-H) phases with longer average chain lengths of SiO4/AlO4 tetrahedra. The C-S-H phases are investigated in detail and it is shown that the Al/Si ratio for the chains of tetrahedra is quite constant during the time studied for the hydration (6 h to 2 years) but increases for higher concentration of the NaAlO2 solution. The average chain lengths of “pure” silicate and SiO4/AlO4 tetrahedra demonstrate that Al acts as a linker for the silicate chains, thereby producing aluminosilicate chains with longer average chain lengths. Finally, it is shown that NaAlO2 reduces the quantity of ettringite and results in larger quantities of monosulfate and a calcium Aluminate Hydrate phase.
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characterization of white portland cement hydration and the c s h structure in the presence of sodium Aluminate by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2004Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Joergen SkibstedAbstract:The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium Aluminate (NaAlO{sub 2}) at 5 and 20 deg. C are investigated by {sup 27}Al and {sup 29}Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO{sub 2} accelerates the hydration of alite and belite and results in calcium-silicate-Hydrate (C-S-H) phases with longer average chain lengths of SiO{sub 4}/AlO{sub 4} tetrahedra. The C-S-H phases are investigated in detail and it is shown that the Al/Si ratio for the chains of tetrahedra is quite constant during the time studied for the hydration (6 h to 2 years) but increases for higher concentration of the NaAlO{sub 2} solution. The average chain lengths of 'pure' silicate and SiO{sub 4}/AlO{sub 4} tetrahedra demonstrate that Al acts as a linker for the silicate chains, thereby producing aluminosilicate chains with longer average chain lengths. Finally, it is shown that NaAlO{sub 2} reduces the quantity of ettringite and results in larger quantities of monosulfate and a calcium Aluminate Hydrate phase.
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C−S−H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO2 solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by 27Al and 29Si MAS NMR spectroscopy. 27Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the 27Al isotropic chemical shift (δiso) and quadrupolar product parameter (PQ = CQ ) for tetrahedrally coordinated Al incorporated in the C−S−H phase and for a pentacoordinated Al site. The latter site may originate from Al3+ substituting for Ca2+ ions situated in the interlayers of the C−S−H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (δiso = 5.0 ppm and PQ = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C−S−H phase has been quan...
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C-S-H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO(2) solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by (27)Al and (29)Si MAS NMR spectroscopy. (27)Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the (27)Al isotropic chemical shift (delta(iso)) and quadrupolar product parameter (P(Q) = C(Q)) for tetrahedrally coordinated Al incorporated in the C-S-H phase and for a pentacoordinated Al site. The latter site may originate from Al(3+) substituting for Ca(2+) ions situated in the interlayers of the C-S-H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (delta(iso) = 5.0 ppm and P(Q) = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C-S-H phase has been quantitatively determined from (27)Al MAS spectra at 14.09 T and indirectly observed quantitatively in (29)Si MAS NMR spectra by the Q(2)(1Al) resonance at -81.0 ppm. A linear correlation is observed between the (29)Si MAS NMR intensity for the Q(2)(1Al) resonance and the quantity of Al incorporated in the C-S-H phase from (27)Al MAS NMR for the different samples of Hydrated wPc. This correlation supports the assignment of the resonance at delta(iso)((29)Si) = -81.0 ppm to a Q(2)(1Al) site in the C-S-H phase and the assignment of the (27)Al resonance at delta(iso)((27)Al) = 74.6 ppm, characterized by P(Q)((27)Al) = 4.5 MHz, to tetrahedrally coordinated Al in the C-S-H. Finally, it is shown that hydration of wPc in a NaAlO(2) solution results in a C-S-H phase with a longer mean chain length of SiO(4) tetrahedra and an increased quantity of Al incorporated in the chain structure as compared to the C-S-H phase resulting from hydration of wPc in water.
Jorgen Skibsted - One of the best experts on this subject based on the ideXlab platform.
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a new aluminium Hydrate species in Hydrated portland cements characterized by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2006Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:Abstract Recent 27 Al MAS NMR studies of Hydrated Portland cements and calcium-silicate-Hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known Aluminate species in Hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different Hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered Aluminate Hydrate which contains Al(OH) 6 3− or O x Al(OH) 6- x (3+ x )− units. The formation of the new Aluminate Hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70–90 °C. From the experiments in this work it is proposed that the new Aluminate Hydrate is either an amorphous/disordered Aluminate hydroxide or a calcium Aluminate Hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed.
