Representative elementary volume (REV) of cementitious materials from three-dimensional pore structure analysis

Yio, M.H.N.; Wong, H.S.; Buenfeld, N.R.

doi:10.1016/j.cemconres.2017.09.012

Cited by 48 publications

(29 citation statements)

References 41 publications

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“…Six to eight sub-volumes (2 to 4 from each imaging spot) of approximately 100 3 μm 3 consisting of ~953 3 voxels (0.105 3 µm 3 per voxel) were captured for analysis. This sampling size has been shown in [33] to be sufficiently large to achieve the representative elementary volume (REV) for capillary pore characterisation. According to the Nyquist theorem, the minimum resolvable pore size in the XY and Z directions were  0.242 µm (2.3× voxel width) and  0.534 µm (2.3× voxel depth)…”

Section: Lscm and 3d Pore Analysismentioning

confidence: 99%

“…respectively. The voxel depth was multiplied by a factor of 1.05 to correct for the mismatch in refractive indices between the objective immersion oil and epoxy and then compressed by a factor of 0.725 to correct for axial distortion due to elongation of the point spread function [26,33]. Fig.…”

Section: Lscm and 3d Pore Analysismentioning

confidence: 99%

“…All samples were treated in the same manner for consistency. Full details of the imaging, serial sectioning and reconstruction, pore segmentation processes are given in [33].…”

Section: Lscm and 3d Pore Analysismentioning

confidence: 99%

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3D pore structure and mass transport properties of blended cementitious materials

Yio

Wong

Buenfeld

2019

Cement and Concrete Research

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The effect of supplementary cementitious materials on three-dimensional pore structure and how this influences mass transport properties are not well understood. This paper examines the effect of silica fume, fly ash and ground granulated blastfurnace slag on 3D structure of capillary pores (> 0.24 m) within 100 3 m 3 cement paste for the first time using laser scanning confocal microscopy, combined with backscattered electron imaging and mercury intrusion porosimetry. Pastes containing different binder types, w/b ratios and curing ages were tested. Results show that SF enhances 3D pore structure from early ages whereas PFA and GGBS show improvements at later ages. SCMs not only reduce the volume and size of accessible pores, but also decrease connectivity and increase tortuosity, pore coordination number and formation factor. Measured 3D pore parameters were used as modelling inputs to estimate diffusivity and permeability. Predictions to within a factor of five from measured values were obtained.

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Section: Lscm and 3d Pore Analysismentioning

confidence: 99%

Section: Lscm and 3d Pore Analysismentioning

confidence: 99%

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3D pore structure and mass transport properties of blended cementitious materials

Yio

Wong

Buenfeld

2019

Cement and Concrete Research

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“…8 shows no clear correlation between lab performance and total area analysed. This is perhaps not surprising given that the size of capillary pores is in the micron range and the representative elementary volume for cement paste is * 100 3 lm 3 [30] Therefore, a sampling area of…”

Section: Other Observationsmentioning

confidence: 98%

Microscopy techniques for determining water–cement (w/c) ratio in hardened concrete: a round-robin assessment

Wong

Poole

Wells³

et al. 2020

Mater Struct

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Water to cement (w/c) ratio is usually the most important parameter specified in concrete design and is sometimes the subject of dispute when a shortfall in concrete strength or durability is an issue. However, determination of w/c ratio in hardened concrete by testing is very difficult once the concrete has set. This paper presents the results from an interlaboratory round-robin study organised by the Applied Petrography Group to evaluate and compare microscopy methods for measuring w/c ratio in hardened concrete. Five concrete prisms with w/c ratios ranging from 0.35 to 0.55, but otherwise identical in mix design were prepared independently and distributed to 11 participating petrographic laboratories across Europe. Participants used a range of methods routine to their laboratory and these are broadly divided into visual assessment, measurement of fluorescent intensity and quantitative backscattered electron microscopy. Some participants determined w/c ratio using more than one method or operator. Consequently, 100

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“…In fact, previous literature states that the notion of representative property exists at three scales [31,32]: a centimetre-sized REV consisting of a mix of aggregates and cement matrix, a REV of the cement matrix (around 100 3 μm 3 [1]), and a micrometre-sized REV of hydrated foam. e representative property concerned in this research is the second scale (NMR, MIP, NS, and XCT) and third scale (FIB/SEM).…”

Section: Influence Of Microcracks On Porosity Psd and Porementioning

confidence: 99%

Pore Structure Characterization of Hardened Cement Paste by Multiple Methods

Song¹,

Zhou²,

Bian³

et al. 2019

Advances in Materials Science and Engineering

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Pore structure characterization of hardened cement paste is important to concrete mechanical and transport properties. Hence, we apply indirect methods (NS, MIP, and NMR) and direct methods (XCT, FIB/SEM, and HIM) to provide a general view of the pore structure of hardened cement paste. e results show that the 3D pore network of hardened cement paste is isolated in microscale yet is largely connected by large capillary pores, small capillary pores, and microcracks in nanoscale. In indirect methods, MIP and NMR have a wide measurement range and permit observing most of the porous volume with an average porosity of 8.4-9.9% of hardened cement paste. In contrast, direct methods have a relatively narrow measurement range and thus lead to a large porosity scattering of 1.8-16.4%. e pore size distribution (PSD) curves by indirect methods show that the pore structure is mainly concentrated in three sections of 1-10 nm, 10-100 nm, and around 10 μm, which correspond to the imaging range of HIM, FIB/SEM, and XCT. However, FIB/SEM implies that the most porous part of hardened cement paste (10-100 nm) is underestimated by MIP due to the "ink-bottle" effect. Another "underestimation" of NMR is because C-S-H gels swell during the wetting, and the swelling separates the capillary pores into smaller ones. e microcracks induced by sample preparation contribute 0.1-0.2% (XCT) and 4.5-8.1% (FIB/SEM) of porosity to the porous volume of cement paste, but they have limited influence on the pore size distribution and pore connectivity.

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Representative elementary volume (REV) of cementitious materials from three-dimensional pore structure analysis

Cited by 48 publications

References 41 publications

3D pore structure and mass transport properties of blended cementitious materials

3D pore structure and mass transport properties of blended cementitious materials

Microscopy techniques for determining water–cement (w/c) ratio in hardened concrete: a round-robin assessment

Pore Structure Characterization of Hardened Cement Paste by Multiple Methods

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