A method for determining the risk of corrosion of reinforcing steel in a reinforced concrete structure building

Abstract

The application discloses a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which comprises the following steps: calculating the internal chloride ion concentration in the reinforced concrete structure building, monitoring the external chloride ion concentration of the environment where the reinforced concrete structure building is located, comparing the external chloride ion concentration with the internal chloride ion concentration, judging that the reinforced concrete structure building has an external corrosion risk when the external chloride ion concentration is greater than the internal chloride ion concentration, and judging that the reinforced concrete structure building has no external corrosion risk when the external chloride ion concentration is less than the internal chloride ion concentration. The application can provide guidance for the operation and maintenance management and repair construction of the reinforced concrete structure building.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building engineering, in particular to a method for judging the corrosion risk of steel bars in a reinforced concrete structure building. BACKGROUND

[0002] The steel bars of a reinforced concrete structure are prone to corrosion due to the internal chloride ion content in the concrete paste and the invasion of external chloride ions in the air environment, which leads to problems such as strength reduction, volume expansion, cracking, and structure loosening of the reinforced concrete structure, affecting the quality and service life of the concrete structure. The principle of the steel bars of the reinforced concrete structure being prone to corrosion due to the chloride ion content is as follows: In the reinforced concrete structure, the surface of the steel bars in the concrete gap liquid will form a passive oxide film in the presence of alkaline substances such as sodium and potassium and saturated calcium hydroxide solution, which can effectively prevent the steel bars from contacting water and oxygen, forming a protective effect. However, when the chloride ion content in the concrete paste and the external chloride ions invade the steel bars, the passive oxide film on the surface of the steel bars will be destroyed, leading to corrosion of the steel bars. For the evaluation of the chloride ion content in the internal parameters of the concrete paste, the potential of the steel bars in the concrete is currently measured to establish a migration model equation of the chloride ion corrosion process to obtain the concentration distribution of the chloride ions in the reinforced concrete structure. This method can predict the long-term migration and distribution of the chloride ions in the reinforced concrete structure and judge whether the chloride ion concentration in the reinforced concrete structure reaches a critical value to determine whether the steel bars inside the reinforced concrete structure are at risk of corrosion. However, the method of obtaining the concentration of chloride ions in the reinforced concrete structure through the migration model has too many influencing factors and a complex calculation process, and the accuracy of the results is poor. There is currently no evaluation method for corrosion caused by the invasion of external chloride ions, which cannot provide a basis for the operation and maintenance management and repair construction of the reinforced concrete structure. SUMMARY

[0003] The purpose of the present application is to provide a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, to solve the problem of poor accuracy of the calculation of the chloride ion concentration based on the migration model when judging the corrosion risk of the steel bars in the reinforced concrete structure by whether the chloride ion concentration in the reinforced concrete structure reaches a critical value, which cannot provide accurate reference for the operation and maintenance management and repair construction of the reinforced concrete structure.

[0004] To solve the above technical problems, the present application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, comprising:

[0005] According to formula (4), calculate the chloride ion content evaluation coefficient of the reinforced concrete structure building:

[0006] (4);

[0007] In formula (4), is the distribution of chloride ions in the reinforced concrete structure building in unit volume, is the internal chloride ion concentration in the reinforced concrete structure building of the 1st to the n is the internal chloride ion concentration in the reinforced concrete structure building of the 1st to the is the average value of the internal chloride ion concentration in the reinforced concrete structure building of the 1st to the n is the average value of the internal chloride ion concentration in the reinforced concrete structure building of the 1st to the n is the number of divisions of the reinforced concrete structure building;

[0008] According to the formula (1), determines whether the steel bars in the reinforced concrete structure building have internal corrosion risk, when >0, it is determined that the steel bars in the reinforced concrete structure building have internal corrosion risk; when =0, it is determined that the steel bars in the reinforced concrete structure building do not have internal corrosion risk.