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C−S−H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO2 solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by 27Al and 29Si MAS NMR spectroscopy. 27Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the 27Al isotropic chemical shift (δiso) and quadrupolar product parameter (PQ = CQ ) for tetrahedrally coordinated Al incorporated in the C−S−H phase and for a pentacoordinated Al site. The latter site may originate from Al3+ substituting for Ca2+ ions situated in the interlayers of the C−S−H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (δiso = 5.0 ppm and PQ = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C−S−H phase has been quan...
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C-S-H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO(2) solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by (27)Al and (29)Si MAS NMR spectroscopy. (27)Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the (27)Al isotropic chemical shift (delta(iso)) and quadrupolar product parameter (P(Q) = C(Q)) for tetrahedrally coordinated Al incorporated in the C-S-H phase and for a pentacoordinated Al site. The latter site may originate from Al(3+) substituting for Ca(2+) ions situated in the interlayers of the C-S-H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (delta(iso) = 5.0 ppm and P(Q) = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C-S-H phase has been quantitatively determined from (27)Al MAS spectra at 14.09 T and indirectly observed quantitatively in (29)Si MAS NMR spectra by the Q(2)(1Al) resonance at -81.0 ppm. A linear correlation is observed between the (29)Si MAS NMR intensity for the Q(2)(1Al) resonance and the quantity of Al incorporated in the C-S-H phase from (27)Al MAS NMR for the different samples of Hydrated wPc. This correlation supports the assignment of the resonance at delta(iso)((29)Si) = -81.0 ppm to a Q(2)(1Al) site in the C-S-H phase and the assignment of the (27)Al resonance at delta(iso)((27)Al) = 74.6 ppm, characterized by P(Q)((27)Al) = 4.5 MHz, to tetrahedrally coordinated Al in the C-S-H. Finally, it is shown that hydration of wPc in a NaAlO(2) solution results in a C-S-H phase with a longer mean chain length of SiO(4) tetrahedra and an increased quantity of Al incorporated in the chain structure as compared to the C-S-H phase resulting from hydration of wPc in water.
Hans J. Jakobsen - One of the best experts on this subject based on the ideXlab platform.
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a new aluminium Hydrate species in Hydrated portland cements characterized by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2006Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:Abstract Recent 27 Al MAS NMR studies of Hydrated Portland cements and calcium-silicate-Hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known Aluminate species in Hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different Hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered Aluminate Hydrate which contains Al(OH) 6 3− or O x Al(OH) 6- x (3+ x )− units. The formation of the new Aluminate Hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70–90 °C. From the experiments in this work it is proposed that the new Aluminate Hydrate is either an amorphous/disordered Aluminate hydroxide or a calcium Aluminate Hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed.
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characterization of white portland cement hydration and the c s h structure in the presence of sodium Aluminate by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2004Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Joergen SkibstedAbstract:Abstract The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium Aluminate (NaAlO2) at 5 and 20 °C are investigated by 27Al and 29Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO2 accelerates the hydration of alite and belite and results in calcium-silicate-Hydrate (C-S-H) phases with longer average chain lengths of SiO4/AlO4 tetrahedra. The C-S-H phases are investigated in detail and it is shown that the Al/Si ratio for the chains of tetrahedra is quite constant during the time studied for the hydration (6 h to 2 years) but increases for higher concentration of the NaAlO2 solution. The average chain lengths of “pure” silicate and SiO4/AlO4 tetrahedra demonstrate that Al acts as a linker for the silicate chains, thereby producing aluminosilicate chains with longer average chain lengths. Finally, it is shown that NaAlO2 reduces the quantity of ettringite and results in larger quantities of monosulfate and a calcium Aluminate Hydrate phase.
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characterization of white portland cement hydration and the c s h structure in the presence of sodium Aluminate by 27al and 29si mas nmr spectroscopy
Cement and Concrete Research, 2004Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Joergen SkibstedAbstract:The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium Aluminate (NaAlO{sub 2}) at 5 and 20 deg. C are investigated by {sup 27}Al and {sup 29}Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO{sub 2} accelerates the hydration of alite and belite and results in calcium-silicate-Hydrate (C-S-H) phases with longer average chain lengths of SiO{sub 4}/AlO{sub 4} tetrahedra. The C-S-H phases are investigated in detail and it is shown that the Al/Si ratio for the chains of tetrahedra is quite constant during the time studied for the hydration (6 h to 2 years) but increases for higher concentration of the NaAlO{sub 2} solution. The average chain lengths of 'pure' silicate and SiO{sub 4}/AlO{sub 4} tetrahedra demonstrate that Al acts as a linker for the silicate chains, thereby producing aluminosilicate chains with longer average chain lengths. Finally, it is shown that NaAlO{sub 2} reduces the quantity of ettringite and results in larger quantities of monosulfate and a calcium Aluminate Hydrate phase.
