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  • Influence of lead and chromium ions as toxic heavy metals ...

    Influence of lead and chromium ions as toxic heavy metals between AFt and AFm phases based on C3A and C4A3 ... the formation of AFt and AFm phase based C4A3 was faster than C3A. Especially, ... cementitious materials causing numerous AFt or AFm phases in cement hydration for S/S materials have attracted growing attention [1].

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  • Cement and Concrete Composites - cvut.cz

    Tensile strength of hydrated cement paste phases assessed by micro-bending tests and nanoindentation J. Neme cek a, *,1,V.Kralík a, 2,V.Smilauer a, 3, L. Polívka b, 4,A.J€ager b, 5 a Czech Technical University in Prague, Faculty of Civil Engineering, Department of Mechanics, Thakurova 7, 166 29 Prague 6 Czech Republic b Laboratory of Nanostructures and Nanomaterials, Institute of Physics ...

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  • Cement hydration - Understanding Cement

    If there is eventually more alumina than sulfate available, all the sulfate will be as monosulfate, with the additional alumina present as hydroxyl-substituted AFm phase (hydroxy-AFm). If there is a small excess of sulfate, the cement paste will contain a mixture of monosulfate and ettringite.

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  • The AFm phase in Portland cement, Cement and Concrete ...

    2/1/2007· The AFm phase in Portland cement The AFm phase in Portland cement Matschei, T.; Lothenbach, B.; Glasser, F.P. 2007-02-01 00:00:00 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− .

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  • Crystal Structures and Phase Transition of Cementitious Bi ...

    I. Introduction. T he AFm phases are hydrated tetracalcium aluminate compounds belonging to the lamellar double hydroxide (LDH) family. They occur during the hydration process of many kinds of cement. AFm phases are composed of positively charged main layer [Ca 2 Al(OH) 6] + and negatively charged interlayer [X·nH 2 O] − where X is either one monovalent anion or half a divalent anion.

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  • Origins of phase contrast in the atomic force microscope ...

    8/18/2009· We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation .

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  • Strätlingite: compatibility with sulfate and carbonate ...

    10/30/2015· 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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  • 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 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 water content) depending on the relative humidity ...

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  • 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.

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

    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 ...

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  • Tapping-Mode AFM Studies Using Phase Detection for ...

    The nanophase separated hard segment domains in solvent cast films of a segmented polyurethane and a segmented polyamide elastomer were imaged in real space using phase and topographical information from tapping-mode AFM techniques. A styrene triblock copolymer was used as a control to demonstrate the contrast mechanisms.

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  • EFFECT OF CARBONATION ON CHLORIDE PENETRATION IN .

    ions fixed in AFm phase become stable and keep at a constant level of 5 moles of chloride ions in respect to 1 mole of AFm and (3) the fixing rate and finely fixed amount of chloride ions in AFm phase are not varied with the initial concentration of NaCl. If the Fig.1 Reactor fixation of chloride ion in AFm phase .

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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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  • Influence of graphene oxide as dispersed phase in cement ...

    In the present investigation, graphene oxide (GO) was prepared using oxidative treatment of graphite by Hummer's method. The synthesized graphene oxide (GOa) was characterized by FTIR, SEM/EDS, TEM, XRD, TGA and AFM. Size-reduction of GOa (which had a 14 nm sheet thickness and 900 nm average sheet size) was done us

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  • An AFM-SEM investigation of the effect of silica fume and ...

    Atomic force microscopy (AFM) was used to observe particle shape and surface texture details of normal portland cement and supplementary cementing materials (silica fume, low-calcium fly ash, and high-calcium fly ash). The latter materials mixed with cement were examined after prolonged hydration. Significant innovative information on ...

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  • Quantitative refractive index distribution of single cell ...

    5/31/2017· By combining optical phase-shifting interferometry (PSI) and atomic force microscope (AFM) imaging, we constructed a label free, non-invasive and quantitative refractive index of single cell ...

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  • Journal of Physics D: Applied Physics RAPID COMMUNICATION ...

    (SPFM), non-contact mode and tapping-mode atomic force microscopy (AFM) [1–4]. Cement paste is a porous material with a complicated microstructure. In brief, it is composed of an amorphous phase (C–S–H gel), crystallites in the micrometre range and bound water [5,6]. The surface of the paste is .

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

    The transition of the Friedel phase to the chromate-AFm phase in chromate solution and the thermal stability of the products was investigated using thermal analysis combined with mass spectrometry, X-ray diffraction and Fourier transform infrared spectrometer. The results indicated that Cr O 4 2− easily substituted for Cl in the Friedel phase forming chromate-AFm.

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  • The Density of Cement Phases M. Balonis* and F.P. Glasser

    synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software. A density value is presented for each phase.

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  • NanoElectrical Lab | Bruker AFM | Bruker

    Conductive AFM results are influenced by the applied sample voltage, depicting important performance transitions of a material or device. DCUBE-TUNA enables simultaneous acquisition of nanomechanical information and electrical conductivity at a multitude of sample voltages in a single measurement, building a dense data cube of sample information.

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