[0009] Further, the steel bar corrosion risk determination method for the reinforced concrete structure building provided by the present application further comprises:

[0010] According to the formula (2), the internal chloride ion concentration in the reinforced concrete structure building is calculated:

[0011] (2);

[0012] In formula (2), is the internal chloride ion concentration in the reinforced concrete structure building, is the total weight of the internal chloride ions in the reinforced concrete structure building, which is determined according to the total amount of the concrete slurry of the reinforced concrete structure building and the internal chloride ion content percentage of the concrete slurry in unit volume when the reinforced concrete structure building is poured and constructed, is the molar mass of the chloride ions in the reinforced concrete structure building, is the water content in the reinforced concrete structure building;

[0013] The external chloride ion concentration of the environment where the reinforced concrete structure building is located is monitored ;

[0014] The external chloride ion concentration is compared with the internal chloride ion concentration, when , it is determined that the building concrete structure building has external corrosion risk; when , it is determined that the building concrete structure building does not have external corrosion risk.

[0015] Further, the application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which comprises the following steps: firstly, judging whether the reinforced concrete structure building has external corrosion risk; and secondly, judging whether the steel bars in the reinforced concrete structure building have internal corrosion risk when the steel bars in the reinforced concrete structure building have no external corrosion risk.

[0016] Further, the application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which calculates the chloride ion content in the concrete slurry by means of mercury nitrate titration method or ammonium thiocyanate volumetric method.

[0017] Further, the application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which monitors the external chloride ion concentration of the environment where the reinforced concrete structure building is located by means of ion chromatography method, potential method or atomic absorption spectrometry method.

[0018] Further, the application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which calculates the internal chloride ion content percentage of the corresponding preparation parameters in the concrete slurry according to the weight of cement, mineral admixture, sand, stone and additive per unit volume.

[0019] Further, the application provides a method for judging the corrosion risk of steel bars in a reinforced concrete structure building, which calculates the total weight of internal chloride ions in the reinforced concrete structure building according to formula (1).

[0020] (1);

[0021] In formula (1), is the total weight of internal chloride ions in the reinforced concrete structure building, , , , , is the weight of cement, mineral admixture, sand, stone and additive respectively, , , , , is the internal chloride ion content percentage of cement, mineral admixture, sand, stone and additive respectively.

[0022] Compared with the prior art, the method for judging the corrosion risk of steel bars in a reinforced concrete structure building has the following beneficial effects:

[0023] The method for judging the corrosion risk of steel bars in a reinforced concrete structure building judges whether the steel bars in the reinforced concrete structure building have internal corrosion risk by means of the chloride ion content evaluation coefficient of the reinforced concrete structure building, thereby providing a new technical route for judging whether the steel bars have internal corrosion risk. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a flow chart of a steel bar corrosion risk judgment method in a reinforced concrete structure building. DETAILED DESCRIPTION

[0025] The application will be described in greater detail with reference to the drawings, in which:

[0026] Reference should be made to Figure 1 The application provides a steel bar corrosion risk judgment method in a reinforced concrete structure building, comprising:

[0027] Step S101, before pouring the reinforced concrete structure building, preparing the concrete slurry, calculating the internal chloride ion content percentage of the concrete slurry preparation parameter information of the reinforced concrete structure building under unit volume, and calculating the water content of the reinforced concrete structure building. The internal chloride ion content percentage is the weight percentage. The concrete slurry preparation parameters include cement, mineral admixture, sand, stone, and admixture. The internal chloride ion content percentage of each parameter can be calculated by the mercuric nitrate titration method or the ammonium thiocyanate volumetric method. When pouring the reinforced concrete structure building, the total weight of the chloride ion in the reinforced concrete structure building is determined according to the total amount of the concrete slurry of the reinforced concrete structure building (unit: g) and the internal chloride ion content percentage of the concrete slurry under unit volume, that is, the total weight of the internal chloride ion of the reinforced concrete structure building is calculated according to formula (1):

[0028] (1);

[0029] In formula (1), is the total weight of the internal chloride ion of the reinforced concrete structure building, , , , , are the weights of the cement, mineral admixture, sand, stone, and admixture, respectively, , , , , are the internal chloride ion content percentages of the cement, mineral admixture, sand, stone, and admixture, respectively. The mineral admixture is a selected material.

