Evaluating the chloride diffusion coefficient of cement mortars based on the tortuosity of pore structurally-designed cement pastes

Guo, Yiqun; Zhang, Tongsheng; Du, Junpeng; Wang, Chao; Wei, Jiangxiong; Yu, Qijun

doi:10.1016/j.micromeso.2021.111018

Cited by 34 publications

(10 citation statements)

References 65 publications

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“…Guo et al [ 48 ] applied the effective medium theory and established the relationship between the D RCM of cement mortar and the tortuosity of cement paste and ITZ using Equation (6):

…”

Section: Resultsmentioning

confidence: 99%

Efficient Use of Graphene Oxide in Layered Cement Mortar

Liu

Chen

et al. 2022

Materials

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Graphene oxide (GO) has been found to be an attractive nanomaterial to improve the properties of cementitious composites. However, the use of GO in the industry is limited by its high cost. To achieve a higher cost/performance ratio, GO can be strategically applied in certain parts of cementitious composites structure according to the principle of functionally graded materials. In this study, graded distribution of GO in cement mortar was achieved by sequentially casting a fresh GO-incorporated cement layer on another cement mortar layer. The mechanical properties, especially flexural strength, of layered cement mortar were found to be dependent on the GO content, the delay time, and the interface formed due to layering fabrication. With the GO incorporated in the tensile region only (30% of the total depth), the flexural strength of the layered beam attained 90.91% of that of the beam, with GO uniformly distributed throughout the sample. Based on the results of rapid chloride migration tests, when 12 mm GO-incorporated cement mortar layer was used, the chloride migration coefficient was reduced by 21.45%. It was also found that the measured chloride migration coefficient of layered cement mortar agreed with the series model. The present investigation provides an efficient approach to use GO in cement-based materials from the perspective of mechanical and durability properties.

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“…Guo et al [ 48 ] applied the effective medium theory and established the relationship between the D RCM of cement mortar and the tortuosity of cement paste and ITZ using Equation (6):

…”

Section: Resultsmentioning

confidence: 99%

Efficient Use of Graphene Oxide in Layered Cement Mortar

Liu

Chen

et al. 2022

Materials

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“…Moreover, the duration of the analysis and requirement for pre-conditioning conflict with the rate at which the hydration reaction occurs, especially in the very early stages studied here. Sample tortuosity has also been previously related to the permeability [39] and chloride diffusion coefficients [40] in the literature, and these may also be able to give a reasonable assessment of the complexity of the pore structure. However, those methods are similarly incompatible with microtomographic assessment as carried out here.…”

Section: Measuring the Migration Of Precipitated Materialsmentioning

confidence: 97%

Time-resolved 3D characterisation of early-age microstructural development of Portland cement

et al. 2022

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Time-resolved in-situ synchrotron X-ray microtomography reveals new levels of detail about the chemical and physical processes that take place as Portland cement hardens. The conversion of a fluid paste into a hardened product can be monitored on a sub-minute time-scale, and with sample movement/settlement corrections applied to enable individual particles to be tracked as they react, hydrate, and become interconnected into a single strong monolith. The growth of the strength-giving hydrate phases surrounding cement grains, and of the fluid-filled pore network that surrounds them, is able to be directly viewed at the level of individual cement particles through the application of this tracking protocol. When cement is brought into contact with water, a layer which differs in density from the bulk of the cement grains becomes observable on the grain surfaces during the induction period (during which time the heat evolution from the paste is relatively low). As hydration continues, reaction products grow both from particle surfaces into the initially fluid-filled region, and also into the space originally occupied by the cement particles, forming a density gradient within the microstructure. As the reaction accelerates and larger volumes of solid phases precipitate, the newly-formed solid structure percolates via interconnection of agglomerated low-density outer hydrates, which then densify as hydration continues. This eventually leads to solidification of the structure into a hardened porous matrix. Graphical abstract

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“…The average tortuosity is closely related to the fractal dimension or porosity of the material [11][12][13]. In this paper, the Sierpinski carpet with a fractal unit of kk  is constructed by the porosity of the porous medium material, and then the Sierpinski carpet with a fractal unit of kk  is used to construct the average tortuosity model.…”

Section: Calculation Of Average Tortuosity Based On Heat Flow Pathsmentioning

confidence: 99%

“…At present, the methods of calculating tortuosity are experimental measurement, numerical simulation and theoretical analysis. Numerical simulation methods are random walk numerical simulation [7][8]15], corrugated pore structure model (CPSM) [9][10][11], maximum sphere method [12], lattice gas simulation method (LG) [13], FLUENT numerical simulation [4], etc. These methods don't require too much theoretical basis and they can be calculated by software.…”

Section: Introductionmentioning

confidence: 99%

Construction of a model for calculating average tortuosity of porous media based on optimal fractal structure

Cai¹,

Wang²

2022

FCIS

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The distribution of pores and skeletons in porous media materials are irregular, and its distribution of curved pore channels is uneven and complex. The bending degree of pores affects the internal heat transfer process. The tortuosity is not only a parameter to describe the bending degree of pore channels, but also is one of the important structural basic parameters of porous media materials. According to the porosity of the porous media materials, Sierpinski carpet model is established to characterize its structures. The calculation model of the average tortuosity of the porous media materials is derived by using the average value of the route of the heat flow through Sierpinski carpet. In order to find the best fractal unit structure and the number of iterations in the average tortuosity calculation model, an optimization discriminant model is established. The results of the average tortuosity calculation model of this model and the other three scholars are compared, and their average relative errors are calculated to be all less than 1 %, indicating that the average tortuosity calculation model established in this study is effective and reliable. The average tortuosity prediction model is related to the fractal unit structure and stage of the carpet, and there is no empirical constant in this model. It can be used to calculate the average tortuosity of other porous media materials, providing a new idea for calculating the average tortuosity.

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Evaluating the chloride diffusion coefficient of cement mortars based on the tortuosity of pore structurally-designed cement pastes

Cited by 34 publications

References 65 publications

Efficient Use of Graphene Oxide in Layered Cement Mortar

Efficient Use of Graphene Oxide in Layered Cement Mortar

Time-resolved 3D characterisation of early-age microstructural development of Portland cement

Construction of a model for calculating average tortuosity of porous media based on optimal fractal structure

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