Empirical Estimation of Pore Size Distribution in Cement, Mortar, and Concrete

Gong, Fuyuan; Zhang, Dawei; Sicat, Evdon; Ueda, Tamon

doi:10.1061/(asce)mt.1943-5533.0000945

Cited by 106 publications

(22 citation statements)

References 22 publications

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“…Many models have been proposed to explain the mechanism of frost damage such as hydraulic pressure (Powers 1945), crystallization pressure (Scherer and Valenza 2005) and cryosuction pressure (Sun and Scherer 2010a). A comprehensive hydraulic model was also developed by Gong et al (2015a) to explain the relationship between internal pressure and deformation of concrete. According to Gong et al's model, to obtain the internal pressure with freeze-thaw cycles (FTCs), it is rational to apply the sum of the above three pressures.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Wang

Gong

Zhang

et al. 2016

ACT

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Ice content is an essential factor that affects the internal pressure of cement-based materials during freeze-thaw cycles (FTCs). Since the electrical conductivity of mortar is closely related to its moisture content, it is possible to estimate the ice content based on electrical conductivity variation of mortar. As a result, the ice formation process during FTCs can be monitored. This paper proposed a model to estimate the ice content by applying electrical measurements and clarified the combined effects of temperature and moisture content for electrical conductivity of mortar. The ice content of mortar was estimated with the model by conducting the electrical test. The results are found in acceptable agreement with theoretical results from thermodynamic analysis, and the relationship between ice content and temperature is similar to existing calorimetric test results, which confirm the reliability of the model and the proposed test method.

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Section: Introductionmentioning

confidence: 99%

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Wang

Gong

Zhang

et al. 2016

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“…Among those experimental data, Sun's test (2010a) is chosen to give general characters of ice forming and melting process, because the experiments were more precisely controlled and the results can correlate different variables reasonably and comprehensively, such as the ice content, pore shape, pore size distribution and deformation. In addition, the majority of formed ice is in the smaller pores (r < 100 nm), of which the normalized pore size distributions are very similar among different W/C ratios (Gong et al, 2014). Therefore, the ice content of fully saturated specimen can be empirically regressed based on Sun's DSC data (2010a), in regarding with the temperature: 4 2 3.585 10 0.0236…”

Section: Ice Formation and Permeabilitymentioning

confidence: 99%

“…3, and the pore size distribution can be obtained by experiments or empirical equations (Gong et al, 2014). Also in Fig.…”

Section: Proposed Hydraulic Pressure Modelmentioning

confidence: 99%

“…9 (c)). The critcal radius r 0 between empty and fullfilled pores can be estimated combining pore size information and saturation condition (Gong et al 2014), which is shown in Table 1. Finally Fig.…”

Section: Experiments and Simulationmentioning

confidence: 99%

“…The critical radius (r 0, the radius between empty pores and pores filled with water according to Fig. 3) can also be estimated using the empirical pore size distribution (Gong et al 2014), and for the macro pores (r>10μm), the estimation formula is (Shimomura et al, 1992):…”

Section: Experiments and Simulationmentioning

confidence: 99%

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Stress Analysis for Concrete Materials under Multiple Freeze-Thaw Cycles

Gong

Sicat

Zhang

et al. 2015

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Once ice forms in highly saturated concrete material, internal tensile stress will be generated and causes damage to the material, which is a serious problem for concrete structures in cold and wet regions. On one hand, each component (porous body, ice and liquid) should satisfy the compatibility of stress and strain, which has been discussed by the poromechanical theories. On the other hand, if some empty voids exist, the hydraulic pressure will release when liquid water escapes from the expanded area according to Darcy's law. Recent closed freeze-thaw tests on the saturated mortar showed a consistent tendency: as the number of freeze-thaw cycles (FTC) increases, the deformation changes from the expansion to the contraction. In order to make clear the physical and mechanical changes during this process, a more comprehensive hydraulic model is developed, which combines both the mechanisms mentioned above. The estimated strain behavior by this model is in a good agreement with experimental measurements, and also, it has good potential and is more flexible to be applied to different cases such as different saturation degrees and cooling rates. The permeability change can be also considered in this model as a reflection of frost damage level.

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Quantification of the Knudsen Effect on the Effective Gas Diffusion Coefficient in Partially Saturated Pore Distributions

Strangfeld

2021

Adv Eng Mater

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The effective gas diffusion coefficient describes the process of gas diffusion in porous materials. Several materials have a significant number of micropores in the lower nanometre range leading to a reduction of gas diffusion (Knudsen effect). In the case of partial pore saturation during adsorption, the available pore space is further reduced, as is the gas diffusion. In this study, the influence of partially saturated pores on the Knudsen effect and on the gas diffusion is quantified. Three different pore geometries are investigated (slit, cylindrical and spherical pores) and three different types of pore size distribution, including a broad equal distribution, three narrow normal distributions and two measured distributions of concrete. Besides the intensive computation of the exact pore saturation, a simplified model with low computational requirements is suggested. This study shows that the influence of the water layer thickness on the effective diffusion becomes significant for pore radii below 50 nm and the assumed pore geometry is important. At the end, the overall effect is quantified for an amorphous material with most pore radii below 30 nm. At a moisture level of 50% relative humidity, the effective diffusion is reduced by 35% due to partial saturation.

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Empirical Estimation of Pore Size Distribution in Cement, Mortar, and Concrete

Cited by 106 publications

References 22 publications

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Estimation of Ice Content in Mortar Based on Electrical Measurements under Freeze-Thaw Cycle

Stress Analysis for Concrete Materials under Multiple Freeze-Thaw Cycles

Quantification of the Knudsen Effect on the Effective Gas Diffusion Coefficient in Partially Saturated Pore Distributions

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