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EFFECT OF CARBONATION ON CHLORIDE PENETRATION …

deterioration of concrete due to the compound effect of chloride ions ingress and carbonation following models are needed:(1) a model of cement hydration, i.e. the formation model of AFm phase; (2) a model for describing the fixation of chloride ions in AFm phase, i.e. the formation model of Friedel's salt; (3) models applied to characterize

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Premature Stiffening of Cement Paste Associated with AFm ...

other AFm phase. The stiffening of cement paste will be monitored using both oscillatory shear rheology and modified ASTM C403 penetration resistance test. The validity of penetration resistance test for monitoring stiffening of cement paste has been thoroughly investigated by Struble and colleagues [4, 5]. ...

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Cement Hydration Kinetics - Precast

Cement hydration products. The main products of cement hydration reactions are calcium silicate hydrate (CSH), calcium hydroxide (CH), and the AFt and AFm phases. The AFt and AFm phases found in hydrated cement are compounds of C 3 A, anhydrite and water. The most common AFt phase is ettringite and the most prevalent AFm phase is monosulfate.

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Lecture 10: Basics of Atomic Force Microscope (AFM)

Mode AFM, the cantilever is excited into resonance oscillation with a piezoelectric driver. • Phase imaging is used to map variations in surface properties such as elasticity, adhesion and friction, which all may cause the phase lag. • Phase detection images can be produced while an instrument is operating in

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Study on the hydration and microstructure of Portland ...

The AFm phase in Portland cement Journal Article Matschei, T ; Lothenbach, B ; Glasser, F - Cement and Concrete Research The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO.Al{sub 2}O{sub 3}.13-19 H{sub 2}O.

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The AFm phase in Portland cement (Journal Article) | …

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO.Al {sub 2}O {sub 3}.13-19 H {sub 2}O. However OH {sup -} may be replaced by SO {sub 4} {sup 2-} and CO {sub 3} {sup 2-}. Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these ...

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Hydration states of AFm cement phases (Journal Article ...

@article{osti_22475511, title = {Hydration states of AFm cement phases}, author = {Baquerizo, Luis G., E-mail: luis.ba[email protected] and Matschei, Thomas and Scrivener, Karen L. and Saeidpour, Mahsa and Wadsö, Lars}, abstractNote = {The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate …

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AFm phase - Wikipedia

An AFm phase is an "alumina, ferric oxide, monosulfate" phase, or aluminate ferrite monosulfate, or Al 2 O 3, Fe 2 O 3 mono, in cement chemist notation.AFm phases are important in the hydration of hydraulic cements.. They are crystalline hydrates with general, simplified formula 3CaO·(Al,Fe) 2 O 3 ·CaSO 4 ·nH 2 O. They form inter alia when tricalcium aluminate (C 3 A: …

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Phase Changes of Monosulfoaluminate in NaCl Aqueous Solution

Among the hydrated cement phases, Al 2 O 3-Fe 2 O 3-mono (AFm) phases, which have a layered double hydroxide (LDH) structure, are important "sinks" for chloride ions. The binding process of the AFm phases has been extensively studied [3,4,5,6,7,8,9,10,11,12,13].

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Coupled chemo-transport-mechanical modelling and numerical ...

It is commonly accepted that the main reactions in ESA in cementitious materials made up with Portland cement (CEM I) involve, in addition to the progressive decalcification of the hydrated products, the sulfate ions and monosulfate (AFm) initially present in the solid phase to precipitate into ettringite, and possibly these sulfate ions and ...

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Transition of Friedel phase to chromate-AFm phase ...

easily substituted for Cl in the Friedel phase forming chromate-AFm. The chemical formula of chromate-AFm was characterised as 3CaO·Al 2 O 3 ·CaCrO 4 ·12H 2 O. Chromate-AFm gave two steps of dehydration, two steps of dehydroxylation and one step of redox reaction of Cr(VI) in the whole heating process from 40 to 1000°C. The Fourier transform infrared …

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Crystal structures of Boro-AFm and sBoro-AFt phases ...

Crystal structures of boron-containing AFm (B-AFm) and AFt (B-AFt) phases have been solved ab-initio and refined from X-ray powder diffraction. 11 B NMR and Raman spectroscopies confirm the boron local environment in both compounds: three-fold coordinated in B-AFm corresponding to HBO 3 2 − species, and four-fold coordinated in B-AFt corresponding …

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Strätlingite: compatibility with sulfate and carbonate ...

Cement could also be blended with limestone, mainly CaCO 3, and atmospheric CO 2 is readily uptaken by wet cements pastes cured in the open. In this way, sulfate and carbonate phases form normally in the hydration process of cement paste. We know that AFm and AFt are common sulfate and carbonate bearing phase product of cement hydration.

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The AFM phase in Portland cement | Request PDF

However, in cement science, hydrocalumite is an AFm phase (Matschei et al. 2007; Tian and Guo 2014). This compound could be formed as the major stable hydration phase of concrete and cement paste ...

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Thermodynamic and crystallographic model for anion uptake ...