[0030] The overall water content of the reinforced concrete structure building can be calculated by the weight ratio of the cement, mineral admixture, sand, stone, and admixture and the water content, so as to calculate the water content of the reinforced concrete structure building , the molar mass of the chloride ion is .

[0031] When pouring the reinforced concrete structure by the prepared concrete slurry, the reinforced concrete structure test piece can be poured at the same time.

[0032] In step S102, the internal chloride ion concentration in the reinforced concrete structure building is calculated according to formula (2):

[0033] (2);

[0034] In formula (2), is the internal chloride ion concentration in the reinforced concrete structure building, is the total weight of the internal chloride ion in the reinforced concrete structure building, When pouring the reinforced concrete structure building, the total amount of the concrete slurry of the reinforced concrete structure building and the internal chloride ion content percentage of the concrete slurry per unit volume are determined, is the molar mass of the chloride ion in the reinforced concrete structure building, is the water content in the reinforced concrete structure building. By formula (2), the internal chloride ion concentration in the reinforced concrete structure building is calculated, which avoids the problem of poor accuracy of chloride ion concentration calculation caused by many influencing factors and complex calculation of the migration model of the chloride ion erosion process to calculate the chloride ion concentration distribution in the reinforced concrete structure.

[0035] For example: the mixing ratio of a C50 concrete laboratory test block concrete slurry is:

[0036] Cement: 480 kg / m 3 P.O 52.5 grade ordinary portland cement;

[0037] Water: 175 kg / m 3 ;

[0038] Sand: 685 kg / m 3 Medium sand, fineness modulus 2.6-3.0, good gradation;

[0039] Stone: 1060 kg / m 3 5-20 mm continuous gradation gravel, low needle content, crushing index <10%;

[0040] Admixture: 1.0% of the cement dosage is added into high-performance polycarboxylic acid water reducing agent (water reducing rate is about 25%);

[0041] The parameter information obtained in the construction of a 150mm x 150mm x 150mm reinforced concrete laboratory test block (the chloride ion content of which, except for the cementitious material, can be ignored):

[0042] The volume of the reinforced concrete structure building is: 0.00375 m 3 ;

[0043] Cement: 1800g

[0044] Water: 656.25g;

[0045] Sand: 2568.75g;

[0046] Stone: 3975g;

[0047] Admixture: 18g;

[0048] The chloride ion content of the cementitious material in the concrete slurry is 0.14% as determined by the phosphoric acid distillation-mercury salt titration method; the chloride ion content of the sand and mixing water can be determined by the silver nitrate titration method to be 0.004%+42mg / L (which can be ignored); that is, the chloride ion content in the concrete slurry is reflected by determining the chloride ion content of the cementitious material in the concrete slurry. The cementitious material mainly includes cement, and when mineral admixtures are selected, mineral admixtures are also included as auxiliary cementitious materials.

[0049] The chloride ion content of the cementitious material is: (1800+18) x 0.14% = 2.5452g;

[0050] The chloride ion content of the sand and mixing water is: (2568.75+3975) x 0.004% + 0.65625L x 42 1000=0.2645g;

[0051] Therefore, the total weight of chloride ions inside the reinforced concrete laboratory test block =2.5452g +0.2645g ≈2.8g;

[0052] =175kg / m 3 x 0.00375 m 3 =656.25g / 1000=0.65625L;

[0053] =35.45 g / mol

[0054] Substituting the numerical values into formula (2) gives:

[0055] 。

[0056] Step S103, the external chloride ion concentration of the reinforced concrete structure building environment can be monitored by ion chromatography, potentiometry or atomic absorption spectrometry. .

[0057] Step S104, compare the external chloride ion concentration with the internal chloride ion concentration:

[0058] When , it is judged that the building concrete structure building has external chloride ion intrusion risk, that is, the steel in the reinforced concrete structure building has external rust risk; At this time, the reinforced concrete structure building can be executed to prevent external chloride ion intrusion (such as impressed current method, sacrificial anode method and other measures).

