Ettringite formation features prominently in many situations but there are several other processes, such as the conversion of portlandite to gypsum and reversible hydration/dehydration reactions of sulfate salts, such as the Na 2 SO 4 (thenardite) ↔ Na 2 SO 4.10H 2 O (mirabilite) system, that have also been implicated.

on the reaction of anions with common minerals in bottom ash, such as ettringite. 37 However, this formation has a low permeability, and Flyhammar (2009)

DEF definition: Ettringite is formed in hydrated Portland cement system as a result of the reaction of calcium aluminate with calcium sulfate, both present in Portland cement. The formation of ettringite in the fresh, plastic concrete is the mechanism that controls stiffening. Ettringite is a primary constituent of hydration of Portland cement concrete. Its formation plays an important role in the control of setting. Minor amounts of secondary ettringite are often encountered in air voids of hardened concretes, regardless of the type of cement used. Ettringite is normally one of the earliest phases formed during cement hydration.

Leachability of many Delayed Ettringite Formation (försenad ettringitbildning). DSS. Dynamisk Spårstabilisator. RÖK. Räl överkant. SFT. Spänningsfri temperatur (°C).

The formation of ettringite in the fresh, plastic concrete is the mechanism that controls stiffening.

Karen L. Scrivener and. 15 Feb 2010 The tests showed that the ettringite formation might increase the expansion due to the alkali-silica reaction as well as in the mortars cured at Ettringite is the mineral name for calcium sulfoaluminate. (3CaO•Al2O3•3CaSO4• 32H2O), which is normally found in portland cement concretes.

2017-03-16 · The primary ettringite formation in the initial stage of the hydration is seen as a positive effect because it enables the setting regulation, a damaging role is often attributed to delayed ettringite formation in hardened concrete. Damaged concretes often show large amounts of ettringite in structure damages even if they we

[Thai Language]ความรู้พื้นฐานเกี่ย 2019-04-01 2021-03-12 2016-07-07 Delayed Ettringite Formation (DEF) is an internal sulfate attack caused by heat-induced decomposition and/or prevention of normal ettringite formed during the initial hydration of cement at elevated temperature (above about 70°C) and its re-crystallization in the hardened matrix. This reaction is a physico-chemical phenomenon inducing an expansion of the cement paste that could lead to PhD | Multi-scale study of delayed ettringite formation in concrete Application Deadline: 31/03/2021 23:00 - Europe/Brussels Contact Details. Where to send your application. EEF Early Ettringite Formation. 1,365 likes · 3 talking about this.

It has been proposed that this expansion is affected by coexisting hydration products such as calcium-silicate-hydrates (C-S-H), although the mechanism has not yet been clarified. The present study experimentally examined the effects of coexisting materials on secondary ettringite View Academics in Ettringite Formation on Academia.edu.
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6. Vatten i anläggningsprojekt Göteborg 2013-11-. 27 air void cement paste aggregate monosulfate formation of ettringite by reaction with sulfate and moisture.

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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TY - JOUR. T1 - The kinetics of ettringite formation and dilatation in a blended cement with beta-hemihydrate and anhydrite as calcium sulfate. AU - Evju, C.

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Delayed Ettringite Formation (DEF) is an internal sulfate attack caused by heat-induced decomposition and/or prevention of normal ettringite formed during the initial hydration of cement at elevated temperature (above about 70°C) and its re-crystallization in the hardened matrix. This reaction is a physico-chemical phenomenon inducing an expansion of the cement paste that could lead to

Delayed Ettringite Formation Concrete Properties. Since DEF only occurs when cement has hydrated at temperatures above 70 °C it can be avoided simply Chemical degradation of concrete. J. Bensted, DEF is a fairly weakly expansive mechanism, and so is likely to Types and causes of 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. Delayed Ettringite Formation (DEF): Hardened concrete that has been subjected to high-temperature heat curing or high internal hydration heat temperature may suffer from expansion and cracking during subsequent exposure to moisture.

phases are formed is dictated mainly by the contents of elements of highest (Cl,F,OH). Ettringite. Ca6Al2(SO4)3(OH)12·26H2O. Gypsum. CaSO4·2H2O. A-7

28 Nov 2014 Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on the mechanical properties of hydrated cementitious Relating Ettringite Formation and Rheological Changes during the Initial Cement Hydration: A Comparative Study Applying XRD Analysis, Rheological Sulfate resistance cement can be used to prevent the ettringite formation due to excluding alumina ions in its production process. However, clayey soils might This form of ISA is widely known as Delayed Ettringite Formation or DEF. Despite its general use, this term can be misleading as it has long been known that in Abstract.

Some possible causes of the (re)crystallization and/or new formation of ettringite are: Ostwald ripening, variations in pH, / SO Al O. 3 2 3.