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C−S−H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO2 solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by 27Al and 29Si MAS NMR spectroscopy. 27Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the 27Al isotropic chemical shift (δiso) and quadrupolar product parameter (PQ = CQ ) for tetrahedrally coordinated Al incorporated in the C−S−H phase and for a pentacoordinated Al site. The latter site may originate from Al3+ substituting for Ca2+ ions situated in the interlayers of the C−S−H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (δiso = 5.0 ppm and PQ = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C−S−H phase has been quan...
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incorporation of aluminum in the calcium silicate Hydrate c s h of Hydrated portland cements a high field 27al and 29si mas nmr investigation
Inorganic Chemistry, 2003Co-Authors: Morten Daugaard Andersen, Hans J. Jakobsen, Jorgen SkibstedAbstract:The calcium silicate Hydrate (C-S-H) phase resulting from hydration of a white Portland cement (wPc) in water and in a 0.3 M NaAlO(2) solution has been investigated at 14 and 11 hydration times, respectively, ranging from 6 h to 1 year by (27)Al and (29)Si MAS NMR spectroscopy. (27)Al MAS NMR spectra recorded at 7.05, 9.39, 14.09, and 21.15 T have allowed a determination of the (27)Al isotropic chemical shift (delta(iso)) and quadrupolar product parameter (P(Q) = C(Q)) for tetrahedrally coordinated Al incorporated in the C-S-H phase and for a pentacoordinated Al site. The latter site may originate from Al(3+) substituting for Ca(2+) ions situated in the interlayers of the C-S-H structure. The spectral region for octahedrally coordinated Al displays resonances from ettringite, monosulfate, and a third Aluminate Hydrate phase (delta(iso) = 5.0 ppm and P(Q) = 1.20 MHz). The latter phase is tentatively ascribed to a less-crystalline Aluminate gel or calcium Aluminate Hydrate. The tetrahedral Al incorporated in the C-S-H phase has been quantitatively determined from (27)Al MAS spectra at 14.09 T and indirectly observed quantitatively in (29)Si MAS NMR spectra by the Q(2)(1Al) resonance at -81.0 ppm. A linear correlation is observed between the (29)Si MAS NMR intensity for the Q(2)(1Al) resonance and the quantity of Al incorporated in the C-S-H phase from (27)Al MAS NMR for the different samples of Hydrated wPc. This correlation supports the assignment of the resonance at delta(iso)((29)Si) = -81.0 ppm to a Q(2)(1Al) site in the C-S-H phase and the assignment of the (27)Al resonance at delta(iso)((27)Al) = 74.6 ppm, characterized by P(Q)((27)Al) = 4.5 MHz, to tetrahedrally coordinated Al in the C-S-H. Finally, it is shown that hydration of wPc in a NaAlO(2) solution results in a C-S-H phase with a longer mean chain length of SiO(4) tetrahedra and an increased quantity of Al incorporated in the chain structure as compared to the C-S-H phase resulting from hydration of wPc in water.
Frías Moisés - One of the best experts on this subject based on the ideXlab platform.
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Activation of kaolinite based coal waste: Chemical and thermal activation and their mineralogy
'Japanese Society of Applied Entomology & Zoology', 2020Co-Authors: Casas Angulo Marina, Frías Moisés, García-giménez Rosario, Martínez-ramírez S., Vigil De La Villa, Raquel, Caneda-martínez Laura, Vegas ÍñigoAbstract:Trabajo presentado a la 10th International Conference on the Environmental and Technical Implications of Construction with Alternative Materials (WASCON), celebrada en Tampere (Finlandia) del 6 al 8 de junio de 2018.One inconvenience presentad by the thermal activation of kaolinite(K)-based waste is its low content of metakaolinite, a highly pozzolanic product listed in current standards for the manufacture of commercial cements. The addition of a chemical activator during the thermal activation process is a priority line of research to increase the reactivity of the recycled metakaolinite. The objective of the present investigation is to analyze the combined effect of the activation of a K-based coal waste on pozzolanic reactivity and on the evolution of mineralogical phases in a metakaolínitellime system cured at 1, 3, 7, 28, 90 and 360 days of reaction time. To do so, activation temperaturas between 550°C and 650°C were analyzed as well as percentages of ZnO between 0.05 and 3.0% by sample weight. In this paper, an additional chemical activator, ZnO, is studied and its effect on both pozzolanic properties and the evolution of mineralogical phases in the thermal activation of coal waste with a reaction time of up to 360 days in the pozzolanllime system. To do so, activation temperaturas of between 550°C and 650°C were selected and additions of chemical activator (ZnO) in percentages of 0.0%-3.0% by weight of coal waste, because it is an activator with a positive effect on a 100% natural kaolinite. Different techniques were used for the material characterization. Mineralogical