Afm Phase Cement

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Afm Phase Cement

Cement and Concrete Research

Cement and Concrete Research

Lowering the pH below 12 lead to reduced chloride binding in part due to dissolution of AFm. Chloride binding approached zero at a pH of 9. The influence of . the chemical and physical binding of chlorides in cement. The main chloride binding phase, Friedel's salt, is more stable at a pH slightly lower than the 13–13.5 which is common in .

Cement and Concrete Research

Cement and Concrete Research

Lowering the pH below 12 lead to reduced chloride binding in part due to dissolution of AFm. Chloride binding approached zero at a pH of 9. The influence of . the chemical and physical binding of chlorides in cement. The main chloride binding phase, Friedel's salt, is more stable at a pH slightly lower than the 13–13.5 which is common in .

Electrostatic Force Microscopy (EFM) - AFM System

Electrostatic Force Microscopy (EFM) - AFM System

Electrostatic Force Microscopy (EFM) with Park AFM maps electric properties on a sample surface by measuring the electrostatic force between the surface and a biased AFM cantilever. EFM applies a voltage between the tip and the sample while the cantilever hovers above the surface, not touching it.

Influence of Nucleation Seeding on the Hydration .

Influence of Nucleation Seeding on the Hydration .

the cohesion of hydrated cement, results from an inversion of the effective surface charge in the presence of divalent calcium ions and high pH in the surrounding solution. 6,7 The colloidal, or nanogranular, nature of the C - S - H gel has a controlling effect on many of the bulk properties of cement paste and concrete. 8- 11

Activation of slag in blended cement | Cement Science

Activation of slag in blended cement | Cement Science

Blended with Portland cement, slag can be activated with a relatively high pH solution of blend system caused by the hydration phase CH, which is one of the main hydration products of C 3 S and C 2 S in Portland cement. slag has been successfully used with Portland cement to produce blended cements. As soon as water is added into the slag and .

Structural Insight into Iodide Uptake by AFm Phases .

Structural Insight into Iodide Uptake by AFm Phases .

The ability of cement phases carrying positively charged surfaces to retard the mobility of 129I, present as iodide (I–) in groundwater, was investigated in the context of safe disposal of radioactive waste. 125I sorption experiments on ettringite, hydrotalcite, chloride-, carbonate- and sulfate-containing AFm phases indicated that calcium–monosulfate (AFm–SO4) is the only phase that .

The influence of metakaolin on limestone reactivity in .

The influence of metakaolin on limestone reactivity in .

Recent studies have demonstrated that in the presence of limestone (CaCO 3), carbonate-AFm phases (i.e., hemi- and/or mono-carboaluminate) may be stabilized at the expense of sulfate-AFm, which is more commonly found in cement systems.This suggests that enhancing AFm phase formation may be a novel way of incorporating increased quantities of limestone as a reactive component in cementbased .

Tricalcium aluminate - Wikipedia

Tricalcium aluminate - Wikipedia

The aluminate then reacts slowly to form the AFm phase 3CaO·Al 2 O 3 ·CaSO 4 ·12H 2 O. These hydrates contribute little to strength development. Tricalcium aluminate is associated with three important effects that can reduce the durability of concrete: heat release, which can cause spontaneous overheating in large masses of concrete.

Ettringite - Wikipedia

Ettringite - Wikipedia

In the cement system, the presence of ettringite depends on the ratio of calcium sulfate to tri-calcium aluminate (C 3 A); when this ratio is low, ettringite forms during early hydration and then converts to the calcium aluminate monosulfate (AFm phase .

Advances in Cement Research - ICE Virtual Library

Advances in Cement Research - ICE Virtual Library

Stratlingite, like any AFm-type phase, has a layer structure with the following general formula [Ca 2 Al(OH) 6]X·yH 2 O. For stratlingite, X is the [SiAlO 2 (OH) 4] − anion which forms a double tetrahedral layer containing ~ 50% vacancies. Moreover, iron-bearing stratlingite may also be formed by partial substitution of aluminium in the octahedral layer ().

Comparison of FT-IR, Thermal Analysis and XRD for .

Comparison of FT-IR, Thermal Analysis and XRD for .

Fourier Transform Infrared Spectroscopy (FT-IR), thermal analysis and X-Ray Diffraction (XRD) are commonly performed to study the hydration products in cement pastes. The three methods were compared in this frame to detect products of cement hydration at different ages, especially at early ages (before 24h ages). The results indicate from the present experiment that CH (Calcium hydroxide) can .

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

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

The AFm phase actually consists of several structurally-related compositions which form incomplete solid solutions. The AFt phase is close to its ideal stoichiometry at 25 deg. C but at low temperatures, < 20 deg. C, extensive more » solid solutions occur with CO{sub 3}-ettringite.

Dissolution kinetics of hydrated calcium aluminates (AFm .

Dissolution kinetics of hydrated calcium aluminates (AFm .

The determination of reliable weathering/dissolution rates for cement phases is of fundamental importance for the modelling of the temporal evolution of both radioactive waste repositories and CO 2 geological storage sites (e.g. waste matrix, plug in boreholes). Here, the dissolution kinetics of AFm-Cl (hydrated calcium aluminates containing interlayer Cl) has been studied using flow-through .

STUDY OF BROWNMILLERITE PREPARED AT 1200 II. .

