Study on the correlation between SHPC pore structure and air permeability

Zhang, Xiantang; Li, Zexi; Qian, Ma; Zhou, Xiaochen; Wang, Qing

doi:10.17559/tv-20170412102921

Cited by 4 publications

(5 citation statements)

References 9 publications

(9 reference statements)

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“…Therefore, it is preferable to use the total pore volume from the cement paste to study the correlation with air permeability. The total pore volume reported by Zhang et al [13] is too large as a total pore volume of concrete. It is not stated in their paper, but it is likely that they calculated the total pore volume per cement paste volume.…”

Section: Resultsmentioning

confidence: 85%

“…The total pore volume reported by Hilal et al [33] is large because they studied foamed concrete samples. By removing the results of mortars and cement pastes (including those from Zhang et al [13]) from Fig. 4, the determination coefficient becomes 0.32, which is still low.…”

Section: Resultsmentioning

confidence: 92%

“…The equation for calculating the mean pore diameter can be found in Ref. [13]. Mizuno et al [15] performed MIP on hardened cement pastes twice to obtain a continuous pore size distributions.…”

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confidence: 99%

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Correlations between air permeability coefficients and pore structure indicators of cementitious materials

Sakai

2019

Construction and Building Materials

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Correlations between the air permeability coefficient and various pore structure indicators in cementitious materials were examined to determine the pore structure indicator that best evaluated air permeability using data from previous studies of air permeabilities and pore structures. The determination coefficients of air permeability with total pore volume, critical pore diameter, and ordinary threshold pore diameter were low, although these have often been used as indicators. The median and threshold pore diameters obtained by percolation theory showed high determination coefficients. The equation using the threshold pore diameter better estimated the air permeability coefficient than the Katz-Thompson equation. Keywords: air permeability, total pore volume, critical pore diameter, threshold pore diameter, median pore diameter, Katz-Thompson equation Highlights• Air permeability and pore structure of cementitious materials are closely related • Data from reports on air permeability and porosity in cements were analysed • Percolation theory-derived threshold pore diameter gives the best estimates • Proposed equation yields better results than Katz-Thompson relationship 1. Introduction The air permeability coefficient of concrete is important in evaluating the durability of concrete structures because the permeation of carbon dioxide and oxygen into concrete causes deterioration by carbonation and corrosion of reinforcement bars. Researchers have studied the relationship between the air permeability coefficient and the pore structures of concrete to understand the transportation mechanism of air and establish models that predict the air permeability of concrete; various characteristic indicators of the pore structure have been proposed. Among indicators characterising pore structure, the relationship between the total pore volume and air permeability has been reported the most extensively. The total pore volume is generally measured in one of three ways: calculation using the difference between the water-saturated and oven-dried weights [1-3], the maximum volume of cumulative intruded mercury in mercury intrusion porosimetry (MIP) [4][5][6], and image analysis of the area fraction of pores [7,8]. Some researchers set maximum and minimum pore sizes in calculating the total pore volume [9,10] without clear theoretical reason. However, as Diamond [11] noted, the pore size distribution obtained by MIP is not a true pore size distribution because of ink-bottle effects; the validity of using a total porosity with certain maximum and minimum pore sizes is unclear. Hamami et al. [12] used the main pore diameter D c , defined as the mean value of the normal distribution fitted on the main peak of a pore size distribution, as an indicator of the pore structure and reported that the square of D c multiplied by the total pore volume fraction φ showed good correlation with the air permeability coefficient. This method can be difficult to apply because the pore size distribution of concrete can be far from a normal distribut...

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 92%

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Correlations between air permeability coefficients and pore structure indicators of cementitious materials

Sakai

2019

Construction and Building Materials

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“…Their findings unveiled a robust correlation between the median and new threshold pore sizes with concrete permeability, further proposing their use as metrics for the evaluation of concrete pore structures. Additional studies by Tsivilis S et al [ 30 ] and Zhang X et al [ 31 ] show that average and median pore sizes, respectively, have a significant impact on the permeability and absorption of concrete. Zhang J et al [ 32 ] highlighted that, with an increasing median and critical pore size, the intrinsic gas permeability of concrete also elevates; this trend showcases a strong correlation and the median pore size shows a slightly stronger correlation than the critical pore size.…”

Section: Introductionmentioning

confidence: 99%

Effect of SF and GGBS on Pore Structure and Transport Properties of Concrete

Chen,

Wu,

Liang

2024

Materials

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Ground Granulated Blast-Furnace Slag (GGBS) and silica fume (SF) are frequently utilized in gel materials to produce environmentally sustainable concrete. The blend of the two components contributes to an enhancement in the pore structure, which, in turn, increases the mechanical strength of the material and the compactness of the pore structure and decreases the permeability, thereby improving the durability of the concrete. In this study, the pore structures of GGBS and SF blends are assessed using Nuclear Magnetic Resonance (NMR) and Mercury Intrusion Porosimetry (MIP) tests. These methodologies provide a comprehensive evaluation of the effect of GGBS and SF on the pore structure of cementitious materials. Results showed that the addition of SF and GGBS reduces the amount of micro-capillary pores (10 < d < 100 nm) and the total pore volume. The results indicate that the transport properties are related to the pore structure. The incorporation of SF reduced the permeability of the concrete by an order of magnitude. The pore distribution and pore composition had a significant effect on the gas permeability. The difference in porosity obtained using the MIP and NMR tests was large due to differences in testing techniques.

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“…The gas permeability of cementitious materials can be measured by laboratory tests; previous studies indicated that the gas permeability is influenced by the pore characteristics such as the porosity, the critical pore diameter, and the pore size distribution [6,7]; other factors such as moisture content, aggregate size effects, and microcracking also have obvious influence on the gas permeability [8,9]. However, the measurement of gas permeability requires high air tightness and accuracy for the test instrument, which increases the difficulty and cost of test instrument manufacture and makes the measurement of gas permeability is less universal.…”

Section: Introductionmentioning

confidence: 99%

Gas Permeability Prediction of Mortar Samples Based on Different Methods

et al. 2022

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Gas permeability is one of the durability indicators of cementitious materials; permeability predictions based on pore characteristics are useful approaches to obtain gas permeability when experimental conditions are limited. In this study, the gas permeabilities of mortar are predicted by using the Hagen–Poiseuille equation combined with a processed backscattered electron (BSE) image, the Katz–Thompson equation, and the Winland model with pore parameters obtained from MIP tests. The permeabilities calculated by the BSE method are different from the measured value because the observation range is limited and it is difficult to completely display the actual pore structure. The Katz–Thompson equation underestimates the contribution of coarse capillary pores on permeability, thus the results are two orders of magnitude lower than the measured value. The results obtained from the Winland model are close to the measured permeabilities, which indicate that the Winland model is the most suitable method for predicting gas permeability among the three methods described in this paper.

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Study on the correlation between SHPC pore structure and air permeability

Cited by 4 publications

References 9 publications

Correlations between air permeability coefficients and pore structure indicators of cementitious materials

Correlations between air permeability coefficients and pore structure indicators of cementitious materials

Effect of SF and GGBS on Pore Structure and Transport Properties of Concrete

Gas Permeability Prediction of Mortar Samples Based on Different Methods

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