hydration of calcium aluminate cements a solid state 27
The Atomic-Level Structure of Cementitious Calcium
Mar 17 2020 · main hydration product of such blended cements is calcium aluminate silicate hydrate (C-A-S-H) a calcium silicate hydrate (C-S-H)6 7that incorporates aluminum into its structure normally with an atomic ratio of Al Si ≤ 0.25.
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Hydrothermal transformation of the calcium aluminum oxide
Dec 01 2005 · 1. Introduction. The calcium aluminates Ca 3 Al 2 O 6 (C 3 A) Ca 12 Al 14 O 33 (C 12 A 7) and CaAl 2 O 4 (CA) are the most reactive aluminates in the hydration of Portland cements and calcium aluminate cements .In the hydraulic reactions a number of metastable hydrated phases as CaAl 2 O 4 ·10H 2 O (CAH 10) Ca 2 Al 2 O 5 ·8H 2 O (C 2 AH 8) and Ca 4 Al 2 O 7 ·xH 2 O (x=7
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Reactions and Surface Interactions of Saccharides in
Complementary solid-state 1D and 2D 1H 13C 29Si and 27Al NMR methods are used to establish the structures and interactions of saccharide species at hydrating calcium silicate and aluminate surfaces in heterogeneous cement slurry mixtures. The results are correlated with macroscopic measure-ments of cement hydration to identify on a
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Exploiting in-situ solid-state NMR spectroscopy to probe
We report a high-field in-situ solid-state NMR study of the hydration of CaAl2O4 (the most important hydraulic phase in calcium aluminate cement) based on time-resolved measurements of solid-state 27Al NMR spectra during the early stages of the reaction. A variant of the CLASSIC NMR methodology involving alternate recording of direct-excitation and MQMAS 27Al NMR spectra was used to monitor
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PREPARATION OF Al O –CaAl O –ZrO COMPOSITE CERAMIC
The calcium aluminates in CACs react with water to form calcium aluminate hydrates of various possible forms depending on the water-solid ratio time and temperature of hydration 5 10-11 . The following cal-cium aluminate hydrate phases may be formed in the hydration of calcium aluminates CAH 10 C 2 AH 8 C 3 AH 6 C 4
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of Calcium Aluminate CementMDPI
the hydration reaction was brought forward due to the addition of CS. According to these results and analyses the differences in the hydration process for CAC with and without CS can be attributed to the distribution and nucleation effect of SiO2 nanoparticles. Keywords colloidal silica calcium aluminate cement hydration 1. Introduction
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Origins of saccharide-dependent hydration at aluminate
May 31 2011 · Solid-state (1)H (13)C (29)Si and (27)Al nuclear magnetic resonance (NMR) spectroscopy measurements including at very high magnetic fields (19 T) distinguish and quantify the different molecular species their chemical transformations and their site-specific adsorption on different aluminate and silicate moieties.
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X-ray investigations of solid solutions of monocalcium
Monoclinic calcium monoaluminate and monoclinic strontium aluminate form a partial solid-solution series. The hydration behaviour of different solid solutions was also investigated using calorimetry. The newly formed strontium aluminate hydrates could be identified while similar strontium aluminate hydrates are formed.
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PREPARATION OF Al O –CaAl O –ZrO COMPOSITE CERAMIC
The calcium aluminates in CACs react with water to form calcium aluminate hydrates of various possible forms depending on the water-solid ratio time and temperature of hydration 5 10-11 . The following cal-cium aluminate hydrate phases may be formed in the hydration of calcium aluminates CAH 10 C 2 AH 8 C 3 AH 6 C 4
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Preparation of Refractory Calcium Aluminate Cement
To evaluate the performance of the synthesized calcium aluminates commercial calcium aluminate cement called Secar 71 supplied by Lafarge was used as a reference. According to the manufacturer this cement consists of CA CA 2 and C 12 A 7 phases with contents of 61 37.5 and 1.5 wt. ( ) respectively. Pastes made of cement and alumina
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Solid state NMR investigations on the role of organic
May 01 2006 · The hydration of the calcium aluminum oxide clinker phases within Portland cement in the early age of hydration can be best understood from 27 Al NMR spectra as shown in Fig. 1. Within the Portland cement aluminum oxides and aluminate clinker phases are converted from tetrahedral to octahedral co-ordination.
