A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jørgen

doi:10.1016/j.cemconres.2005.04.010

Cited by 294 publications

(198 citation statements)

References 35 publications

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“…S3, Supporting Information) showed that the resonance at 4.2 ppm corresponding to a third aluminate hydrate declined slightly with reaction time, but decreased drastically with an increase in curing temperature (from 20 to 60 • C). These results are wholly consistent with the findings reported by Andersen et al [23] The resonance at 9.8 ppm is due to the presence of monosulfoaluminate. The wide resonance in the 50-80 ppm region peaked at 67.7 ppm in the early-age hydrated samples (3 and 9 days), while for the older (124-day) samples the peak appeared at 64.6 ppm.…”

Section: Blended Cement Pastes Containing 10% Mk At 60 • Csupporting

confidence: 83%

“…The resonance at 67.7 ppm was attributed to the aluminium taken up in the C-S-H gel. [23] From these results, it is posible to follow the amorphous and crystalline phases by Raman spectroscopy formed during the hydration of white cement with MK by monitoring the signal of portlandite and C-S-H gel. Furthemore, the identification of the Q 1 and Q 2 units in the C-S-H gel is possible.…”

Section: Initial Phasesmentioning

confidence: 99%

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Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin

Frías

Martínez-Ramírez

2009

J Raman Spectroscopy

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Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin-bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X-ray diffraction) due to their poor crystallinity. Consequently, micro-Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 • C). This led to the identification, for the first time using Raman spectroscopy, of phases C 2 ASH 8 1 (stratlingite) and C 3 ASH 6 , which appear in the MK-white cement reaction. The C-S-H gel formed was characterized by Q 1 dimers and a C/S ratio of 1.3-1.5. Raising the curing temperature favored the formation of C 4 AH 13 .

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Section: Blended Cement Pastes Containing 10% Mk At 60 • Csupporting

confidence: 83%

Section: Initial Phasesmentioning

confidence: 99%

Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin

Frías

Martínez-Ramírez

2009

J Raman Spectroscopy

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“…(Salih et al 2014). The binding capability of the C-S-H gel could have been improved provided there was enough Al 2 O 3 to be incorporated in the bridging sites of the SiO 2 chains (Andersen et al 2006;Harvey and Dent Glasser 1989). The figure also shows clearly the dependence of the compressive strength among other factors on the molarities of NaOH (aq).…”

Section: Resultsmentioning

confidence: 99%

POFA-Engineered Alkali-activated Cementitious Composite Performance in Acid Environment

Salami

Johari

Ahmad

et al. 2017

ACT

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The durability performance of palm oil fuel ash engineered alkali-activated cementitious composite (POFA-EACC) mortar exposed to different acid solutions is assessed in this study. 50 mm cubic specimens used for the study were prepared from 100% POFA, alkali-activator (Na 2 SiO 3(aq) /NaOH (aq) ) ratios of 2.5, different molarities (10, 12 and 14 M) of NaOH (aq) and 2% volume fraction of polyvinyl alcohol (PVA) fibres. Specimens were exposed to 10% H 2 SO 4(aq) , 10% HNO 3(aq) and 10% HCl (aq) at pH of 0.56, 0.52 and 0.42 respectively for 3, 6 and 9 months, with unexposed specimens as control. Small changes in compressive strength were identified with POFA mortar specimens during exposure to H 2 SO 4(aq) , while exposure to HNO 3(aq) and HCl (aq) greatly reduced the strength of the POFA mortar specimens. The results were supported through microstructural examinations using SEM, while the characterization was done using XRD and FTIR. The high resistance of POFA-EACC mortar to H 2 SO 4(aq) is the contribution received through the formation of gypsum, which hinders the infiltration of more acids into the matrix microstructure.

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“…The 2D 27 Al{ 1 H} HETCOR spectrum provides enhanced resolution in which intensity correlations from multiple 27 Al signals are partially resolved. These are visible in the projected spectrum along the 27 31 to as the third aluminate hydrate (TAH). These 27 Al peak assignments are based on previous 27 Al NMR studies 31,32,56−58 and establish that a mixture of aluminate hydrates, including both calcium aluminates and calcium aluminate sulfates, are formed under the hydration conditions examined.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Reactions and Surface Interactions of Saccharides in Cement Slurries

Smith

Roberts²,

Funkhouser

et al. 2012

Langmuir

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Glucose, maltodextrin, and sucrose exhibit significant differences in their alkaline reaction properties and interactions in aluminate/silicate cement slurries that result in diverse hydration behaviors of cements. Using 1D solutionand solid-state 13 C nuclear magnetic resonance (NMR), the structures of these closely related saccharides are identified in aqueous cement slurry solutions and as adsorbed on inorganic oxide cement surfaces during the early stages of hydration. Solid-state 1D 29 Si and 2D 27 Al{ 1 H} and 13 C{ 1 H} NMR techniques, including the use of very high magnetic fields (18.8 T), allow the characterization of the hydrating silicate and aluminate surfaces, where interactions with adsorbed organic species influence hydration. These measurements establish the molecular features of the different saccharides that account for their different adsorption behaviors in hydrating cements. Specifically, sucrose is stable in alkaline cement slurries and exhibits selective adsorption at hydrating silicate surfaces but not at aluminate surfaces in cements. In contrast, glucose degrades into linear saccharinic or other carboxylic acids that adsorb relatively weakly and nonselectively on nonhydrated and hydrated cement particle surfaces. Maltodextrin exhibits intermediate reaction and sorption properties because of its oligomeric glucosidic structure that yields linear carboxylic acids and stable ring-containing degradation products that are similar to those of the glucose degradation products and sucrose, respectively. Such different reaction and adsorption behaviors provide insight into the factors responsible for the large differences in the rates at which aluminate and silicate cement species hydrate in the presence of otherwise closely related saccharides. ■ INTRODUCTIONSaccharide reactions and interactions at hydrating inorganic oxide surfaces significantly influence diverse surface chemistry processes that include carbonate formation in marine organisms, biosynthesis at aluminosilicate surfaces, biofuel production over heterogeneous catalysts, corrosion inhibition, and cement hydration. 1−7 The competitive adsorption of organic molecules and water at heterogeneous inorganic oxide surfaces influences reaction mechanisms, kinetics, molecular compositions and structures, and macroscopic material properties. Importantly, saccharide molecules are commonly used to alter the hydration processes and material properties of cements, such as the calcium aluminates and silicates that are widely used in synthetic structural materials. 8 In particular, the hydration kinetics of hydraulic aluminate/ silicate-based cements are critical to concrete construction and oilwell cementing, in which organic additives are often used to slow (inhibit) hydration processes or alter the rheological properties of cement−water mixtures, commonly referred to as cement "slurries". Despite their enormous technological importance, much remains to be known about the physicochemical interactions of the inorganic silicate or alumi...

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A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

Cited by 294 publications

References 35 publications

Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin

Use of micro‐Raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin

POFA-Engineered Alkali-activated Cementitious Composite Performance in Acid Environment

Reactions and Surface Interactions of Saccharides in Cement Slurries

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