The use of mercury intrusion porosimetry or helium porosity to predict the moisture transport properties of hardened cement paste

The coupling effect of flexural loading and environmental factors has great influence on the pore structures in hardened cement paste. In this paper, Mercury intrusion porosimetry (MIP) and field emission scanning electron microscope (SEM) were used to analyze and observe the changes of pore structures in hardened cement paste subjected to flexural loading and wet-dry cycles in simulated seawater. The results show that the porosity greatly increases when the flexural loading level is raised from 0 f (the ultimate flexural loading capacity) to 0.8 f. Micro-cracks are observed and the connectivity, width and density of micro-cracks increase with the increment of flexural loading. The peaks position of pore size shifts toward greater micro-pores when the flexural loading was raised from 0 f to 0.8 f. The flexural loading and simulated seawater accelerate the degradation of pore structures.

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Three-Dimensional Modeling of Transport Properties in Hardened Cement Paste Using Metal Centrifugation-Based Pore Network

Journal of Materials in Civil Engineering ◽

10.1061/(asce)mt.1943-5533.0004004 ◽

2021 ◽

Vol 33 (12) ◽

Author(s):

Cheng Liu ◽

Rusheng Qian ◽

Guojian Liu ◽

Mingzhong Zhang ◽

Yunsheng Zhang

Keyword(s):

Transport Properties ◽

Cement Paste ◽

Three Dimensional ◽

Pore Network ◽

Hardened Cement ◽

Hardened Cement Paste ◽

Three Dimensional Modeling ◽

Dimensional Modeling

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On Phase Identification of Hardened Cement Pastes by Combined Nanoindentation and Mercury Intrusion Method

Materials ◽

10.3390/ma14123349 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3349

Author(s):

Jingwei Ying ◽

Xiangxin Zhang ◽

Zhijun Jiang ◽

Yijie Huang

Keyword(s):

Mechanical Properties ◽

Pore Structure ◽

Cement Paste ◽

Phase Distribution ◽

Gaussian Mixture ◽

Hardened Cement ◽

Phase Identification ◽

Hardened Cement Paste ◽

Cement Pastes ◽

Mercury Intrusion

The micro-mechanical properties of hardened cement paste can be obtained by nanoindentation. Phases at different locations can generally be determined by using the Gaussian mixture model (GMM) method and the K-means clustering (KM) method. However, there are differences between analysis methods. In this study, pore structure and porosity of hardened cement paste aged three, seven, and 28 days were obtained by mercury intrusion porosimetry (MIP), and their micro-mechanical properties were obtained by the nanoindentation method. A new method, GMM-MIP and KM-MIP, was proposed to determine the phase of hardened cement paste based on the pore structure and nanoindentation results. The results show that GMM-MIP and KM-MIP methods are more reasonable than GMM and KM methods in determining the phase of hardened cement paste. GMM-MIP can be used to obtain reasonable phase distribution. If the micro-mechanical properties of each phase in hardened cement paste do not satisfy the normal distribution, the GMM method has significant defects.

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Pore Size Distributions in Hardened Cement Paste by Sem Image Analysis

MRS Proceedings ◽

10.1557/proc-370-217 ◽

1994 ◽

Vol 370 ◽

Cited By ~ 34

Author(s):

Sidney Diamond ◽

Mark E. Leeman

Keyword(s):

Image Analysis ◽

Pore Size ◽

Cement Paste ◽

Hardened Cement ◽

Size Distributions ◽

Hardened Cement Paste ◽

Mercury Intrusion ◽

Sem Image ◽

Pore Size Distributions ◽

Sem Image Analysis

AbstractTechnical requirements for determining the size distribution of capillary pores in hardened cement paste by SEM image analysis are discussed. Results of such measurements are reported for a set of hardened cement pastes of w:c ratio 0.40 and 0.25, and of ages ranging from 1 to 28 days. Pore size distributions based on conventional mercury intrusion porisimetry are presented for the same pastes. Estimates of pore diameters by mercury intrusion are two orders of magnitude smaller than the sizes revealed by the image analysis. Diameters of air voids are even more drastically underestimated by mercury intrusion. Typical micrographs are provided to illustrate the physical reality of the image analysis results, and the technical reasons underlying the conventional misinterpretation of MIP results for hydrated cements are reviewed.

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