Influence of coarse aggregate on the permeation, durability and the microstructure characteristics of ordinary Portland cement concrete

Basheer, Lulu; Basheer, P. A. M.; Long, Adrian

doi:10.1016/j.conbuildmat.2005.02.022

Cited by 144 publications

(46 citation statements)

References 9 publications

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“…The results indicated that as the proportion of larger size aggregate increases in the mix, the air permeability increases. According to Basheer et al (17), this fact is a consequence of the increase of the local porosity at the interfacial transition zone and could be explained because there is a reduction in the tortuosity of the flow path, which tends to increase the air permeability, and also because the possibility of the bleed water getting collected below the coarse aggregate increases (17). Cabrera et al (18) concluded that the shape and surface texture of fines particles has a great impact on concrete and mortar rheology, observable in the increase in water demand in crushed sand compared to natural sand concretes.…”

Section: Discussionmentioning

confidence: 99%

Effect of the aggregate grading on the concrete air permeability

Argiz¹,

Sanjuán²,

Muñoz-Martialay³

2014

Mater. construcc.

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Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on). Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a D air increase of 40-80%. RESUMEN: Efecto de la granulometría de los áridos en la permeabilidad al aire del hormigón.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.). El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad.Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del D air del 40-80%.

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Section: Discussionmentioning

confidence: 99%

Effect of the aggregate grading on the concrete air permeability

Argiz¹,

Sanjuán²,

Muñoz-Martialay³

2014

Mater. construcc.

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“…Concrete is typical anisotropic porous composites and its sub-microstructures, such as porous system, ITZs between aggregate and paste matrix, volume fraction of unhydrated cement gains, are related to the engineering properties of concrete, i e, strength, permeability and volume stability of concrete [1][2][3] . As mineral admixtures can alleviate the burden of environment, there exist a large number of literatures on effects of mineral admixtures on the microscopic characteristics of concrete [4,5] .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of sub-microstructure in concrete with low water-binder ratio by SEM-BSE image analysis

Qian

Guo³

et al. 2010

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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The coarse pore system, interfacial transition zone (ITZ) between aggregate and paste matrix and volume fraction of unhydrated cement in concrete (w/c＝0.3) containing mineral admixtures were quantitatively characterized by the scanning electron microscope-backscattered electron (SEM-BSE) image analysis technique. The experimental results show that compound addition of slag and fly ash decreases the coarse porosity from 10.17% to 3.74% and the threshold diameter of coarse pore size from 345 µm to 105 µm compared with concrete (w/c＝0.30) without mineral admixtures; Moreover with compound addition of fly ash and slag, the volume proportion of unhydrated cement in paste matrix is reduced by 30%, the maximum amount of coarse pores in the ITZ between aggregate and paste decreases from 13.11% to 5.57% and the thickness of ITZ is reduced by 37% , compared with concrete without mineral admixtures.

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“…Basheer et al (2005) have reported that there is an increase in air permeability of concrete when the size of coarse aggregate and the proportion of larger size coarse aggregate increases in the mixture. Increase in permeability of concrete with increase in the w/c ratio is widely reported in literature (Ruettgers et al 1935;Powers et al 1954;Concrete Manual 1975;Verbeck 1975, Collins et al 1986Elsharief et al 2003;Mindess et al 2003).…”

Section: Introductionmentioning

confidence: 99%

“…The test results reported by them indicate that for same degree of hydration, the transport coefficients increase when sand volume increased from 35 to 45% but the transport coefficients decrease when sand volume was further increased from 45 to 55%. The reason for decrease in the permeability of concrete with increase in the fine aggregate content is attributed to the increase in tortuosity of the pore system with increase in the fine aggregate content (Basheer et al 2005).…”

Section: Introductionmentioning

confidence: 99%