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.

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.

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 …

phase on the reaction of cement with TEA is highlighted. At a low dosage, ... (AFt) to monosulfate (AFm), and retards the tricalcium silicate (C 3S) hydration. 12,16 Contrary to the monotonic effect of TEA on hydration, the effect of TEA on the setting of cement paste is complex.16,21 It can be

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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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 ...

Hydrated Calcium Aluminate Cement (CAC) is known for many beneficial characteristics such as high mechanical strength, sulphate resistance and rapid hardening even at low temperatures. ... C 2 AH X is a so called AFm-phase and thus structurally closely related to other AFm-phases such as carbonate-AFm, monosulfate, Friedel's salt, etc.

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, as …

During hydration, the water used in the mixing of cement paste is divided into bound water which will form the hydrated products, and into free water, adsorbed in the existing pores or present in the capillaries, remaining available for the hydration of the anhydrous particles [1, 2].The bound water is composed of water associated to hydrated products as the portlandite and the ettringite, of ...

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 ...

aerated concrete, autoclaved, 341, 343, 346 AFm phase (sees also formulae of individual compounds), 157-166 alkali substitution, 161 as a hydration product of pure compounds, 182-186 as a normal hydration product of Portland cement 188-191, 196,, 198, 200-202, 204 content of Fe, 204, 208

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.

AFm-phase in cementitious materials ... The paper describes the whole family of potentially occurring AFm-phases in cement and their role during hydration of cements but also their role as new ...

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 ...

Abstract. Bentonite and chalk are the most popular auxiliary additives to portland cement for borehole cementation. The authors studied by physicochemical analysis methods (x-ray phase, derivatographic, and scanning and electron microscopy in combination with microdiffraction) the newly formed solid-phase composition of cement-bentonite and cement-chalk mortars (binder-additive ratio 9:1 ...

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-. Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these compositions do not form solid solutions and ...

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 ...

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.

Here we report for the first time wet chemistry and spectroscopic data on the interaction of the most relevant selenium anion species under the expected strongly reducing conditions, i.e. HSe −, with two AFm phases commonly found in cement, monocarbonate (AFm-MC) and hemicarbonate (AFm-HC).

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.

The influences of aluminum sulfate (AS) introduction and dosage on setting time, hydration heat evolution, hydration product type and pore structure of Portland cement were studied, and the influence of AS on concrete strength was investigated also. The results indicate that AS can effectively accelerate setting time of Portland cement and enhance concrete at early age (1 day) …

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

Stratlingite, Ca4Al2(OH)12[AlSi(OH)8]2·2H2O, is an AFm phase which appears as a hydration product of aluminium-rich cements. These binders may be calcium aluminate cements, calcium sulfoaluminate cements and also belite calcium sulfo-aluminate (BCSA) cements. The structure of stratlingite is known from single-crystal studies of tiny minerals but their bulk formation, crystal …

The general definitions of these phases are somewhat technical, but for example, ettringite is an AFt phase because it contains three (t-tri) molecules of anhydrite when written as C 3 A.3CaSO 4.32H 2 O and monosulfate is an AFm phase because it contains one (m-mono) molecule of anhydrite when written as C 3 A.CaSO 4.12H 2 O.

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 ...

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO·Al 2 O 3 ·13–19 H 2 O. However OH − may be replaced by SO 4 2− and CO 3 2−.Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these compositions do not form solid solutions and, from the mineralogical standpoint, …

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 ...

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 ...

Portland cement systems (OPC) are included in the databases such as a solid solution model for the calcium silicium hydrates (C-S-H phases), AFm phases (as monocarboaluminate, strätlingite), AFt phase (ettringite and tricarboaluminate), hydrogarnet, and hydrotalcite. The database is

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 …

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. It is known that these phases present different hydration states (i.e. varying ...

@article{osti_22475511, title = {Hydration states of AFm cement phases}, author = {Baquerizo, Luis G., E-mail: [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 cement based systems, …

The second peak was attributed to the hydration of tricalcium aluminate (formation of ettringite and conversion of ettringite to the AFm phase) in cement, the heat of dissolution of the tricalcium ...

AFm phase while others do not. The majority of the effort is given for calculating the influences on AFm and AFt stability of alkali and carbonate components, both of which are typi-cally present in cementitious binders. Higher alkali content shifts the equilibria of both AFt and AFm to lower Ca but higher Al and S concentrations in solution.

A thermodynamic analysis of the reactions of calcium chloride and calcium nitrate with tricalcium aluminate when used as a hardening accelerator for portland cement, as well as decomposition reactions of calcium hydrochloraluminate (CHChA) and calcium hydronitroalyuminate (CHNA) formed during the hardening was performed. The conditions of stable existence of CHChA and CHNA in the cement …