composition of the bulk samples was determinad by XRD. The mineralogical quantification was performed with the Rietveld method. Morphological observation and microanalyses of the samples were carried out by SEM/EDX. A confocal Renishaw lnvia Raman microscope equipped with a Leica microscope and an electrically refrigerated CCD camera was used for sample analy sis. The FTIR analyses determinad the spectra in the range of compressed frequencies of between 4000 and 400 cm-1. The results showed that the incorporation of ZnO highly reduces the reactivity of the recycled metakaolinite and in consequence, the capacity of the metakaolinite to react with the surrounding lime; even more so when the content of added chemical activator was raised. In none of the cases under analysis was the chemical activator able to significantly improve the properties of metakaolinite in comparison with those of the reference. Thermal activation (550°C-650°C) without the addition of ZnO maintained a very similar mineralogy. The crystalline Hydrated phases that appeared in the pozzolanic reaction were tetracalcium Aluminate Hydrate, stratlingite, ettringite, monosulfoAluminate Hydrate and LDH (phyllosilicate/carbonate). The laminar morphological compounds were formed to the detriment of the C-S-H gels that acted as a substrate for crystallization and were found interspersed with them, forming aggregates.This research has been supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund Project BIA-2015-65558-C3-1,2,3-R) (MINECO/FEDER) andas well as the Spanish Training Program, co-financed by the European Social Fund (MINECO/FSE) (BES-2016-078913 and BES-2016-078454). The authors are also grateful to the S.A. Hullera Vasco-Leonesa, SI KA (Spain) and to lECA for their assistance with this research
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Advances in the combined effect of activation for kaolinite based waste as supplementary cementitious materials
2018Co-Authors: Frías Moisés, Martínez-ramírez S., Fernández-carrasco Lucía, García Rosario, Vigil De La Villa, Raquel, Vegas ÍñigoAbstract:International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, Montreal, Canada, 2nd - 4th October 2017. -- https://www.rilem.net/agenda/1047The effect of the incorporation of 1% ZnO on the reactivity of metakaolin, prior to the thermal activation of kaolinite-based coal waste (600° C / 2h), is investigated. The mineralogy of the pozzolanic reaction in the pozzolan/lime system is also studied at 28 days of reaction. The results are compared with those obtained for 100% thermally activated natural kaolinite. The results of the pozzolanic reaction show important differences with and without the addition of ZnO, in accordance with the nature of the material. The crystalline phases in a natural kaolinite are C2ASH8, mica, and LDH (carbonate-phyllosilicate) type compounds; however, the addition of 1% ZnO inhibits the formation of LDH-type compounds. The crystalline phases in the coal waste/lime system are identified as tetracalcium Aluminate Hydrate (C4AH13), LDH (carbonate-phyllosilicate) type compounds and C2ASH8, which are not identified with the addition of ZnO. Using SEM/EDX, the presence of C-S-H gels with different morphologies (spongy or fibrous) was observed in accordance with the presence or absence of ZnO.Peer Reviewe
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Influence of ZnO on the activation of kaolinite-based coal waste: Pozzolanic activity and mineralogy in the pozzolan/lime system
'Elsevier BV', 2018Co-Authors: García-giménez Rosario, Martínez-ramírez S., Fernández-carrasco Lucía, Vigil De La Villa, Raquel, Frías MoisésAbstract:One inconvenience presented by the thermal activation of kaolinite-based wastes is their low content of metakaolinite, a highly pozzolanic product listed in current standards for the manufacture of commercial cements. The addition of a chemical activator during the thermal activation process is a priority line of research to increase the reactivity of the recycled metakaolinite. In this paper, an additional chemical activator, ZnO, is studied and its effect on both pozzolanic properties and the evolution of mineralogical phases in the thermal activation of coal waste with a reaction time of up to 90 days in the pozzolan/lime system. To do so, activation temperatures of between 550 °C/650 °C were selected and additions of chemical activator (ZnO) in percentages of between 0.0% and 3.0% by weight of coal waste, because it is an activator with a positive effect on a 100% natural kaolinite. The results showed that the incorporation of ZnO inhibited the reactivity of the recycled metakaolinite and in consequence, the capacity of the metakaolinite to react with the surrounding lime; even more so when the content of added chemical activator was raised, albeit with some exceptions, in the samples activated at 550 °C and 650 °C with 0.5% of chemical activator. In none of the cases under analysis was the chemical activator able to improve the properties of the metakaolinite in comparison with the properties of the reference sample activated only with temperature. The Hydrated phases that appeared in the pozzolanic reaction were tetracalcium Aluminate Hydrate, stratlingite, monosulfoAluminate Hydrate and LDH (phyllosilicate/carbonate)The authors wish to express their gratitude and sincere appreciation to the Spanish Ministry of the Economy and Competitiveness under coordinated projects MAT2012-37005-CO3-01, BIA2015-65558-C3-1-2-3R (MINECO/FEDER) for financing this research work and grateful to the Sociedad Anónima Hullera Vasco-Leonesa (Spain) and to the Spanish Cement Institute (IECA) for their assistance with this research.Peer reviewe