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The solid state chemistry of metakaolin-blended ordinary
The hydration of ordinary Portland cement (OPC) pastes containing 0 and 20 metakaolin was monitored by differential thermal analysis (DTA) and solid state magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). The presence of hydrated gehlenite and a relative reduction in calcium hydroxide content of the metakaolin-blended OPC pastes observed by DTA are indicative of
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Exploiting in-situ solid-state NMR spectroscopy to probe
Exploiting in-situ solid-state NMR spectroscopy to probe the early stages of hydration of calcium aluminate cementdata Hughes Colan E. and Walkley Brant and Gardner Laura J. and Walling A. and Bernal Susan A. and Iuga Dinu and Provis John L. and Harris Kenneth D.M. (2019) Exploiting in-situ solid-state NMR spectroscopy to probe the early stages of hydration of calcium
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Evaluation of Calcium Aluminate/Calcium Phosphate Based
Calcium aluminate cement hydrates with water and the major crystalline hydration products are CAH 10 at low temperatures(5-10 o C) C 2 AH 8 and AH 3 at 22-35 o C and C 3 AH 6 (katoite) and AH 3 (gibbsite) at >35 o C. Depending upon temperature and curing period all hydration products will be converted to C 3 AH 6 and AH 3 in process called
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Exploiting in-situ solid-state NMR spectroscopy to probe
We report a high-field in-situ solid-state NMR study of the hydration of CaAl2O4 (the most important hydraulic phase in calcium aluminate cement) based on time-resolved measurements of solid-state 27Al NMR spectra during the early stages of the reaction. A variant of the CLASSIC NMR methodology involving alternate recording of direct-excitation and MQMAS 27Al NMR spectra was used to monitor
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purity aluminate cement. It is believed that CA 6 is most readily formed in alumina castables when using CA 2 as a precursor 7. Alumina (A) is sometimes present as an addition and this is especially true in the case of 80 alumina calcium aluminate cements. 3 Calcium aluminate cement hydration In contrast to Portland cements where the
Get PriceThe Hydration Products of a Refractory Calcium Aluminate
preparation of calcium aluminate cement powder as well as its pure anhydrous phases. Most of them tried it through solid state sintering while others tried chemical routes but in almost all cases people tried to investigate the hydration properties of the prepared products
Get PriceReactions and Surface Interactions of Saccharides in
Complementary solid-state 1D and 2D 1H 13C 29Si and 27Al NMR methods are used to establish the structures and interactions of saccharide species at hydrating calcium silicate and aluminate surfaces in heterogeneous cement slurry mixtures. The results are correlated with macroscopic measure-ments of cement hydration to identify on a
Get PriceSolid-state 27Al and 29Si NMR characterization of hydrates
Aug 01 2008 · Chemicals used in the solid-state synthesis of calcium aluminates were aluminum hydroxide hydrate (Al (OH) 3 ·0.949H 2 O Aldrich Milwaukee WI USA) and calcium carbonate (CaCO 3 Merck Darmstaadt Germany).
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Characterization of Calcium Aluminate Hydrates and Related
27 Al multi quantum (MQ) MAS NMR spectroscopy was used for the first time to characterize calcium aluminate hydrates which are of importance in the chemistry of high alumina and Portland cements. Substitution sites of silicon by aluminum in the calcium silicate hydrates (C-S-H) which are the main component of Portland cement paste were studied too.
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Acoustic emission characterisation of calcium aluminate
Mar 01 2003 · 1.. IntroductionCalcium aluminate cements are widely used for many special applications in the construction and refractory industries due to their ability to gain strength rapidly and to withstand aggressive environments and high temperature.1 2 3 The long-term behaviour of a cement paste is closely related to its state at an early age and in particular its hydration behaviour.
Get PriceHydrothermal transformation of the calcium aluminum oxide
Dec 01 2005 · 1. Introduction. The calcium aluminates Ca 3 Al 2 O 6 (C 3 A) Ca 12 Al 14 O 33 (C 12 A 7) and CaAl 2 O 4 (CA) are the most reactive aluminates in the hydration of Portland cements and calcium aluminate cements .In the hydraulic reactions a number of metastable hydrated phases as CaAl 2 O 4 ·10H 2 O (CAH 10) Ca 2 Al 2 O 5 ·8H 2 O (C 2 AH 8) and Ca 4 Al 2 O 7 ·xH 2 O (x=7
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Solid State Nuclear Magnetic Resonance
Exploiting in-situ solid-state NMR spectroscopy to probe the early stages of hydration of calcium aluminate cement Colan E. Hughesa Brant Walkleyb Laura
Get PriceMolecular Silicate and Aluminate Species in Anhydrous and
Similarly solid-state 1D27Al NMR measurements have shown that aluminate species in anhydrous Portland cement have principally 4-fold coordination (AlIV) a significant fraction of which is converted upon hydration into five-coordinate AlV six- coordinate AlVI and different AlIVspecies.4 30The primary aluminate (C 3A) and aluminoferrite (C
Get PriceExploiting in-situ solid-state NMR spectroscopy to probe
Jul 01 2019 · We report a high-field in-situ solid-state NMR study of the hydration of CaAl2 O 4 (the most important hydraulic phase in calcium aluminate cement) based on time-resolved measurements of solid-state 27 Al NMR spectra during the early stages of the reaction.
Get PriceOrigins of saccharide-dependent hydration at aluminate
Quantitative analyses of tricalcium aluminate hydration.The extent ofC3A hydrationandthequantities ofdifferentaluminatehydra-tion products can be established in detail by solid-state 1D and 2D 27Al NMR measurements. At very high magnetic fields (18.8 T) single-pulse 1D
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Incorporation of Aluminum in the Calcium Silicate Hydrate
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
Get PriceMono-(Strontium- Calcium-) Aluminate Based Cements
Strontium has been shown to affect the hydration behavior of calcium zirconium aluminate cement 5 13 . Furthermore strontium-containing cements attract the attention of materials scientists due
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Hydration of Calcium Aluminate Cements A Solid‐State 27
Hydration of Calcium Aluminate Cements A Solid‐State 27 Al NMR Study Xiandong Cong Department of Geology and Center for Advanced Cement‐Based Materials University of
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