[0059] When , it is judged that the building concrete structure building has no external chloride ion intrusion risk, that is, the steel in the reinforced concrete structure building has no external rust risk.

[0060] The embodiment of the application provides a steel rust risk judgment method in a reinforced concrete structure building, which compares the external chloride ion concentration with the internal chloride ion concentration to judge whether the steel in the reinforced concrete structure building has external rust risk, solves the problem that there is no evaluation of the external chloride ion intrusion into the reinforced concrete structure to cause the steel to rust in the prior art, and thus provides guidance basis for operation and maintenance management and repair construction of the reinforced concrete structure.

[0061] The embodiment of the application provides a steel rust risk judgment method in a reinforced concrete structure building, which is particularly suitable for judging the steel rust risk of the reinforced concrete structure building located in a coastal city, helps to improve the operation and maintenance management ability of the reinforced concrete structure building in the coastal environment, and according to the judgment result, whether the reinforced concrete structure building located in the coastal city is repaired and constructed, and what kind of countermeasures are taken.

[0062] In order to judge whether the steel in the reinforced concrete structure building has internal rust risk, the embodiment of the application further provides a steel rust risk judgment method in a reinforced concrete structure building, which can further include:

[0063] Step S105, the reinforced concrete structure building is divided into n layers along the height direction, and the internal chloride ion concentration in each layer of the reinforced concrete structure building is calculated according to formula (2).

[0064] Step S106, the average value of the internal chloride ion concentration of the n layer reinforced concrete structure building is calculated according to formula (3):

[0065] (3);

[0066] In formula (3), for n The average value of internal chloride ion concentration of reinforced concrete structure buildings 、 、……、 From the 1st to the n Internal chloride ion concentration value of a multi-story reinforced concrete structure building.

[0067] Step S107, calculate the chloride ion content evaluation coefficient of the reinforced concrete structure building according to formula (4):

[0068] (4);

[0069] In formula (4), is the distribution of chloride ions per unit volume in reinforced concrete structures. From the 1st to the n Internal chloride ion concentration in reinforced concrete structures, for n The average value of internal chloride ion concentration of reinforced concrete structure buildings n The number of floors of a reinforced concrete structure building.

[0070] Step S108, according to Determine whether there is a risk of internal corrosion of steel bars in reinforced concrete structures: When >0, it is judged that there is a risk of internal corrosion of the steel bars in the reinforced concrete structure; when = 0, it is judged that there is no risk of internal corrosion of steel bars in reinforced concrete structures. The principle is: when When >0, the chloride ions in reinforced concrete structures are unevenly distributed. The excessive number of unevenly distributed chloride ions in the steel bar area corrodes the steel bar passivation film, resulting in the risk of internal corrosion of the steel bar.

[0071] When executing steps S105 to S108, the test piece may be used to replace the reinforced concrete structure building body to determine whether the steel bars of the reinforced concrete structure building have an internal corrosion risk.

[0072] After the steps S101 to S108 are executed, the risk of corrosion of the steel bars in the reinforced concrete structure building can be judged from two aspects of the outside and the inside, that is, the first aspect judges whether the steel bars have the risk of external corrosion, and the second aspect judges whether the steel bars have the risk of internal corrosion, so that the type of the risk of corrosion of the steel bars is determined to be the type of the risk of external corrosion of the steel bars or the type of the risk of internal corrosion of the steel bars, so that different repair construction modes are used to ensure the safety of the reinforced concrete structure building. After the steps S101 to S104 are executed and it is judged that the steel bars have the risk of external corrosion, the step of judging the risk of internal corrosion is not executed, and the steps S105 to S108 are not executed; after it is judged that the steel bars do not have the risk of external corrosion, the steps S105 to S108 are executed to judge whether the steel bars have the risk of internal corrosion.

