Device and method for measuring critical chloride ion concentration of reinforcing steel bar depassivation in cement-based material

Abstract

The invention discloses a device and a method for measuring the critical chloride ion concentration of steel bar depassivation in a cement-based material. The device comprises a to-be-tested piece, achloride ion electromigration device and an electrochemical testing device. The method comprises the steps of chloride ion electromigration cycle test, corrosion current density characteristic parameter measurement and steel bar electrode test surface depassivation quantitative judgement criterion. The chloride ion electromigration cycle test is carried out by utilizing the chloride ion electromigration device, corrosion current density characteristic parameters are measured and calculated by utilizing the electrochemical testing device, and whether a testing surface of a steel bar electrode in the cement-based material is depassivated or not is judged according to the quantitative depassivation judgement criterion of the testing surface of the steel bar electrode. The transmission of chloride ions in the cement-based material can be accelerated, so the test period of the test is remarkably shortened; and whether the test surfaces of the plurality of steel bar electrodes in the to-be-tested piece are depassivated or not can be quantitatively judged at the same time, so that the critical chloride ion concentration of steel bar depassivation in the cement-based material can be rapidly and accurately determined.

Description

Technical field [0001] The present invention relates to an apparatus and method of reinforced cement-based material in corrosion resistance testing. Background technique [0002] Cement-based mortar, concrete and other materials are widely used in buildings, bridges, dams and ports and other engineering structures. Aggressive chloride ions in the external environment by diffusion, convection, migration, etc. constantly internal transmission to the cement-based material in an oxygen and sufficient water conditions, when the chloride ion concentration of the cement-based material in the steel surface reached a critical chloride ion concentration when, steel passivation film damage occurs, so that reinforcement corrosion, thereby affecting the normal use of the structure and function engineering carrier safety. Thus, accurate determination of the critical concentration of chloride ions in cement-based materials reinforced depassivation has important for engineering evaluation of dur...

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Problems solved by technology

Chinese patent 201010039690.3 discloses an accelerated test method for simulating non-uniform corrosion of steel bars in concrete with built-in electrodes. The method uses concrete specimens with pre-embedded stainless steel sheets as the specimens to be tested, and undergoes electroosmosis treatment, dry-wet cycle and constant current electrification treatment. Accelerate the transmission of chloride ions and the corrosion of steel bars in other ways, but this method cannot test the critical chloride ion concentration for depassivation of steel bars; The test piece is used as the test piece, and the strain gauge is pasted in the semicircular groove inside the steel bar section, and the groove is reserved on the top of the test piece to hold sea water. The whole test piece is placed in the glass groove filled with tap water, and the steel bar The annulus of the steel bar is used as the test surface. Although this method can judge the corrosion of the steel bar through the test data of the strain gauge, it cannot test the critical chloride ion concentration of the steel bar depassivation; Concentration method. In this method, the concrete specimen with pre-embedded reference electrode and reinforced electrode is used as the specimen to be tested. The anode solution is placed on the left side of the specimen to be tested, and the cathode solution is placed on the right side. The annulus of a single steel bar electrode is used as the working electrode test surface, and the corrosion state of the steel bar electrode is judged according to the macro-cell current formed by the working electrode and the reference electrode; similarly, Chinese patent 200910152758. A rapid determination method for the chloride ion threshold value. In this method, the cathodic solution is placed in the small water tank on the top of the test piece, the anode solution is placed in the large water tank on the lower side of the test piece, and the single steel bar pre-buried in the test piece is The ring surface of the electrode is used as the test surface of the working electrode, and then the corrosion state of the steel electrode is judged according to the change of the half-cell potential

It can be seen from the analysis that the above test method has the following technical defects: (1) Due to the different distances between the points on the steel electrode ring surface and the exposed surface of the test piece, the chloride ion concentration and depassivation time of each point on the working electrode test surface are different. , so the above method uses the annulus of the steel bar electrode as the test surface of the working electrode, which will significantly reduce the test accuracy of the critical chloride ion concentration of steel bar depassivation; (2) Since cement-based materials such as mortar and concrete are heterogeneous materials, the above method For each piece to be tested, only a single working electrode is pre-embedded, and it is difficult to accurately determine the critical chloride ion concentration for depassivation of steel bars in cement-based materials by using the test results of a single working electrode; (3) the above method is based on the specific values ​​of the measured parameters It is difficult to accurately judge the real corrosion state of steel bars, so it is impossible to accurately determine the critical chloride ion concentration for depassivation of steel bars in cement-based materials

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