Method for predicting effective diffusion coefficient of chloride ions in cement paste

A chloride ion diffusion and diffusion coefficient technology, applied in the field of predicting the effective diffusion coefficient of chloride ions, can solve the problems of poor operability, difficult to measure directly, low efficiency of multi-scale models, etc. Effect

Active Publication Date: 2021-03-26
SOUTHEAST UNIV
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Problems solved by technology

However, multi-scale models need to set a large number of parameters when describing from nanoscale to microscale, and some parameters are difficult to measure directly in experiments.
In addition, multi-scale models usually have technical problems such as low efficiency and poor operability

Method used

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  • Method for predicting effective diffusion coefficient of chloride ions in cement paste
  • Method for predicting effective diffusion coefficient of chloride ions in cement paste
  • Method for predicting effective diffusion coefficient of chloride ions in cement paste

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Embodiment Construction

[0047] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0048] The cement slurry mentioned in the examples of the present invention is prepared by mixing ordinary Portland cement with water. The porous structure of the cured cement paste contains gel pores and capillary pores. Pores in cement paste exhibit complex geometric shapes and random spatial distribution.

[0049] A method for predicting the effective diffusion coefficient of chloride ions in cement slurry, comprising the steps of:

[0050] (1) Cement powder and pure water are mixed according to the mass ratio of 5:2, stirred evenly, poured into a cylindrical mold with a diameter of 40mm and a height of 160mm for molding, sent to a standard curing room for curing, demoulded after 24 hours, and sent again The standard curing room is maintained for 28 days.

[0051] (2) Remove the cured test piece from the standard curing room, cut it into small cylindric...

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Abstract

The invention discloses a method for predicting the effective diffusion coefficient of chloride ions in cement paste. The method comprises the following steps: forming and maintaining the cement paste, and carrying out CT scanning on the maintained sample to obtain a CT image; regarding pixel points in the obtained three-dimensional CT image as porous unit bodies, and establishing a mapping relation between nominal porosity and gray values; calculating the free porosity for chloride ion diffusion in the porous unit body by applying a fractal theory; according to the obtained free porosity, establishing a chloride ion diffusion coefficient corresponding to the pixel point by combining a tortuosity model; and according to the obtained diffusion coefficient three-dimensional array corresponding to the CT image, utilizing a finite element method to solve the effective diffusion coefficient of the chloride ions in the cement paste. Theoretical and calculation systems are mature and complete, the compatibility is high, parameter setting is simple, and operability is high. A predicted value and a measured value of the effective diffusion coefficient of the cement paste chloride ions are combined, the matching degree between the values is high.

Description

technical field [0001] The invention relates to a method for predicting the effective diffusion coefficient of chloride ions, in particular to a method for predicting the effective diffusion coefficient of chloride ions in cement slurry. Background technique [0002] The chloride ion diffusion coefficient plays an important role in the durability design of reinforced concrete structures. The current laboratory testing of the chloride ion diffusion coefficient of cement-based materials, such as electromigration method and electric flux method, usually consumes too high manpower and material costs, and it is difficult to achieve non-destructive testing in actual engineering. More and more researchers are considering Development of predictive methods based on the microstructure of cement-based materials. Generally speaking, traditional forecasting methods can be divided into two categories: analytical methods and numerical methods. The analytical method establishes a reasonab...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N13/00G01N23/046
CPCG01N13/00G01N23/046G01N2013/003G01N2223/401G01N2223/42
Inventor 高云
Owner SOUTHEAST UNIV
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