The study compared the ettringite content and the measurable expansion in CLSM samples under different curing regimes to identify the role of water in expansion of ettringite …
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Ettringite is a hydrous calcium aluminum sulfate mineral first described in 1874 from Ettringer Bellerberg, Germany. The mineral was named after its place of discovery. …
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Ettringite Group. Although it is generally assumed that a solid solution series between ettringite and thaumasite exists, both species have different space groups and a possible discontinuity was identified, characterised by a gap in the a-dimension of the solid-solution phases (Barnett et al., 2000).Further work showed a miscibility gap in the solid solution …
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It is known that ettringite is formed from the aluminate phase (3CaO·Al 2 O 3) and gypsum (CaSO 4 ·2H 2 O) during the early stage of cement hydration. 8) One reason for the concrete deterioration, there is a phenomenon called "delayed ettringite formation (DEF)," which causes expansion and destruction of concrete. 9,10) This happens when ...
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The mineral compound ettringite ([Ca3Al(OH)6]2·(SO4)3·26H2O) occurs rarely in nature, but is common for cement-based materials. Ettringite has wide …
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Ettringite is a key compound of cementitious materials, formed during hydration that influences the rheological behavior of the cement paste. Despite its …
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Because sulfate ions show a higher affinity to ettringite than selenate,15,24 20 mg of selenate ettringite was added to 50 mL of 0.001–10 mM Na 2SO 4 for destructuralization. Since ettringite is an alkaline material and stable at pH values higher than 10.7,17 theinitialpHwasadjustedto12.00 0.01using0.1mMNaOH.
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Ettringite is either colorless or white in color. It is transparent in appearance and non-magnetic. The mineral is non-fluorescent with white streak, perfect cleavage and vitreous luster. It forms needle-like crystals. The hardness of ettringite ranges from 2 to 2.5, and its density is 1.8 g/cm 3.
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Ettringite is Ca hydrosulfatoaluminate Ca 6 Al 2 (SO 4) 3 (OH) 12 ⋅26H 2 O, which was found in nature as a secondary mineral in metamorphosed Ca-rich volcanic and/or sedimentary rocks. This mineral attracts much interest because of some of its physical properties, first of all, because this phase is an important constituent of set …
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The paper presents results of a physicochemical study of ettringite, natural calcium hydrosulfoaluminate Ca6Al2(SO4)3(OH)12⋅26H2O, from N'Chwaning, Kalahari, …
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The third main difference between ettringite and thaumasite is a band at ∼1400 cm −1, which is very intensive in the thaumasite IR spectrum. This band corresponds to the asymmetric stretching C–O vibration of the CO 3 2 − anion. In the IR spectrum of ettringite, a small band at 1410 cm −1 is observed. It can indicate a carbonate ...
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2. Formation of ettringite. Ettringite is a rare mineral phase in nature, while it exists commonly and largely in cement paste. Almost all alumina source, such as Al(OH) 3 gel, aluminium sulfate hydrate, C 3 A, can be reactive to form ettringite crystals [18], [27], [28]: with the addition of some calcium and sulfate source, the desired compound can be …
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에트링가이트 (Ettringite). 에트링가이트 의 투명한 결정은 길고 육각형이지만 무색이고 매우 부드럽기 때문에 보석으로 잘리지 않습니다. 이 광물은 종이를 코팅하여 "새틴 화이트"마감을 만드는 데 사용되며, 강화 과정의 화학 반응 중에 생성되는 시멘트의 중요한 수화 생성물이기도합니다.
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Бүтээгдэхүүн; ... пералатан тамбанг биджи нигерия. дробилка дан мельница унтук пабрик тамбанг ди мидлум метод пенамбанган батубара opencast тамбанг биджи беси ди танах лаут Civil amp Geotechnical engineering ...
