Delayed ettringite formation (DEF) is expansion and cracking of concrete associated with the delayed formation of the mineral ettringite which is a normal product of early cement hydration. DEF is a result of high early temperatures (above 70 o C – 80 o C) in the concrete which prevents the normal formation of ettringite.
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الحزام الناقل ، معدات معالجة الجبس ، كسارة Vsi نرحب بك للاتصال بنا في أي وقت . وفقًا لتغطية أعمال sks ، فقد أنشأنا فرقًا قوية لمهندسي التركيب وقسمناهم إلى عدة أجزاء وفقًا للأعمال ، بما في ذلك بناء الفريق الكلي ، وفريق ...
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Jul 1, 2017 · During the experiments we made use of Ordinary Portland cement, calcium aluminate cement and calcium sulphate (α-Hemihydrate). In these so-called ettringite systems [23], there are several situations depending on the proportions of each material.The used formulations that were studied here are shown in Table 1.In System A …
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May 1, 2003 · Ettringite crystals that grow in the presence of a polynaphthalene sulfonate are found to have a morphology quite different from the ones observed in the absence of superplasticizers [10], [11], [12]. In the presence of a superplasticizer ettringite crystals grow as small and massive crystals, which shape contrasts with the long needle-like ...
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May 10, 2024 · A few low carbon binders with ettringite as one of the major binding phases have been developed e.g. calcium sulfoaluminate (CSA) cement [9], supersulfated cement (SSC) [10] and excess-sulfate phosphogypsum-slag cement [11].The detailed information of these binders is shown in Table 1.The calcium sulfoaluminate cement contains mainly …
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Jan 1, 1994 · The transformation of ettringite to monosulfate in the presence of C4AH13 thus can be written: Caj;A1206(S04)3 - 32Hß0 + Ca4A1207' 13Hz0 -> 2Ca4A120eS04 - 12Hz0 + 20X20 + 2Caz+ + S04- + 20X- (1) The reaction shows that decreases in calcium and sulfate activities, which will occur after gypsum and syngenite have been depleted, …
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Feb 15, 2011 · The ettringite surface is mimicked as an impenetrable wall bearing a smeared out surface charge (σ s) set equal to the structural charge of ettringite, σ s = 1.25 e/nm 2.In the simulations, the electrolyte solution is, thus, confined in a simulation box of dimensions W × W × L, depicted in Fig. 1, which consists in a charged surface at z = 0 …
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CSA cements are a good binder for S/S of heavy metals (Peysson et al., 2005).In fact, heavy metal cations can substitutes calcium in the flexible structure of ettringite (Berger et al., 2011).The crystal structure of ettringite consists of columns and channels running parallel to c-axis with SO 4 2− groups and H 2 O molecules lying in the channels (Cau …
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Sep 12, 2019 · The dissolution of alite leads to the precipitation of poorly-crystalline calcium silicate hydrate (C–S–H) and portlandite [] (p. 113).Thereby, the nanostructure of C–S–H is changing during hydration from X-ray amorphous, consisting of monomeric silicon tetrahedrons, to a “long-range ordered” dimeric C–S–H, which can be detected by X-ray …
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