The report comprises a review and analysis of the available literature pertaining to the causes, effects and prevention of secondary (delayed) ettringite in concrete. Over 300 publications have been examined. Case studies of damage in concrete possibly caused by secondary ettringite formation are examined first.

Delayed Ettringite Formation (DEF) modelling is addressed in the context of structural analysis. First, a chemical model is specified to simulate the effects of the heating of concrete in terms of reactions involving sulfates, aluminates and alkalis.

First, a chemical model is specified to simulate the effects of the heating of concrete in terms of reactions involving sulfates, aluminates and alkalis. 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. DEF is diagnosed by the presence of gaps around aggregate particles. Brown, P.W., Hooton, R.D. and Clark, B.A. (2003) The co-existence of thaumasite and ettringite in concrete exposed to magnesium sulfate at room temperature and the influence of blast-furnace slag substitution on sulfate resistance. Cement and Concrete Composites, 25, 939 – … DURABILITY AND POTENTIAL OF DELAYED ETTRINGITE FORMATION IN MASS CONCRETE STRUCTURES By Lucy Acquaye May 2006 Chair: Abdol Chini Major Department: Design, Construction and Planning The Florida Department of Transportation (FDOT) has in recent years recorded Can the deposition of ettringite in air-voids jeopardise the resistance of the concrete to frost damage?

Ettringite in concrete

2000-02-28 Ettringite Cements Made From Blastfurnace Slag. Ettringite and C-S-H are the first phases formed in the presence of sulfate. They Pozzolanas and Pozzolanic Materials. The AFt phase ettringite forms rapidly in cements containing natural pozzolanas 197 Chemical degradation of concrete. J. 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 is a primary constituent of hydration of Portland cement concrete.

Ettringite formation is associated with expansion and many hypotheses of ettringite related expansion have been advanced (2-4). However, not necessarily any ettringite-related expansion produces damaging disruption of concrete structures. When ettringite occurs homogeneously and immediately (within hours), it

Delayed ettringite formation (DEF) is the destructive development of ettringite in concrete, months or years after placement in an environment where moisture exposure is frequent (Hime and Marusin, 1999). DEF is a worldwide phenomenon having been found in railway ties (sleepers) produced in Delayed Ettringite Formation (DEF) modelling is addressed in the context of structural analysis.

15 Feb 2010 The simultaneous occurrence of the delayed ettringite formation mechanism and the alkali-silica reaction in concrete structures is not well

Effects on Ettringite. Sodium Sulfate Experiments. 15. Sulfate + Crystallization Inhibitor Experiments. 16.

Special type of internal sulfate attack is heat-induced sulfate attack or so call delayed ettringite formation (DEF). Delayed ettringite formation DEF occurs if the ettringite which normally forms during hydration is decomposed , then subsequently re-forms in the hardened concrete. Damage to the concrete 2 Apr 2021 Delayed Ettringite Formation (DEF), is one of the different Internal Sulfate The composite samples, consist of a 15 mm thick cement paste Project Title: Preventing Premature Concrete Deterioration due to Alkali-silica reaction (ASR) and delayed ettringite formation (DEF), or combinations of the the growth of ettringite, C-S-H, and portlandite at different times on the surface of the clinker grains. 2 Properties of cement.
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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.

The formation of ettringite or cement bacillus has been recognized as the cause of excessive expansion, cracking and even complete disintegration of concrete subjected to intensive sulfate attack. Ettringite is a normal product of cement hydration, and persists indefinitely in the hydration products of many cements. Because small crystals are unstable relative to larger ones, it tends to recrystallize in any available cracks or other spaces. An ettringite formation in hardened concrete does not in every case lead to a direct damage of the concrete structure.
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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.

Page 2. C3A + 3CSH2 = C3A· 3CS aq. 2C3A Reduction of new ettringite formation in concrete blocks also reduced expansion and cracking of the blocks. This relationship clearly links concrete expansion with It is a high water mineral that is primarily formed at an early period of the hydration of Portland cement. Its structure is hexagonal, with needle-like crystals [ 1]. pH value, the morphology of the resulting ettringite, the expansion kinetics, and the strength of cement stone and concrete based on it. The studies of the 12 Feb 2014 The expansive sulphate internal reaction due to Delayed Ettringite Formation ( DEF) can damage concrete structures severely.

Jul 5, 2017 High temperature experienced by these sleepers in form of steam curing during their production in factories may lead to Delayed Ettringite

We list out many concrete alternatives for all projects including driveways, walkways, fence Delayed Ettringite Formation (DEF) and Alkali Aggregate Reaction (AAR) are Internal Swelling Reactions (ISR) that can affect concrete. They lead to cracking Jul 5, 2017 High temperature experienced by these sleepers in form of steam curing during their production in factories may lead to Delayed Ettringite It can be understood that ettringite is usual product of hydration and occurs both in fresh and degraded concretes. Ettringite causes concrete decaying only in case Understanding the mechanisms by which concrete structures can be adversely of gypsum (calcium sulfate) and calcium mono-sulfoaluminate (ettringite).

Ettringite is often found in voids, cracks and around aggregates grain in concrete. This may be due to re-crystallization which occurs due to so-called Ostwald ripening [4]. can have an impact on precast concrete beam manufacture.