Dependence of unsaturated chloride diffusion on the pore structure in cementitious materials

Zhang, Yong; Yang, Zhiliang; Ye, Guang

doi:10.1016/j.cemconres.2019.105919

Cited by 45 publications

(25 citation statements)

References 42 publications

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“…e study performed by Zhang et al [14] confirmed that RH played an important role in the chloride diffusion coefficient; that is, the chloride diffusion coefficient increased with RH increasing. Zhu et al [15] explored the effect of environmental RH on the permeability of chloride in unsaturated concrete.…”

Section: Introductionmentioning

confidence: 85%

Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Zhang

Wang

Ling

et al. 2021

Advances in Materials Science and Engineering

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Marine atmosphere environment accelerates the process of chloride penetration into concrete under the coupling effect of ambient temperature and relative humidity, thereby reducing the durability and service life of concrete. This paper aims to investigate the change of water equilibrium saturation and the chloride transport properties of concrete materials in different environments. The water equilibrium saturation tests at three temperatures and five relative humidity (RH) and salt spray erosion tests at three temperatures were performed. The influence of RH and temperature on the equilibrium saturation of concrete and the influence of temperature and time on the chloride diffusion coefficient are investigated. The results show that, in the process of moisture absorption and desorption, the equilibrium saturation of concrete gradually decreases as temperature rises. At the same depth of concrete, the chloride content gradually increases with temperature increasing, as well as the chloride diffusion coefficient. However, as the corrosion time of salt spray increases, the altering of chloride diffusion coefficient becomes less. Based on the Kelvin equation, a relationship between capillary pressure and water saturation in concrete was established, and a moisture transfer model for concrete in the process of moisture absorption and desorption was derived. Further, based on the established chloride diffusion equation and heat balance equation, a model of temperature-wet-chloride coupling chloride transfer was derived. Theory model simulation results show the transfer speed of chloride under the coupling of diffusion and capillary is higher than pure diffusion in moisture in the absorption process. However, the opposite is true in the desorption process. Moreover, with the increment of saturation rate, the capillary effect on chloride transport is enhanced.

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Section: Introductionmentioning

confidence: 85%

Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Zhang

Wang

Ling

et al. 2021

Advances in Materials Science and Engineering

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“…Mercury intrusion porosimetry (MIP) was applied for characterizing the pore structure of various paste mixtures. The paste specimens were split into pieces (around 1 cm 3 ) and then immersed in liquid nitrogen to stop further hydration and subsequently moved to a freeze-drier under vacuum and at -24 °C [25]. After the mass loss was below 0.01 % per day, the paste specimens can be used for MIP tests.…”

Section: Pore Structure By Mipmentioning

confidence: 99%

Hydration, Microstructure and Compressive Strength Development of Seawater-mixed Calcium Sulphoaluminate Cement-based Systems

Zhang

Niu

2021

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In-depth understanding of the calcium sulphoaluminate (CSA) cement, a type of environment-friendly cement, is essential for its wide application in engineering practice. Partial replacement of CSA by alternative alumina-rich powders has significant potential in the production of cost-effective CSA cement. In this work various supplementary cementitious materials (SCMs) including slag, metakaolin and silica fume with different replacement levels were added into CSA cement, and mixing with seawater, to prepare paste and concrete specimens. The development of hydration products in the paste specimens was characterized by X-ray diffraction and Thermogravimetric analysis. The pore structures of the seawater-mixed paste specimens obtained from mercury intrusion porosimetry tests, along with the pH value and free chloride content in the pore solution, were analyzed. Results show that various SCMs have significantly different effects on the pore solution chemistry, hydration and microstructural formation of the seawater-mixed CSA cement, resulting in different mechanical behavior and durability properties. The results of this work are helpful for the development of cost-effective CSA cement-based concrete used in marine constructions.

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“…The present paper constitutes one part of a series of several interrelated papers devoted to examining the chloride transport in unsaturated concretes [1][2][3][4]. It is hoped that these papers, taken together, can constitute a coherent conceptual framework that enables to understand the chloride transport in a manner approaching to the realistic situation, and that it will provide a scientific background for service life prediction based on unsaturated chloride transport.…”

Section: Introductionmentioning

confidence: 98%

New insights into long-term chloride transport in unsaturated cementitious materials: Role of degree of water saturation

Zhang

Yang

2020

Construction and Building Materials

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Dependence of unsaturated chloride diffusion on the pore structure in cementitious materials

Cited by 45 publications

References 42 publications

Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Investigation on Numerical Simulation of Chloride Transport in Unsaturated Concrete

Hydration, Microstructure and Compressive Strength Development of Seawater-mixed Calcium Sulphoaluminate Cement-based Systems

New insights into long-term chloride transport in unsaturated cementitious materials: Role of degree of water saturation

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