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Scientific and technical behaviour of blended Cement made from coal mining waste
2017Co-Authors: Frías Moisés, García-giménez Rosario, Sánchez De Rojas, María Isabel, Savastano H., Vigil R., Martínez-ramírez S.Abstract:Proceedings of the 6th Amazon & Pacific Green Materials Congress and Sustainable Construction Materials, Cali, Colombia, April 27-29th, 2016Cement industry traditionally uses in its productive process a huge quantity of waste and by-products. The use of supplementary cementing materials in the manufacture of eco-efficient cements is focused in industrial by-products and wastes. Research studies founded on kaolinite based waste, are being followed with special attention from the scientific community to obtain recycled metakaolinite. One of these lines of research is based on the industrial waste from coal mining. A coal gangue waste coming from a landfill at an opencast mine (Sociedad Anónima Hullera Vasco-Leonesa, Spain) was used for this investigation. As all kaolinite based waste, it was previously activated at 600ºC for two hours from environmentally, economic and energy viewpoint. This paper focussed on the scientific advances (chemistry, pozzolanic properties, Hydrated phases, etc.) of activated coal mining waste as well as technical advances (physical and mechanical) up to 365 days of hydration in 20% pozzolan blended cement system. Finally, it assesses the requirements according to European standard on the manufacture of common cements. The results clearly show that these industrial wastes, once subjected to controlled thermal activation process, had high pozzolanic properties comparable to metakaolinite obtained by activating a natural kaolinite. The blended cement produced with 20% of pozzolan showed a similar mechanical behavior to the reference OPC, as a consequence of the formation of Hydrated phases from the pozzolanic reaction between pozzolan and lime generated during the reaction of hydration of cement particles. The presence of crystalline Hydrated phases were a) tetracalcium Aluminate Hydrate (C4AH13); b) stratlingite (C2ASH8) (stable phase); c) monosulfoAluminate Hydrate (C3A·SO4Ca·12H2O) and d) LDH compounds (phyllosilicate/carbonate) (metastable phase). The resulting 20% blended cement complies with the requirements of the current standard for cements CEM II-A. Therefore, this residue could be used in developing the future eco-efficient and innovative cements, constituting an alternative source for obtaining of recycled metakaolinite, pozzolan collected in the existing standards as Q (calcined pozzolan).Peer Reviewe
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Thermodynamic evaluation of pozzolanic reactions between activated pozzolan mix of clay waste/fly ash and calcium hydroxide
'American Society of Civil Engineers (ASCE)', 2017Co-Authors: Vigil De La Villa, Rosario, García-giménez Rosario, I. De ,soto, Frías MoisésAbstract:The mixture of activated paper sludge and fly ash can successfully be used as pozzolans for the manufacture of a more ecological portland cement. The saturation indexes and the mineral stability fields of a pozzolanic reaction are studied at 1, 3, 7, 28, 90, and 360 days into the reaction. The system is formed of a pozzolanic mix (activated clay waste and fly ash) and a saturated solution of Ca(OH)2Ca(OH)2 at 40°C. The behavior of the reactions is predicted in this study by means of a thermodynamic model running on a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. The concentration of soluble species in the aqueous solution is determined by inductively coupled plasma mass spectrometry. The evolution of the Hydrated phases formed in this study and the mineral stability fields are evaluated with the geochemical programs PHREEQC and SUPCRT92. The Hydrated phases produced during the pozzolanic reactions were C─ S─ H gels, C4AH13C4AH13 (calcium Aluminate Hydrate), C4AcH12C4AcH12 (calcium monosulfoAluminate), and layered double hydroxide (LDH)–type structures or hydrotalcite are anionic clays. The saturation index values indicate that the LDH-type structures (phyllosilicate/carbonate) are the most thermodynamically stable phase in the activated clay/fly ash–Ca(OH)2Ca(OH)2 system after 7 days of reaction. Mineral stability fields situate all the samples among the LDH-type structures (phyllosilicate/carbonate).Peer reviewe