Jul 19, 2024 · Corrosionpedia Explains Ettringite . Ettringite is also known as c ement bacillus, which is the name of a naturally occurring mineral of the same composition and structure. The formation of ettringite or cement bacillus has been recognized as the cause of excessive expansion, cracking and even complete disintegration of concrete …
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Jun 1, 2004 · Fig. 1 displays patterns from the hydrothermal reactions of the sample heated from 25°C to 120°C. The sample was a moist mixture made approximately 5 min before the first pattern was recorded at 25°C.C 3 A is the most reactive of the calcium aluminum oxides investigated [8].The intensity of the 020 gypsum reflection at 2θ=6.91° (d=7.63 Å) …
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Ettringite occurs in xenoliths or metamorphosed limestone near igneous contacts. It also occurs as weathering crusts on larnite rocks. The minerals that are closely associated with ettringite include gypsum, mayenite, hydrocalumite, afwillite, hydrocalumite and portlandite. References. Ettringite – Mindat; Ettringite Mineral Data – Webmineral
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May 31, 2022 · The chemical composition of ettringite is [Ca 6 Al 2 (SO 4) 3 (OH) 12 ·26H 2 O]. Ettringite is also referred to as Aft, which can absorb much water, imparting expansive propensity to the matrix. Ettringite form of sulfate attack is a conventional form of sulfate attack caused by the reaction between sulfate, calcium, and alumina-bearing phases ...
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From the view of the ettringite phase crystal structure,the influence factors of the ettringite phase formation and stability was investigated,as well as the ettringite expansion mechanism.A large number of literature show that most of scholars agree with the solution-precipitation theory of the ettringite phase formation;the speed of AlO 2-dissolution,the …
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Apr 25, 2015 · With many large scale civil engineering construction projects being undertaken, there is a possibility to find large concrete pours in thick members. Due to the hydration process, temperatures in concrete will increase during early stages and when the temperature exceeds 700C, Delayed Ettringite Formation (DEF) can take place. DEF …
Dec 6, 2023 · of synthesized ettringite crystals is extremely dependent on the pH value of the reaction solution (Fig. 5). Long, fiber-shaped crystals were formed at pH values between 10 and 12, but extremely microcrystalline ettringite was present at pH values above 13.0. Fig. 5: Change in ettringite habit (length-thickness ratio of the ettringite crystals)
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Jan 1, 1994 · The formation and expansion of ettringite crystals are discussed on the basis of principles of physico-chemistry. It is suggested that ettringite forms by a through-solution mechanism and that expansive force results from crystallization pressure as well as swelling pressure converted from the reduction of chemical potentials in the reaction of ettringite …
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Jan 1, 2021 · The ettringite has an expansive characteristic when formed late, which spreads throughout the cement paste matrix and the transition zone, leading to cracks in the system that progress over time ...
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The formation and transformation of ettringite were studied by measuring the ion concentration in liquid phase and analyzing the composition in solid phase. The effects of C3A, gypsum, lime and C−S−H gel on ettringite formation and transformation were also investigated. The experimental results show that, when gypsum was presented in solid …
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