Formation of hydrogarnets: Calcium hydroxide attack on clays and feldspars

Aardt, J.H.P. van; Visser, Susan A.

doi:10.1016/0008-8846(77)90006-0

Cited by 31 publications

(7 citation statements)

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“…Although there are different criteria for the characteristics that the solutions to test alkali release from aggregates [1][2][3][6][7][8][27][28][29][30][31] should have, it was decided to use a NaOH solution since it is employed both in the chemical test method [19] and in the mortar bar accelerated test method [32] to assess aggregate reactivity.…”

Section: Methodsmentioning

confidence: 99%

Na2O, K2O, SiO2 and Al2O3 release from potassic and calcic–sodic feldspars into alkaline solutions

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et al. 2010

Cement and Concrete Research

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are

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Section: Methodsmentioning

confidence: 99%

Na2O, K2O, SiO2 and Al2O3 release from potassic and calcic–sodic feldspars into alkaline solutions

Locati

Marfil

Baldo

et al. 2010

Cement and Concrete Research

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“…Así, podemos apreciar si los áridos son o no reactivos dependiendo de los efectos que la reacción árido-álcali ha causado en cada superficie en un punto determinado (19)(20)(21)(22). Por ejemplo, en el estudio de una de las corneanas se aprecia como se disuelve el cristal de biotita después del tratamiento alcalino (Figura 6).…”

Section: Método De Reactividad Superficial: Microscopía Electrónica Dunclassified

“…The results obtained upon studying the surfaces of the aggregates allowed us to determine whether an alkali-aggregate reaction had taken place (19)(20)(21)(22). For example, it was clear upon studying one of the hornfels that the biotite crystals had dissolved upon base treatment ( Figure 6).…”

Section: Surface Reactivity Investigation: Scanning Electron Microscomentioning

confidence: 99%

Reactividad árido-álcali en áridos empleados para hormigón

et al. 2010

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RESUMENEste trabajo pretende contribuir al conocimiento de las reacciones de interacción entre los áridos y los componentes de la fase intersticial del hormigón y determinar si estos áridos, empleados posteriormente en la fabricación del hormigón, son reactivos y por tanto susceptibles de provocar una disminución progresiva de sus propiedades iniciales.Para la caracterización de cada árido se ha realizado un estudio petrográfico, fundamental a la hora de determinar su posterior comportamiento en términos de reactividad frente a diversos factores. Seguidamente, se ha analizado la reactividad potencial de diferentes áridos silicatados (pizarras, gneis, corneanas, granitos, cuarcita y serpentina) mediante los dos métodos normalizados existentes: el método químico para la determinación de la reactividad potencial de áridos y el método acelerado en probetas de mortero; y para contrastar ambos hemos seguido el método de la reactividad superficial.Los resultados determinan que algunos áridos son susceptibles de reaccionar con los componentes de la fase intersticial de hormigón. La observación de su textura antes y después del ataque denota la existencia de esta interacción.Palabras clave: reacción álcali-sílice, degradación, expansión, mortero, SEM. SUMMARYThe aim of this work is to contribute to the knowledge of the interactions between aggregates and the components of the interstitial phase of concrete and to determine whether those aggregates that are subsequently used in the manufacture of concrete are reagents and are therefore likely to undergo a progressive deterioration of their initial properties.An initial petrographic study of each aggregate is performed in order to be able to determine its subsequent behaviour and reactivity under the influence of various factors. The potential reactivity of different silicaceous aggregates (slates, gneiss, hornfels, granites, quartzite and serpentine) is then determined by a chemical method for evaluating the potential reactivity of aggregates and an accelerated method in mortar specimens, and finally the surface reactivity is investigated.The results of these studies suggest that some aggregates are able to react with the components of the interstitial phase of concrete. The existence of this kind of interaction is confirmed by the results of the surface investigations before and after the basic reaction.Keywords: alkali-silica reaction, degradation, expansion, mortar, SEM. INTRODUCCIÓNUna reacción álcali-silicato se produce cuando interaccionan áridos, que contienen minerales silicatados potencialmente reactivos, con los álcalis del cemento. Esta reactividad lleva consigo la formación de geles que en presencia de humedad se expanden, manifestándose en agrietamientos y movimientos diferenciales y con ello, una disminución drástica de la durabilidad (1-5) Por tanto, este proceso viene determinado en gran medida con la humedad relativa del ambiente y la tensión mecánica a la cual esta sometida cada elemento estructural (6-11).Las fases de la reacción árido-álcali se pueden...

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“…Different aggregates may give rise to the leaching of alkalis to the concrete. According to [1][2][3][4][5][6] the leaching of alkalis from feldspars has been confirmed. Likewise, [4,6,7] indicate that the leaching of alkalis takes place in micas.…”

Section: Introductionmentioning

confidence: 99%

Incidence of Alkali Release in Concrete Dams. Evaluation of Alkalis Releasable by Feldspars

2018

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Alkali release from aggregates can constitute a source of alkalis in concrete exposed to wet environments for long periods of time. Feldspars are one of the minerals that can release alkalis to the concrete with time. The formation of reaction products in the interface with the paste due to the alkali release from sodium and potassium feldspars has been observed in a concrete with granite aggregates. This has been observed after more than 25 years of exposure. It is necessary to evaluate the amount of alkalis releasable to define the formulation of concrete before manufacturing. Different test methods have been used to evaluate the potential alkali release from the granite extracted from the same quarry as that used in the dam. The test solutions have different composition and concentration, and different temperatures were used. Finally, the results of potential extraction are evaluated to determine the most realistic with respect to the field behavior.

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Formation of hydrogarnets: Calcium hydroxide attack on clays and feldspars

Cited by 31 publications

References 3 publications

Na2O, K2O, SiO2 and Al2O3 release from potassic and calcic–sodic feldspars into alkaline solutions

Na2O, K2O, SiO2 and Al2O3 release from potassic and calcic–sodic feldspars into alkaline solutions

Reactividad árido-álcali en áridos empleados para hormigón

Incidence of Alkali Release in Concrete Dams. Evaluation of Alkalis Releasable by Feldspars

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