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To investigate the influence of ettringite on the hydration properties of CaO/fluorgypsum-activated granulated blast furnace slag binders, the ettringite content in hydrated pastes with different amounts of fluorgypsum added was measured by selective dissolution in an ethylene glycol/methanol solvent system. The effects of ettringite …
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Ettringite crystals have a trigonal structure, consisting of central columns and channels parallel to the columns [4].Fig. 1 illustrates the composition of the structural unit and the lattice parameters of ettringite crystals. The lattice parameters of ettringite crystals are a = 1.123 ± 0.002 nm and c = 2.145 ± 0.005 nm, and the composition of the …
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Up to now, dehydration kinetic investigations of ettringite (3CaO·Al 2 O 3 ·3CaSO 4 ·32H 2 O) have been carried out in the nitrogen atmosphere. The partially dehydrated ettringite is termed as meta-ettringite (3CaO·Al 2 O 3 ·3CaSO 4 ∙nH 2 O, n ≠ 0) which contains various water molecules numbers (n in Eq. 1) ranging between 8 and …
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Ettringite (AFt) is a very important hydration product of hardened cement pastes in the early stage. The effect of ethanol-diisopropanolamine (EDIPA) on the formation and transform process of AFt in cement pastes was systematically investigated in this paper. The results indicate that the AFt content in hardened cement pastes notably decreases …
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The first endothermic effect in the temperature ranges of 40–200°C corresponds to the loss of molecular water from ettringite. The second effect, at 240–390°C, represents the losses of water arising from dehydration of calcium monosulfoaluminate hydrate, assuming the monosulfate has been presented in the …
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fication of ettringite is always lower than for the revised ettringite model (Figure 2). Degree 2 Cu Kθα o observed data-- calculated data Rwp = 20.51 R Bragg = 10.50 Figure 1: Difference plot from Rietveld refinement with TOPAS 2.1 for synthetic ettringite refined with ettringite structure data of Moore & Taylor Degree 2 Cu Kθα o observed data
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Chemical precipitation is one of the most widely known methods for treatment of industrial wastewaters with high sulphate content, where sulphate can be precipitated as practically insoluble ettringite (Ca6Al2(SO4)3(OH)12·26H2O). This treatment method is also widely recognised for solidifying hazardous components and …
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Here, we report on a first mechanochemical synthesis of ettringite, an important cement hydrate phase. The mineral compound ettringite ([Ca3Al(OH)6]2·(SO4)3·26H2O) occurs rarely in nature, but is common for cement-based materials. Ettringite has wide technical application in the ceramic and paper industry. …
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ettringite (Ca 6 Al 2 (SO 4) 3 (OH) 12•26H 2 O) precipitates. This paper concerns the ettringite precipitates that form during water treatmentfor the removal of sulfate. Properties of ettingite precipitates Ettringite can refer to both the mineral and the ettringite crystal structure (Tishmack and Burns 2004; Damons and Petersen 2002).
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With the increasing number of vehicles in the world, the amount of waste tires is increasing day by day. In this case, the disposal of expired tires will cause serious environmental problems. In recent years, instead of disposing of tire wastes, most of them have been started to be recycled to produce fiber-reinforced concrete. Thus, steel fibers …
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The spontaneous crystallisation of ettringite from combined calcium hydroxide (Ca(OH)2) and aluminium sulfate (Al2(SO4)3) solutions was investigated in the presence and absence of three different kinds of polycarboxylate superplasticisers. The crystallisation period was limited to 10 s only to study the initial crystals, which provide …
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Compared with polymer-modified ordinary-Portland-cement-based materials, research on cement materials based on polymer-modified sulfoaluminate is still in the preliminary stage and lacks an understanding of the mechanism of the interaction interface. The aim of this work is to study the bond performance of ettringite, the main hydration …
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H-ettringite (synthesized by hydration reaction) and S-ettringite (solution synthesis) samples are synthesized in this study. By thermogravimetric analysis we …
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Ettringit. 3CaO x Al 2 O 3 x 3CaSO 4 x 32H 2 O. Geläufige Bezeichnung für Calciumsulfoaluminat. Es entsteht bei der Hydratation des Zements durch Reaktion von Tricalciumaluminat (C 3 A) und Wasser mit Gips oder Anhydrit, die zur Regelung des Erstarrens zugegeben werden, und ist in dieser Phase unschädlich. Werden dem …
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The hydration of the SSC occurs from the reaction between gehlenite (C 5 S 3 A), the main slag component, with calcium hydroxide (CH), calcium sulfate (CS̅), and water (H). The main hydrated phases are ettringite (C 6 AS̅ 3 H 32), which is responsible for the development of initial resistance (first 7 days), and calcium silicate hydrate (C–S–H), …
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The application of silane in sulfoaluminate cement repair materials can improve its waterproof, permeability, freeze–thaw, and other properties, but it would reduce the mechanical properties of sulfoaluminate cement-based materials, making it unable to better meet the engineering requirements and durability indices. The modification of …
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Ettringite is an important cement hydration product and has a significant effect on cement performance. H-ettringite (synthesized by hydration reaction) and S-ettringite (solution synthesis) samples are synthesized in this study. By thermogravimetric analysis we found that S-ettringite undergoes a higher mass loss (~ 29 water …
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Ettringite acts as host to a number of these ions in both the columnar and channel sections of the crystal structure. Substitutions have been made at the calcium, aluminum, hydroxide and sulfate sites. C-S-H also hosts a number of the waste species in both ionic and salt form. Immobilization mechanisms for C-S-H include sorption, phase …
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1. Introduction. Ettringite Ca 6 Al 2 (SO 4) 3 (OH) 12 ⋅ 26H 2 O(C 6 A S ¯ 3 H 32 in cement chemistry notation) is one of the prominent compounds formed during cement hydration. Ettringite crystal structure has columns which run parallel to the c or needle axis [1].Its unit-cell is hexagonal, space group P31c, with a = 11.167 Å and c = 21.354 Å …
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ettringite decomposes. It has been postulated that up to approximately 70 ºC, ettringite is the stable component in concrete but some research indicates that ettringite can exist in equilibrium with its aqueous solution in the range of 75 …
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