Carbonation, moisture and empty pores

Parrott, Leslie

doi:10.1680/adcr.1992.4.15.111

Cited by 78 publications

(45 citation statements)

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“…De Schutter and Audenaert (2004); de Vries et al (1998); Dhir et al (1994a; 1994b;1996;2004); Dinakar et al (2007); Dinku and Reinhardt (1996) Parrott (1990;1992a;1992b;1996) …”

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confidence: 99%

Carbonation resistance of GGBS concrete

Lye

Dhir

Ghataora

2016

Magazine of Concrete Research

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This study presents an analysis of a 30 000 strong data matrix derived from 227 studies originating from 35 countries since 1968. Similar to the fly ash effect, the carbonation of concrete increases with the incorporation of ground granulated blast-furnace slag (GGBS), but the rate increases as GGBS content is increased. This effect is greater for concrete designed on an equal water/cement (w/c) basis to the corresponding Portland cement (PC) concrete than on an equal strength basis. The Eurocode 2 specification for XC3 carbonation exposure in terms of the characteristic cube strength of concrete (or its w/c ratio) may need to be increased (or decreased) with the addition of GGBS. Other influencing factors, including GGBS fineness, total cement content and curing, were also investigated. In some cases, the carbonation of in-service GGBS concrete has been estimated to exceed the specified cover before 50 years of service life. Measures to minimise the carbonation of GGBS concrete are proposed. Fully carbonated reinforced GGBS concrete is assessed to show a higher corrosion rate. In relation to PC concrete, the carbonation of GGBS concrete is essentially similar when exposed to 3-5% carbon dioxide accelerated or indoor natural exposure, and the conversion factor of 1 week accelerated carbonation equal to 0·6 year is established. Introduction BackgroundGround granulated blast-furnace slag (GGBS), a by-product of iron manufacture, because of its latent hydraulic nature requires alkali activation, from Portland cement (PC) for example. Indeed, the use of GGBS in combination with PC in concrete (GGBS concrete) has long been acknowledged. The first blast-furnace slag cement works was opened in Germany in 1865 and specifications for GGBS use with PC began to appear in Germany towards the end of the nineteenth century and in the UK during the early part of the twentieth century (BSI, 1923). The allowable proportion of GGBS as a cement component increased from about 30% in the 1910s to 90% in the 1970s (BSI, 1968).With sustainability increasingly an issue, and sustainable construction materials seen as central to the sustainability agenda, the use of increasingly high proportions of GGBS in attempts to reduce the carbon dioxide footprint of cement used in construction has become attractive. Its use is now covered by all the major standards, such as BS EN 197-1 (BSI, 2011), and permissible GGBS content can be as high as 95% (known as CEM III/C cement).Notwithstanding the above, as durability forms a major element of concrete specification and is directly connected with sustainable construction, issues related to durability need to be carefully examined. In terms of chemical composition, GGBS can be assumed to improve the resistance of concrete to chloride ingress (and thereby reduce the risk of reinforcement corrosion), sulfate attack and alkali-silica reaction. However, despite the great deal of research undertaken, with 227 published papers in the English medium from 35 countries mainly since 1985, consensus on the effec...

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“…De Schutter and Audenaert (2004); de Vries et al (1998); Dhir et al (1994a; 1994b;1996;2004); Dinakar et al (2007); Dinku and Reinhardt (1996) Parrott (1990;1992a;1992b;1996) …”

mentioning

confidence: 99%

Carbonation resistance of GGBS concrete

Lye

Dhir

Ghataora

2016

Magazine of Concrete Research

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“…Sin embargo, es necesario tener presente que los perfiles TG han demostrado que más bien existe una zona de transición que una interface aguda (Rahman y Glasser, 1989;Parrott, 1992;Houst y Wittmann, 2002) en el frente carbonatado. Sin embargo, también es adecuado medir el frente carbonatado con indicadores químicos (fenolftaleína) para pruebas de profundidad estándar, ya que probablemente proporciona el mejor indicador en lo que se refiere a la despasivación general del acero (Rahman y Glasser 1989).…”

Section: Técnicas Y Procedimientosunclassified

“…However, itt is necessary to be aware that it has been proved, by TG profiles, that there is a transitional zone rather than a sharp interface (Rahman and Glasser, 1989;Parrott, 1992;Houst and Wittmann, 2002) in the carbonation front. However, testing the carbonation front using chemical indicators (phenolphthalein) is also satisfactory for standard depth of carbonation tests and probably gives the best indication as far as the overall depassivation of the steel is concerned (Rahman y Glasser 1989).…”

Section: Técnicas Y Procedimientosmentioning

confidence: 99%

“…This type of behaviour is the same for the other two phases: Ettringite and CSH (only available for OPC). Se esperaba que ( (Parrott, 1992), que para obtener condiciones ambientales normales de CO 2 y humedad relativa, la carbonatación fuera controlada por difusión de gas, a través de poros vanos en la capa de la superficie) el índice de carbonatación fuera un proceso controlador de difusión. Sin embargo, aquí ha quedado demostrado que el paso controlador del índice de carbonatación es la difusión del CO 2 , a través de la zona carbonatada externa de la muestra, lo que revalida el empleo de la simple ley de raíz cuadrada del tiempo (Rahman y Glasser, 1989;Venuat y Alexandre, 1968;Weber, 1983;Smolczyck, 1968), para describir el avance en el frente bajo condiciones determinadas, por lo tanto, el conjunto de ecuaciones aplicables para muestras cilíndricas son: Donde: X s : Conversión fraccional del reactor sólido -s; en tiempo -t…”

Section: Development Of the Modelunclassified

“…It was expected (in (Parrott, 1992), it was stated that under normal environmental conditions of CO 2 and relative humidity, carbonation was controlled by gas diffusion through the empty pores in the surface layer) that the rate of the carbonation was a diffusion controlled process. However, here it has been demonstrated that the controlling step in the carbonation rate is the diffusion of the CO 2 through the external carbonated part of the sample, that revalidates the simplified use of the simple law of the square root of time (Rahman y Glasser, 1989;Venuat y Alexandre, 1968;Weber, 1983;Smolczyck, 1968), to describe the advance of the front in given conditions, and therefore, the set of equations to apply for a cylindrical specimens are:…”

Section: Development Of the Modelmentioning

confidence: 99%

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