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Study of nucleation and growth processes of ettringite in ...

2020-1-1  Growth process of ettringite crystals was studied by a step-by-step crystallization method. Ettringite crystals were first synthesized with the previously described synthesis method with β = 2.25. This supersaturation degree enabled the production of a large amount of ettringite crystals.

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Ettringite Formation and the Performance of Concrete

2000-2-28  ettringite could reduce the protection the air void system affords against freeze-thaw damage (see discussion of freeze-thaw resistance below). Ettringite formed by dissolution and recrystallization in void spaces and cracks is often referred to as “secondary ettringite.” Secondary ettringite is not detrimental to concrete performance.

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Case study modelling for an ettringite treatment process

2018-3-20  Process description The ettringite process flow diagram used for simulation is illustrated in Figure 3. The process has three principal processing stages followed by a pH adjustment step. A portion of the ettringite sludge from the ettringite precipitation reactor, Reactor 3, is recycled and mixed with the

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Process for the preparation of ettringite fibers - Societe ...

15. A process as claimed in claim 5 wherein the mixture comprises a refractory alumina cement, gypsum and lime. 16. A process as claimed in claim 5 wherein the calcium aluminate is finely ground. 17. A product obtained by a process as claimed in claim 5 and consisting essentially of ettringite fibers having a length from 2 to 350 microns. 18.

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US4255398A - Novel ettringite whiskers, production and ...

This disclosure deals with ettringite whiskers, methods of synthesizing such whiskers and ettringite whisker composites. The ettringite whiskers, having a new crystal form, are 1-2 μm in diameter, 50-100 μm in length and approximately 30-50 of aspect ratio. The ettringite whiskers are especially useful in industry as a high tensile strength reinforcement, they increase self-extinguishability ...

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Novel ettringite whiskers, production and uses - Hyogo ...

Thus, ettringite whiskers can be synthesized by adding lime, an aluminous material (preferably one having the composition C 3 A) and optionally a metal salt catalyst, to a calium sulfite slurry prepared from a desulfurization process, i.e. the gypsum-lime method, the gypsum-limestone method, the soda-lime method and ammonia-lime methods and so ...

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Ettringite - an overview ScienceDirect Topics

Ettringite Group (Ca 3 [ (Si,Al) (OH) 6 ] (SO 4 ,CO 3) 2 12H 2 O) A representative of this group, which may be approximated as kottenheimite-thaumasite solid solution (or dehydrated ferroan kottenheimite) with minor add of ettringite and other end-members, was located in the sample LdS12. It is undoubtedly of a secondary origin (Figure 13.2.6D ).

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Delayed Ettringite Formation A Concern for Precast

2018-11-1  identified as delayed ettringite attack, a process whereby the normal formation of ettringite in plastic portland cement concrete is either delayed or is formed and then decomposed, only to destructively re­ form in the hardened concrete after months or years of exposure to water. Reasons for the apparent newness of the phenomenon, and

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Ettringite Precipitation vs. Nano-Filtration for Efficient ...

2012-11-5  1996). This precipitation process is well-understood, reliable and can be easily controlled. The SAVMIN process is similar to the Walhalla process. It consists of successive steps for metal, gypsum and ettringite precipitation. A specialty of the SAVMIN process is the recycling of aluminum

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SOME ASPECTS OF THE DELAYED ETTRINGITE

2011-2-28  temperature accelerates the hydration of cement. It is applied to speed up the production process in manufacturing of prefabricated (precast) concrete elements (beams, columns, curbs, sills, concrete pipes, railroad ties etc.). Why ettringite formation in the concrete that was exposed to elevated temperature cause

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Case study modelling for an ettringite treatment process

2018-3-20  Process description The ettringite process flow diagram used for simulation is illustrated in Figure 3. The process has three principal processing stages followed by a pH adjustment step. A portion of the ettringite sludge from the ettringite precipitation reactor, Reactor 3, is recycled and mixed with the

Get Price

Enhanced Ettringite Formation: A Treatment Option for the ...

1997-3-3  The enhanced ettringite formation process (EEFP) was developed at the Energy Environmental Research Center (EERC) through a research project performed for Gas Research Institute (GRI). The EEFP will remove boron and other select trace elements such as arsenic, chromium, molybdenum, selenium, and vanadium from contaminated water and other ...

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Process for the preparation of ettringite fibers - Societe ...

15. A process as claimed in claim 5 wherein the mixture comprises a refractory alumina cement, gypsum and lime. 16. A process as claimed in claim 5 wherein the calcium aluminate is finely ground. 17. A product obtained by a process as claimed in claim 5 and consisting essentially of ettringite fibers having a length from 2 to 350 microns. 18.

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Novel ettringite whiskers, production and uses - Hyogo ...

Thus, ettringite whiskers can be synthesized by adding lime, an aluminous material (preferably one having the composition C 3 A) and optionally a metal salt catalyst, to a calium sulfite slurry prepared from a desulfurization process, i.e. the gypsum-lime method, the gypsum-limestone method, the soda-lime method and ammonia-lime methods and so ...

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ettringite milling equipment production

ettringite production process - ME Mining Machinery. Ettringite Formation and the Performance of Concrete. ettringite processing equipment production. Ettringite sludge is easily dewatered, and may be reused in the process as seed sludge to reduce the quantity of coagulant required. Process equipment required for a continuous-flow operation may ...