STUDY OF BROWNMILLERITE PREPARED AT 1200 II. .

hydrate (the AFm phase) and hydrogarnet CJ(A, F)H6 [2, 3]. The literature cited deals with the technological consequences of the formation of these phases in the process of the cement pastes hardening. The main ferritic phase in cement clinker, brownmillerite, has been described in the literature in detail including its reactivity with water [4 .

Chloride-Binding Capacity of Portland Cement Paste Blended .

Chloride-Binding Capacity of Portland Cement Paste Blended .

If the concentration of chloride ions is high within the AFm phase in concrete, the compounds where chloride ions are fixed between positively charged layers of the AFm phase increase [19, 22, 23].This can effectively delay the penetration of chloride ions into concrete.

Strätlingite: compatibility with sulfate and carbonate .

Strätlingite: compatibility with sulfate and carbonate .

Oct 30, 2015 · The silicate AFm, strätlingite, has been shown to be stable in high aluminosilicate cement systems but its stability with respect to the anion content of hydrated Portland cement paste is unknown. The stability of strätlingite in the presence of sulfate and carbonate phases relevant to cement systems are reported. Results show that strätlingite .

Transition of Friedel phase to chromate-AFm phase .

Transition of Friedel phase to chromate-AFm phase .

Oct 04, 2008 · 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 spectra showed different .

Hydration of C3A with Calcium Sulfate Alone and in the .

Hydration of C3A with Calcium Sulfate Alone and in the .

Tricalcium aluminate (C3A) is one of the main constituents of Portland cement. Even though it represents less than 10% of the total composition, its strong reaction with water can lead to a rapid setting, called flash set. Gypsum is added to regulate this reaction and preserves the workability of the cement paste at early ages. The understanding of the C3A-gypsum reaction is therefore crucial .

Application of FTIR for Quantification of Alkali in Cement

Application of FTIR for Quantification of Alkali in Cement

Concrete is produced, in general terms, by beginning with the quarrying of limestone. Depending on the homogeneity of the quarry site, the chemical compositions of cement can vary. The quarried limestone is then crushed into smaller pieces which are then mixed with clays,

The AFm phase in Portland cement - ScienceDirect

The AFm phase in Portland cement - ScienceDirect

Thus in Portland cement, the anions in AFm are hydroxide, sulfate and carbonate while in blended cement, e.g., slag cement, the characteristic anion is an aluminosilicate species. In service, chloride often displaces other anions. The content of AFm phase in hydrated pastes is variable but in many slag-blended cements it may exceed 20%.

Modeling the influence of limestone filler on cement .

Modeling the influence of limestone filler on cement .

AFmc in a cement-based system, the above scheme was chosen for its simplicity in implementation in the CEM-HYD3D codes and the fact that it does yield the desired effect: the formation of the AFmc phase at the expense of the AFm phase.

Thermal Analysis and Crystal Chemistry of important AFm .

Thermal Analysis and Crystal Chemistry of important AFm .

MOTIVATION Aluminous Ferrous Mono (AFm - ) phases with a general chemical composition [Ca2(Al,Fe)(OH)6]+[½ Y or X ·nH 2O]-Y = divalent anion, X = monovalent anion, crystallize during the hydration process of cementitious products. Those phases are members of a large family, the so called LDHs (layer double hydroxides), which are of technical and applied interest in industry due to their .

Stability of strätlingite in the CASH system | SpringerLink

Stability of strätlingite in the CASH system | SpringerLink

Abstract. Strätlingite, a siliceous AFm-type phase associated with blended cement hydration, is often assigned a fixed composition, 2CaO·Al 2 O 3 ·SiO 2 ·8H 2 O, but our knowledge of its stability and compatibility with other phases is limited. The phase relations and thermal stability of strätlingite in the CASH system are reported.

Hydration states of AFm cement phases - Infoscience

Hydration states of AFm cement phases - Infoscience

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 .

Influence of Nucleation Seeding on the Hydration .

Influence of Nucleation Seeding on the Hydration .

the cohesion of hydrated cement, results from an inversion of the effective surface charge in the presence of divalent calcium ions and high pH in the surrounding solution. 6,7 The colloidal, or nanogranular, nature of the C - S - H gel has a controlling effect on many of the bulk properties of cement paste and concrete.

PCA Concrete and Cement Thesaurus Term: AAR Term: .

PCA Concrete and Cement Thesaurus Term: AAR Term: .

PCA Concrete and Cement Thesaurus Term: AAR Use... Alkali aggregate reactions (AAR) Term: AASHO road test Used for... National road test

The AFm phase in Portland cement — The University of Aberdeen

The AFm phase in Portland cement — The University of Aberdeen

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO center dot Al2O3 center dot 13-19 H2O. However OH- may be replaced by SO42- and CO32-.

Effect of redox conditions on the structure and solubility .

Effect of redox conditions on the structure and solubility .

16 S(VI)-, S(IV)-, S(II)-AFm phases to account for a range of possible redox conditions in a cement-based 17 repository for low and intermediate level radioactive waste. 18 The X-ray spectra revealed crystalline AFm phases with trigonal or pseudo-trigonal structure.

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

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

The AFm phase in Portland cement

PCA Concrete and Cement Thesaurus Term: AAR Term: .

PCA Concrete and Cement Thesaurus Term: AAR Term: .

PCA Concrete and Cement Thesaurus Term: AAR Use... Alkali aggregate reactions (AAR) Term: AASHO road test Used for... National road test