Decomposition of synthesized ettringite by carbonation

Nishikawa, Tadahiro; Suzuki, Kazuyuki; Ito, Suketaka; Sato, Kazunori; Takebe, Toshimasa

doi:10.1016/0008-8846(92)90130-n

Cited by 185 publications

(62 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the initial stage, the form of calcium carbonate resulting from this reaction is vaterite, while in a later stage aragonite becomes predominant [9] (at room temperature and ambient pressure, vaterite and aragonite are unstable allotropic modifications of CaCO3).…”

Section: Curing Reactions In Mortarsmentioning

confidence: 99%

Composition of lime-cement and air-entrained cement mortar as a function of distance to the brick-mortar interface: consequences for masonry

Brocken¹,

Pers²,

Larbi³

2000

Mat. Struct.

View full text Add to dashboard Cite

A B S T R A C T R I~ S U M I 5The composition of a lime-cement mortar and an airentrained cement mortar was studied as a function of distance to the brick-mortar interface. Both mortars had the same cement-to-sand ratio and the same water-to-cement ratio; in the lime-cement mortar the binder-to-sand ratio was highest. The measurements indicate that the mortar composition (i.e. the contents of sand, cured binder and voids) and the contents of chemical substances of the cured binder (i.e. the contents of calcite, portlandite and ettfingite) change with distance to the brick-mortar interface. For the mortar composition the tendency of these changes is the same, but for the contents of the chemical substances of cured binder for the two mortar types the tendency of these changes is opposite and also the extent of the changes is significantly different. For the air-entrained cement mortar, the observations are explained by the enrichment of binder towards the brick-mortar interface, resulting from the compaction of flesh mortar. In the lime-cement mortar such an enrichment of binder hardly occurs and the observations are explained by the intense carbonation that takes place. As a result, the contents of the chemical substances in the mortars is very much different. In the air-entrained cement mortar, near the brick-mortar interface the enrichment of cement and the low water content (resulting from the low water retentivity of this mortar), lower the water-to-cement ratio and as a consequence the cement is not fully hydrated. In the lime-cement mortar, as the Ca(OH)2 content and the water content is higher, near the brick-mortar interface, a carbonated zone is formed which is hardly permeable for CO 2 (and probably water). This does not occur in the air-entrained cement mortar, it remains permeable. La composition d'un mortier de ciment et de chaux et d'un mortier de ciment h air entrafn~ a ~t~ examin& en fonction de la distance par rapport a l'interface brique-mortier. Les rapports dment-sable et eau-ciment (taient identiques pour les deux mortiers. Le rapport liant-sable ~tait le plus ~lev( clans le mortier de ciment et de chaux. Les mesures indiquent que la composition du mortier (teneurs en sable, liant durci et vides) et les teneurs en produits chimiques du liant durci (teneurs en calcite, portlandite et ettringite) changent en fonction de la distance par rapport h l'intetface brique-mortier. Pour Ia composition du mortier, la tendance de ces changements est identique, par contre, en ce qui conceme les teneurs en produits chimiques du liant durci, la tendance de ces changements est oppos& pour les deux types de mot

show abstract

Section: Curing Reactions In Mortarsmentioning

confidence: 99%

Composition of lime-cement and air-entrained cement mortar as a function of distance to the brick-mortar interface: consequences for masonry

Brocken¹,

Pers²,

Larbi³

2000

Mat. Struct.

View full text Add to dashboard Cite

show abstract

“…Ettringite would decompose to CaSO 4 ⋅2H 2 O, CaCO 3 , and alumina gel as the following equation [20]: reaction has to occur if there is water, gas, or insoluble product formation [20,21]. Figure 13: Stability of ettringite as a function of NaCl concentration and temperature [14].…”

Section: Degradation Mechanisms By Carbonationmentioning

confidence: 99%

Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

Zhang

Gong

Kang

2017

Advances in Materials Science and Engineering

View full text Add to dashboard Cite

The hydration products of calcium sulfoaluminate (CSA) cement are different from those of Portland cement. The degradation of CSA cement subjected to wet-dry cycles in sulfate solution was studied in this paper. The surface corrosion was recorded and the microstructures were examined by scanning electron microscopy (SEM). The results show that SO 4 2− , Na + , Mg 2+ , and Cl − have an effect on the stability of ettringite. In the initial period of sulfate attack, salt crystallization is the main factor leading to the degradation of CSA cement specimens. The decomposition and the carbonation of ettringite will cause long-term degradation of CSA cement specimens under wet-dry cycles in sulfate solution. The surface spalling and microstructure degradation increase significantly with the increase of wet-dry cycles, sulfate concentration, and water to cement ratio. Magnesium sulfate and sodium chloride reduce the degradation when the concentration of sulfate ions is a constant value.

show abstract

“…However, at the calcite equilibrium (pH approximately 8.2), which is attained by the carbonation of portlandite in the uppermost layers of the abandoned waste deposits, ettringite becomes unstable. At a pH lower than 10.7 ettringite dissolves incongruently to gypsum (6), (amorphous) Al-hydroxide and Ca-aluminate type phases; or in the presence of atmospheric CO 2 into Ca-sulphate, Al-gel and calcium carbonate polymorph -aragonite or vaterite (γ-CaCO 3 ) as an intermediate phase [56][57][58]. …”

Section: Diagenesis Of Ash In Depositsmentioning

confidence: 99%

Open-Air Deposition of Estonian Oil Shale Ash: Formation, State of Art, Problems and Prospects for the Abatement of Environmental Impact

Kuusik¹,

Uibu²,

Kirsimäe³

et al. 2012

Oil Shale

View full text Add to dashboard Cite

show abstract

Decomposition of synthesized ettringite by carbonation

Cited by 185 publications

References 3 publications

Composition of lime-cement and air-entrained cement mortar as a function of distance to the brick-mortar interface: consequences for masonry

Composition of lime-cement and air-entrained cement mortar as a function of distance to the brick-mortar interface: consequences for masonry

Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

Open-Air Deposition of Estonian Oil Shale Ash: Formation, State of Art, Problems and Prospects for the Abatement of Environmental Impact

Contact Info

Product

Resources

About