Results 141 to 150 of about 3,590 (187)
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Cement and Concrete Research, 1979
Abstract The study was conducted on the effects of Cr2O3, Fe2O3, Cu(OH)2, ZnO and Pb2O(OH)2 on the formation of ettringite and microstructure of hardened ettringite. The cement samples were prepared by mixing C3A synthesized and CaSO4·2H2O and adding 5 % by weight of above additives. The heavy metal oxides and hydroxides promote the crystal growth of
C. Tashiro, J. Oba, K. Akama
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Abstract The study was conducted on the effects of Cr2O3, Fe2O3, Cu(OH)2, ZnO and Pb2O(OH)2 on the formation of ettringite and microstructure of hardened ettringite. The cement samples were prepared by mixing C3A synthesized and CaSO4·2H2O and adding 5 % by weight of above additives. The heavy metal oxides and hydroxides promote the crystal growth of
C. Tashiro, J. Oba, K. Akama
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Heat Curing and Delayed Ettringite Formation
MRS Proceedings, 1994AbstractThis paper reports some preliminary results from a study of the effect of elevated temperature curing on mortars and the phenomenon of delayed ettringite formation (DEF). Mortars made from cements with sulphate levels of 3%, 4%, and 5% and with 5% sulphate and added alkali were cured at 20 and 90° C and subsequently stored in water.
Lewis, M. C. +2 more
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The solubility of ettringite at 25°C
Cement and Concrete Research, 1994Abstract Available solubility constants indicate that ettringite should be the stable form of calcium aluminate sulfate hydrate with respect to monosulfate in cement porewater. However, monosulfate is generally present in mature cement pastes, usually in the absence of ettringite.
C.J. Warren, E.J. Reardon
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Decomposition of synthesized ettringite by carbonation
Cement and Concrete Research, 1992The stability of ettringite (3CaO·Al2O3·3CaSO4·32H2O) in contact with CO2 gas has been studied using synthesized ettringite. Carbonation were carried out at water/solid ratios(W/S) of 0.6∼3.5 in a moist CO2-incubator. According to the SEM-EDAX examination, the carbonation without water makes compositional changes slightly in ettringite, maintaining ...
T. Nishikawa +4 more
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In-situ observation of ettringite crystals
Journal of Crystal Growth, 2009In-situ observation of growing ettringite crystals in solution has been carried out and the morphology change of ettringite has been investigated under various conditions. In particular, the acceleration behavior of ettringite growth in the presence of calcite, the cause of which is not yet understood, is examined.
Ryuichi Komatsu +3 more
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Kinetics and mechanism of the carbonation of ettringite
Advances in Cement Research, 2000Synthetic, phase pure ettringite has been exposed to a moist CO2 atmosphere at 68 and 88% relative humidity (RH) both at 21–25°C and at 40°C. Physically, the ettringite was carbonated in the form of powders and pellets, pressed to ∼80% theoretical density.
Q. Zhou, F. P. Glasser
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Expansive admixtures (mainly ettringite)
Cement and Concrete Composites, 1998Abstract The hydration chemistry of expansive cements is described with emphasis on the components for formation of ettringites. Expansive cement concrete as ‘shrinkage-compensating concrete’ or ‘chemical prestressing concrete’ is applied to many kinds of concrete construction.
S. Nagataki, H. Gomi
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The formation of ettringite at elevated temperature
Cement and Concrete Research, 1993Abstract The formation of ettringite was investigated by isothermal calorimetry over the range of temperature from 50 to 70°C. Ettringite was formed using three sources of alumina: tricalcium aluminate, high alumina cement and calcium aluminate sulfate. In accord with a diffusionally controlled reaction mechanism, the kinetics of ettringite formation
E. Grusczscinski, P.W. Brown, J.V. Bothe
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C4A3 hydration ettringite formation, and its expansion mechanism: I. expansion; Ettringite stability
Cement and Concrete Research, 1981Abstract C 4 A 3 S hydration, the mechanism of C 4 A 3 S expansion, ettringite formation and its thermal stability are examined in a 3-part study. In this part, the amount of ettringite formed and the C 4 A 3 S degree of hydration are interrelated, and correlated with the degree of expansion beyond an induction period for the ...
K. Ogawa, D.M. Roy
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