[0073] The embodiment of the present application also provides a method for judging the risk of corrosion of steel bars in a reinforced concrete structure building. The risk of internal corrosion of the steel bars in the reinforced concrete structure building is judged, so that guidance is provided for the operation and maintenance management and repair construction of the reinforced concrete structure, that is, only the steps S105 to S108 are executed, and the steps S101 to S104 are not executed. The risk of internal corrosion of the steel bars in the reinforced concrete structure building is judged by the chloride ion content evaluation coefficient of the reinforced concrete structure building, so that a new technical route is provided for judging the risk of internal corrosion of the steel bars, and the problem that the accuracy of the judgment result is poor due to the poor accuracy of the calculation of the chloride ion concentration value in the reinforced concrete structure based on the migration model of the chloride ion corrosion process is avoided.

[0074] The present application is not limited to the above-mentioned specific embodiments. Obviously, the above-mentioned embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application. Those skilled in the art can make other levels of modifications and changes to the present application. Therefore, if these modifications and changes of the present application belong to the scope of the claims of the present application, the present application also intends to include these modifications and changes.

Claims

1. A method for determining the risk of steel bar corrosion in reinforced concrete structures, characterized in that: include: The internal chloride ion concentration in reinforced concrete structures is calculated according to formula (2): （2）； In formula (2), is the internal chloride ion concentration in reinforced concrete structures, The total weight of chloride ions inside reinforced concrete structures is determined based on the total amount of concrete slurry used and the percentage of internal chloride ion content per unit volume of concrete slurry during the pouring and construction of reinforced concrete structures. is the molar mass of chloride ions in reinforced concrete structures, is the moisture content in reinforced concrete structures; The chloride ion content evaluation coefficient of reinforced concrete structure buildings is calculated according to formula (4): （4）； In formula (4), is the evaluation coefficient of chloride ion content per unit volume of reinforced concrete structure. From the 1st to the n Internal chloride ion concentration in reinforced concrete structures, for n The average value of internal chloride ion concentration of reinforced concrete structure buildings n The number of floors for reinforced concrete structures; according to Determine whether there is a risk of internal corrosion of steel bars in reinforced concrete structures. When >0, it is judged that there is a risk of internal corrosion of steel bars in reinforced concrete structures; when =0, it is judged that there is no risk of internal corrosion of steel bars in reinforced concrete structures.

2. A method for judging steel corrosion risk in reinforced concrete structures according to claim 1, characterized in that: Also includes: Monitoring of external chloride ion concentration in the environment surrounding reinforced concrete structures ; Comparing the external chloride ion concentration with the internal chloride ion concentration, when When the building concrete structure is judged to have external corrosion risk; when When judging that there is no risk of external corrosion in the concrete structure of the building.

3. The method for judging steel corrosion risk in reinforced concrete structures according to claim 2, characterized in that: First, determine whether the concrete structure building has the risk of external corrosion. When the steel bars in the reinforced concrete structure building do not have the risk of external corrosion, then determine whether the steel bars in the reinforced concrete structure building have the risk of internal corrosion.

4. The method for determining the risk of steel bar corrosion in a reinforced concrete structure according to claim 2, wherein: The chloride ion content in the concrete paste is calculated by mercuric nitrate titration or ammonium thiocyanate volumetric method.

5. The method for judging steel bar corrosion risk in reinforced concrete structures according to claim 2, characterized in that: The external chloride ion concentration of the environment surrounding reinforced concrete structures is monitored by ion chromatography, potentiometry or atomic absorption spectrometry.

6. The method for judging steel bar corrosion risk in reinforced concrete structures according to claim 2, characterized in that: The percentage of internal chloride ion content in the concrete paste corresponding to the preparation parameters is calculated based on the weight of cement, mineral admixtures, sand, stone and admixtures in the concrete paste per unit volume.

7. The method for judging steel bar corrosion risk in reinforced concrete structures according to claim 2, characterized in that: Calculate the total weight of chloride ions inside reinforced concrete structures according to formula (1): （1）； In formula (1), is the total weight of chloride ions inside reinforced concrete structures, 、 、 、 、 are the weights of cement, mineral admixtures, sand, stone and admixtures respectively. 、 、 、 、 They are the percentage of internal chloride ion content of cement, mineral admixtures, sand, stone and admixtures respectively.

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