Percolation and pore structure in mortars and concrete

Winslow, Douglas N.; Cohen, Menashi D.; Bentz, Dale P.; Snyder, Kenneth A.; Garboczi, Edward J.

doi:10.1016/0008-8846(94)90079-5

Cited by 264 publications

(85 citation statements)

References 14 publications

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“…This marked increase in permeability was also observed in Halamickova's work (1995), when aggregate volume increased from 0.45 to 0.55. This is also in agreement with the MIP results of Winslow et al (1994), which was concluded as an indication that ITZ has reached a high connection degree.…”

Section: Effect Of Aggregate On Chloride Migrationsupporting

confidence: 91%

“…Normally two opposite effects should be taken into account when the aggregate was introduced into the hydrated cement paste (Care 2003;Delagrave et al 1997;Shane et al 2000;Yang and Cho 2005): the dilution, tortuosity and densification of bulk paste reduce concrete permeability while the ITZ and its percolation effects increase. More specifically, when aggregates are sufficiently closely-spaced that the adjacent ITZs overlap, fluid and ions transport would be significantly enhanced (Rangaraju et al 2010;Winslow et al 1994). This might be the reason for the enhanced migration coefficient when the aggregate content reached 0.6.…”

Section: Effect Of Aggregate On Chloride Migrationmentioning

confidence: 99%

“…Therefore, the percolation of pores in the ITZ is of great interest for studying the transport phenomena in Portland cement-based materials Bonneau et al 2000;Care 2003;Princigallo et al 2003;Scrivener and Nemati 1996;Yang 2005;Yang and Cho 2005). By using mercury intrusion porosimetry (MIP) test, Winslow et al (1994) found that a sudden increase in intruded pore space was observed when the sand volume fraction increased from 45% to 49% (Winslow et al 1994). Other studies on mortars also attributed the increase in the paste porosity to the presence and percolation of ITZ (Delagrave et al 1997).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of the Interfacial Transition Zone and Interconnection on Chloride Migration of Portland Cement Mortar

Schutter

et al. 2015

ACT

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Available experimental studies on the effect of the interfacial transition zone (ITZ) on transport properties of cement-based composite materials appear to be ambiguous. The main objective of this work was to enhance the understanding of the relationship between ITZ and transport properties of Portland cement-based materials by using both a rapid chloride migration test and theoretical calculations. A densification factor which is related to aggregate volume content was introduced to further determine the transport properties of ITZ. Results indicate that the overall porosity decreased with increasing aggregate volume content due to the dilution effect by impermeable aggregates. The porosity was above the theoretical dilution line obtained from P 0 ×(1-V agg ) for mortars with more than 20% of aggregate, which can be attributed to the presence of high porous ITZ. On the other hand, more porous ITZ was expected to be accompanied by a denser bulk cement matrix, which leaded to a decrease in the porosity of mortar with less than 35% of aggregate. The ITZ effect would dominate the blocking aggregate, densification and tortuosity of bulk paste when aggregate volume content exceeded 0.35. The ratio between the migration coefficient of the ITZ and that of the matrix (D ITZ /D matrix ) increased with aggregate volume content and assumed ITZ thickness. In addition, the influence of ITZ increased with increasing the degree of interconnection slightly until 1.0. Beyond this value, a sudden increase in D ITZ /D matrix ratio was observed indicating the negative percolation effect when the adjacent ITZ start to interconnect.

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Section: Effect Of Aggregate On Chloride Migrationsupporting

confidence: 91%

Section: Effect Of Aggregate On Chloride Migrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the Interfacial Transition Zone and Interconnection on Chloride Migration of Portland Cement Mortar

Schutter

et al. 2015

ACT

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“…Some researchers have reported that the percolation of ITZ can significantly increase the transport properties of mortar and concrete [24,34]. In the present study, a burning algorithm [35] based on the same rules for connectivity shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Modelling the diffusivity of mortar and concrete using a three-dimensional mesostructure with several aggregate shapes

Abyaneh

Wong

Buenfeld

2013

Computational Materials Science

164

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This paper presents a numerical investigation into the effect of ITZ and aggregate shape on the diffusivity of mortar and concrete using a three-dimensional model. Concrete is treated as a three-phase composite consisting of aggregate particles, bulk cement paste and aggregate-paste interface, i.e. the 'interfacial transition zone' (ITZ). The model is set up in two stages. First, a three-dimensional representative volume element of the concrete mesostructure is generated. Then, a finite difference method is used to simulate molecular diffusion through the mesostructure. The transport properties of the conductive phases (bulk cement paste and ITZ) are determined based on the water/cement ratio, degree of hydration and porosity gradients away from aggregate particles. The model is validated against available experimental data and compared with analytical relationships for ideal cases. The model is then used to study the effect of aggregate shape on diffusivity, which has not been attempted before in three-dimensions. The model is also applied to assess the effects of water/cement ratio, degree of hydration, aggregate size, volume fraction, shape and orientation, ITZ width and percolation on diffusivity. Some of these effects are impractical to quantify from laboratory experimentation alone. It was found that the shape and orientation of aggregate particles have a significant effect on diffusivity. Diffusivity decreased when spherical aggregate particles are replaced with ellipsoidal particles due to the consequent increase in tortuosity of the cement paste.Keywords: Concrete; Mortar; Cement-based materials; Modelling; Diffusivity; Aggregate shape Highlights:• Diffusivity of cementitious materials is modelled using a three-dimensional model.• The required characteristics of Representative Elementary Volume were investigated.• The simulations were verified by comparing with experimental and analytical results.• The effects of different variables influencing diffusivity were investigated.• The diffusivity decreased with the increase of aspect ratio of aggregate particles.

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“…In this test, the aggregate of concrete was sands and binders, as we all know, from [21] the aggregate contents influence on the percolation, reducing aggregates have possibilities on reducing the interfacial zone percolation. In this test, the quantitative results of percolation were not calculated.…”

Section: ( ) (1 ) ( )mentioning

confidence: 99%

Experimental Test on Drying Shrinkage of 3D-printed Fiber-reinforced Concrete at Early Ages

Hui¹,

Almansa²

2018

AJCEA

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Drying shrinkage due to capillary tension in porous pores has been proven to affect the structural behaviour of concrete. Thus, this paper focuses on the drying shrinkage of 3D-printed fiber-reinforced concrete (3D-printed FRC). The specimens consisted of two groups fabricated by 3D printer for characterization and with a minimal friction of steel fibers in the concrete. One group was used for the compression strength test. The other group was used for drying shrinkage tests in a curing chamber with constant conditions over 60 days. The comparison of expected results and FIB model concrete 2010 suggest that porous structure effects of 3D-printed fiber-reinforced concrete (3D-printed FRC) should be considered. Thus, optimizing cement concrete matrix is necessary in proposing coefficients in moisture diffusion formulations.

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Percolation and pore structure in mortars and concrete

Cited by 264 publications

References 14 publications

Influence of the Interfacial Transition Zone and Interconnection on Chloride Migration of Portland Cement Mortar

Influence of the Interfacial Transition Zone and Interconnection on Chloride Migration of Portland Cement Mortar

Modelling the diffusivity of mortar and concrete using a three-dimensional mesostructure with several aggregate shapes

Experimental Test on Drying Shrinkage of 3D-printed Fiber-reinforced Concrete at Early Ages

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