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Ettringite formation in soil-cement interaction process

Ettringite is known as one of the important minerals which forms in the process of cement hydration. Sulfate resistance cement can be used to prevent the ettringite formation due to excluding alumina ions in its production process. However, clayey soils might contribute to the formation of ettringite due to the solubility of alumina ions at ...

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Ettringite Precipitation vs. Nano-Filtration for Efficient ...

2012-11-5  1996). This precipitation process is well-understood, reliable and can be easily controlled. The SAVMIN process is similar to the Walhalla process. It consists of successive steps for metal, gypsum and ettringite precipitation. A specialty of the SAVMIN process is the recycling of aluminum

Get Price

Materials Free Full-Text Relating Ettringite Formation ...

The amount of ettringite formation strongly depends on temperature and is the main process that drives the change in rheology during initial hydration of cement paste before setting. With increasing ambient temperature the initial ettringite formation is accelerated, which results in higher measured torque values.

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Delayed Ettringite Formation (DEF) in Precast Concrete ...

2019-12-16  process of Portland cement and, in the presence of water, ettringite decomposes to calcium monosulphoaluminate. When the concrete cools down, the calcium, the aluminates and the sulphates of the monosulphoaluminate react with the sulphates that are in solution, leading to formation of ettringite. The crystallization of ettringite generates

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Formation of Nano-Sized Ettringite Crystals Identified as ...

The nano-scale ettringite was identified via X-ray diffraction, elemental analysis and thermogravimetry. It can be separated from a cement paste by centrifugation where it appears as a gel-like, viscous top layer. ... Copolymer for cement admixtures and its production process and use, US patent 6,727,315, assigned to Nippon Shokubai LTD. Google ...

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Enhanced Ettringite Formation: A Treatment Option for the ...

1997-3-3  The enhanced ettringite formation process (EEFP) was developed at the Energy Environmental Research Center (EERC) through a research project performed for Gas Research Institute (GRI). The EEFP will remove boron and other select trace elements such as arsenic, chromium, molybdenum, selenium, and vanadium from contaminated water and other ...

Get Price

Process for the preparation of ettringite fibers - Societe ...

15. A process as claimed in claim 5 wherein the mixture comprises a refractory alumina cement, gypsum and lime. 16. A process as claimed in claim 5 wherein the calcium aluminate is finely ground. 17. A product obtained by a process as claimed in claim 5 and consisting essentially of ettringite fibers having a length from 2 to 350 microns. 18.

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Materials Free Full-Text Relating Ettringite Formation ...

The amount of ettringite formation strongly depends on temperature and is the main process that drives the change in rheology during initial hydration of cement paste before setting. With increasing ambient temperature the initial ettringite formation is accelerated, which results in higher measured torque values.

Get Price

Delayed Ettringite Formation (DEF) in Precast Concrete ...

2019-12-16  process of Portland cement and, in the presence of water, ettringite decomposes to calcium monosulphoaluminate. When the concrete cools down, the calcium, the aluminates and the sulphates of the monosulphoaluminate react with the sulphates that are in solution, leading to formation of ettringite. The crystallization of ettringite generates

Get Price

Delayed Ettringite Formation A Concern for Precast

2018-11-1  identified as delayed ettringite attack, a process whereby the normal formation of ettringite in plastic portland cement concrete is either delayed or is formed and then decomposed, only to destructively re­ form in the hardened concrete after months or years of exposure to water. Reasons for the apparent newness of the phenomenon, and

Get Price

Ettringite precipitation – Mine Closure

The SAVMIN Process uses aluminium oxide (aluminiumtrihydroxide in amorphous or gibbsite form) to create the ettringite, with recovery, whereas the CESR process uses a proprietary Al-containing chemical obtained from cement production, without recovery of the aluminium source.

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Delayed Ettringite Formation Request PDF

Ettringite can form in cementitious materials after the hardening process due to the presence of excessive amounts of sulfates (SO 4 2− ) within [55]. Sulfate ions react with the calcium ...

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SOME ASPECTS OF THE DELAYED ETTRINGITE

2011-2-28  temperature accelerates the hydration of cement. It is applied to speed up the production process in manufacturing of prefabricated (precast) concrete elements (beams, columns, curbs, sills, concrete pipes, railroad ties etc.). Why ettringite formation in the concrete that was exposed to elevated temperature cause

Get Price

Formation of Nano-Sized Ettringite Crystals Identified as ...

[Show full abstract] Sulfate resistance cement can be used to prevent the ettringite formation due to excluding alumina ions in its production process. However, clayey soils might contribute to ...

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Removal of Phosphate Using Ettringite Synthesized from ...

2018-5-25  Removal of phosphate using ettringite synthesized from industrial by-products was evaluated in this study. Ettringite was synthesized by combining basic oxygen furnace (BOF) slag, alum, and flue-gas-desulfurization (FGD) gypsum at molar ratio ([Ca]:[Al]:[SO4]) of 3:2:3, pH 11.74, and 28 °C for 24 h. Kinetic study showed that the adsorption of phosphate by ettringite reached equilibrium after ...

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