This type of stacking defect has been described repeatedly for AFm during SO 4 2− /I − exchange 8, for C-S-H (the main cement phase) 43,56, and more generally for several types of layered ...

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Synthesis and characterization of sulfite-containing AFm ...

OSTI.GOV Journal Article: Synthesis and characterization of sulfite-containing AFm phases in the system CaO-Al{sub 2}O{sub 3}-SO{sub 2}-H{sub 2}O

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(PDF) The AFm phase in Portland cement | Barbara ...

PDF. Download Full PDF Package. Translate PDF. Cement and Concrete Research 37 (2007) 118 – 130 The AFm phase in Portland cement T. Matschei a,⁎, B. Lothenbach b, F.P. Glasser a a Department of Chemistry, University of Aberdeen, Meston Building, Meston Walk, Old Aberdeen, AB24 3UE Scotland, UK b EMPA, Swiss Federal Laboratories for ...

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X-AFm Stabilization as a Mechanism of Bypassing Conversion ...

We demonstrate that the CA2 increases an AFm phase in the Portland cement system, and the incorporation of CA2 consequently enhances the chloride-binding capacity of …

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Chloride-BindingCapacityofPortlandCementPaste ...

AFm phase in concrete, the compounds where chloride ions are •xed between positively charged layers of the AFm phase increase [19, 22, 23].šis can e€ectivelydelay the penetration ofchlorideionsintoconcrete,asitreducestheamountoffree chloride. It is well known that anhydrous C 3A (3CaO·Al 2O 3), C 4AF (4CaO·Al 2O 3·Fe 2O 3), and AFm ...

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Hydration States of AFm Cement Phases | Request PDF

The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered …

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The density of cement phases (Journal Article) | OSTI.GOV

Hydrogarnet, C{sub 3}AH{sub 6}, is destabilised at low carbonate contents and/or low temperatures < 8 deg. C and is unlikely to form in calcite-saturated Portland cement compositions cured at < 40 deg. C. The AFm phase actually consists of several structurally-related compositions which form incomplete solid solutions.

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Surface analysis | Atomic Force Microscopy in Formulation ...

The core component of AFM is a nanoscopic tip mounted on the end of a flexible cantilever (), most commonly V-shaped or beam-shaped, made from silicon or silicon nitride.The tip is brought into contact with the surface using a piezoelectric actuator ('piezo') ().Once the sample and the tip are in contact, the piezo moves in the x and y direction to raster scan over the selected area.

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Crystal Structures and Phase Transition of Cementitious Bi ...

Monosulfate (3CaO·(Alx Fe1x )2O3·CaSO4·12H2O) is an AFm phase that can be formed during the hydration of cement. Fe‐containing monosulfate and (Al,Fe) mixed monosulfate were synthesized and ...

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Hydration states of AFm cement phases - ScienceDirect

The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer.

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Strätlingite: compatibility with sulfate and carbonate ...

amounts of sulfate. Cement could also be blended with limestone, mainly CaCO 3, and atmospheric CO 2 is readily uptaken by wet cements pastes cured in the open. In this way, sulfate and carbonate phases form normally in the hydration process of cement paste. We know that AFm and AFt are common sulfate and carbonate bearing phase product of ...

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Phase evolution of slag-rich cementitious grouts for ...

Other AFm phases, such as hemicarboaluminate and monocarboaluminate, are detected (10·75° and 11·5° 2θ) as a result of reaction of the small amount of calcite in the cement (as identified by XRD, Figure 4) during hydration, and potentially some superficial carbonation contamination of the samples.

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AH3 phase in the hydration product system of AFt-AFm-AH3 ...

In this study, apart from the AFm-12 phase, the AFm-10.5 phase with the 2θ of 10.8° was the only AFm-type phase observed. The diffraction peak of AFm-10.5 phase was much lower, indicating that there is only a small amount of the AFm-10.5 phase. Table 2 shows the quantitative phase analysis results for the M-A and E-A pastes at different ages.

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Retention and diffusion of radioactive and toxic species ...

cement hydration (Taylor, 1997). AFm phases also formed during cement hydration, they have a lamellar structure composed of a posi-tively charged main layer and a negatively charged interlayer, [X⋅nH2O] 2, X: 2 singly charged or 1 doubly charged anion (Buttler et al., 1959).

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AH3 phase in the hydration product system of AFt-AFm …

In this study, apart from the AFm-12 phase, the AFm-10.5 phase with the 2θ of 10.8° was the only AFm-type phase observed. The diffraction peak of AFm-10.5 phase was much lower, indicating that there is only a small amount of the AFm-10.5 phase. Table 2 shows the quantitative phase analysis results for the M-A and E-A pastes at different ages.

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Advances in Cement Research - ICE Virtual Library

The distribution of heavy metal elements in cement pastes doped with nitrate salts of chromium ... (AFt/AFm) phases, but they were most inclined to be immobilised in the AFt/AFm phase, and then in C–S–H. When the dosage (mass percentage of heavy metal elements in the cement) reached 1·0%, chromium was also immobilised by precipitation as ...

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