Method for measuring migration depth and apparent migration coefficient of chloride ions in concrete

A technology of migration coefficient and concrete, applied in measurement devices, surface/boundary effects, instruments, etc., can solve the problems of limiting the accurate application of silver nitrate color development method, high equipment requirements, and cumbersome test steps for layer-by-layer sampling, so as to improve discoloration. The boundary does not appear, the construction operation is simple, and the test is fast.

Inactive Publication Date: 2014-07-09
HUNAN UNIV
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  • Summary
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  • Application Information

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Problems solved by technology

However, the layer-by-layer sampling test steps are cumbersome, and the requirements for equipment are also high, which has certain limitations in the application of actual engineering.
At the same time, due to the large variation range of the chloride ion concentration at the boundary of the parameter color change measured by the silver nitrate chromogenic method, this greatly limits the precise application of the silver nitrate chromogenic method.

Method used

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  • Method for measuring migration depth and apparent migration coefficient of chloride ions in concrete
  • Method for measuring migration depth and apparent migration coefficient of chloride ions in concrete
  • Method for measuring migration depth and apparent migration coefficient of chloride ions in concrete

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Examples 1 and 2 of the present invention both adopt concrete specimens to carry out natural diffusion experiments. The immersion liquid adopts 3.5% NaCl solution, and the immersion time is 300 days. The test fits are shown in Table 1.

[0024] Table 1 Example 1, 2 concrete mix ratio

[0025]

[0026] After reaching the immersion age designed for the experiment, according to NT Build443, the chloride ion content of each layer of samples was measured by the Profile method of layer-by-layer cutting sampling and chemical analysis. The cylindrical specimen is fixed on the cutting machine tool, and the cutting machine is used to dry cut the powder layer by layer. The powder thickness of each layer is 1mm. The obtained powder was measured by the acid-dissolution method to measure the chloride ion content in the powder, and the apparent diffusion coefficient of the specimen was calculated according to the least square method and formula (1).

[0027] C ...

Embodiment 2

[0030] (1) After immersing the cylindrical specimen in 3.5% NaCl solution for 300 days for natural diffusion experiment, place the specimen horizontally, apply a force in the middle of the upper part, and apply supporting force at 1 / 3 of the lower part, along the permeable surface Split in parallel directions until the specimen is completely split;

[0031] (2) Adopt the vertical section spraying method, spray 0.1N silver nitrate solution, and the spraying amount is 300±60ml / m 2 , the ambient temperature is controlled at 20-25 degrees Celsius,

[0032] (3) Measure the discoloration depth by ruler and gauge method. After spraying the silver nitrate solution, about 10-30 minutes later, it depends on the humidity of the experimental environment. When there is no water mark on the section of the specimen, use a thinner pen to draw the discoloration boundary clearly, and then use a ruler to stick to the side of the specimen , test a discoloration depth value every 1cm, test at le...

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Abstract

The invention discloses a method for measuring the migration depth and the apparent migration coefficient of chloride ions in concrete. The method comprises the following steps: selecting a cylindrical test piece by performing core-drilling on a concrete structure to be detected; horizontally arranging the selected cylindrical test piece, splitting the cylindrical test piece along the direction parallel to a penetration surface until the test piece is completely split; spraying 0.05 to 0.2N silver nitrate solution by a vertical section spraying method, wherein the spraying amount is 200 to 400 ml/m<2>, and the ambient temperature is controlled to be 20 to 25 DEG C; after the silver nitrate solution is sprayed for 10 to 40 minutes, drawing a color-changing boundary clearly by using a fountain pen, testing a color-changing depth value every 0.5 to 2cm, and averaging the tested color-changing depth values; according to the obtained color-changing depth value, the Fick's second law, and the water-cement ratio of the concrete, selecting the concentration of the chloride ions at the color-changing boundary, and calculating an apparent diffusion coefficient, wherein the limit chloride ion concentration of the corrosion of a reinforcing steel bar can be used for calculating the remaining life of a detected object.

Description

technical field [0001] The invention relates to the technical field of unsteady-state migration coefficient test, in particular to a method for measuring the migration depth and apparent migration coefficient of chloride ions in concrete. Background technique [0002] The serious decline in the service life of major projects caused by the durability of concrete structures has increasingly attracted the attention of engineers and researchers. As we all know, the main factors leading to the durability of concrete structures are: chloride ion attack, sulfate attack, freeze-thaw cycle, carbonation, alkali-aggregate reaction, fresh water dissolution and erosion, stress failure, etc. Among them, the destruction of concrete structures caused by corrosion of steel bars has become an increasingly prominent problem of widespread concern all over the world. The corrosion of steel bars caused by chloride ions accounts for about 80% of them. Due to the widespread existence of chloride ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N13/00
Inventor 史才军何富强胡翔
Owner HUNAN UNIV
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